Printer Friendly

Screening the cucumber germplasm collection for fruit yield and quality. (Plant Genetic Resources).

CUCUMBER is thought to have originated in India or China (Harlan, 1975), with domestication occurring later throughout Europe. Cucumber is a member of the Cucurbitaceae family, which comprises 90 genera and 750 species (Sitterly, 1972). Cucumber is thought to be one of the oldest vegetable crops, being grown for at least five thousand years. Cucumber is a thermophilic and frost-susceptible crop, growing best at temperatures >20[degrees]C. The crop is grown throughout the world and is the fourth most important vegetable crop after tomato (Lycopersicon esculentum Mill.), cabbage (Brassica oleracea var. capitata L.), and onion (Allium cepa L.) (Tatlioglu, 1993).

Cucumber is grown as a number of different types and is used as either a fresh or processed vegetable. Some of the types of cucumber grown throughout the world are American pickling, European pickling, American slicing (fresh market), European greenhouse (parthenocarpic), oriental trellis, middle-eastern (Beit Alpha), and schalgurken. Cucumber types differ based on the type of use (fresh market or processed), fruit length, diameter, color, color uniformity, skin thickness, and skin surface protrusions. In the United States in 1998, 17 264 ha were planted to pickling cucumber with a total production of 615 310 Mg of fruit (USDA, 1998). The total area and production of slicing cucumber for 1997 was 9760 ha with a production of 202 514 Mg (USDA, 1998). Cucumber is the second most important vegetable crop in North Carolina, with a production area of [approximately equal to] 9717 ha (USDA, 1997). Nationally, North Carolina was ranked third in pickling cucumber production after Michigan and Florida, and fifth in slicing cucumber production after Georgia, Florida, Michigan, and California during 1997 (USDA, 1997).

Breeding for yield in cucumber has been one of the important objectives of many cucumber breeding programs since the 1900s (Wehner, 1989). Yield of pickling cucumber has been improved by breeding for disease resistance (Peterson, 1975), as well as through the use of improved cultural practices (Cargill et al., 1975). Increased yield of cucumber cultivars has been due also to the improvement of qualitative traits such as gynoecious sex expression, improved fruit color (improved percentage marketable fruit), and direct yield improvement (Wehner, 1989).

The average yield of pickling cucumber in the United States (USDA, 1959-1998) has increased by 100% across the last four decades due to improved cultural practices, and selection for yield and disease resistance. Most of the productivity increase was during the first two decades, with a plateau in the last two decades. Thus, there is a need to focus more on yield improvement. To identify new sources of high yield in the cucumber germplasm collection for use in breeding, we are using a three-stage process: First, all available plant introduction accessions, cultivars, and breeding lines (hereafter collectively referred to as cultigens) are tested for combining ability with a gynoecious tester; second, all available cultigens are tested for yield per se; and third, the best cultigens are evaluated using larger trials with multiple harvests, seasons, and years.

Measurement of the yield of a large and diverse set of cucumber cultigens is costly. Previous research has provided some guidelines for the design of efficient yield trials. Fruit number was found to be a more stable measure of productivity than fruit weight or value in a once-over harvest trial for cucumber (Ells and McSay, 1981). Fruit number was more highly heritable (0.17) than fruit weight (0.02) (Smith et al., 1978). Evaluation of yield in single-plant hills was poorly correlated with multiple-harvest yield in replicated field trials, indicating the necessity for testing in row plots (Wehner and Miller, 1984; Wehner, 1986). In addition, greenhouse evaluation for yield based on fruit number on single plants was not correlated (r = 0.09 to 0.15) with yield at two field locations (Nerson et al., 1987).

Once-over harvest trials having three replications were recommended for maximum efficiency to determine which cucumber lines should be tested further in multiple-harvest trials (Wehner and Miller, 1984; Wehner, 1986). A plot size of 1.2 x 1.5 m was found to be optimum for yield evaluation for once-over harvest of pickling cucumber cultigens harvested using paraquat (1,1'-dimethyl-4,4'-bipyridinium ion; Swallow and Wehner, 1986). In cucumber, small-plot, single-harvest trials were found to be more efficient than large-plot, multiple-harvest trials (Wehner, 1986, 1989). Wehner et al. (1984) recommended the use of paraquat to defoliate plots for efficient yield measurement in once-over harvest trials.

Swallow and Wehner (1989) calculated that maximum efficiency was achieved by allocating test plots of cucumber cultigens to different seasons and years rather than locations and replications. Another study showed that yield evaluation at the Clinton location was more efficient (information relative to cost) than three other North Carolina locations tested (Wehner, 1987).

Miller and Hughes (1969) reported that harvesting at 14 to 31% oversized fruit stage in a plot was found to be optimum for maximum value in once-over harvest for `Piccadilly' and `Southern Cross' gynoecious pickling hybrids in North Carolina. Oversize is >51-mm diameter for pickling and >60-mm diameter for slicing cucumber. Chen et al. (1975) used a computer simulation and reported that plots harvested at 10% oversized fruit stage gave an optimum yield for Piccadilly hybrid under North Carolina conditions. Colwell and O'Sullivan (1981) reported that the optimum harvest stage to maximize yield for `Femcap' and `Greenstar' gynoecious hybrids occurred when 5 to 15% of fruit in a plot were oversized. Studies using a diverse array of pickling and slicing cucumber cultigens revealed no effect on fruit yield and quality traits (with the exception of early yield of pickling type) between harvesting cucumber when fruit in a plot reached 10 or 50% oversized fruit stage (Sherry, 1999).

Cucumber plants produce one or more of three types of flowers: staminate, pistillate, and perfect. Exogenous application of ethylene is known to promote the production of pistillate flowers in monoecious cucumber lines, resulting in increased fruit yield (McMurray and Miller, 1968; Robinson et al., 1968; Miller et al., 1970; Rudich et al., 1972; Hogue and Heeney, 1974; Cantliffe and Phatak, 1975). Ethephon treatments significantly improved the total yield, percentage of culled fruit, and fruit quality traits evaluated in pickling cucumbers (Shetty, 1999). Shetty (1999) observed higher total yields with a single ethephon application and did not observe an additional benefit beyond a single application at the first-true-leaf stage.

Ethephon also was found to have an effect on vegetative and floral traits (days to first flower set, days to 50% flower set, days to first fruit set, days to 50% fruit set, and fruit quality in a group of cucumber cultigens which differed in their sex expression. This study also concluded that one application of ethephon was optimum. More ethephon applications usually increased the number of days to reach a particular growth stage (days to first flower set, days to 50% flower set, days to first fruit set, and days to 50% fruit set). However, ethephon did not have an effect on fruit yield and quality traits on a set of slicing cucumber cultigens (Shetty, 1999). Ethephon treatment of isogenic lines of cucumber differing in sex expression improved gynoecious rating, fruit number (total, early, and marketable), and fruit weight (total, early, and marketable) compared with the untreated control. Ethephon was effective in increasing pistillate flower number on monoecious inbreds, but had little effect on gynoecious inbreds.

The objective of this experiment was to evaluate all available cucumber cultigens in the USDA germplasm collection for fruit yield and quality under field conditions in North Carolina.

MATERIALS AND METHODS

All experiments were conducted at the Horticultural Crops Research Station, Clinton, NC, during the spring and summer seasons of 1997 and 1998. For this experiment, 817 cultigens were evaluated (810 plant introduction accessions and seven check cultivars and breeding lines). Plant introduction accessions were obtained from the USDA North Central Regional Plant Introduction Station at Ames, Iowa. The cultigens originated in 50 different countries, with the greatest number coming from Turkey, People's Republic of China, the former Yugoslavia, Iran, the former USSR, Japan, India, and Spain (Table 1).

Seeds were planted on raised, shaped beds in rows 1.5 m apart. The soil type in the study was a mixture of Norfolk (fine-loamy, kaolinitic, thermic Typic Kandiudults), Orangeburg (fine-loamy, kaolinitic, thermic Typic Kandiudults), and Rains (fine-loamy, siliceous, semiactive, thermic Typic Paleaquults), with some Goldsboro (fine-loamy, siliceous, subactive, thermic, Aquic Paleudults).

Plots were 1.2-m long and 1.5-m wide with 1.2-m alleys at each end. Plots were planted with 16 seeds and thinned to a uniform stand of 12 plants per plot. Recommended horticultural practices (Schultheis, 1990) were used for all experiments. Fertilizer was incorporated before planting at a rate of 90-39-74 kg [ha.sup.-1] (N-P-K), with an additional 34 kg [ha.sup.-1] N applied at the vine tip-over stage. Curbit [ethalfluralin N-ethyl-N-(2-methyl-2-propenyl) -2,6-dinitro-4-(trifluoromethyl)benzenamine] was applied for weed control. Irrigation was applied when needed for a total (irrigation plus rainfall) of 25 to 40 mm per week. `Sumter' pollenizer was planted in side rows and end plots to provide additional pollen and border competition for the test plots.

No disease problems were observed in the spring season of either year. Some foliar diseases were observed in the plots during the summer season, but symptoms were mild due to the routine spray program followed as part of recommended cultural practices (Schultheis, 1990). Each plot was harvested once-over when the plants had 15% oversized fruit. Although the usual index for yield evaluation for testing populations in our breeding program is 10%, we used a 15% index in this study to avoid penalizing low yielding or late-maturing cultigens.

Ethephon was applied at the first to second true leaf stage (approximately one month after planting). A backpack sprayer at 100 to 140 kPa (15 to 20 psi) was used to spray the ethephon on the leaves until run-off. Ethephon was prepared using Florel (3.9% ethephon, Southern Agricultural Insecticides, Inc., Palmetto, FL) (1) at the rate of 2.5 mL [L.sup.-1].

Data were collected as plot means, and consisted of number of total, early, and cull fruit per plot. Early fruit were the number of oversized fruit at harvest. The number of marketable fruit was calculated as total--cull. Percentage of culls was calculated as 100 x cull fruit number/total fruit number. Similar formulas were used to compute percentage of early (by weight and by number) fruit and percentage (by weight and by number) of marketable fruit. Fruit weight was recorded for all grades (early, marketable, cull, and total) during the spring season of 1997. In all other environments, only total fruit weight was recorded. In those environments, early, marketable, and cull fruit weights were estimated from early, marketable, and cull fruit number along with total fruit weight using regression relationships from the spring season (Shetty, 1999).

Fruit quality was rated, based on fruit color and shape, on a 1 to 9 scale (1-3 = poor overall with curved and tapered shape and nonuniform light green color; 4-6 = intermediate; 7-9 = excellent overall with straight, cylindrical, and blocky shape and uniform dark green color). Thus, the scale has three main levels, with three sublevels in each, resembling a +/- system (7 = excellent-, 8 = excellent, 9 = excellent +). Days to harvest and fruit quality rating were also recorded. All cultigens were grouped into one of four types: pickling, slicing, middle-eastern (Beit Alpha), and oriental trellis. Digital photographs of fruit of all cultigens used in the study were recorded to verify fruit type.

The experiment was a randomized complete block design with 817 cultigens, two seasons (spring, summer), two years (1997, 1998), and three replications. The two years and two seasons were considered to be four environments to simplify the statistical analysis. Data were analyzed using GLM procedures of SAS 6.12 (SAS Institute, Inc., Cary, NC). Yield was expressed as thousands of fruit [ha.sub.-1] for fruit number, and Mg [ha.sup.-1] for fruit weight to make comparisons with other studies easier. Plots with a stand count (plant number) of <50% were eliminated from the statistical analysis, and plots with stand count ranging from 50 to 75% of target stand (12 plants) were corrected using the formula:

corrected yield = 12 x (total yield/stand), according to the method of Cramer and Wehner (1998).

RESULTS AND DISCUSSION

Data collected in spring and summer seasons of 1997 and spring 1998 were excellent. However, poor stand establishment conditions occurred in summer 1998, and data were obtained for only 70% of the plots in one replication, and 30% in the other two replications. Thus, we used only the data from three environments (eliminating data for summer 1998).

The main effect of environment was not significant for any traits except percentage marketable fruit weight (Table 2). There were significant differences among the 817 cultigens for fruit yield and quality, and for days to harvest. The interaction of cultigen and environment was significant for all traits, except percentage of culls. However, the effect of cultigen was much larger than that of cultigen x environment for all the traits (Table 2). Therefore, fruit yield and quality traits are presented as averages across the three environments.

The complete dataset for yield of 817 cultigens was submitted to the Germplasm Resources Information Network (http://www.ars-grin.gov/) for those interested in particular cultigens. The cultigens evaluated were grouped into four distinct categories based on the fruit type data. There were 249 pickling, 116 slicing, 265 middle-eastern (Beit Alpha types), and 187 oriental trellis cucumber cultigens (Tables 3, 4, 5, and 6).

Because some cultigens produce a large number of fruit with a small fruit weight, and because breeders and growers are most interested in fruit weight, we presented the data for cultigens ranked by total fruit weight. The most interesting cultigens would be those with highest fruit weight and number within a particular fruit type. Also of interest are early and marketable fruit weight and number, percentage of culls, fruit quality rating, and days to harvest (Tables 3, 4, 5, and 6).

Pickling Cucumber

Forty-seven cultigens produced higher yields (total fruit number) than the highest yielding check Calypso. The cultigens with the highest fruit number were PI 215589, PI 344440, PI 356809, PI 370643, PI 249561, PI 209065, PI 288992, PI 179678, PI 531314, and PI 422191. PI 215589 produced 267 thousand fruit [ha.sup.-1], compared with Calypso, with 105 thousand fruit [ha.sup.-1]. PI 209065 (USA OH) and PI 531314 (Hungary) were the only two cultigens with both a higher fruit number and fruit weight than Calypso (Table 3).

Cultigens with the highest early fruit weight were PI 209065, PI 285610, PI 175111, PI 137848, PI 264666, PI 269481, PI 306180, PI 370019, PI 482463, PI 211728, and PI 163216. All yielded more than 20 Mg [ha.sup.-1]. Only 21 cultigens had higher early yield than the best check, Calypso. A total of 68 cultigens had a higher early yield percentage (by weight) than the best check cultivar, Sumter. PI accessions of pickling type that had the highest early yield percentage (by weight) were PI 211728, PI 512336, PI 175121, PI 500359, PI 344432, PI 370447, PI 163218, PI 163216, PI 212896, and PI 512607. Cultigens with higher early fruit weight and higher early yield percentage (by weight) than the best checks were PI 174160, PI 175111, PI 175121, PI 209065, PI 269481, PI 285610, PI 344432, and PI 370019.

Thirty PI accessions had higher early yields (by number), and 111 PI accessions had higher early yield percentage (by number) than the best check, Calypso. PI accessions with the highest early yield (by number) were PI 209065, PI 422191, PI 531314, PI 169397, PI 215589, PI 379278, and PI 269480. All were estimated to produce more than 66 thousand fruit [ha.sup.-1]. Cultigens with the highest early yield percentage (by number) were PI 500359, PI 222986, PI 370447, PI 175120, PI 175121, PI 217946, PI 512607, and PI 221440. All had >70% of yield in numbers as early yield. Cultigens with both high early fruit yield and high early yield (by number) compared with the checks were PI 169397, PI 209065, PI 212985, PI 263047, PI 263079, PI 269480, PI 269481, PI 326597, PI 330628, PI 370019, PI 379278, PI 390954, PI 422191, PI 458855, PI 458856, PI 504567, and PI 512620. PI 269481 was the only cultigen that had high early yield (number and weight) and had a high percentage of early yield (number and weight) (Table 3).

There were cultigens with marketable yields (by weight) higher than the best check, Calypso. Cultigens producing >5 Mg [ha.sup.-1] marketable fruit were PI 326598, PI 197087, PI 478367, PI 206043, PI 326596, PI 512597, PI 531312, PI 169397, PI 379278, PI 209065, PI 531309, PI 271753, and PI 531314. There were 88 cultigens with a higher marketable yield percentage (by weight) than the best check, Calypso. Cultigens with both high marketable weight and high marketable yield percentage (by weight) were PI 197087, PI 206043, PI 271753, PI 326596, PI 326598, PI 379278, PI 478367, PI 512597, PI 531309, and PI 531312 (Table 3).

There were 72 cultigens with higher marketable yield (by number) and 101 cultigens with higher marketable yield percentage (by number) than the best check, Calypso (33 thousand fruit [ha.sup.-1]). Cultigens with high marketable fruit number were PI 215589, PI 179678, PI 288992, PI 249561, PI 267087, PI 356809, PI 205995, PI 344440, PI 292012, PI 390953 (all >53 thousand fruit [ha.sup.-1]). Those with high marketable yield percentage (by number) were PI 179678, PI 215589, PI 200815, PI 164734, PI 532162, PI 288992, PI 135122, PI 267087, PI 264226, and PI 482463 (all >50%). Pickling cultigens ranked in the top 10% category for high marketable fruit number and high marketable yield percentage (by number) were PI 179678, PI 215589, PI 267087, and PI 288992 (Table 3).

A total of 100 pickling PI accessions had a lower culled fruit percentage (by weight) than the best check Calypso. Calypso had lower cull weight than the other pickling check, Sumter, for total cull fruit weight but had the same culled fruit percentage (by number). There were 114 cultigens with a lower percentage of culled fruit than Calypso. Cultigens which ranked in the top 10% for fewest number and weight of culls were PI 135122, PI 175121, PI 283902, PI 289698, PI 370447, PI 504570, PI 512634, PI 512637, PI 512640, and PI 532162 (Table 3). In general, the PI accessions evaluated had poor fruit quality ratings compared with the standard checks used in the study. Four pickling cultigens had similar or better ratings for fruit quality: PI 422180, PI 422182, PI 506461, and PI 435947 (Table 3).

There were 36 cultigens that required fewer days to harvest than Calypso. The best one (PI 343452) was 4 d earlier than Calypso. The latest one (PI 512336) required 28 d more than Calypso to harvest. The earliest cultigens were PI 205995, PI 271334, PI 164816, PI 531309, PI 342950, PI 257486, PI 351139, PI 164819, PI 264226, PI 267746, PI 137848, and PI 343452 (Table 3).

The cultigens with the highest total yield in terms of fruit weight among the pickling cucumber cultigens evaluated in the study were PI 209065, PI 326598, PI 137848, PI 285610, and PI 264666. There were 17 cultigens that produced higher total fruit weight than the check cultivar Calypso. In general, all 17 cultigens identified had higher or similar early and marketable fruit weight and number than Calypso. However, fruit quality ratings were lower for the 17 cultigens. In general, the number of days to harvest for the 17 cultigens also was higher than for Calypso. The lowest yielding cultigens in the study were PI 179921, PI 163222, PI 222986, PI 164465, and PI 481612, which also showed low fruit quality rating and high number of days to harvest (Table 3).

Slicing Cucumber

Nine cultigens had more fruit weight than the high yielding slicing check `Sprint 440'. Four cultigens, PI 234517, PI 118279, PI 304085, and PI 512614, also had higher total fruit number than the check. The nine cultigens were similar for early, marketable, and cull fruit weight. However, PI 118279 from Brazil had a high number of total, early, and marketable fruits with fruit weight similar to the other eight PI accessions identified, but had smaller size. The nine cultigens identified were similar for days to harvest with the exception of PI 304805 and PI 368560, which took 8 d longer. The fruit quality ratings for the nine cultigens were lower than the checks, Sprint 440 and `Dasher II'. Of the check cultivars, Sprint 440 and Dasher II had similar fruit yield, quality rating, and days to harvest. Sprint 440 and Dasher II had the highest yields in terms of total fruit weight, followed by the remaining two slicing checks used in the study `Poinsett 76' and `Marketmore 76' (Table 4).

There were 16 cultigens with a higher number of total fruit than the check cultivar Sprint 440, three cultigens (PI 118279, PI 304805, PI 561145) with a higher total fruit number than Poinsett 76, and five cultigens (PI 118279, PI 304805, PI 561145, PI 234517, PI 512614) with a higher total fruit number than Dasher II. Cultigens with both high fruit weight and number were PI 118279 (Brazil), PI 234517 (USA SC), PI 304805 (USA NY), and PI 512614 (Spain). The four cultigens produced higher total, early, and marketable fruit weight and number than the check cultivars of the same type. Their percentage of cull fruit weight was higher than Sprint 440, but their percentage of cull fruit number was lower. Fruit quality ratings were lower than the check, and PI 234517 had the best fruit quality rating of the four. The four PI accessions had similar days to harvest. However, PI 304805 took 8 d longer than the check (Table 4).

Seven cultigens produced higher early yields (by weight) (PI 234517, PI 118279, PI 368560, PI 173893, PI 165499, PI 512614, and PI 512615) and by fruit number (PI 118279, PI 234517, PI 173893, PI 288996, PI 390259, PI 512614, and PI 561148) than the best check, Dasher II. Forty PI accessions had a higher early yield percentage (by weight) than the best check, Dasher II. Cultigens with the highest early yield percentage (by weight) were PI 338234, PI 368551, PI 368559, PI 173893, PI 368560, PI 379283, PI 250147, PI 357860, PI 561144, PI 267745, and PI 391570. Cultigens with both high early yield and high early yield percentage (by weight) were PI 173893 and PI 288996. Thirteen cultigens had a higher early yield percentage (by number) compared with the highest yielding check Sprint 440. PI 118279 was the only cultigen with a high early fruit yield and high early yield percentage (by weight) compared with the high check (Table 4).

Eighteen cultigens produced higher marketable yields (by weight) while 11 cultigens had a higher marketable yield percentage (by weight) compared with the best performing slicing cucumber check, Poinsett 76. Cultigens with both high marketable yield and higher marketable yield percentage (by weight) compared with the checks were PI 304805, PI 369717, PI 390244, PI 504815, and PI 512598. Five cultigens (PI 504816, PI 401732, PI 304805, PI 432864, and PI 118279) had high marketable yield (by number) compared with the best check, Sprint 440. Eleven cultigens (PI 481616, PI 504816, PI 432864, PI 390244, PI 401732, PI 525075, PI 561146, PI 390260, PI 512633, PI 344347, and PI 512639) had a higher marketable yield percentage (by number) compared with the high check, Poinsett 76. PI 401732, PI 432864, and PI 504816 had both high marketable yield and high marketable yield percentage compared with the best checks (Table 4).

Of the four slicing cultigens used as checks in this study, Marketmore 76 had the lowest culled fruit percentage (by weight) followed by Sprint 440, Poinsett 76, and Dasher II. Two cultigens (PI 338234 and PI 481616) had a lower culled fruit percentage (by weight) than Marketmore 76. The check cultigens with the lowest culled fruit percentage (by number) were Marketmore 76, Sprint 440, Dasher II, and Poinsett 76. Eight cultigens (PI 390238, PI 481614, PI 250147, PI 379280, PI 368560, PI 512625, PI 338234, and PI 481616) had a lower culled fruit percentage (by number) than Marketmore 76 (Table 4).

The four slicing cucumber checks had the highest fruit quality ratings of the four cucumber types. PI 306785 from Canada was the only PI accession that had a similar fruit quality rating compared with the checks. Slicing cultigens that ranked just below the checks for fruit quality were PI 561148, PI 561145, PI 512633, PI 422192, PI 451976, and PI 406473 (Table 4). PI 176519 was the only slicing cultigen that was harvested as early (55 d) as Marketmore 76, the earliest slicing check. The latest cultigen was PI 481616, which took 81 d to harvest (Table 4).

Middle-Eastern (Beit Alpha) Cucumber

WI 2757 was included as a check representing late-maturing, low-yielding, gynoecious inbreds. A total of 229 middle-eastern (Beit Alpha) cultigens produced higher total fruit weight than the check WI 2757, while 32 cultigens produced higher fruit weight than the standard pickling cucumber check, Calypso. The cultigens with the highest total fruit weight were PI 167050, PI 163213, PI 532519, PI 211978, PI 357864, PI 183231, and PI 211117. Nine cultigens had twice the total fruit weight of WI 2757. There were 97 cultigens with a higher fruit number than WI 2757, while 25 cultigens produced higher fruit number than Calypso (Table 5). Cultigens with highest total fruit number were PI 175693, PI 532519, PI 292010, PI 176956, PI 171601, PI 181910, PI 293923, PI 175690, PI 535881, and PI 525152. The cultigens which were ranked in the top 10% for both total fruit number and total fruit weight were PI 137856, PI 169391, PI 171601, PI 175693, PI 181755, PI 292010, PI 525152, PI 532519, PI 534540, PI 534543, and PI 535881 (Table 5).

There were 164 cultigens with higher early yield and higher early yield percentage (by weight) compared with the check WI 2757, while 32 cultigens were higher in early yield compared with the standard pickling check, Calypso. Cultigens with the highest early yield and highest early yield percentage (by weight) were PI 357849, PI 512628, PI 379287, PI 169384, PI 344433, PI 211589, PI 182188, PI 172852, PI 357859, and PI 357834. Of the cultigens with high early yield, 147 had higher early yield (by number) than WI 2757, while 225 had a higher early yield percentage (by number) than WI 2757. PI 172852 was the only cultigen common to both groups (Table 5).

A total of 164 middle-eastern PI accessions had a higher marketable yield (by weight) than the best check. Cultigens in the top 10% category that had >6 Mg [ha.sup.-1] marketable yield were PI 171601, PI 176924, PI 534543, PI 163213, PI 211117, PI 176951, PI 175693, PI 169380, and PI 344437. There were 72 cultigens with a higher marketable yield percentage (by weight) than the best check. Cultigens with the best performance for marketable yield percentage (by number) were PI 172844, PI 176924, PI 174173, PI 357843, PI 176522, and 176951. PI 171601, PI 176924, PI 176951, and PI 357843 were in the top 10% group for both high marketable weight and high marketable yield percentage (by weight) (Table 5).

There were 87 cultigens with a higher marketable yield (by number) than the check, WI 2757, while 76 cultigens had a high marketable yield percentage (by number). Cultigens in the top category for marketable yield, which also produced >50 000 marketable fruit [ha.sup.-1], were PI 534543, PI 293923, PI 181910, PI 292010, and PI 171601. Cultigens in the top 10% for marketable yield percentage (by number) were PI 171604, PI 357843, PI 176924, PI 169385, PI 169380, PI 357854, and PI 169383 (Table 5).

There were 214 and 89 cultigens, respectively, having a lower percentage of culls (by weight and number) than the check, WI 2757. The PI accessions that were in the top 10% for lowest percentage of culled fruit (by weight and number) were PI 169385, PI 172852, PI 176924, PI 222243, PI 357843, PI 357849, and PI 512628 (Table 5). There were 30 PI accessions with fruit quality ratings better than the middle-eastern (Beit Alpha) check, WI 2757. Some of the PI accessions with high fruit quality ratings were PI 535881, PI 532519, PI 525153, PI 534539, PI 534541, PI 525154, PI 422197, PI 292010, PI 525155, and PI 525165 (Table 5).

There were 222 PI accessions with earlier yield than WI 2757, which took 64 d to harvest. The earliest middle-eastern (Beit Alpha) cultigen took 52 d to harvest. Some of the other cultigens that took fewer days to harvest were PI 226509, PI 175694, PI 174177, PI 344439, and PI 211975, which all took between 52 and 54 d to harvest. PI 357853 took the longest to produce fruit (77 d) (Table 5).

Trellis Cucumber

Trellis type cultigens with the highest total fruit weight were PI 264228, PI 478366, PI 390262, PI 532524, PI 390267, and PI 532520 (Table 6). Cultigens with high total fruit number were PI 432849, PI 264228, PI 275411, PI 532520, PI 390262, PI 489754, PI 518854, PI 478364, PI 478366, and PI 532523. Eight cultigens (PI 263085, PI 264228, PI 275411, PI 390262, PI 390267, PI 478366, PI 511820, and PI 532520) were in both lists of the top 10% for fruit weight and number. Cultigens of the trellis type that had high early yield (by weight) and high early yield percentage (by weight) were PI 357837, PI 418963, PI 422167, and PI 432889. Cultigens with high early yield and high early yield percentage (by number) were PI 192940, PI 193497, PI 212233, PI 264228, PI 275412, PI 432851, and PI 432889 (Table 6).

Cultigens with the highest yields for marketable fruit weight were PI 478366, PI 264228, PI 532524, PI 518851, PI 390262, PI 390267, PI 422167, PI 275411, PI 419182, and PI 419010 (all greater than 20 Mg [ha.sup.-1]). PI accessions of the trellis type with high marketable yield percentage (by weight) were PI 192940, PI 357841, PI 390263, PI 368554, PI 267742, PI 470254, PI 357837, PI 418963, and PI 193497. PI accessions ranked in the top 10% for marketable fruit weight and marketable yield percentage (by weight) were PI 264228, PI 357837, PI 422167, PI 432889, and PI 518851. PI accessions with high marketable fruit number were PI 264228, PI 275411, PI 511820, PI 518851, PI 390267, and PI 478366 (all greater than 40,000 fruit [ha.sup.-1]). PI 368554 from Yugoslavia had 100% marketable fruit in all replications in all environments of the study. Cultigens that ranked in the top category for both marketable fruit number and marketable yield percentage (by number) were PI 192940, PI 193497, PI 212233, PI 264228, PI 275412, PI 432851, and PI 432889. PI 264228 and PI 432889 were in the top group for marketable fruit (number and weight) and percentage of marketable fruit (number and weight) (Table 6).

PI accessions with the lowest percentage of culls in the trellis type (by weight and number) were PI 192940, PI 212233, PI 255938, PI 357830, PI 368554, and PI 368555 (Table 6). Cultigens with the highest fruit quality ratings among the trellis type cultigens were PI 422184, PI 255935, PI 285608, PI 422167, PI 372893, PI 356833, PI 511821, PI 255933, PI 390262, PI 508460, and PI 275410 (Table 6). The earliest of the trellis cultigens were PI 263081, PI 419183, PI 518854, PI 432849, PI 267742, and PI 275411 (Table 6).

CONCLUSIONS

The USDA cucumber germplasm collection was screened for fruit yield, earliness, and quality. Digital photographs of the germplasm collection for fruits also have been recorded to verify fruit type of each accession. Several high yielding cultigens were identified in each of the four cucumber types. The cultigens outyielded the check cultivars in the study. The high yielding cultigens evaluated in the study should be tested in multiple-harvest trials to evaluate their performance further. High yielding cultigens identified could be used to develop breeding populations of each of the four cucumber types. These populations could be improved using recurrent selection and directly in cultivar development. Finally, high-yielding cultigens with poor qualitative traits (some aspects of fruit quality) could be improved using backcross breeding.
Table 1. Seed source for 817 cucumber cultigens tested for fruit
yield in North Carolina.

                               No. of
Seed source                   cultigens

Afghanistan                      15
Australia                         1
Bhutan                            3
Brazil                            2
Burma                             2
Canada                            3
Former Czechoslovakia            29
Denmark                           3
Egypt                            19
Ethiopia                          2
France                            6
Georgia                           1
Germany                           4
Great Britain                     2
Greece                            1
Hong Kong                         2
Hungary                          21
India                            45
Puerto Rico                       3
Spain                            43
Sweden                            4
Syria                            11
Taiwan                           10
Thailand                          2
Turkey                          149
Ukraine                           3
USA                              19
Indonesia                         1
Iran                             59
Iraq                              1
Israel                            6
Italy                             3
Japan                            47
Kenya                             2
Korea                            17
Lebanon                           4
Malaysia                          2
Mauritius                         1
New Zealand                       2
The Netherlands                  15
Oman                              3
Pakistan                          7
The Philippines                   3
Poland                           13
P.R. China                      111
USSR                             49
Uzbekistan                        4
Former Yugoslavia                62
Zambia                            1
Zimbabwe                          2

Cultivars (checks)                7

Table 2. F ratios for mean squares of yield, quality, and harvest
traits for the cucumber cultigens evaluated during 1997-1998 at
  Clinton, NC.

                                                    Total

Source of variation                df        Wt.             No.

                                         Mg [ha.sup.-1]   1000 fruit
                                                          [ha.sup.-1]

Environment                          2           0.8         1.28
Rep (Environment)                    6         147         152
Cultigen                           816           2.3 **      5.5 **
Cultigen x Environment            1521           1.3 **      1.3 **

                                    Early

Source of variation          Wt.              No.

                        Mg [ha.sup.-1]     1000 fruit
                                          [ha.sup.-1]

Environment                   0.8             1.6
Rep (Environment)           132              45.6
Cultigen                      1.9 **          2.9 **
Cultigen x Environment        1.3 **          1.2 **

                                  Marketable

Source of variation          Wt.              No.

                        Mg [ha.sup.-1]     1000 fruit
                                          [ha.sup.-l]

Environment                   2.1             1.5
Rep (Environment)            52             117
Cultigen                      1.7 **          3.5 **
Cultigen x Environment        1.1 **          1.3 **

                                    % cull

Source of variation          Wt.              No.

                        Mg [ha.sup.-1]     1000 fruit
                                          [ha.sup.-l]

Environment                   3.5             0.2
Rep (Environment)            76              42
Cultigen                      3.0 **          2.1 **
Cultigen x Environment        1.0             1.2 **

                               Fruit           Harvest
Source of variation           quality           days
                             ([dagger])    ([double dagger])

Environment                      2.3            2.2
Rep (Environment)             1115            140
Cultigen                         8.6 **         8.7 **
Cultigen x Environment           1.3 **         1.4 **

** Significant at the 0.01 probability level.

([dagger]) Fruit quality ratings were based on fruit shape and color
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent).

([double dagger]) Harvest days is the number of days from planting to
harvest.

Table 3. Yield, quality, and harvest traits for the three checks, 20
highest, and 10 lowest yielding (out of 249 total) pickling cucumber
cultigens evaluated during 1997-1998 at Clinton, NC.

                                          Total

Cultigen      Seed source          Wt.             No.

                                   Mg          1000 fruit
                             [ha.sup.-1]       [ha.sup.-1]

`Calypso'   Check-USA               26             105
`Sumter'    Check-USA               19              98
WI 2757     Check-USA               15              79

                                    Highest yielding 20

PI 209065   USA OH                  33             146
PI 326598   Hungary                 30              92
PI 137848   Iran                    30             123
PI 285610   Poland                  29              80
PI 264666   Germany                 29              84
PI 175111   lndia                   28              73
PI 169397   Turkey                  28             116
PI 306180   Poland                  28              85
PI 379278   Yugoslavia              27             104
PI 426169   The Philippines         27              89
PI 370019   India                   26              99
PI 531314   Hungary                 26             135
PI 269481   Pakistan                26              99
PI 326597   Hungary                 26             102
PI 174160   Turkey                  26              73
PI 264665   Germany                 25              75
PI 206043   USA PR                  25             105
PI 379285   Yugoslavia              25              81
PI 163216   India                   25              50
PI 482463   Zimbabwe                25              21

                                    Lowest yielding 10

PI 267087   USSR                    9              120
PI 179678   India                   9              137
PI 512336   Hong Kong               9               14
PI 357857   Yugoslavia              9                8
PI 512634   Spain                   9               23
PI 179921   India                   8               27
PI 163222   India                   8               26
PI 222986   Iran                    7               18
PI 164465   India                   4               15
PI 481612   Bhutan                  3               12

Mean                                18              82
Range                               30             260
LSD, 5%                             8               30
CV, %                               49              40

                         Early

Cultigen          Wt.              No.

                  Mg            1000 fruit
              [ha.sup.-1]      [ha.sup.-1]

`Calypso'         18                55
`Sumter'          15                47
WI 2757           10                33

                   Highest yielding 20

PI 209065         24                92
PI 326598         16                52
PI 137848         22                65
PI 285610         23                48
PI 264666         21                45
PI 175111         22                40
PI 169397         20                69
PI 306180         21                44
PI 379278         20                67
PI 426169         20                50
PI 370019         20                65
PI 531314         18                72
PI 269481         21                66
PI 326597         19                58
PI 174160         20                39
PI 264665         19                50
PI 206043         17                39
PI 379285         19                40
PI 163216         20                31
PI 482463         20                11

                   Lowest yielding 10

PI 267087          5                44
PI 179678          5                42
PI 512336          9                12
PI 357857          9                 3
PI 512634          7                11
PI 179921          7                13
PI 163222          6                15
PI 222986          5                11
PI 164465          3                 6
PI 481612          3                 5

Mean              13                40
Range             21                89
LSD, 5%            6                21
CV, %             54                56

                       Marketable

Cultigen          Wt.              No.

                  Mg            1000 fruit
              [ha.sup.-1]      [ha.sup.-1]

`Calypso'          5                33
`Sumter'           3                28
WI 2757            3                27

                   Highest yielding 20

PI 209065          5                19
PI 326598          1                31
PI 137848          5                36
PI 285610          5                21
PI 264666          5                18
PI 175111          4                19
PI 169397          6                27
PI 306180          5                24
PI 379278          6                28
PI 426169          5                18
PI 370019          4                16
PI 531314          5                35
PI 269481          3                20
PI 326597          4                25
PI 174160          5                22
PI 264665          4                 9
PI 206043          7                50
PI 379285          4                17
PI 163216          3                 8
PI 482463          4                10

                    Lowest yielding 10

PI 267087          3                63
PI 179678          3                96
PI 512336          0                 1
PI 357857          1                 3
PI 512634          3                10
PI 179921          1                11
PI 163222          1                 7
PI 222986          1                 3
PI 164465          1                 2
PI 481612          0                 6

Mean               3                27
Range             12               183
LSD, 5%            2                19
CV, %             77                79

                         % cull

Cultigen          Wt.              No.

                  Mg            1000 fruit
              [ha.sup.-1]      [ha.sup.-1]

`Calypso'          7                16
`Sumter'           7                21
WI 2757            7                24

                   Highest yielding 20

PI 209065          6                20
PI 326598          5                10
PI 137848          7                20
PI 285610          4                17
PI 264666          9                25
PI 175111          5                19
PI 169397          7                16
PI 306180          7                19
PI 379278          7                11
PI 426169          8                22
PI 370019          8                19
PI 531314         13                22
PI 269481          6                15
PI 326597         10                18
PI 174160          4                18
PI 264665          8                22
PI 206043          5                14
PI 379285          9                28
PI 163216          4                19
PI 482463          3                0

                    Lowest yielding 10

PI 267087          3                12
PI 179678          5                 0
PI 512336          5                13
PI 357857         35                38
PI 512634          3                 4
PI 179921          6                21
PI 163222          8                14
PI 222986         10                 8
PI 164465          7                48
PI 481612          4                17

Mean               8                18
Range             33                48
LSD, 5%            6                14
CV, %             86                83

                 Fruit          Harvest
Cultigen        quality          days
              ([dagger])    ([double dagger])

`Calypso'         7.4               55
`Sumter'          7.2               58
WI 2757           6.8               64

                   Highest yielding 20

PI 209065         5.7               57
PI 326598         6.8               64
PI 137848         5.0               52
PI 285610         5.9               61
PI 264666         5.9               58
PI 175111         3.8               55
PI 169397         5.4               55
PI 306180         5.7               61
PI 379278         5.4               59
PI 426169         4.7               56
PI 370019         3.1               56
PI 531314         5.3               58
PI 269481         2.9               58
PI 326597         7.1               63
PI 174160         6.0               60
PI 264665         6.0               59
PI 206043         6.9               63
PI 379285         5.1               60
PI 163216         5.0               78
PI 482463         6.0               73

                   Lowest yielding 10

PI 267087         2.6               55
PI 179678         2.0               80
PI 512336         4.8               83
PI 357857         5.7               73
PI 512634         6.0               76
PI 179921         4.6               75
PI 163222         4.1               72
PI 222986         5.5               64
PI 164465         3.8               78
PI 481612         3.2               80

Mean              4.8               60
Range             5.9               31
LSD, 5%           0.9                4
CV, %            20                  7

([dagger]) Fruit quality ratings were based on fruit shape and color
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent).

([double dagger]) Harvest days is the number of days from planting to
harvest.

Table 4. Yield, quality, and harvest traits for the four checks,
20 highest, and 10 lowest yielding (out of 116 total) slicing cucumber
cultigens evaluated during 1997-1998 at Clinton, NC.

                                             Total

Cultigen        Seed source            Wt.             No.

                                       Mg          1000 fruit
                                   [ha.sup.-1]     [ha.sup.-1]

`Sprint 440'    Check-USA               28              88
`Dasher II'     Check-USA               27             101
`Poinset76'     Check-USA               25             106
`Marketmore76'  Check-USA               13              39

                                       Highest yielding 20

PI 234517       USA SC                  35             105
PI 118279       Brazil                  35             148
Pi 304805       USA NY                  32             114
PI 368560       Yugoslavia              32              55
PI 173893       India                   31              80
PI 512614       Spain                   30             102
PI 512615       Spain                   28              69
PI 165499       India                   28              64
PI 414159       USA HW                  27              87
PI 288238       Egypt                   26              79
PI 288996       Hungary                 26              82
PI 512623       Spain                   26              95
PI 406473       The Netherlands         26              94
PI 561145       USA NY                  26             109
PI 401733       Puerto Rico             25              87
PI 357860       Yugoslavia              25              54
Pl 283901       Czech Rep.              25              71
PI 561148       USA NY                  25              95
PI 390246       Japan                   24              65
PI 422177       Czech Rep.              24              85

                                        Lowest yielding 10

PI 357856       Yugoslavia              9               27
PI 267743       PR China                9               26
PI 422192       Czech Rep.              8               19
PI 512619       Spain                   8               23
Pl 390238       Japan                   8               31
PI 321009       Taiwan                  7               18
PI 512625       Spain                   6               23
PI 379280       Yugoslavia              6               15
PI 368559       Yugoslavia              6               16
PI 481616       Bhutan                  2                3

Mean                                    19              64
Range                                   33             145
LSD, 5%                                 10              27
CV, %                                   55              45

                             Early

Cultigen              Wt.              No.

                      Mg            1000 fruit
                  [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'          22                42
`Dasher II'           21                43
`Poinset76'           19                41
`Marketmore76'         9                25

                       Highest yielding 20

PI 234517             28                55
PI 118279             27                80
Pi 304805             21                43
PI 368560             27                37
PI 173893             26                55
PI 512614             23                48
PI 512615             23                41
PI 165499             24                30
PI 414159             20                36
PI 288238             21                37
PI 288996             20                50
PI 512623             20                39
PI 406473             20                40
PI 561145             17                41
PI 401733             18                35
PI 357860             21                36
Pl 283901             19                34
PI 561148             18                47
PI 390246             18                29
PI 422177             18                43

                        Lowest yielding 10

PI 357856              7                12
PI 267743              6                16
PI 422192              8                 9
PI 512619              6                 9
Pl 390238              6                15
PI 321009              5                 9
PI 512625              6                 8
PI 379280              6                 8
PI 368559              5                12
PI 481616              0                 0

Mean                  14                28
Range                 28                80
LSD, 5%                8                18
CV, %                 62                70

                           Marketable

Cultigen              Wt.              No.

                      Mg            1000 fruit
                  [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'           4                35
`Dasher II'            3                37
`Poinset76'            4                44
`Marketmore76'         3                14

                       Highest yielding 20

PI 234517              5                33
PI 118279              5                45
Pi 304805              9                46
PI 368560              3                13
PI 173893              2                 8
PI 512614              5                40
PI 512615              3                19
PI 165499              2                18
PI 414159              4                36
PI 288238              2                14
PI 288996              4                18
PI 512623              3                30
PI 406473              3                25
PI 561145              5                39
PI 401733              5                31
PI 357860              2                 9
Pl 283901              3                11
PI 561148              6                34
PI 390246              4                20
PI 422177              4                25

                       Lowest yielding 10

PI 357856              1                 8
PI 267743              2                 5
PI 422192              2                 4
PI 512619              1                 8
Pl 390238              1                11
PI 321009              1                 7
PI 512625              2                11
PI 379280              2                 5
PI 368559              0                 3
PI 481616              2                 3

Mean                   3                22
Range                  9                53
LSD, 5%                2                15
CV, %                 92                72

                             % cull

Cultigen              Wt.              No.

                      Mg            1000 fruit
                  [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'           6                14
`Dasher II'            6                20
`Poinset76'            6                20
`Marketmore76'         4                 0

                       Highest yielding 20

PI 234517              5                16
PI 118279              7                15
Pi 304805              6                23
PI 368560              3                 9
PI 173893              7                20
PI 512614              5                20
PI 512615              6                 9
PI 165499              8                25
PI 414159              9                18
PI 288238             13                34
PI 288996              9                16
PI 512623              9                27
PI 406473             10                29
PI 561145             10                27
PI 401733              9                23
PI 357860              4                15
Pl 283901             19                37
PI 561148              4                16
PI 390246              8                25
PI 422177              9                21

                        Lowest yielding 10

PI 357856              9                19
PI 267743              7                14
PI 422192              4                29
PI 512619              6                23
Pl 390238              4                11
PI 321009              6                17
PI 512625              3                21
PI 379280              4                18
PI 368559              5                 5
PI 481616              0                 0

Mean                   7                21
Range                 33                47
LSD, 5%                6                15
CV, %                 90                77

                     Fruit           Harvest
Cultigen            quality            days
                  ([dagger])     ([double dagger])

`Sprint 440'          7.9               61
`Dasher II'           7.8               61
`Poinset76'           7.6               64
`Marketmore76'        7.7               55

                       Highest yielding 20

PI 234517             6.9               63
PI 118279             5.3               57
Pi 304805             6.5               69
PI 368560             4.9               69
PI 173893             3.9               59
PI 512614             5.6               59
PI 512615             5.2               62
PI 165499             4.3               59
PI 414159             6.9               63
PI 288238             5.9               62
PI 288996             4.7               60
PI 512623             5.6               60
PI 406473             7.0               63
PI 561145             7.4               65
PI 401733             5.4               62
PI 357860             5.0               66
Pl 283901             4.6               61
PI 561148             7.4               68
PI 390246             6.0               70
PI 422177             6.4               63

                       Lowest yielding 10

PI 357856             5.8               64
PI 267743             5.3               66
PI 422192             7.3               71
PI 512619             5.4               68
Pl 390238             5.6               72
PI 321009             5.3               71
PI 512625             5.0               69
PI 379280             4.8               69
PI 368559             4.4               70
PI 481616             3.0               81

Mean                  5.5               64
Range                 4.9               26
LSD, 5%               0.9                4
CV, %                 17                 8

([dagger]) Fruit quality ratings were based on fruit shape and color
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent).

([double dagger]) Harvest days is the number of days from planting to
harvest.

Table 5. Yield, quality, and harvest traits for the three checks, 20
highest, and 10 lowest yielding (out of 265 total) middle-eastern
(Beit-alpha) cucumber cultigens evaluated during 1997-1998 at
Clinton, NC.

                                       Total

Cultigen   Seed source         Wt.              No.

                               Mg           1000 fruit
                           [ha.sup.-1]      [ha.sup.-1]

`Calypso'  Check-USA            26              105
`Sumter'   Check-USA            19               98
WI 2757    Check-USA            15               79

                                Highest yielding 20

PI 167050  Turkey               34               69
PI 163213  India                33               78
PI 532519  USSR                 33              131
PI 211978  Iran                 33               66
PI 357864  Yugoslavia           31               85
PI 183231  Egypt                30               99
PI 211117  Israel               30               97
PI 292010  Israel               30              127
PI 172852  Turkey               30               87
PI 169401  Turkey               29               86
PI 181755  Lebanon              29              111
P! 169385  Turkey               29               88
PI 167079  Turkey               28              105
PI 534543  Syria                28              155
PI 169388  Turkey               28               55
PI 218036  Iran                 28               72
Pl 535881  Poland               28              115
PI 137856  Iran                 28              111
PI 211988  Iran                 28               88
PI 204569  Turkey               28               92
PI 344437  Iran                 28               78

                                 Lowest yielding 10

PI 248778  Iran                 12               56
PI 172839  Turkey               11               38
PI 368556  Yugoslavia           11               32
PI 357867  Yugoslavia           11               22
PI 344433  Iran                 11               25
PI 357853  Yugoslavia           10               10
PI 211980  Iran                 9                42
PI 171604  Turkey               9                29
PI 379287  Yugoslavia           6                17
PI 357849  Yugoslavia           6                13

Mean                            20               73
Range                           28              145
LSD, 5%                         8                25
CV, %                           46               37

                     Early

Cultigen       Wt.             No.

               Mg           1000 fruit
           [ha.sup.-1]     [ha.sup.-1]

`Calypso'      18               55
`Sumter'       15               47
WI 2757        10               33

               Highest yielding 20

PI 167050      26               36
PI 163213      24               40
PI 532519      23               40
PI 211978      26               45
PI 357864      22               32
PI 183231      19               53
PI 211117      20               44
PI 292010      20               49
PI 172852      24               58
PI 169401      22               42
PI 181755      21               52
P! 169385      20               38
PI 167079      21               61
PI 534543      17               56
PI 169388      22               37
PI 218036      22               49
Pl 535881      20               49
PI 137856      19               57
PI 211988      19               49
PI 204569      19               49
PI 344437      18               38

                Lowest yielding 10

PI 248778       8               27
PI 172839       8               15
PI 368556       8               15
PI 357867       8               14
PI 344433       9               17
PI 357853      10                9
PI 211980       6               23
PI 171604       6               10
PI 379287       5                7
PI 357849       5               11

Mean           14               35
Range          21               62
LSD, 5%         6               17
CV, %          51               52

                  Marketable

Cultigen       Wt.             No.

               Mg           1000 fruit
           [ha.sup.-1]     [ha.sup.-1]

`Calypso'       5               33
`Sumter'        3               28
WI 2757         3               27

                Highest yielding 20

PI 167050       5               18
PI 163213       8               35
PI 532519       5               50
PI 211978       5               13
PI 357864       5               34
PI 183231       4               20
PI 211117       7               39
PI 292010       6               55
PI 172852       4               26
PI 169401       4               25
PI 181755       4               42
P! 169385       6               45
PI 167079       4               29
PI 534543       8               68
PI 169388       3               11
PI 218036       4               12
Pl 535881       5               37
PI 137856       5               23
PI 211988       4               18
PI 204569       5               25
PI 344437       6               21

                Lowest yielding 10

PI 248778       2               21
PI 172839       2               15
PI 368556       2                8
PI 357867       2                6
PI 344433       1                6
PI 357853       2                0
PI 211980       2               12
PI 171604       2               17
PI 379287       0                6
PI 357849       1                2

Mean            4               24
Range           9               68
LSD, 5%         2               16
CV, %          75               74

                     % cull

Cultigen       Wt.             No.

               Mg           1000 fruit
           [ha.sup.-1]     [ha.sup.-1]

`Calypso'       7               16
`Sumter'        7               21
WI 2757         7               24

                Highest yielding 20

PI 167050       6               18
PI 163213       4                6
PI 532519       8               30
PI 211978       5               14
PI 357864       9               23
PI 183231      13               25
PI 211117       7               13
PI 292010       8               21
PI 172852       3                3
PI 169401       6               19
PI 181755      10               19
P! 169385       4                6
PI 167079       7               15
PI 534543      13               22
PI 169388       5               10
PI 218036       7               15
Pl 535881       7               24
PI 137856      13               25
PI 211988      12               26
PI 204569       7               20
PI 344437      10               25

                Lowest yielding 10

PI 248778      10               12
PI 172839       8               21
PI 368556       7               30
PI 357867       6               15
PI 344433       5               11
PI 357853       7               50
PI 211980      13               19
PI 171604       5                5
PI 379287       6               22
PI 357849       2                0

Mean            8               19
Range          18               50
LSD, 5%         6               13
CV, %          73               77

              Fruit          Harvest
Cultigen     quality           days
           ([dagger])   ([double dagger])

`Calypso'      7.4              55
`Sumter'       7.2              58
WI 2757        6.8              64

               Highest yielding 20

PI 167050      6.3              64
PI 163213      5.5              65
PI 532519      7.7              59
PI 211978      6.0              59
PI 357864      5.7              62
PI 183231      6.2              61
PI 211117      7.0              65
PI 292010      7.3              62
PI 172852      6.0              64
PI 169401      7.0              63
PI 181755      6.3              57
P! 169385      6.3              54
PI 167079      6.2              60
PI 534543      6.2              56
PI 169388      5.8              62
PI 218036      6.0              61
Pl 535881      7.9              57
PI 137856      4.8              55
PI 211988      5.8              59
PI 204569      5.5              57
PI 344437      5.9              58

                Lowest yielding 10

PI 248778      5.3              57
PI 172839      6.2              66
PI 368556      5.1              67
PI 357867      6.0              73
PI 344433      5.6              70
PI 357853      3.3              77
PI 211980      5.2              59
PI 171604      5.0              72
PI 379287      4.7              75
PI 357849      5.5              72

Mean           5.9              60
Range          4.6              24
LSD, 5%        0.9               3
CV, %          17                6

([dagger]) Fruit quality ratings were based on fruit shape and color
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent).

([double dagger]) Harvest days is the number of days from planting to
harvest.

Table 6. Yield, quality, and harvest traits for the four checks, 20
highest, and 10 lowest yielding (out of 187 total) trellis cucumber
cultigens evaluated during 1997-1997 at Clinton, NC.

                                            Total

   Cultigen      Seed source          Wt.           No.

                                      Mg        1000 fruit
                                  [ha.sup.-1]   [ha.sup.-1]

`Sprint 440'   Check-USA              28             88
`Dasher II'    Check-USA              27            101
`Ponsett75'    Check-USA              25            106
`Marketmore76' Cbeck-USA              13             39

                                     Highest yielding 20

PI 264228      France                 40            127
PI 478366      PR China               40             99
PI 390262      Japan                  36            105
PI 532524      Japan                  34             85
PI 390267      Japan                  34             95
PI 532520      USSR                   33            115
PI 275411      The Netherlands        33            116
PI 419010      PR China               33             80
PI 518851      PR China               32             89
PI 511820      Taiwan                 32             93
PI 422167      Czech Rep.             32             84
PI 432884      PR China               31             89
PI 419009      PR China               31             74
P! 418964      PR China               31             72
PI 263085      PR China               31             92
PI 432887      PR China               30             65
PI 257487      PR China               30             90
PI 432873      PR China               30             85
PI 419136      PR China               30             91
PI 419040      PR China               30             82

                                      Lowest yielding 10

PI 263082      PR China               14             51
PI 267935      Japan                  13             50
PI 451973      PR China               13             63
PI 504572      PR China               12             47
PI 105340      PR China               11             54
PI 470254      Indonesia               9             29
PI 357830      Yugoslavia              9             41
PI 167223      Turkey                  8             38
PI 368555      Yugoslavia              8             26
PI 368554      Yugoslavia              5              5

Mean                                  23             71
Range                                 35            134
LSD, 5%                               10             25
CV, %                                 49             38

                            Early

   Cultigen          Wt.              No.

                     Mg           1000 fruit
                 [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'          22              42
`Dasher II'           21              43
`Ponsett75'           19              41
`Marketmore76'         9              25

                      Highest yielding 20

PI 264228             24              61
PI 478366             26              41
PI 390262             21              35
PI 532524             23              34
PI 390267             21              42
PI 532520             18              35
PI 275411             20              48
PI 419010             20              36
PI 518851             23              45
PI 511820             18              46
PI 422167             21              30
PI 432884             19              29
PI 419009             16              31
P! 418964             19              36
PI 263085             19              34
PI 432887             18              22
PI 257487             17              32
PI 432873             17              25
PI 419136             17              33
PI 419040             16              34

                       Lowest yielding 10

PI 263082              8              18
PI 267935              6              14
PI 451973              7              17
PI 504572              6              21
PI 105340              6              22
PI 470254              7              15
PI 357830              3               5
PI 167223              4               9
PI 368555              5              11
PI 368554              4               5

Mean                  14              28
Range                 23              56
LSD, 5%                7              15
CV, %                 58              58

                          Marketable

   Cultigen          Wt.              No.

                     Mg           1000 fruit
                 [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'          4               35
`Dasher II'           3               37
`Ponsett75'           4               44
`Marketmore76'        3               14

                      Highest yielding 20

PI 264228             7               18
PI 478366             6               20
PI 390262             6               32
PI 532524             5               30
PI 390267             6               29
PI 532520             8               40
PI 275411             6               39
PI 419010             6               24
PI 518851             4               18
PI 511820             6               24
PI 422167             5               26
PI 432884             7               36
PI 419009             7               23
P! 418964             5               20
PI 263085             4               23
PI 432887             5               16
PI 257487             6               26
PI 432873             5               23
PI 419136             5               22
PI 419040             5               26

                      Lowest yielding 10

PI 263082             2               15
PI 267935             3               11
PI 451973             3               24
PI 504572             3               13
PI 105340             4               22
PI 470254             1                9
PI 357830             5               32
PI 167223             2               16
PI 368555             2               12
PI 368554             1                0

Mean                  4               22
Range                 8               48
LSD, 5%               3               15
CV, %                69               72

                            % cull

   Cultigen          Wt.              No.

                     Mg           1000 fruit
                 [ha.sup.-1]      [ha.sup.-1]

`Sprint 440'           6              14
`Dasher II'            6              20
`Ponsett75'            6              20
`Marketmore76'         4               0

                       Highest yielding 20

PI 264228             13              26
PI 478366             12              39
PI 390262             17              33
PI 532524             14              25
PI 390267             15              22
PI 532520             19              35
PI 275411             15              24
PI 419010             14              27
PI 518851             14              28
PI 511820             22              26
PI 422167             11              31
PI 432884             14              25
PI 419009             21              25
P! 418964             15              22
PI 263085             18              37
PI 432887             17              42
PI 257487             17              35
PI 432873             22              40
PI 419136             21              40
PI 419040             26              34

                      Lowest yielding 10

PI 263082             23              41
PI 267935             28              44
PI 451973             15              38
PI 504572             17              29
PI 105340             11              20
PI 470254              9              25
PI 357830              8              17
PI 167223             14              24
PI 368555              5              15
PI 368554              8               0

Mean                  17              29
Range                 27              49
LSD, 5%                9              16
CV, %                 57              61

                    Fruit           Harvest
   Cultigen        quality           days
                  ([dagger])   ([double dagger])

`Sprint 440'         7.9              61
`Dasher II'          7.8              61
`Ponsett75'          7.6              64
`Marketmore76'       7.7              55

                      Highest yielding 20

PI 264228            5.8              62
PI 478366            6.5              67
PI 390262            7.0              66
PI 532524            6.3              67
PI 390267            6.8              64
PI 532520            6.6              66
PI 275411            5.3              58
PI 419010            6.1              62
PI 518851            6.3              64
PI 511820            6.6              61
PI 422167            7.3              66
PI 432884            6.4              69
PI 419009            6.4              66
P! 418964            5.9              67
PI 263085            4.8              61
PI 432887            6.0              68
PI 257487            6.8              61
PI 432873            6.3              70
PI 419136            6.0              62
PI 419040            5.3              65

                      Lowest yielding 10

PI 263082            5.1              63
PI 267935            4.4              68
PI 451973            5.9              61
PI 504572            4.8              63
PI 105340            3.0              73
PI 470254            3.4              78
PI 357830            7.0              79
PI 167223            6.0              61
PI 368555            5.8              71
PI 368554            5.6              75

Mean                 5.9              64
Range                4.9              26
LSD, 5%              0.9               5
CV, %               16                 8

([dagger]) Fruit quality ratings were based on fruit shape and color
(1-3 = poor, 4-6 = intermediate, 7-9 = excellent).

([double dagger]) Harvest days is the number of days from planting to
harvest.


ACKNOWLEDGMENTS

The authors gratefully acknowledge the technical assistance of Christopher Cramer, Tammy Ellington, Fred McCuistion, Joel Shuman, Ronghao Song, Bruton Strange, Alan Walters, and Jiahua Xie. The authors thank the USDA North Central Regional Plant Introduction Station at Ames, IA, for kindly providing seeds for the study.

(1) Use of trade names in this publication does not imply endorsement by the NCARS of the products named, or criticism of similar ones not mentioned.

REFERENCES

Cantliffe, D.J., and S.C. Phatak. 1975. Use of ethephon and chlorflurenol in a once-over pickling cucumber production system. J. Am. Soc. Hortic. Sci. 100:264-267.

Cargill, B.F., D.E. Marshall, and J.H. Levin. 1975. Harvesting cucumbers mechanically. Ext. Bull. 859. Mich. State Univ., East Lansing, MI.

Chen, L.H., C.H. Miller, and R.S. Sowell. 1975. Simulation models for harvesting of pickling cucumbers. J. Am. Soc. Hortic. Sci. 100: 176-179.

Colwell, H.T.M., and J. O'Sullivan. 1981. Economics of harvest timing for once over harvesting of cucumbers. J. Am. Soc. Hortic. Sci. 106:163-167.

Cramer, C.S., and T.C. Wehner. 1998. Stand correction methods for cucumber fruit yield. Cucurbit Genet. Coop. Rpt. 21:18-20.

Ells, J.E., and A.E. McSay. 1981. Yield comparisons of pickling cucumber cultivar trials for once-over harvesting. HortScience 16:187-189.

Harlan, J.R. 1975. Crops and Man. ASA and CSSA, Madison, WI.

Hogue, E.J., and H.B. Heeney. 1974. Ethephon and high density plantings increase yield of pickling cucumbers. HortScience 9:72-74.

McMurray, A.L., and C.H. Miller. 1968. Cucumber sex expression modified by 2-chloroethanephosphonic acid. Science (Washington, DC) 162:1396-1397.

Miller, C.H., and G.R. Hughes. 1969. Harvest indices for pickling cucumbers in once-over harvest systems. J. Am. Soc. Hortic. Sci. 94:485-487.

Miller, C.H., R.L. Lower, and H.P. Fleming. 1970. Evaluation of pickles from cucumber plants treated with 2-chloroethylphosphonic acid. HortScience 5:434-435.

Nerson, H., H.S. Paris, Z. Karchi, A. Govers, M. Edelstein, and Y. Burger. 1987. Comparison of fruit-set concentration of pickling cucumbers under greenhouse and field conditions. Cucurbit Genet. Coop. Rpt. 10:2-3.

Peterson, C.E. 1975. Plant introductions in the improvement of vegetable cultivars. HortScience 10:575-579.

Robinson, R.W., S. Shannon, and M.D. de la Guardia. 1968. Regulation of sex expression in the cucumber. BioScience 19:141-142.

Rudich, J., A.H. Halevy, and N. Kedar. 1972. The levels of phytohormones in monoecious and gynoecious cucumbers as affected by photoperiod and ethephon. Plant Physiol. 50:585-590.

Schultheis, J.R. 1990. Pickling cucumbers. Horticulture Information Leaflet No. 14-A. N.C. State Ag. Ext., Raleigh, NC.

Shetty, N.V. 1999. Evaluation of the cucumber germplasm collection for fruit yield and quality. Ph.D. diss. North Carolina State Univ., Raleigh, NC.

Sitterly, W.R. 1972. Breeding for disease resistance in cucurbits. Ann. Rev. Phytopathol. 10:471.

Smith, O.S, R.L. Lower, and R.H. Moll. 1978. Estimates of heritabilities and variance components in pickling cucumbers. J. Am. Soc. Hortic. Sci. 103:222-225.

Swallow, W.H., and T.C. Wehner. 1986. Optimum plot size for measurement of yield in multiple and once over harvest trials of pickling and fresh market cucumbers. Euphytica 35:493-501.

Swallow, W.H., and T.C. Wehner. 1989. Optimum allocation of plots to years, seasons, locations, and replications, and its applications to once-over harvest cucumber trials. Euphytica 43:59-68.

Tatlioglu, T. 1993. Cucumbers. In G. Kalloo and B.O. Bergh (ed.) Genetic improvement of vegetable crops. Pergamon Press, New South Wales, Australia.

USDA. 1959-1998. Agricultural statistics. U.S. Gov. Print. Office, Washington, DC.

Wehner, T.C. 1986. Efficiency of 3 single-harvest tests for evaluation of yield in pickling cucumber. Euphytica 35:493-501.

Wehner, T.C. 1987. Value of 12 season-location combinations for cucumber yield trials in North Carolina. Cucurbit Genet. Coop. Rpt. 6:38-39.

Wehner, T.C. 1989. Breeding for improved yield in cucumber. Plant Breed. Rev. 6:323-359.

Wehner, T.C., and C.H. Miller. 1984. Efficiency of single-harvest methods for measurement of yield in fresh-market cucumbers. J. Am. Soc. Hortic. Sci. 109:659-664.

Wehner, T.C., T.J. Monaco, and A.R. Bonanno. 1984. Chemical defoliation of cucumber vines for simulation of once-over harvest in small-plot yield trials. HortScience 19:671-673.

Nischit V. Shetty and Todd C. Wehner *

Dep. Hortic. Sci., North Carolina State Univ., Raleigh, NC 27695-7609. The research was funded in part by the North Carolina Agricultural Research Service (NCARS). Received 25 June 2001. * Corresponding author (todd_wehner@ncsu.edu).
COPYRIGHT 2002 Crop Science Society of America
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2002 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Shetty, Nischit V.; Wehner, Todd C.
Publication:Crop Science
Geographic Code:1USA
Date:Nov 1, 2002
Words:10370
Previous Article:Variation among accessions of Pisum fulvum for resistance to pea weevil. (Plant Genetic Resources).
Next Article:Salinity tolerance in Phaseolus species during early vegetative growth. (Plant Genetic Resources).
Topics:

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters