INTERACCION GENOTIPO-AMBIENTE EN PRODUCTUVIDAD Y CALIDAD PROTEINICA DE VARIEDADES SINTETICAS TROPICALES DE MAIZ.
INTERACAO GENOTIPO-AMBIENTE EM PRODUTIVIDADE E QUALIDADE PROTEICA DE VARIEDADES SINTETICAS TROPICAIS DE MILHO
Maize (Zea mays L.) has an important role in human and animal nutrition in some 25 developing countries worldwide, especially in Africa and Latin America (Prasanna et al., 2001), providing on average 37 and 46% of the daily protein and energy requirements for the human body (FAO, 2014). Like other cereals, maize has a low biological value compared against proteins from animal sources; therefore, family nuclei in the rural zones of Mexico usually eat maize products accompanied with beans, which help to somehow balance this protein deficiency, so as to compensate for the maize limitations (Krivanek et al., 2007).
The improvement of quality protein maize (QPM) began with the aim of improving the nutritional value of the protein in the maize kernel (Krivanek et al., 2007). The commonly used approach is based on manipulating the opaco-2 (o2) mutation, a recessive gene that increases lysine and tryptophan levels in maize kernels (Ignjatovic-Micic et al., 2010).
However, the incorporation of the o2 gene into high yield cultivars has not been commercially successful due to its pleiotropic effect (soft endosperm, susceptibility to pests in stored grains, uprooting by winds, etc.). Fortunately, these problems have been corrected through the manipulation of three genetic systems: a) the simple recessive allele of the opaco-2 gene; b) endosperm modifiers contained in o2o2, which increase lysine and tryptophan levels; and c) genes that modify the soft endosperm and transform it into hard endosperm (Vasal, 2000; Vivek et al., 2008).
The term QPM (quality protein maize) refers to maize with a higher lysine and tryptophan content and a relatively hard endosperm, which makes it resistant to pests during storage (Galicia et al., 2011). Thus, the contribution of QPM to human nutrition, especially in poor countries where maize is the staple food, has been well documented (Bressani, 1994; Krivanek et al., 2007; Vivek et al., 2008; Nuss and Tanu mihardjo, 2011). However, in Mexico the use of these varieties has not become general practice, and native maize is grown or varieties with a normal endosperm offered by seed producers (Zepeda-Bautista et al., 2009).
The local conversion of different groups of normal lines to QPM began in 2002, within the Maize Program of the Cotaxtla Experimental Field (CECOT, from its Spanish initials), which belongs to the National Institute of Forestry, Agricultural and Livestock Research (INIFAP), Mexico. Initially, the lines were crossbred with line CML-144 from the International Maize and Wheat Improvement Center (CIMMYT), which acted as the donor of the o2 characteristic. The crossbreeds self-pollinated and the selected lines were backcrossed to recover the characteristic. After this selection process, in 2008, simple crosses were formed through a diallel scheme to find the specific combinatory aptitude (SCA) and the general combinatory aptitude (GCA) of the participating lines (AndresMeza et al., 2011). Using the lines with the highest grain yield and high GCA, 11 maize synthetics were integrated. Under this context, the present goal was to determine the genotype-environment interaction on the productive capability, physical characteristics and protein quality in 16 synthetic tropical maize varieties.
Materials and Methods
Field evaluations were carried out on 16 maize varieties, 11 of which are new experimental synthetic maize varieties, integrated from lines with different levels of inbreeding and selected for their good performance per se and high effects of general combinatory aptitude of the component lines (Andres-Meza et al., 2011). Three are experimental synthetics selected for drought tolerance (TS6, LPSC3, and 3 SC), and two were commercial varieties (VS-536 and V-537C), the first of the latter was obtained through genetic recombination of nine inbred lines from the maize programs in Cotaxtla, Veracruz, Iguala, Guerrero, Rio Bravo, Tamaulipas, and Ocotlan, Jalisco, Mexico, while the second one was obtained through genetic recombination of 10 half-sib families from the Poza Rica 8763 population (Table I).
The varieties were sown in seven different environments during the years 2012 and 2013. Five environments were established in the central zone of Veracruz state and the other two in Iguala, Guerrero, Mexico. The planting and harvest times, planting conditions, and fertilization doses are shown in Table II. Total fertilizer [P.sub.2][O.sub.5], [K.sub.2]O and one third of N were applied 10 days after planting (dap) and the remaining N (as urea) was applied 30 dap.
The precipitation patterns and amounts differed markedly between the 2012 and 2013 growing seasons. Standard weather data were recorded for each site using the nearest weather observatories set up in ~1km from the experimental sites. Each station recorded the daily maximum and minimum air temperature ([degrees]C) and rainfall (mm) (Figures 1a, b).
The establishment of the essays in each location coincided with the beginning of the rainy season, except for the fall-winter cycle, when sufficient auxiliary irrigation (seven times) was applied so the plants would not suffer from water stress. The experimental unit was two rows, 5m long by 0.8m wide each. Planting was done tapa pie, with the feet, which is the traditional way to plant in the region. Three seeds were planted per hole, 0.4m from each other, to be later thinned to two plants (62500 plants/ha).
Yield and physical characteristics of the kernel
Grain yield (t x [ha.sup.-1]) was estimated on the field, represented by the weight of the cob per lot, adjusted to 14% humidity and multiplied by the ratio of the size of the lot compared against an hectare, thus transforming it to t x [ha.sup.-1]. The weight per 100 kernels (PCG) (Billeb and Bressani, 2001) was recorded. The flotation index (FI), which estimates the relative density of kernels and is an indirect measure of kernel hardness was determined: 100 grains were immersed in sodium nitrate solutions (41g in 100ml of water) with a density of 1.25 at 23[degrees]C; the grains were stirred and after 1min the number of floating grains was counted. Hardness classification of kernels was based on the scale proposed by Salinas et al. (1992), such that FI values of 0-12% are very hard kernels, of 13-37% hard, 38-62% intermediate, 63-87% soft and >87% very soft kernels. Finally, visual grading (VG) of the type of endosperm as an indirect hardness of the kernel: values between 1-2 are very hard (VH), 3-4 hard (H), 5-6 intermediate (I), 7-8 soft (S), and 9-10 very soft (VS) endosperm (Vazquez et al., 2012).
Nitrogen, lysine, and tryptophan quantification
Samples of endosperm (without tip cap, pericarp, and germ) as well as from the whole kernel were taken from each genotype. The samples were ground in a Tecator Cyclotec 1093 grinder, sieve size 0.5mm. The obtained flour was subjected to a de-greasing process using petroleum ether in a Soxhlet intermittent extractor for 6h. Afterwards, they were dried in the open air to eliminate excess petroleum ether (Galicia et al., 2009, 2012).
Nitrogen quantification was carried out with a Technicon II Autoanalyzer (#334-74, 1997) following the methodology of Galicia et al. (2009). The amount of protein was estimated from the nitrogen value by multiplying the nitrogen percentage (N)x6.25 (conversion factor for maize) (Vivek et al., 2008). Lysine quantification was done following the colorimetric method described by Villegas et al. (1984) modified by Galicia et al. (2011), which is based on the reaction of 2-chloro, 3,5-dinitropyrine; reading was done in a microplate reader ([mu]Quant MQX200, BioTek[R]) to determine optical density (DO) at 390nm. Lastly, tryptophan quantification was done according to the method by Nurit et al. (2009) modified by Galicia et al. (2012), which is based on the reaction of glyoxilyc acid; reading was done in a plate spectrophotometer at 560nm. Both amino acids are expressed as a percentage of protein.
Laboratory analyses were performed in duplicate. All the evaluated variables were analyzed under a completely random design, except for the grain yield variable, which was done in a completely random block design with three replicates. Combined variance analyses and mean comparison tests (Tukey) were done with the SAS/STAT[R]software, version 9.0 (SAS, 1990).
With regard to the combined analysis, there were significant differences (P<0.01) among varieties (V), environments (E), and the variety x environment (VxE) interaction on yield, physical characteristics, and protein quality (Table III). These differences are due to the genetic variability among varieties due to particular genetic characteristics, to the effect of the environment, and to crop management. The variation coefficients fluctuated from 2.33 to 20.84. These values suggest reliability in the obtained results. Research results have demonstrated the competitiveness for grain yield of QPM with the best normal maize cultivars in numerous tropical environments (Vergara et al., 2000). In some works hybrids yielded more grain than open-pollinated cultivars, but mean grain yield did not differ for single cross, threeway, and double-cross hybrids (Cordova and Pandey, 1999; Pixley and Bjarnason, 2002).
Genotype x environment interaction on yield and physical characteristics of the kernel
The differences among varieties (P<0.01) show different levels of productivity that were affected by the VxE interaction. Across all environments, varieties 9C, 10C, and 11C, with mean yields of 3.94, 3.95, and 3.96t x [ha.sup.-1], respectively, were statistically similar to the better control variety VS-536, which showed the highest mean yield (4.08t x [ha.sup.-1]) (Table IV). On their part, locations Cotaxtla 2012B (E1) and Iguala 2012B (E4) (where 'B' stands for 'spring-summer growing season') showed the highest yields (Table V). The best variety for environment E1 was 9C, and for E4, it was 10C, with mean yields of 6.18 and 6.27t x [ha.sup.-1], respectively (data not shown). In E1 the flowering took place in August 2012, when the minimum average temperature was 20.6[degrees]C while the maximum average temperature was 31.3[degrees]C, and the rainfall was 347.3mm (Figure 1a). On the other hand, E4 flowering occurred in September 2012, when the minimum average temperature was 17.8[degrees]C, the maximum average temperature was 31.5[degrees]C, and rainfall was 48.8mm (Figure 1a).
The location Iguala 2013B (E7) had the lowest grain yield. In this location, the best performance was that of variety 10C with a mean yield of 3.17t x [ha.sup.-1] (data not shown). The results found in this location can be attributed to the fact that during the crop cycle, the climatic conditions were atypical, particularly so during the month of September, when it rainfall was 357mm, followed by a period of drought in October, with rainfall of 38.2mm and relatively hotter than the E6 location (Cotaxtla 2013B), thus affecting grain filling (Figure 1b). According to Stapper and Fischer (1990), during grain filling, for each degree centigrade of temperature rise, development increases more than growth, which reduces grain yield up to 4%.
In Cotaxtla 2013A (E5) (where 'A' stands for 'fall-winter growing season'), under irrigation, the mean yield of all varieties was greater than those of Cotaxtla 2013B (E6), rainfed, at 3.9 and 2.8t x [ha.sup.-1], respectively. Environment E6 differed from E5 because the establishment of the crop was late, since according to the technical recommendations by INIFAP, late plantings are more susceptible to pests and diseases. In the latter environment, the best performance was that of variety 4C with 3.45t x [ha.sup.-1] (data not shown).
With regard to the physical characteristics of the kernel, the lowest weight per 100 kernels (WHG) (smallest kernel size) and the highest flotation index (IF) (intermediate hardness) was obtained for varieties VS-536, V-537C and 3SEQ throughout all seven study environments. Also, when visually classifying for the type of endosperm, these showed a hard kernel (Table V). Kernel hardness is related with the time that it needs for nixtamalization; the harder the kernel, the more cooking time is needed to obtain a nixtamal (tortilla dough) with the adequate characteristics for quality dough (Serna-Saldivar and Rooney, 2003; Rooney and Serna-Saldivar, 2003).
All the maize varieties evaluated had small kernels ([less than or equal to] 33g/100 kernels); however, those planted in E7 had a greater WHG (24.3g/100 kernels), and were statistically different (P [less than or equal to] 0.05) from those in E5 and E6 (Table V). The reduced weight and size of the kernels is attributed to the lower temperature in E5 during the first three months of the year (Figure 1b). Environment E6 is characterized for suffering the climatological phenomenon known as canicula or 'midsummer drought', which lasted for 40 days from August to September, mainly affecting the individual weight of the kernels (Figure 1b). Maize hardness has been shown to have an influence on the production efficiency or quality of the final product (Fox and Manley, 2009).
Protein, lysine, and tryptophan content
The mean content of total raw protein in QPM varieties in all seven test environments varied from 9.8 to 11.5% in kernels and from 7.4 to 8.6 in the endosperm (Table IV). These values are similar to those reported for whole kernels (7-10.1%) by Fufa et al. (2003) in five Ethiopian quality protein and normal maize cultivars; although they are higher than those reported for whole kernels (9.2-9.4%) by Pixley and Bjarnason (2002) in a group of tropical QPM with a wide genetic base. The QPM varieties in environment E2 developed greater protein content in the kernels and endosperm. In this location, the best registered values were those of the variety TS6 with 13.8% in kernels and 10.3 in the endosperm (data not shown).
The endosperm of QPM is different from that of normal maize endosperm in that it synthesizes a greater amount of the lysine and tryptophan fractions (albumines, globulines, and glutelines), and less prolamines, which is the major fraction in maize with normal endosperm and deficient in these amino acids. Thus, the protein concentration between these two types of maize might be the same, but what distinguishes QPM is that their endosperm has a greater amount of these amino acids. In this case, the mean protein reduction from the removal of the germ was 2.9% (Table IV).
Throughout all environments, genotypes 1C, 2C, 3C, 4C, 5C, and 10c had a greater concentration of lysine in the kernel than did the QPM control, while 6C, 7C, and 8C were statistically equal to the control V-537C. As far as the endosperm, only variety 1C was better than the control, and eight genotypes were statistically equal to the control in lysine concentration (Table IV). In environment E5, whole kernels and endosperm of all the varieties showed the highest levels of lysine; particularly, the control variety V-537C showed a high mean lysine content in the kernel and endosperm, 4.90 and 3.35g/100g protein, respectively. These increases are because in this cycle, especially, irrigation was applied and therefore water availability was greater, which in turn reflected positively in this variable (Figure 1b).
Regarding the mean tryptophan content in whole kernels and endosperm, it varied from 0.61 to 0.92 and from 0.52 to 0.76g/100g protein, respectively; particularly so in variety 3C, where the level of tryptophan in whole kernels was statistically greater than the control variety V-537C, with 0.92g/100g protein. On the other hand, the tryptophan content of the endosperm was greater in the control (Table IV). In this regard, the maize varieties grown in environment E2 showed low concentrations of this amino acid, while those in environment E7 had the highest levels. It is inferred that great climatic variations positively affected tryptophan content.
With regard to grain yield, throughout all the test environments, all the QPM varieties performed statistically equal (P<0.05) to the best control with normal grain, VS-536, but better than the control QPM variety V-537C. It can be said that these maize varieties show agronomic advantages over varieties with normal endosperm; therefore, they are good options to improve the nutritional level of consumers. In all seven environments, the QPM varieties showed a better performance, except for environments E2 and E3, where the normal endosperm variety VS-536 had the best performance. Previous studies have reported yields of hybrid QPM from the CImMyT that are competitive against the best local normal endosperm cultivars in several tropical locations (Bjarnason and Vasal, 1992; Pixley and Bjarnason, 1993).
According to the physical properties of the kernels, all the evaluated varieties had small kernels ([less than or equal to] 33g/100 kernels). In this regard, it is well-known that kernel weight is an indicator of kernel size and density; bigger kernels have a greater ratio of endosperm than do smaller kernels. Therefore, they have a greater yield in flour, which is an important characteristic for the dough and tortilla industry. Serna-Saldivar and Rooney (2003) indicate that this characteristic favors kernel hydration during the nixtamalization process, which affects the dough and gives off tortillas with better texture. The effect of the crop cycle significantly affected this characteristic (P<0.05), being environment E7 where the biggest kernels developed. Environments E5 and E6, planted with irrigation and rainfed, had no significant differences in kernel size; thus, the expression of the varieties was not affected by the water conditions.
According to the FI, as an indirect measurement of kernel hardness, 56% of the varieties were proven to have a hard grain, while the rest of them developed intermediate kernels. No relationship was found between FI and kernel texture through visual classification regarding the type of endosperm. The terms hard and soft are used to designate the ratio of floury and crystalline areas present within the endosperm of the kernel, a characteristic that influences kernel hardness. Salinas and Vazquez (2006) mention that the nixtamalized dough industry (IHN) and the tortilla dough industry prefer to process maize with intermediate sized kernels.
The highest protein content, both in the kernel and in the endosperm, was observed in the varieties with normal endosperm. Zarkadas et al. (2000) mention that the difference in protein content in favor of normal kernel maize is attributed to a greater presence of prolamines (zeins), especially alpha-zeins. Gutierrez et al. (2008) reported that prolamines make up around 50-70% of the total proteins contained in the endosperm, deficient in lysine and tryptophan. Hasjim et al. (2009) mention that QPM are considered to have high quality proteins since they have sufficient lysine and tryptophan.
With regard to the amount of lysine and tryptophan present in the kernel and in the endosperm, there were statistical differences (P<0.05) among the synthetic maize varieties through all seven test environments (Table V). The highest lysine contents (g/100g protein) were those of varieties 1C, 3C, 4C, 5C, 6C, 8C, and V-537C, which in turn are related to the highest values of tryptophan and grain yield. According to De Groote et al. (2013), the current quality of maize improved for these characteristics is due to a decrease in the level of total protein. Zeins are the most affected, since they are the prevalent section, relatively increasing the presence of other proteins that are not deficient in lysine or tryptophan, such as albumines and globulines. Given that these cultivars show agronomic advantages as well as in kernel quality, they are a good option to improve the nutritional level of the people living in rural zones, who greatly depend on this cereal.
The effects of variety, environment and their interaction affected size, hardness, and kernel quality. The QPM varieties were competitive with regard to the controls VS-536 with normal kernel and QPM V-537C. No relationship was observed between IF and kernel texture through visual classification in the type of endosperm. All varieties developed small kernels and are thus accepTable for household processing as well as for the dough and tortilla industry. Out of the 16 evaluated varieties, only nine of them presented hard kernels, which could be useful for the nixtamalized dough industry. Environment E6 registered maize with the greatest concentrations of tryptophan; under irrigation, the synthetic varieties produced a higher percentage of lysine in the kernels and in the endosperm. The results of the current study indicated the existence of a high level of variability and the possibility of improving QPM cultivars for the traits evaluated. QPM is a nutritional enhanced crop awaiting widespread dissemination and the opportunity its potential for global health improvement.
Recibido: 24/08/2016. Modificado: 12/08/2017. Aceptado: 16/08/2017.
The authors thank the Maize Quality Laboratory of CEVAMEX for allowing to carry out the physical and chemical analyses of the evaluated synthetic varieties, engineers Luz Marufo and Erandi, and technicians Miguel, Lino, and Berna, who collaborated with the analyses.
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Pablo Andres Meza. Doctor in Sciences in Genetics, Colegio de Postgraduados (COLPOS), Mexico. Professor, Universidad Veracruzana (UV), Mexico.
Maria Gricelda Vazquez Carrillo. Doctor in Sciences in Genetics, COLPOS), Mexico. Researcher, Instituto Nacional de Investigaciones Forestales Agricolas y Pecuarias (INIFAP), Mexico.
Mauro Sierra Macias. (Corresponding autor). Doctor in Agricultural and Forest Sciences, Universidad de Colima, Mexico. Researcher, INIFAP, Mexico. Address: Campo Experimental Cotaxtla, INIfAp. 92277. Medellin de Bravo, Veracruz, Mexico. e-mail: firstname.lastname@example.org
Jose A. Mejia Contreras. Ph.D. in Agronomy, Nebraska University, USA. Professor, COLPOS, Mexico.
Jose D. Molina Galan. Ph.D in Genetics, North Carolina State University, USA. Professor, COLPOS, Mexico.
Alejandro Espinosa Calderon. Doctor in Genetics, COLPOS, Mexico. Researcher, INIFAP, Mexico.
Noel O. Gomez Montiel. Doctor in Genetics, COLPOS, Mexico. Researcher, INIFAP, Mexico.
Gustavo Lopez Romero. Doctor in Genetics, COLPOS, Mexico. Professor, Colegio de Postgraduados (COLPOS), Mexico.
Margarita Tadeo Robledo. Doctor in Genetics, COLPOS, Mexico. Professor, Universidad Nacional Autonoma de Mexico, Mexico.
Pedro Zetina Cordoba. Doctor in Tropical Agroecosystems, COLpOs, Mexico. Professor, Universidad Politecnica de Huatusco, Mexico.
Miguel Cebada Merino. Master in Tropical Horticulture. UV, Mexico.
Caption: Figure 1. Mean rainfall and temperatures during the years 2012 (a) and 2013 (b) throughout seven environments in the states of Veracruz and Guerrero, Mexico; fall-winter cycle = in the months from December to May; spring-summer cycle= in the months from June to November; COT = Cotaxtla; SAU = El Sauce; TEP = Tepetates; IGU = Iguala.
TABLE I GERMPLASM GROWN IN SEVEN ENVIRONMENTS IN THE STATES OF VERACRUZ AND GUERRERO, MEXICO (2012-2013) N[grados] Genealogy Lines * Seeds * Level 1 SYNTHETIC-1C 20 20 Experimental 2 SYNTHETIC-2C 10 15 Experimental 3 SYNTHETIC-3C 9 20 Experimental 4 SYNTHETIC-4C 12 15 Experimental 5 SYNTHETIC-5C 12 15 Experimental 6 SYNTHETIC-6C 9 20 Experimental 7 SYNTHETIC-7C 8 25 Experimental 8 SYNTHETIC-8C 6 15 Experimental 9 SYNTHETIC-9C 6 20 Experimental 10 SYNTHETIC-10C 8 15 Experimental 11 SYNTHETIC-11C 8 20 Experimental 12 SYNTHETIC-TS6 12 15 Experimental 13 SYNTHETIC-LPSC3 12 15 Experimental 14 VS-536 9 15 Commercial 15 V-537C 10 15 Commercial 16 SYNTHETIC-3 SEQ 12 15 Experimental * Number of lines and seeds that integrate each synthetic variety. TABLE II CHARACTERISTICS OF SEVEN MEXICAN ENVIRONMENTS FOR THE EVALUATION OF 16 SYNTHETIC VARIETIES OF QPM) WITH NORMAL ENDOSPERM (2012-2013) Identification Location State Geographical location E1 Cotaxtla 2012B Veracruz 18[degrees] 56' N, 96[degrees] 11' W E2 El Sauce 2012B Veracruz 18[degrees] 42' N, 96[degrees] 04' W E3 Tepetates 2012B Veracruz 19[degrees] 11' N, 96[degrees] 20' W E4 Iguala 2012B Guerrero 17[degrees] 52' N, 99[degrees] 09' W E5 Cotaxtla 2013A Veracruz 18[degrees] 56' N, 96[degrees] 11' W E6 Cotaxtla 2013B Veracruz 18[degrees] 56' N, 96[degrees] 11' W E7 Iguala 2013B Guerrero 17[degrees] 52' N, 99[degrees] 09' W Identification Altitude Planting Planting/ harvest (m) condition dates E1 18 Rainfed 20/06/12-06/11/12 E2 19 Rainfed 26/07/12-27/11/12 E3 18 Rainfed 18/07/12-24/11/12 E4 750 Rainfed 25/07/12-25/11/12 E5 18 Irrigation 21/02/13-12/06/13 E6 18 Rainfed 26/07/13-23/11/13 E7 750 Rainfed 31/07/13-21/11/13 Identification Fertilization (Kg x [ha.sup.-1] N-P-K) E1 161-46-00 E2 161-46-00 E3 140-70-00 E4 90-60-00 E5 161-46-00 E6 161-46-00 E7 90-60-00 TABLE III MEAN SQUARES AND STATISTICAL SIGNIFICANCE OF 16 SYNTHETIC VARIETIES OF QPM WITH NORMAL ENDOSPERM GROWN IN SEVEN ENVIRONMENTS IN THE STATES OF VERACRUZ AND GUERRERO, MEXICO (2012-2013) Source of variation DF GY Visual WHG FI (%) grading Variety (V) 15 2.19 ** 9.18 ** 25.07 ** 419.64 ** Environment (E) 6 58.13 ** 8.19 ** 16.43 ** 3628.57 ** VxE interaction 90 0.77 ** 3.32 ** 19.73 ** 363.58 ** Error 224 0.48 0.48 0.99 12.67 CV (%) 20.09 20.84 4.23 9.87 [R.sup.2] 0.80 0.81 0.98 0.98 Tryptophan ([paragraph]) Protein (%) ([paragraph]) Source of variation (g/100g protein) Kernel Endosperm Kernel Endosperm Variety (V) 3.89 ** 1.98 ** 0.09 ** 0.05 ** Environment (E) 19.79 ** 14.06 ** 0.22 ** 0.31 ** VxE interaction 1 54 ** 1.37 ** 0.04 ** 0.03 ** Error 0.06 0.22 0.01 0.01 CV (%) 2.33 6.04 3.42 6.54 [R.sup.2] 0.97 0.91 0.91 0.94 Tryptophan ([paragraph]) ([paragraph]) Source of variation (g/100g protein) Kernel Endosperm Variety (V) 1.38 ** 0.59 ** Environment (E) 10.84 ** 4.99 ** VxE interaction 0.90 ** 0.41 ** Error 0.14 0.04 CV (%) 12.03 7.77 [R.sup.2] 0.98 0.97 *, ** Different from cero at a 0.05 and 0.01 probability, respectively; GY: grain yield; WHG: one hundred kernel weight; FI: flotation index; DF: degrees of freedom; CV(%): coefficient of variation; ([paragraph][paragraph]) informed in dry base, oil free samples. TABLE IV AVERAGE YIELD, PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE KERNELS FROM 16 SYNTHETIC VARIETIES OF QPM WITH NORMAL ENDOSPERM GROWN IN SEVEN ENVIRONMENTS IN THE STATES OF VERACRUZ AND GUERRERO, MEXICO (2012-2013) GY (t x Protein Lysine ([paragraph]) Variety [ha.sup ([paragraph]) (%) (g/100g protein) .-1]) Kernel End Kernel End 1C 3.48 abc * 10.38 de 7.36 d 3.71 ab 3.25 a 2C 3.43 abc 10.39 de 7.79 bcd 3.35 abc 2.47 cdef 3C 3.83 ab 9.94 f 7.39 d 3.83 a 2.53 bcdef 4C 3.62 abc 10.15 ef 7.79 bcd 3.71 ab 2.79 b 5C 3.44 abc 9.83 f 7.83 bcd 3.37 abc 2.62 bcd 6C 3.52 abc 10.29 e 8.55 a 3.05 cd 2.34 def 7C 3.60 abc 10.64 cd 7.42 d 2.99 cd 2.54 bcdef 8C 3.77 ab 10.42 de 7.35 d 3.06 cd 2.56 bcde 9C 3.96 a 10.64 cd 7.60 cd 2.55 d 2.63 bcd 10C 3.95 a 11.23 ab 7.74 bcd 3.14 bcd 2.41 def 11C 3.94 a 10.95 bc 7.60 cd 2.62 d 2.50 bcdef TS6 3.35 abc 11.46 a 8.34 ab 2.93 cd 2.24 f LPSC3 3.01 c 11.32 a 8.26 ab 3.23 abc 2.73 bc VS-536 4.08 a 11.51 a 8.20 abc 3.03 cd 2.30 ef V-537C 3.11 bc 10.44 de 7.74 bcd 3.10 cd 2.61 bcd 3SC 3.18 bc 10.96 bc 7.46 d 2.81 cd 2.29 ef HSD 0.44 0.32 0.61 0.59 0.32 [R.sup.2] 0.8 0.97 0.91 0.91 0.94 Tryptophan Variety ([paragraph]) VG Hardness type WHG (g/100g protein) of endosperm Kernel End 1C 0.74 d 0.63 bc 4.67 a I 24 b 2C 0.69 fg 0.55 efg 3.10 de H 23 c 3C 0.92 a 0.65 b 3.90 bc H 25 b 4C 0.74 d 0.63 bc 2.95 def H 25 b 5C 0.81 c 0.63 bc 2.90 ef H 22 d 6C 0.72 de 0.55 defg 2.90 ef H 21 d 7C 0.67 fg 0.5 5defg 2.81 ef H 25 b 8C 0.70 ef 0.52 g 2.71 ef H 23 c 9C 0.80 c 0.60 cde 4.33 ab H 22 d 10C 0.68 fg 0.57 defg 3.10 de H 24 b 11C 0.66 g 0.58 def 2.81 ef H 28 a TS6 0.66 g 0.54 fg 2.33 f VH 25 b LPSC3 0.68 fg 0.60 bcd 4.00 ab H 25 b VS-536 0.61 h 0.54 fg 3.19 cde H 21 d V-537C 0.84 b 0.76 a 3.90 bc H 21 d 3SC 0.73 de 0.63 bc 3.67 bcd H 21 d HSD 0.03 0.05 0.76 2.01 [R.sup.2] 0.98 0.97 0.81 0.98 Variety FI (%) Hardness of whole kernel 1C 39.00 bcde I 2C 38.50 bcde I 3C 36.33 cdef H 4C 30.50 fghi H 5C 32.00 efgh H 6C 37.50 bcdef I 7C 23.17 i H 8C 34.50 cdefg H 9C 39.50 bcd I 10C 28.00 ghi H 11C 33.67 defg H TS6 25.17 hi H LPSC3 34.67 cdefg H VS-536 44.33 b I V-537C 58.83 a I 3SC 41.17 bc I HSD 7.35 [R.sup.2] 0.98 * Means with the same letter in a column are not statistically different (Tukey, 0.05). GY: grain yield; VG: visual grading, where: 1-2 Very hard (VH), 3-4 Hard (H), 5-6 Intermediate (I), 7-8 Soft (S), 9-10 Very soft (VS); WHG: one hundred kernel weight; FI: flotation index, where: 0-12% Very hard (VH), 13-37% Hard (H), 38-62% Intermediate (I), 63-87% Soft (S), [greater than or equal to] 87% Very soft (VS); End: endosperm; HSD: honestly significant difference; 1 informed in dry base, oil free samples. TABLE V INFLUENCE OF THE ENVIRONMENT ON GRAIN YIELD, PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE KERNELS IN 16 VARIETIES OF SYNTHETIC QPM WITH NORMAL ENDOSPERM GROWN IN SEVEN ENVIRONMENTS IN THE STATES OF VERACRUZ AND GUERRERO, MEXICO. (2012-2013 Visual Environment GY-1 (t x grading Hardness [WHG.sup. [ha.sup.-1]) ([paragraph] type of [section]] [paragraph]) endosperm E1 4.8 a * 3.4 ab D -- E2 3.2 cd 3.0 c D -- E3 3.3 c 3.3 bc D -- E4 5.1 a 2.6 d D -- E5 3.9 b 3.8 a D 23.1 b E6 2.8 d 3.6 ab D 23.0 b E7 1.9 e 3.6 ab D 24.3 a HSD 0.44 0.76 2.01 Protein Environment [FI.sup.[section] Hardness of ([paragraph]) (%) [section]] (%) whole kernel Kernel Endosperm E1 -- -- 9.75 f 7.22 d E2 -- -- 11.95 a 8.60 a E3 -- -- 10.93 c 8.12 bc E4 -- -- 9.95 e 7.15 d E5 30 b D 10.31 d 8.43 ab E6 30 b D 10.40 d 6.96 d E7 48 a I 11.33 b 7.96 c HSD 7.35 0.32 0.61 Tryptophan Tryptophan ([paragraph]) ([paragraph]) (g/100 g protein) (g/100 g protein) Environment Kernel Endosperm Kernel Endosperm E1 0.71 c 0.57 d 3.00 b 2.78 b E2 0.62 e 0.53 e 2.93 b 2.20 c E3 0.67 d 0.56 d 3.00 b 2.05 d E4 0.67 d 0.63 c 2.67 c 2.78 b E5 0.79 b 0.46 f 4.17 a 2.94 a E6 0.81 a 0.67 b -- -- E7 0.83 a 0.76 a -- -- HSD 0.59 0.32 0.03 0.05 * Means with the same letter in a column are not statistically different (Tukey, 0.05). GY: grain yield; ([paragraph][paragraph) visual grading, where: 1-2 is very hard (VH), 3-4 hard (H), 5-6 intermediate (I), 7-8 soft (S), 9-10 very soft (VS); WHG: one hundred kernel weight; FI: flotation index, where: 0-12% is very hard (VH), 13-37% hard (H), 38-62% intermediate (I), 63-87% soft (S), [greater than or equal to] 87% very soft (VS); 1 informed in dry base, oil free samples. For environment identification see Table II. -: no record.
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|Author:||Andres-Meza, Pablo; Vazquez-Carrillo, Maria Gricelda; Sierra-Macias, Mauro; Mejia-Contreras, Jose Ap|
|Date:||Sep 1, 2017|
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