Studying of planting density influence on dry matter accumulation changes in chicory (Cichorium intybus L.) under irrigation deficit stress regimes.
Drought stress is especially important in countries where crop agriculture is essentially rain-fed (Boyer, 1982 and Ludlow and Muchow, 1990). Drought stress causes an increase in solute concentration in the environment, leading to an osmotic flow of water out of plant cells. This in turn causes the solute concentration inside plant cells to increase, thus lowering water potential and disrupting membranes along with essential processes like photosynthesis. These drought-stressed plants consequently exhibit poor growth and yield. In worst case scenarios, the plants completely die. Certain plants have devised mechanisms to survive under low water conditions. These mechanisms have been classified as tolerance, avoidance or escape (Kramer and Boyer, 1995; Neumann, 1995). Drought stress reduced dry matters of chicory by reduction in the area of the leaf and height plant (Labreveux and Hall, 2002). High plant density may increase relative humidity within the canopy and increase the duration of leaf wetness by reducing air movement and sun light penetration (Burdona and Chilvers, 1982 and Tu, 1997). Thus plant density could have significant impact on plant disease incidence (Burdona and Chilvers, 1982 and Copes and Scherm, 2005). The treatments in an experiment on chicory were 60000, 80000, 130000 and 170000 plants/ha. The average total fresh weight/plant, the marketable fresh weight/plant and head size were higher at the lower plant density. The total yield was higher at the treatment with 4 plants/[m.sup.2] and a double planting line/row. The highest marketable and export quality yield was obtained with the treatment 4 plants/m, single planting line/row. The lowest marketable yield was observed in the highest plant density treatment. The critical plant density was 0.2 m with a single row (Carrasco et al., 1998). Two experiments were conducted in Southern Italy with two cultivars of chicory such us "Cicoria da foglie" (leaf chicory) and "Cicoria di Galatina" ("asparagus chicory") grown at three plant densities (11.1, 5.6 and 3.7 plants/[m.sup.2]). At maturity, the aerial part of the plant was excised or not. With the closest spacing during the second year a high seed yield, stems per plant and germination percentage were noticed. Leaving the plants in situ resulted in a faster germination, while the excised plants showed a decrease in seed yield, seed per plant, 1000 seed weight, plant height and number of stems per plant (Bianco et al., 1994). Water deficit occurs when water potentials in the rhizosphere are sufficiently negative to reduce water availability to sub-optimal levels for plant growth and development (Aliabadi Farahani et al., 2008a). The results of a study showed that drought stress reduced flowering shoot yield, essential oil yield and internode length, and increased essential oil percentage of coriander (Aliabadi Farahani et al., 2008b). Irrigation according and planting density are the most important environmental factors that effect on plants yield. Therefore, this experiment was carried out to study the effects of irrigation according and planting density on biological yield of chicory (Cichorium intybus L.).
Material and Methods
An experiment was carried out using a split plot based randomized complete block design with 4 replications. The factors studied included irrigation according (50, 100 and 150 mm water evaporation from evaporation pan) and planting densities (6, 9, 12 and 15 plants/[m.sup.2]). At the end of growth stage for determination of some characteristics of chicory, we selected 10 plants from each plot and then determined biological yield, stem yield, height plant, lateral stem number, leaf yield, root diameter and etc. Data were subjected to analysis of variance (ANOVA) using the Statistical Analysis System (SAS institute, 1996).
Results and Discussion
The results showed that irrigation according had significantly affected on biological yield, leaf number, pod number and lateral stem number in P<0.01 and height of plant had not significantly affected due to irrigation according (Table 1). Highest biological yield (19708 kg/ha), leaf number (16.8 leaf/plant), pod number (135 pod/plant), lateral stem number (10.7 stem/plant) and height of plant (119.2 cm) were achieved under irrigation according of 50 mm water evaporation from evaporation pan (Table 2). Also, the results showed that planting density had significantly affected leaf number, pod number and lateral stem number in P<0.01. Biological yield and height of plant had not significantly affected due to planting density (Table 1). Highest biological yield (21870 kg/ha) and height of plant (116.3 cm) were achieved under planting density of 15 plant/[m.sup.2]. Highest leaf number (22 leaf/plant), pod number (171.6 pod/plant) and lateral stem number (10.9 stem/plant) were achieved under planting density of 6 plant/[m.sup.2] (Table 2). Interaction of irrigation according and planting density had significantly affected biological yield and lateral stem number in P<0.01 (Table 1). Highest biological yield (20789 kg/ha) was achieved under irrigation according of 50 mm water evaporation and planting density of 15 plant/[m.sup.2] and highest lateral stem number (26.1 stem/plant) was achieved under irrigation according of 50 mm water evaporation and planting density of 6 plant/[m.sup.2] (Table 3). As it was shown in the results of this study, water deficit stress had a negative effect on most of the chicory characteristics under study. This shows that in order to resist water deficit stress, the plant uses different ways. Great reduction in the length and width of the leaf and accordingly reduction in the area of the leaf, reduction in the height plant and lateral stem number, all contribute to the reduction of plant's evaporation area and consequently reduction in the produced dry matter is the final result of the reduction in the plant's photosynthesis which in turn, is the result of water deficit stress. Under water deficit stress, stomatals become blocked or half-blocked and this leads to a decrease in absorbing [Co.sub.2] and on the other hand, the plants consume a lot of energy to absorb water, these cause a reduction in producing photosynthetic matters. It was also seen that as the increase of water deficit stress, its height plant, root diameter and stem yield decreased. Shoot reduction could be due to the reduction in the area of photosynthesis, drop in producing chlorophyll, the rise of the energy consumed by the plant in order to take in water and to increase the density of the protoplasm and to change respiratory paths and the activation of the path of phosphate pentose, or the reduction of the root deploy, etc. This fact indicates that exerting water deficit stress, the flowering shoot yield decreased of chicory. The results showed that highest leaf, pod and lateral stem numbers were achieved under planting density of 6 plant/[m.sup.2], because the plant increased its shoot for increase of assimilation matters by increase of refulgence absorb for compensation of low density in this condition. Therefore were increased leaf and lateral stem number under planting density of 6 plant/[m.sup.2]. Also pod number was increased under low density because flower reproductive cells increased in this condition by low rivalry between plants. The plant increases its root diameter for increase of water absorb under high density by high rivalry between plants, but root length increases under low density because be assimilation matters enough for increase of root length. The increase of planting density causes increase in height plant and debilitates stems by decrease of stem diameter.
The investigation showed that irrigation according and planting density are important effective factors on quantity and quality yield of plants that they can affect on quantity yield of chicory sorely.
The authors are indebted to Dr. Daneshian, Dr. Bigdeli and Dr. Shiranirad for providing financial assistance and continuous encouragement to carry out in the investigation.
Aliabadi Farahani, H., M.H. Lebaschi, A.H. Shiranirad, A.R. Valadabadi, J. Daneshian, 2008a. Effects of arbuscular mycorrhizal fungi, different levels of phosphorus and drought stress on water use efficiency, relative water content and proline accumulation rate of Coriander (Coriandrum sativum L.). Journal of Medicinal Plant Research, 2(6): 125-131.
Aliabadi Farahani, H., M.H. Lebaschi, A. Hamidi, 2008b. Effects of Arbuscular Mycorrhizal Fungi, phosphorus and water stress on quantity and quality characteristics of Coriander. Journal of Advances in Natural and Applied Sciences, 2(2): 55-59.
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(1) Mahdi Taheri Asghari, (1,2) Jahanfar Daneshian and (1) Hossein Aliabadi Farahani
(1) Islamic Azad University of Takestan branch, 10 km Quzwin-Zanjan highway, Azad University of Takestan, Faculty of Agriculture, No. 1 Iran.
(2) Seed and Plant Improvement Institute (SPII), P.O. Box: 4119, Mardabad Rd, Karaj 31585, Iran.
Corresponding Author: Mahdi Taheri Asghari,, Islamic Azad University of Takestan branch, 10 km Quzwin- Zanjan highway, Azad University of Takestan, Faculty of Agriculture, No. 1 Iran.
Table 1: Variance analysis Means Square Value Sources df Biological yield Lateral stem Replication 3 320.501 406.167 ** Irrigation according 2 15028.722 ** 13113.188 ** Error (a) 6 577.908 25.438 Planting density 3 307.714 8290 ** Irrigation according 6 4588.082 ** 343.438 ** Planting density Error (b) 27 621.586 40.995 CV (%) 16.37 7.13 Means Square Value Sources Pod number Height of plant Replication 13996.41 0.102 Irrigation according 1343165.688 ** 0.032 Error (a) 74970.66 0.039 Planting density 341060.41 ** 0.021 Irrigation according 28559.576 0.036 Planting density Error (b) 46365.873 0.031 CV (%) 19.8 18.48 Means Square Value Sources Leaf number Replication 2424.743 * Irrigation according 4414.521 ** Error (a) 331.493 Planting density 11088.188 ** Irrigation according 141.188 Planting density Error (b) 266.984 CV (%) 10.13 * and ** : Significant at 5% and 1% levels respectively. Table 2: Means comparison Treatments Biological Lateral stem Pod number yield (kg/ha) (stem/plant) (pod/plant) Irrigation according 50 mm evaporation 19708 a 10.7 a 135 a 100 mm evaporation 14133 b 9.4 b 92.1 b 150 mm evaporation 14123 b 5.5 c 83.6 c Planting density 6 plant/m2 9480 d 10.9 a 171.6 a 9 plant/m2 13824 c 8.2 b 107 b 12 plant/m2 18192 b 8 b 85 c 15 plant/m2 21870 a 8.2 b 89.1 c Treatments Height of Leaf number plant (cm) (leaf/plant) Irrigation according 50 mm evaporation 119.2 a 16.8 a 100 mm evaporation 100.3 b 15.6 b 150 mm evaporation 95.3 b 13.7 c Planting density 6 plant/m2 92.3 c 22 a 9 plant/m2 102.4 bc 16 b 12 plant/m2 108.7 ab 13.7 b 15 plant/m2 116.3 a 13.5 b Means within the same column and rows and factors, followed by the same letter are not significantly difference (P<0.05). Table 3: Means comparison of interaction Survey instance Biological Lateral stem Pod number qualifications (kg/ha yield) (stem/plant) (pod/plant) 50 mm evaporation 6 plant/m2 14594 c 26.1 a 217 a 9 plant/m2 16766 bc 11.5 bcd 144 bc 12 plant/m2 18950 b 6.7 efg 112.4 c 15 plant/m2 20789 a 4.5 hg 115 c 100 mm evaporation 6 plant/m2 11807 d 23.1 ab 152.1 b 9 plant/m2 13979 cd 10 cde 101.3 cd 12 plant/m2 16163 bc 6.4 efg 67.4 e 15 plant/m2 18002 b 3.3 hi 82.3 d 150 mm evaporation 6 plant/m2 11802 d 19.8 abc 145.7 bc 9 plant/m2 13974 cd 9.4 def 75.9 d 12 plant/m2 16158 bc 6.1 fg 75.3 d 15 plant/m2 17952 b 2.5 i 70 e Survey instance Height of Leaf number qualifications (plant cm) (leaf/plant) 50 mm evaporation 6 plant/m2 148.7 a 37.4 a 9 plant/m2 114.3 b 20 c 12 plant/m2 109 bc 12.7 def 15 plant/m2 92.3 cd 8.8 fg 100 mm evaporation 6 plant/m2 116.3 b 33.1 b 9 plant/m2 111 bc 19.1 c 12 plant/m2 102 bcd 12 efg 15 plant/m2 83.8 d 8.6 g 150 mm evaporation 6 plant/m2 114.5 b 30.7 b 9 plant/m2 109 bc 17.6 cde 12 plant/m2 97.5 bcd 11.8 efg 15 plant/m2 38.2 e 8 g Means within the same column and rows and factors, followed by the same letter are not significantly difference P<0.05 using Duncan's multiple range test.
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|Title Annotation:||Original Articles|
|Author:||Asghari, Mahdi Taheri; Daneshian, Jahanfar; Farahani, Hossein Aliabadi|
|Publication:||American-Eurasian Journal of Sustainable Agriculture|
|Date:||Sep 1, 2009|
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