JWSS - Journal of Water and Soil Science

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Planting density, through its impact on the level of available environmental factors may have significant impacts on grain yield in safflower (Carthamus tinctorius L.). In order to investigate the impacts of plant density on grain yield, yield components and growth characteristics of safflower, a randomized complete block design field experiment with four replicates was conducted in spring-summer, 2000, at Lavark Research Farm (Lat. 32⁰ 32^, N and Long. 51⁰ 23^, E), College of Agriculture, Isfahan University of Technology, Isfahan, Iran. Arak-2811 and Kouseh safflower genotypes were seeded at 16.6, 22.2, 33.3 and 50 plants/m². For establishing these plant densities, plants were seeded in 12, 9, 6 and 4 cm distances, respectively, on ten 8-m-long rows spaced 50 cm apart in each plot. Plant density had no impact on plant growth stages with the exception of button formation. Genotype had significant effects on days to seedling emergence, button formation, and 50% flowering. While both number of days and accumulated growing degree-days for all growth stages decreased with an increase in plant density, Arak-2811 was earlier than Kouseh for most growth stages. Number of branches and heads per plant, number of heads per branch, number of seeds per head and harvest index showed significant decreases with increasing plant density. The decrease in the mentioned grain yield attributes was mainly negated by greater number of plants per m², leading to no significant variation in grain yield between plant densities of the two genotypes. Arak-2811 produced a significantly greater number of heads per branch and 1000-grain weight however, these differences did not lead to any greater grain yield compared to Kousehdue, mainly due to the greater number of branches in the latter. Neither of the leaf area index, leaf area duration, and crop growth rate varied significantly with plant density and between two genotypes, suggesting no difference in dry matter production capabilities of the two genotypes under environmental conditions of the present study.

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Despite its economic importance, not much information exists on growth and productivity of durum wheat in Iran and Isfahan. In order to evaluate growth, grain yield, and attributes in three durum wheat genotypes, Osta/Gata, Dipper-6, and PI40100, with five planting densities of 200, 275, 350, 425 and 500 seeds/m², a four-replicate RCBD field study with a spilt-plot layout was carried out in winter 2000 to spring 2001 at Lavark Research Farm, College of Agriculture, Isfahan University of Technology. Genotypes were the main-plots and planting densities, the sub-plots. Each plot contained six rows, spaced 25cm apart, each 6m in length. While Osta/Gata produced a greater spikes/m², 1000-grain weight and grain yield, PI40100 indicated a greater height, leaf area index (LAI) and biological yield, and Dipper-6 produced a larger number of grains per spike and harvest index, compared to the other two genotypes. Increasing plant density led to an increase in LAI, spikes/m², grain yield, biological yield and harvest index but a decrease in grains/spike and 1000-grain weight. Grain yield was positively correlated with spikes/m², grains/spike and 1000-grain weight, despite negative correlations with LAI and plant height. It may be concluded that with environmental conditions such as those encountered in Isfahan in 2000-2001, Osta/Gata can be planted at approximately 425 seeds/m², if an acceptable grain yield is to be achieved.

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A major source of photoassimilates deposited into the seeds is the closest photosynthetic source to the latter sinks. While the contribution made to grain yield by floral parts and the adjacent photosynthetic surfaces has been determined for a number of crop plants, such information lacks regarding safflower. Thus the present study was aimed at estimating the contribution of photosynthesis of safflower head and the two adjacent leaves to the grain yield of this oil seed crop. A 4-replicate RCBD field experiment was conducted at Lavark Research Farm, Isfahan U. of Tech., using four genotypes (Nebraska10, Kouseh, Arak2811 and K12) and three levels of shading (heads only, heads and the two adjacent leaves and control) on safflower heads following pollination, using khaki paper bags. Genotypes differed in terms of days to heading and maturity, height, number of heads per plant, number of seeds per head, 1000-seed weight, seed weight per head and grain yield per plant. Shading on safflower head and the two adjacent leaves led to a significant decrease in number of seeds per head, 1000-seed weight, seed weight per head, grain yield per plant and harvest index. There was not a significant difference between the two levels of shading treatment. It could be concluded that, with the environmental conditions experienced during spring 2003 at Isfahan, the photosynthetic products of safflower head and the two adjacent leaves may contribute to grain yield per plant by as much as 37 percent.

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Safflower (Carthamus tinctorius L.) is an oilseed crop and can have a considerable contribution to vegetable oil production in the country, since it has a high adaptability to different environmental conditions. This crop is grown in summer time as a second crop in Isfahan province. Therefore, this study was carried out to investigate the agronomic characteristics of the safflower breeding lines which were isolated from local populations of Iran in early spring and summer planting dates. Seven genotypes were evaluated at two planting dates, early spring (16 March) and summer (21 June), using a randomized complete block design (RCBD) with 4 replications at the research farm of Isfahan University of Technology. The results showed that the number of days to emergence, days to flowering and maturity and plant height decreased considerably in the summer planting date. However, the harvest index, seed yield per plant and seed yield per plot and oil yield increased in this planting date. Yield components were not significantly different in the two planting dates, except that 100-seed weight was significantly and considerably more in the second planting date. The average seed yield of genotypes was 2498 and 2845 kg/ha in spring and summer planting dates, respectively. In the first planting date, seed yield varied from 1876 Kg/ha, (for Kouseh genotype as check variety) to 2908 Kg/ha for E2428 line (selected from Isfshan population). In the second planting date, seed yield had a variation of 2124 to 3186 Kg/ha for the genotypes of S3110 (selected line from Khorasan population) and C111 (selected from Kouseh population), respectively. In the second planting date the check variety (Kouseh population) had a seed yield of 2965 Kg/ha. In both first and second planting dates, genotypes of E2428 and C116 (selected line from Kouseh population) had the maximum oil content in the seed, (33.9% and 32.3%د respectively). Genotype by planting date interaction was significant for seed yield and oil yield, since late planting date reduced seed yield in genotypes of S3110 and E2428, but it increased these traits in other genotypes.

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Defining interrelationship of growth analysis factors and yield of crop plants is important in the field crop production practices. This research was aimed at studying growth factors and grain yield of five maize hybrids, consisting of S.C.704, S.C.700, S.C.647, S.C.604, and S.C.301, using two 4-replicate RCBD experiments in Isfahan, in Summer 2004. While one experiment was irrigated normally, the other one was conducted under delayed irrigation conditions. Maize plants were seeded at 95000 plants/ha in 8-row plots, with rows spaced 0.70m apart and 0.15m distance between plants on each row. Delayed irrigation led to a significant decrease in LAI_max, LAD, LAD_Linear and LAD_s-m, but a significant increase in days to silking. While CGR_Linear significantly correlated with LAI_max, LAD, LAD_Linear and LAD_s-m, a significant correlation was observed between total biomass and grain yield. CGR_Linear, LAI_max, and LAD_s-m significantly correlated with total biomass, and grain yield significantly correlated with yield components, harvest index, CGR_Linear and LAI_max. In conclusion, an increase in LAI_max resulted in a higher CGR_Linear and in turn a greater total biomass. But, considering no significant correlation between total biomass and harvest index, it appears that with the genotypes and under conditions of the present study, allocation of dry matter to grain production did not correlate with the leaf area attributes of corn.

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The growth and fluorescence parameters of chlorophyll in four corn hybrids including two sweet (K.S.C. 403 and K.S.C. 404) and two grain hybrids (S.C. 500 and S.C. 700) were evaluated in response to Fe and Zn nutrition in a nutrient solution culture. This study was conducted in a randomized complete block design with a factorial arrangement with three replications at the Soilless Culture Research Center (SCRC). Corn hybrids were exposed to two Fe levels (5 and 50 µM Fe in the form of FeEDTA) and two Zn levels (0 and 2 µM Zn in the form of ZnSO4). Increasing Fe concentration in the nutrient solution increased F0, Fm, and Fv/Fm values by 48, 96, and 123%, respectively. The fluorescence parameters of chlorophyll were affected by corn hybrid and there were significant differences in F0 and Fv/Fm at 1% level and Fm at 5% probability level among the studied hybrids. Iron deficiency significantly (P<0.05) reduced the root dry weight of all the studied hybrids. Zinc deficiency resulted in a significant decrease in the root dry weight of H403 and H500 hybrids while no significant decrease was found in the root dry weight of the H404 and H700 hybrids under Zn condition. The results showed that corn hybrids varied significantly in their tolerance to Fe and Zn deficiency. Based on the results of plant growth and fluorescence parameters of chlorophyll, the studied grain corn hybrids were more tolerant to Fe and Zn deficiency conditions in comparison with sweet corn hybrids. It seems fluorescence parameters of chlorophyll might be suitable parameters to screen corn hybrids in their tolerance to Zn and particularly Fe deficiency condition.