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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In order to study the effects of different levels of nitrogen fertilizer and plant density on grain yield and its components in sunflower, an experiment was conducted using 'Record' cultivar at the Research Farm of College of Agriculture, Isfahan University of Technology in 1996. Four levels of nitrogen (0, 75, 150 and 225 kg/ha) and four plant densities (65000, 75000, 85000 and 95000 plants/ha) were used in a split plot arranged in a randomized complete block design with three replications. Developmental stages, plant height, stem diameter, head diameter, number of head per m2, grain yield, biological yield, harvest index, 1000-grain weight, number of grains per head, grain oil percentage, oil yield and grain protein content were measured. The results indicated that N fertilizer caused an extension of the growth period and means of days to physiological maturity. It also increased plant height, stem diameter and head diameter. While increasing plant density had an incremental effect on plant height, it negatively affected stem diameter and head diameter. N fertilizer up to 150 kg/ha increased the grain yield and biological yield, whereas higher levels of N fertilizer decreased both. Plant density of 85000 plants per hectare was observed as a suitable plant density, whereas the higher plant density had a negative effect on grain yield. N fertilizer via increasing the number of grains per head, and plant density via increasing the number of heads per unit area and also decreasing the number of grains per head influenced the grain yield. One-thousand grain weight was not affected by neither N fertilizer nor plant density. Considering the superiority of 150 kg/ha of N fertilizer and plant density of 85000 plants/ha for grain yield and oil yield, it appears that they could be recommended for producing desirable yield in the regions similar to the study region.

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The appropriate planting pattern of safflower in summer planting might be different from the planting pattern suitable for spring planting, and this has not been determined under Isfahan environmental conditions. A field experiment was conducted in the summer of 2000 at the Agricultural Research Station, Isfahan University of Technology, using a randomized complete block design with a split plot layout and three replications. Main plots consisted of three row distances (30 cm flat and 45 and 60 cm on bed), and sub-plots included three planting densities (30, 40, and 50 plant m^-2). The experiment was planted in June 13 using local safflower variety of Isfahan, named Koseh. Leaf area index, number of heads per branch, number of seeds per head, 1000-seed weight, seed yield per plant and harvest index were not significantly effected by row distance. Increase row distance significantly enhanced most developmental stages and increased number of branches per plant and per square meter, but significantly decreased number of heads per plant and per square meter and seed and petal yields. The highest seed and petal yields (3841 and 373 kg per ha, respectively) were obtained with 30 cm row distance. Plant density had no significant effect on number of branches per plant, number of seeds per head, 1000-seed weight and seed yield per plant and per unit area. Plant density significantly enhanced most developmental stages and increased leaf area index, number of branches and number of heads per square meter, but significantly decreased number of heads per branch and per plant, petal yield and harvest index. The highest seed yield without petal clipping (4341 kg per ha) was obtained with 30 cm row distance and 50 plants m^-2 treatment. The results obtained in this experiment indicate that this planting pattern might be appropriate for summer planting of safflower under conditions similar to this experiment.

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In order to evaluate the effects of plant densities (10, 13, 20 and 40 plant/m² ) on the yield and yield components of two cultivars (Partow, Gohar) and a line (VC-1973A) of mungbean [Vigna radiata (L.) Wilczek] a field experiment was conducted at the Seed and Plant Improvement Institute (SPII) of Karaj in Summer 1998. This research carried out in a factorial experiment based on Randomized Complete Block Design (RCBD) with 4 replications. The results indicated that VC-1973A line had the highest grain yield. This line has superiority to other cultivars, due to the early and uniformity of seed maturity and easy mechanized harvest. Plant density has a significant effect (p<0.01) on the grain yield, in such a way that the densities of 20 and 10 plant/m² outyielded the highest (2221 kg/ha) and lowest (1650 kg/ha) grain yield respectively. Among the yield components, only the number of pods per plant indicated a significant difference due to the plant density. Correlation coefficient between attributes indicated that the plant height and height of first pod internode had a positive correlation with the plant density, while the correlation of the plant density with harvest index (HI), branch number and pod number per plant was negative. More over it seems that the pod number per plant is the most important components of mungbean’s yield, because it has a high (r = 0.88) and significant (p<0.01) correlation with the grain yield.

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This study was conducted to evaluate the effects of four levels of irrigation (irrigation of plants after I₁ = 40, I₂ =60, I₃ = 80 , and I₄ = 100mm of evaporation from class A pan) and four plant densities(D₁ = 30, D₂ = 40, D₃ = 50 and D₄ = 60 plants/m²) on the seed yield and seed quality in three soybean cultivars(V₁=Hobit, V₂=Williams and V₃=Hill) in a split factorial design, based on the completely randomized blocks, with three replication for two years(2001 and 2002). The Irrigation treatments were assigned to the main plots, and the plant densities and cultivars to the sub plots. Results indicated that soybean seed yield was influenced by the different irrigation and plant density levels in the both years. Irrigation levels I₂ produced the highest and I₄ the lowest seed yield. It was also revealed that the plant density D₃ produced the highest and D₁ the lowest seed yields. Among the cultivars under investigation, V₂ produced the highest and V₃ the lowest seed yield . Seed oil and its protein contents both were affected significantly by the irrigation levels, plant densities and cultivars in both years. The plants receiving I₁ treatment had the highest and those having I₄, the lowest percentages of seed oil. Changes in the plant densities also affected seed oil and protein content. The plant density of D₁ caused the seeds to have the highest oil and lowest protein percentages. However, D₄ decreased oil and increased protein percentages. The highest water use efficiency was obtained from I₃ and that of the lowest value from I₁. The results also indicated that D₄ had the highest and D₁ the lowest water use efficiencies. Therefore, it could be concluded that the water use efficiency can be increased by increasing the plant density per unit area. The highest efficiency for biological and grain yield belonged to V₂ and V₁ respectively where as the lowest efficiency for those two mentioned characters belonged to V₁ and V₃, respectively. However, the treatment I₂V₂D₂ is recommended for higer the seed yield production per unit area.

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  Planting patterns through growth indices affect yield formation. To evaluate these effects on safflower, Koseh local variety of Isfahan, a field experiment was conducted in summer, 2004 at the Agricultural Research Station, Isfahan University of Technology. The experiment was performed using a randomized complete block design with a split plot layout and four replications. Main plots consisted of three row distances (20 and 30 cm flat and 45 cm on bed), and sub-plots included two planting densities (40 and 50 plant m^-2). The experiment was planted on June 25. The results showed that p lant canopy closed sooner, leaf area duration (LAD) increased and plant dry matter weight, leaf area index (LAI) and crop growth rate (CGR) were higher up to the middle of seed development as row distance decreased. In addition, the highest relative growth rate (RGR) and net assimilation rate (NAR) were obtained in 20 cm row distance. The highest (3039 kg ha^-1) and lowest (1930 kg ha^-1) seed yields were obtained with 20 and 40 cm row distances, respectively. Plant density did not affect the rate of canopy closure, CGR, RGR, NAR and seed yield. But, maximum plant dry weight, higher LAI and lower LAD values were obtained with 50 plants m^-2. The results obtained in this experiment indicate that 20 cm row distance with 50 plants m^-2 might be appropriate for summer planting of safflower, a local variety of Isfahan, under similar conditions.

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To study the effects of planting date and density on yield and its components in chickpea (Cicer arietinum L.) genotypes under dryland conditions of Khorram-Abad, an experiment was conducted during 2005-2006 growing season at the Agricultural Research Station of Lorestan Weather Department. Three sowing dates (March 6, March 21, and April 5) and two chickpea genotypes (Greet and Flip 93-93) with four plant densities (18, 24, 30 and 36 plants m^-2 ) were evaluated using a randomized complete block design with split-factorial design in three replications. Dates of planting were considered as the main plots, genotypes and plant densities were randomly distributed in sub-plots with factorial arrangement. The result showed that delay in planting from March 6 to April 5 significantly reduced number of pods per plant, number of grains per pod, 100-grain weight, grain yield and dry matter. Increasing plant density led to a significant decrease in number of pods per plant, number of grains per pod and 100-grain weight. However, grain yield and dry matter increased firstly with increasing plant density and then decreased. Planting date and density had no significant effect on harvest index, while genotype of Greet produced a larger number of pods per plant, grain yield as well as final dry matter. Also Flip93-93 produced a bigger number of grains per pod, greater grain weight and harvest index. The maximum grain yield was obtained with genotype of Greet at the first planting date in 30 plants m^-2 density. It could be concluded that due to thermal and drought stress occurring in late spring,, early planting of Greet genotype at 24-30 plants/m² may lead to a suitable increase in grain yield.

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In order to examine the effects of plant density on the morohological traits, yield and essential oil of peppermint, an experiment was conduced in Agricultural College of Tabriz University during 2005 and 2006. The treatments included four plant density levels ( 8,12 ,16,20 plants.m-2) with three replications. The treatments were based on a split plot design in time and result analysis of compound variance was done during two years. The two years’ results of the compound variance showed that the plant density affected the fresh yield, dry yield, the bush essential oil percentage and the essential oil yield, but it had no effect on the bush height and the leaf’s essential oil percentage. In the second year, the maximum fresh yield, dry yield, bush height, the bush essential oil percentage, and the essential oil yield were obtained. In the second year, the maximum essential oil yield in the density of 20 plant/m² was 21.15 li.ha-1.