اثر رژيم هاي مختلف آبياري و تراكم كاشت بر ويژگي هاي رشد، عملكرد و اجزاي عملكرد سه رقم سويا در كشت دوم

Effects of Different Irrigations and Plant Densities on Vegetative Characteristics, Yield and Yield Components of Three Soybean Cultivars [Glycine max (L.) Merr.] as Second Crop

A split plot factorial experiment based on randomized complete block design, with three replications was conducted to study the effects of four irrigation regimes (Ii, 12, I3 and I4: irrigating plants after 40, 60, 80 and 100mm evaporation from class A pan, respectively) and four plant densities (D1=30, D2=40, D3=50 and D4=60 Plants/m2) on vegetative and reproductive characteristics and seed yield of three soybean cultivars (V1= Habit, V2= Williams and V3=Hill) for two years (2001 and 2002). Irrigation treatments were assigned to the main plots, and plant densities and cultivars to the sub-plots. The results showed that the highest and lowest seed yields were produced by I2 and 14 treatments, respectively. It was also revealed that the highest seed yield was produced by V2 with plant density of D3, and lowest by V3 with D1 plant density. Highest growth of vegetative and reproductive characteristics was also due to 12 irrigation regime. Lower plant densities decreased seed yields of single plants, while it increased the yield per unit area. Vegetative and reproductive growth of most of the single plants characteristics decreased by higher plant populations per unit area. Varietal responses to different plant populations were different in such a way that VI, V2 and V3 produced highest seed yields with 60 plants/m2 (D4), 50 plants/m2 (D3) and 40 plants/m2 (D2) respectively.