Effect of planting date and plant density on vegetative characteristics and yield of soybean in Gorgan

To study the effects of planting date and plant density on phonological, and morphological characteristics, as well as yield components and seed yield of soybean (Glycine max L. Merill), a field experiment was conducted in a split plot arranged in a randomized complete block design with three replications at the Agricultural Research Station of Gorgan (former Iraqi Mohaleh) in 2011. Four planting dates (28 May, 12 June, 27 June and 12 July) were the main plots, and four plant densities (21, 28, 35 and 42 plants per square meter) with planting patterns of (30 × 8, 35 × 8, 45 × 8 and 60 × 8 cm) were sub-plots. The results of analysis of variance showed a significant effect of planting date on days to flowering, days to maturity, number of nodes on the main stem, plant height, number of pods per main stem, seed weight and seed yield. Mean comparison using DMRT revealed that the highest and lowest number of days from planting to maturity were obtained at the first and fourth planting dates, respectively. Mean comparison also showed that maximum yield (4325 kg ha-1) was produced at 28 May planting date with plant density of 28 plants m-2. It might be concluded that the cultivar studied in this experiment could produce highest yield using favorable environmental conditions when planted on 28 May with planting density of 28 plants m-2 .