Comparison of nodal distribution of soybean cultivars' yield components in different planting dates.

Aim of this study was to determine planting date effects on Nodal distribution of yield and its components in nine indeterminate soybean cultivars. To meet such a purpose, a split plot design based on a randomized complete block layout with six planting dates (24th April, 10th and 27th May, 10th and 26th June and 11th July) as main plots and nine cultivars (Williams, Clark 63, SRF 450, Steele, Hark, Corsoy, Blackhawk, Woodworth and Bonus) as sub plots have been used in five replications. The results have clarified that height, branch number, pod number, grain number and seed weight plays an important role on yield increasing. So that, medium maturity cultivars have producing maximum number of pods, grains and seed weight in their upper two third of canopy. Also, various cultivars have indicated different reactions for yield components, so that, Williams and Woodworth (medium maturity cultivars), Steele and Bonus (early maturity cultivars) have produced larger seeds in different planting dates. Generally, Woodworth, in comparison with the other cultivars, demonstrating superiorities in all the considered traits. Maximum amount of pod number, grain number and seed weight in early maturity cultivars was belong to 27th of May planting date, however, for Woodworth and Clark 63 (medium maturity) it was 24th of April and 27th of May, respectively. The highest 100 seed weight per node were produced at 26th of June and 27th of May planting dates by Woodworth and Corsoy, respectively. Differences between planting dates for 100 seed weight in Clark 63 and Bonus were not significant.