Effects of sowing date on seed yield and yield attributes of soybean

The experiment was carried out at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during the period from November 2003 to June 2004 to find out the effect of sowing date and variety on the yield and yield attributes of soybean. Eight sowing dates viz. 17 November, 2 December, 17 December, 1 January, 16 January, 31 January, 15 February and 1 March, and two soybean varieties viz. Shohag (PB-1) and Bangladesh Soybean-4 (G-2) were included as experimental treatments. The experiment was laid out in a split-plot design with three replications assigning sowing date in the main plots and varieties in the sub plots. The highest seed yield of 221.11 g re was obtained from 17 December sowing which was reduced by 16, 23, 28, 32, 34, 43 and 44% for 17 November, 2 December, 1 January, 16 January, 31 January, 15 February and 1 March sowings, respectively. The highest seed yield at 17 December sowing was mainly attributed to the highest number of fertile pods planfl, number of seeds m-2 and the highest biological yield. The yield of Shohag was 21% lower that that of Bangladesh Soybean - 4 (178.61 g m-2). The interaction between sowing date and variety was significant for yield and most of its attributes except for straw yield and number of seeds pod-1. The result revealed that higher seed yield of Bangladesh Soybean-4 could be obtained from sowing between mid November and mid December while that for Shohag could be possible from sowing betwe,in mid December and mid January.