Effect of winter planting on growth and seed yield of soybean (Glycine max L. Merr) genotypes in north Khuzestan in Iran

Sowing date and genotype are factors affect different growth stages and yield of soybean. To evaluate the effect of sowing date and genotype on seed yield of soybean a field experiment was carried out as split plot arrangement in randomized complete block design with three replications at Safiabad Agricultural and Natural Resources Research and Education Center, Iran, in 2016 and 2018. The main plots consisted of four sowing dates (21st Januray, 9th February, 23rd February and 9th March) and twelve soybean genotypes (2001, 2002, 504, Saba, Katoul, Saman, Sari, SK93, SG2, SG5, Williams and Salend) were randomized in sub-plots. Results showed that delaying in sowing date led to reduction of flowering and growth duration of all soybean genotypes. Number of pod per plant reduced by 42% in 9th March sowung date compared to 21st Januray. The highest (36 pods) and the lowest (16 pods) number of pods per plant belonged to SK93 and Williams, respectively. The highest (872 kg.ha-1) and the lowest (782 kg.ha-1) seed yield obtained from 21st January and 9th March sowing date, respectively. SK93 genotype had the highest (1291 kg.ha-1) seed yield. Results of this experiment showed that lower seed yield (872 kg.ha-1) for the first sowing date of winter-sown soybean was not economically viable. Considering seed yield of SK93, further experimets are required to identify soybean genotypes adapted to winter planting.