Effects of Different Planting Dates on Growth and Yield Component in Two Ecotypes of Soybean at Paddy Field Condition in the Mid Part of Korea

This experiment was carried out to investigate the differences of the growth and yield characteristics at different planting dates in two soybean ecotypes from 2012 to 2013. Three summer types of soybean varieties, Seaol, Chamol, Hanol and three autumn types, Hwanggum, Taegwang, Daepung were planted 4 times from 1 May to 1 August in paddy field at the experimental field of National Institute of Crop Science in Suwon, Korea. Emergence rate was shown to difference among the varieties and the lowest planting at 29 June cause of the severe drought in 2012. The emergence period and days to flowering shortened as planting date delayed regardless of varieties. Emergence period more reduced in 2013 than in 2012 and days to flowering was more shortened in the summer types than in the autumn types. Stem height, number of main stem nodes, stem diameter were different among the summer types and the autumn types and reduced as planting date delayed. Number of main stem nodes and number of branch were different but no difference were observed in the stem height and stem diameter between 2012 and 2013. The number of pod per plant was the highest planting at 21 May and the lowest planting at 1 August and more in the autumn types than in the summer types. The number of seed per plant was the highest at planting 29 June and the lowest at planting 1 August and more in the autumn types than in the summer types and more in 2012 than in 2013. It was observed that one hundred seed weight was reduced rapidly planting at 1 August and heavier in the summer types than in the autumn types and heavier in 2013 than in 2012. Seed yield was the highest at planting 29 June and the lowest at planting 1 August, and 85kg/10a higher in the autumn types and 47kg/10a higher in 2012 than in the summer types and 2013, respectively.