Jong-Ho Seo

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.

Change of Weeds Occurrence, Early Growth and Yield of Soybean at Simultaneous Planting with Rye as Living Mulch

Introduction of rye living mulch in soybean production is important for labor-saving and reduction of herbicide usage for weeding by weed suppression and for soil conservation by mulching of rye. Soybean and rye were row-planted and broadcasted simultaneously at different planting times (May 15, May 25, June 5) and row widths (35 and 70 cm) in 2010, different soybean cultivars (Daepoong, Singi) and planting times (May 15 and June 1) in 2011, respectively, and investigated weed occurrence, early growth and yield of soybean. Acalypha australis, which is known to herbicide-resistant weed, could be controlled ecologically by rye living mulch. Occurrence of Acalypha australis was controlled effectively also by mixture of alachlor and linulon at no mulch in 2011. Early growth amount of soybean plant per area was increased by narrow row width (35 cm) at rye living mulch, which was helpful in the control of weeds, but grain yield of soybean with narrow row was decreased compared to conventional row width (70 cm) at the planting in early June. It is concluded that soybean planting as row width 70 cm in early June is proper at simultaneous planting with rye.