Difference in Yield and Growth of Soybean Cultivar S.J.4 When Planted at Khon Kaen and Kamphaeng Saen Using Different Planting Dates and Plant Population Densities

Abstract

The study on growth, yield production and cultural practices suitable for soybean (Glycine max (L.) Merrill) cultivar S.J.4 was conducted between 1987-1991. This study presented a collaborative effort between Department of Agronomy, Kasetsart University and Department of Plant Science, Khon Kaen University. The objective of this study was to establish data-base of certain Thai soybean cultivar and its response to environments and cultural practices of the new production areas in the northeast and central plain in which Khon Kaen and Nakorn Pathom provinces were the representatives. In the serial sowing date experiments in which soybean cv. S.J.4 were planted at one month interval in 1987-88, it was shown that soybean cultivar S.J.4 responded similarly to temperature both at Khon Kaen and Kamphaeng Saen. At Khon Kaen, the effect of temperature was more pronounced than those planted at Kamphaeng Saen. On the average, S.J.4 soybean flowered earlier at Khon Kaen and maturity date was shorter at Khon Kaen than at Kamphaeng Saen, therefore dry matter and seed yields per plant of soybeans grown at Kamphaeng Saen were generally higher than those planted at Khon Kaen. It was also indicated that planting soybeans at Khon Kaen in early rainy season would result in high yield production. While, at Kamphaeng Saen, the yield obtained from soybeans planted after rice were higher than those planted in the rainy season. Increasing plant population densities from 200,000 to 800,000 plant. ha-1 would result in the increase in dry matter and seed yield per area of S.J.4 soybean grown at Kamphaeng Saen and Khon Kaen. There was only slight difference in dry matter yield per area obtained from various plant population treatments used at Kamphaeng Saen. However, the dry matter yield at Khon Kaen was higher in early rainy season than in the dry season due to favorable moisture, relative humidity, and night temperature at Khon Kaen. It can be concluded that planting soybean both at Khon Kaen and Kamphaeng Saen using high plant densities resulted in higher seed yield in early rainy than in the dry season. However, the yield difference between both seasons was greater at Khon Kaen than those found at Kamphaeng Saen.