Seed Growth, Yield and Nitrogen Distribution in Various Plant Components of Soybean Variety S.J.4 as Affected by Different Levels of Nitrogen Fertilizer.

Abstract

The study on seed growth, yield, and nitrogen distribution in various plant components of soybean variety S.J.4 as affected by different levels of nitrogen fertilizer was conducted at Kasetsart University, Kamphangsaen Campus between October 1984 to August 1985. Four nitrogen treatments consisted of 0, 20, 40 and 60 kg N/rai in the form of (NH₄)₂SO₄ were applied to the soil prior to planting soybean. The experimental design was randomized complete block with four replications. The yield of soybean increased markedly in the plot receiving 60 kg N/rai. The number of pod per plant which is an index of seed numbers per area also increased significantly when receiving this particular level of nitrogen fertilizer. The number of seed per pod and seed size were not affected by nitrogen treatments. Eventhough the duration of effective seed filling was prolonged only with an application of nitrogen at high rate (60) kg N/rai, days to maturity were remarkedly prolong with increasing rate of nitrogen application. However, the rate of seed filling period was not affected by nitrogen treatments. Regarding nitrogen distribution in various plant parts, it was found that nitrogenous compounds were generally traslocated from the vegetative parts and pod wall to seed during seed filling period of soybean.