Seed growth, dry matter accumulation, yield and yield components of soybeans as affected by rates of N fertilizer
1993
Aphiphan Pookpakdi | Sawai Pongkao | Ancharee Nuntawong (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture. Dept. of Agronomy)
Study on the effect of nitrogen fertilizer on seed growth, rate and duration of seed filling period of soybean cultivar SJ 4, accessions KUSL 20017 and KUSL 20056 was conducted during January-November, 1988. This study composed of two experiments where fertilizer treatments consisted of ammonium sulphate at the rate of 0, 125, 250 and 375 kg N/ha applied as preplanting. Soybean seeds were inoculated with Rhizobium japonicum prior to planting. Nitrogen fertilizer caused an increase in yield per plant and yield per unit area as compared to nil, and the cause of yield increase was due to the increase in pod production. It was also found that nitrogen fertilizer caused an increase in leaf area index as well as total dry matter production. The effect of nitrogen fertilizer was significant in the experiment planted in the wet season. Among the soybean cultivars used, accession KUSL 20017 produced better growth and yield production. In spite of the fact that nitrogen fertilizer had caused an increase in yield, however, it did not exert any significant effect on rate and duration of seed filling period of soybeans. The reason is that nitrogen fertilizer applied at planting may have caused an increase in vegetative growth and produced higher amount of food reserve which is directly available to pod production process rather than seed filling development, which is occurred at a later stage of growth.
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