Effect of amount of nitrogen fertilizer at sowing and flowering on nitrogen fixation and yield of mungbean (Vigna radiata (L.) Wilczek)
1988
Sawai Pongkao (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture. Dept. of Agronomy) | Wiraphong Inthong
Application of 15 kg N/ha to mungbean (Vigna radiata (L.) Wilczek) was superior to nil in all characteristics measured especially produced yield 23 per cent higher and statistically significant. The application of nil and 30 kg N/ha at flowering was superior to 60 and 90 kg N/ha in nodule dry weight and fixation activity. Though the four rates of N applied at flowering did not cause the difference in yield to be statistically significant, however 60 kg N/ha tended to produce the highest yield. The cause of failure in lifting up yield plateau might have been due to various factors. Firstly, mungbean is classified as "self destructive" plant. When its N requirement for seed development from soils is not sufficient, the translocation of N from vegetative parts is forced to have taken place. Thus it causes the maturity of different parts earlier than expected especially dropping of leaves which is the main site for photosynthate production. Secondly, seed filling period in mungbean is only about 15 days which is too short for efficient seed production. Thirdly, the mineralization process of urea fertilizer applied to mungbean took place in relatively longer period, thus the plant cannot make use of nitrogen applied at flowering in time for seed production. And lastly mungbean which is classified as "self destructive" usually does not respond to nitrogen fertilizer applied because nitrogen absorbed partly is utilized for nitrogen fixation process.
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