Effect of Nitrogen Top Dressing at Later Stages on the Growth and Grain Yield of Rice

질소(窒素)의 만기추비(晩期追肥)가 수도(水稻)의 생육(生育)과 수량(收量)에 미치는 영향(影響)

In order to obtain information necessary for attaining maximum yield of rice by increasing nitrogen efficiency, effects of top dressing of nitrogen fertilizer at the later part of growing season were investigated and results obtained are summurized as follows: 1. The increased application of nitrogen fertilizer was very effective in increasing leaf areas and net assimilation rate of rice plants. The spikelets number per hill was also increased due to heavy nitrogen fertilizer. 2. The concentrated top dressing at the later part of plant growth apparently increased the crop growth rate at the reproduction stage and ripening stage of rice, respectively. The nitrogen efficiency was greatly improved by the concentrated top nitrogen dressing through the increase of effective tiller number and the improvement of production organ to non productive organ ratio. 3. The concentrated top nitrogen dressing at the later growing season was considered to be one of the most effective methods of fertilizer applications as well as cultivation of fertilizer resistant varieties for the high yield of rice and improving soil fertility.

우리나라 수도재배상(水稻栽培上) 중요(重要)한 과제(課題)의 하나인 질소효율(窒素效率)을 높이면서 다수확(多收穫)을 기(期)할 목적(目的)으로 생육후기(生育後期)의 질소추비(窒素追肥)의 효과(效果)를 구명(究明)코자 실험(實驗)한 바 다음 결과(結果)를 얻었다. 1. 질소(窒素) 증시(增施)에 의해서 엽면적(葉面績)과 순동화율(純同化率)이 향상(向上)되고 많은 영화수(穎花數)가 확보(確保)되었다. 2 질소(窒素)의 생육후기(生育後期) 중점시용(重點施用)은 생식생장기(生殖生長期)와 결실기(結實期)의 생장속도(生長速度)를 높였으며 분얼(分蘖)의 유효화(有效化)및 생산기관(生産器官) 대(對) 비생산기관(非生産器官) 비율(比率)을 크게 만들어 질소효율(窒素效率)을 높이는데 기여(寄與)하였다. 3. 수도(水稻) 다수확재배(多收穫栽培)에서 질소(窒素)의 생육후기중점시용(生育後期重點施用)은 내파성(耐把性) 품종(品種)의 재배(栽培)및 지력배양(地力培養)과 함께 유효(有效)한 방법(方法)이었다.