Effect of Nitrogen and Balanced Application of NPK on the Low Temperature Injury of Paddy Rice

질소(窒素) 및 삼요소(三要素) 균형시비(均衡施肥)가 벼의 냉해(冷害)에 미치는 영향(影響)

In 1980, the abnormal low temperature was lasted during the late stage of rice growing season, thus low temperature injury occurred severely. The severity of the injury and nutrition absorption were investigated. The result obtained were summarized as follows: 1. It was considered that the severe low temperature injury of rice was caused by the low temperature and shorts of sunshine in the late growing season of rice, especially, the minimum air temperature which was lasted for a few days below critical reproductive growing temperature in the meiosis stage affected high the injury. 2. The low tmperature injury was lightened in the no nitrogen applied plot, and becoming severe with high nitrogen levels, but the balanced application of NPK lessened the low temperature injury. 3. The low temperature injury was more severe in Indica and Japonica hybrid than in Japonica cultivar, and the injury was shown as sterilizing, degraded spiklets, ill emerging of head and inhibition of nutrition absorption, etc. 4. Under the low temperature condition, $SiO_2$ content of rice plant was significantly reduced according to the increase of nitrogen levels. 5. Under the low temperature condition, the optimum application amount of nitrogen for Milyang 23, was 13, 6 kg/10a, this was approximately 10kg/10a smaller than average in usual year. The highly reduced rice yield was resulted from the cool injury, and the reducing rate of yield was larger in Indica and Japonica hybrid cultivar than in Japonica cultivar.

'80년도(年度)는 수도재배기간중(水稻栽培期間中) 이상저온(異常低溫)이 계속(繼續)되었으며 냉해피해(冷害被害)가 컸으므로 냉해(冷害)의 양상(樣相)과 정도(程度) 및 영양흡수(營養吸收)와의 관계(關係)를 조사(調査)한 결과(結果)는 다음과 같았다. 1. '80년도(年度) 벼의 냉해(冷害)는 수도생육(水稻生育) 후기(後期)에 계속(繼續)된 저온(低溫) 및 일조부족(日照不足)과 더불어 감수분열기(減數分裂期)에 있었던 생식생장(生殖生長) 한계온도(限界溫度) 이하(以下)의 저온(低溫)에 크게 영향(影響)을 받았기 때문인 것으로 사료(思料)된다. 2. 삼요소중(三要素中) 질소무시용구(窒素無施用區)에서 냉해피해(冷害被害)가 적었으며 질소시용량(窒素施用量)이 많을수록 냉해(冷害)가 심(甚)한 경향(傾向)이었고 삼요소(三要素) 균형시비(均衡施肥)으로 냉해(冷害)가 경감(輕減)되었다. 3. 냉해(冷害)는 통일계품종(統一系品種)이 일반계품종(一般系品種)보다 심(甚)한 경향(傾向)이었고 냉해(冷害)는 불임(不稔), 영화퇴화(穎花退化), 추수불량(抽穗不良) 및 양분흡수(養分吸收) 억제등(抑制等)으로 나타났다. 4. 저온하(低溫下)에서는 질소시용량(窒素施用量)이 많을수록 식물체내(植物體內) 규산함량(珪酸含量)이 유의성(有意性)있게 감소(減少)되었다. 5. 냉해조건하(冷害條件下)에서의 통일계품종(統一系品種)의 질소비료(窒素肥料) 시용적량(施用適量)은 13.6kg/10a으로서 예년(例年)보다 약(約) 10kg/10a 적었으며 수량(收量)도 크게 감소(減少)되었고 감소율(減少率)은 통일계품종(統一系品種)이 일반계품종(一般系品種)보다 심(甚)하였다.