施肥對于稻熱病之發生及藥劑撒佈效果之影響－（第二報）田間之施肥與稻熱病發生之關係

Abstract

為明瞭稻作於田間施用三要素之用量及施肥時期對于稱病害發生之關係，而舉行此試驗。玆將其主耍結果列舉如後： 1. 如氮肥之施用量增加2倍時，無論燐及鉀肥同時增加或較少者，葉、穗稻熱病之發生最多。 2. 氮及燐肥為普通量，而且鉀肥之施用量增加1.5倍或2倍時，病害之發生程度較輕。 3. 稻紋枯病之發病狀況與稻熱病之罹病狀況略同。 4. 三要素中對病害之發生最有密切之關係者為氮肥。 5. 稻穀之產量與病害之發生程度成為反比例。即無論稱熱病、紋枯病或葉鞘腐敗病之發生多時，其產量為低。 6. 增加鉀肥，而且一半為基肥，其餘為追肥時無論對病害或產量之影響皆最佳。 The relation between the prevalence of rice blast (Piricularia oryzae) disease, and rates and time of N. P. K. fertilizer application were studied. The result indicated that the degree of leaf and neck blast disease infections were greatly increased, despite of simultaneous increase of decrease of phosphorus and potash fertiliers. The blast disease infection was lighter when the N. P. K. fectilizers were applied at the rates of 80, 60, 60 or 80 kilograms per hactre respectively. With regard to the rates of fertilizers application the prevalence of sheath and leaf spots was similar to that of blast disease. Among the three elements applied, nitrogen fertilizer tended apparently to induce the disease infections. The grain yield was greatly reduced as the result of infections with blast, leaf and sheath spots, and sheath rot diseases, howevee, the grain yield was freatly improved when the total amount of potash was increased, and a half of which was used as basic manure and the other half was used as top-dressing.