Fffects of Irrigation at Various Times on the Growth and Yields of Barley and Wheat.

[摘要] Barley (variety Sekitori Sai-No. 1) and wheat (variety Norin No. 50) were grown on a diluvial clay loam soil in every season during 5 years, 1949-53, and the relations of the irrigation period and the growth and yield of the crops were studied, the results being as follows: 1. Though the grain yields were bound more materially affected by the amount of precipitation irrigation, either in the middle of March or in April was effective to increase them. Winter irrigation tended to reduce the yields. The increase in grain yields due to irrigation was generally more conspicuous in wheat than in barley. The barley yield in the irrigated plots showed decided increases only in dryer years, 1949 and 1952 being such cases, while that of wheat increased almost every year of the experiment giving increments of ten to twenty percent of the yield from the unirrigated plots in dry years. 2. The increase in grain yield by spring irrigation was ascribed to those in fruitful tiller percentage, in culm-length and in grain weight per 1000 kernels. 3. The reasons why winter irrigation did not favoured the yield, even reducing it in some cases, might be explained as follows: a) Both the crops concerned do not require much water in the early and middle stages of their growth. b) In winter, the soil moisture does not decrease so much as in spring. c) Frost and ice crust formation, promoted by irrigation, and besides the soil temperature fall due to their thawing, may retard the plant growth. such adverse effects of winter irrigation upon barley crops may probably be due to shallowness of root zones and high susceptibility to water lodging of soil of the plant as compared with wheat. 4. It may be duely concluded that irrigation of wheat or barley should be practised most favourably in spring.

[学科分类] 农业科学（综合）