播種期の変動と灌漑の有無がグレインソルガム生育収量におよぼす影響

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This field research was conducted at the Experimental Farm of Nagoya University to examine growth pattern and yield production of irrigated and nonirrigated grain sorghum planted at various dates. Grain sorghum (Sorghum bicolor (L.) Moench) hybrid H-726 was planted on May 1, 15, June 1, 15, July 1, 1978 in rows 60cm apart and 3m long and thinned to 30 plants per row after emergence. In this experiment, 5 irrigated and 5 nonirrigated plots were used, each plot consisting of four rows. Fertillizers were applied at the rate of 3.0Kg N, 1.5Kg P_2O_5 and 2.0Kg K_2O per a as Urea 46% N, Fused Phosphatic fertilizer 20% P_2O_5 and Potassium Chloride 50% K_2O respectively. Nitrogen application was divided into three parts ; 30% prior to planting, 50% at 6th leaf shooting stage and 20% at flag leaf stage. Irrigated treatments received water 2 times a week during the growing season, while irrigation was stopped from 6th leaf shooting stage in the nonirrigated treatments. The results obtained are as follows ; 1. There was a remarkable increase in plant height, panicle length, number of leaves, number of grains per panicle and grain and dry matter yield in irrigated treatments compared with nonirrigated treatments at all planting dates. A similar result was obrained in previous experiments. 2. A declination of growth and yield was observed for plants planted on June 1 and 15 as compared with other treatments. This decline may be caused by high rainfall and low solar radiation during the early growth stages, although there was a gradual rise in temperature during this period. 3. From the dry weight of plant parts expressed as percentage of whole plant, it was observed that early planting (May 1) produced the highest panicle weight. When planting was postponed on May 15, only the dry weight of stem increased, while there was no change in the dry weight of leaf. Planting on June 1 increased dry weight of both stem and leaf. Later planting (June 15 and July 1) increased the dry weight of only the leaf. Therefore, it may be said that, translocation of nutrient elements into the panicle easily occurred at early planting (May 1). When planting was postponed (June 15 and July 1) more nutrient elements accumulated in the leaves and less translocated into panicle resulting in a substantial decrease of panicle weight. 4. Compared with later planting, early palnting (May 1, 15) resulted in higher grain yield in both irrigated and nonirrigated treatments. Although cumulative temperature during vegetative period was the same for both early and late planting, the length of vegetative period was longer at early planting. This seems to indicate that low temperature at vegetative period and high temperature at maturity are favorable conditions for grain sorghum.
日本作物学会の論文
1979-03-31

播種期の変動と灌漑の有無がグレインソルガム生育収量におよぼす影響

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