グレインソルガムの収量とたんぱく含量におよぼす窒素施肥と土壌乾燥処理との効果

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To investigate the effects of nitrogen fertilization and drought treatments on the grain yield and protein content of grain sorghum, pot experiment was carried out in the Nagoya University Experimental Farm under glasshouse conditions in 1978. The seeds of grain sorghum (Sorghum bicolor (L.) Moench) hybrid H-726 were planted on May 15 in 1/2000 a Wagner's pot and then thinned to 2 plants per pot after emergence. Each treatment included 5 pots. The soil was fertilized with N-P-K fertilizer prior to planting using 10g fused phosphatic fertilizer, 6g potassium chloride and 2 or 4g urea according to the treatments. The nitrogen fertilizer was applied three times during the growing season, pre-planting, 6th leaf emergence stage and heading stage at the rates of 2-2-2g respectively in control, and in the treatments, the following rates were applied : 2-4-2g, 2-4-4g, 2-2-4g and 4-4-4g. These rates of nitrogen application i.e. 2-4-2g, 2-2-4g and 2-4-4g were combined with daily irrigation (first group), 10 days drought at 6th leaf emergence stage (second group) and first wilting conditions at 12th leaf emergence stage (third group). All treatments were irrigated daily in the same manner as the control except for the first wilting and drought conditions when irrigation was suspended in order to impose first wilting and 10 days drought at the respective growth stages. Heading occurred at the same time on July 7 and the plants harvested on August 25. The results obtained are summarized as follows : 1. Although the length of panicle and plant height increased in 4-4-4g treatment, the growth and grain and fodder yields decreased more than that in control. 2. In general, the growth and grain and fodder yields decreased in all the 2-4-4 treatments than that in 2-4-2 and 2-2-4 treatments. It seems that 2-4-4 was also heavy application for grain sorghum in this experiment. 3. Nitrogen content in grain increased in all the 2-4-2 and 2-2-4 treatments than that in 2-2-2 (control) and 4-4-4 treatment and in the vegetative parts, the nitrogen content increased with higher application of nitrogen. Therefore, it seems that with higher application of nitrogen, the absorbed nitrogen by the plant accumulated more in vegetative parts and less translocated in the grains. 4. In general, with the higher application of nitrogen (2-4-4 and 4-4-4 treatments), percent crude protein in grains increased than that in control, on the contrary, the grain yield decreased. There was no significant differences between treatments for percent crude starch in grain. These results confirmed the results of our previous water culture experiments. 5. Dry weight of panicle, dry weight of grains per panicle, number of grains per panicle and nitrogen content in grains increased in the second group treatments more than that in first group treatments. Because the rates of nitrogen application were the same in the two groups, it seems that, this increase was caused by drying of the soil for a short period. 6. In our previous experiment it was observed that dry weight of panicle, grain yield and nitrogen content in grain increased in first wilting treatments more than that in control. Therefore, the slight decrease in the third group compared with the first group was unexpected. In this experiment, number of grains per panicle decreased in plants which were passed through first wilting at 12th leaf emergence stage as was observed in our previous experiments. This decrease seems to be caused by the drying of the soil to impose first wilting at 12th leaf emergence stage which almost coincided with young panicle formation stage (11th leaf emergence stage). The decrease of grain yield and dry weight of panicle in this experiment seems to be caused by extending drought period (15 days, more than two times that in the previous experiment) to reach first wilting conditions due to climatic factors. 7. Although the percent crude protein in grains increased in all treatments than that in control, and was almost the same in three groups, the increase of nitrogen content in grains in second group and decrease of nitrogen content in grains in third group compared with first group were due to increase and decrease of grain yield respectively.
日本作物学会の論文
1979-11-30

グレインソルガムの収量とたんぱく含量におよぼす窒素施肥と土壌乾燥処理との効果

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