Studies on the Culture for Seed Production of Italian Ryegrass (Lolium multiflorum Lam.) : I. Nitrogen level, ratio of split application and time of top dressing

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  • MOMMA Eihide
    National Grassland Researcn Institute:(Present address)Hokkaido National Agricultural Experiment Station
  • SUZUKI Shinji
    National Grassland Researcn Institute

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Other Title
  • イタリアンライグラスの採種栽培に関する研究 : I.窒素施用量・分施割合および追肥時期
  • イタリアンライグラスの採種栽培に関する研究-1-窒素施用量・分施割合および追肥時期
  • イタリアンライグラス ノ サイシュ サイバイ ニカンスルケンキュウ 1 チッソ

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The effects of the amount of nitrogen application, the ratio of split application, that is, the proportion of basic to top dressing and the time of top dressing were investigated in early-heading Italian ryegrass, Waseaoba, grown for seed. The seed yield was increased by raising the amount of nitrogen throughout the tested range from 0 to 12kg/10a. Split application of nitrogen produced a higher seed yield than the plot applied all nitrogen as basic fertilizer and the difference in the seed yield between 8kg N/10a (8N) and 12kg N/10a (12N) became smaller by splitting the nitrogen application. The seed yield was higher in the proportion of one basic to three top dressing (1-3) and two to two (2-2) in 4N and 2-2 in 8N and 12N than in the other proportions in the same amount of nitrogen, thus the seed yields of 2-2 and 1-3 in 4N and 2-2 in 8N became higher than that of the plot applied all nitrogen as basic fertilizer in 8N and 12N, respectively. This shows the marked improvement of nitrogen efficiency. An increase in the seed yield due to increased nitrogen application and split application of nitrogen was produced by the increase in number of ears and/or number of seeds per ear. From a comparison among times of top dressing in spring, nitrogen applied on April 13, the time of rapid stem elongation around 2 weeks after the beginning of stem elongation, was recognized to be the most beneficial for seed. Lodging at the beginning of flowering time tended to increase by raising the amount of nitrogenous fertilizer and by splitting the application of it. Judging from these experimental results, the following method of nitrogen application to Italian ryegrass grown for seed would be recommended. The amount of nitrogen application is recommended to be 8 to 12kg/10a, which should consist of a half as basic dressing and another half as top dressing at about 2 weeks after the beginning of stem elongation, when they are rapidly elongating. Taking into account of nitrogen efficiency and lodging, however, the amount of nitrogen application would be desirable to be less within the recommended amount.

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