Studies on the Limit of Possibility of the lncrease in Number of Leaves and Grains of the Main Stem of Rice Varieties. 2.Influences of Long Day-Length and Removing Tillers

1.The influences of long day-length and removing tillers during period from transplanting to fruiting stage on the heading time and the number of leaves and grains of the main stem were examined with 5 varieties of paddy rice. The rice varieties used for this examination were as follows: (1)Mutuhikari Early variety (2) Norin N0. 1 Early variety (3) Kameji Medium variety (4) Senbon-asahi Late variety (5)Norin N0.18 Late variety 2.By removing titters in which all tillers of the plants were cut off as soon as they appeared, only the main stem being left, the number of leaves of the main stem increased and a conspicuous increase in the number of grains of the main stem was seen. The heading time of the main stem was somewhat late in the early varieties and was hastened a little in the medium and late varieties. 3, Under the condition of long day-length(illuminated all night),the number of leaves of the main stem increased and the heading time of the main stem was later than the normal by about 20 days. The number of grains of the main stem was decreased in the early and medium varieties and was increased in the late varletles. 4. By using both treatments (removing tillers and long day-1ength),the number of leaves and grains of the main stem increased and the heading time of the main stem was late. These results were pointed as the synthesis of the effects of each individual treatment.

水稲品種

主稈葉数

籾数

雑加可能限界

長日処理

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