Studies on the Limit of Possibility of the lncrease in Number of Leaves and Grains of the Main Stem of Rice Varieties. 3. Influence of Sunlight lntensity

1.In this experiment, the influence of different sunlight intensity on the number of leaves and grains and the heading time of the main stem was investi-gated. The different intensities of sunlight were given to 5 rice varieties after transplanting. 2. Under the condition of the hard intensity of sunlight(using the sunlight reflector, the ratio of the sunlight intensity: 107%),the number of leaves of the main stem and the number of tillers increased and the number of grains of the main stem was inclined to decrease. The heading time of the main stem was hastened a little in the case of late varieties such as “Senbon-asahi” and 4‘Norin N0.18” and was delayed in the other varieties. 3. Under the condition of weak intensity of sunlight (using victoria lawn to cover the plants, the ratio of the sunlight intensity: 92%),the heading time of the main stem was hastened a little showing decrease in the number of leaves of the main stem and the number of tillers, and the number of grains of the mainstem increased.

水稲品種

主稈葉数

籾数

増加可能限界

日照