Study on Productive Ecology of a High Yielding Japonica-Indica Hybrid Rice Cultivar "Suweon258"

[摘要] Two Japonica-Indica hybrid cultivars, Suweon258 and Akenohoshi, and a Japonica cultivar, Reiho, grown in the paddy field, were investigated on their growth responses to solar radiation, transplanting time and planting density. The high yielding mechanism of Suweon258 was elucidated by comparing the growth features of the three cultivars. In Suweon258 the number of grains per head was large (122 on the average) and less changeable (CV=10%) under the different growth conditions. Therefore a large increase was observed in the number of grains per unit area under the growth conditions such as dense planting where the number of tillers per unit area was highly increased. Suweon258 had vigorous tillering and the number of tillers varied largely with growth stage. After the maximum tiller number stage, the number of tillers rapidly decreased, and finally reaching about 60% of the maximum. In addition, Suweon258 was characterized by the erect grass type. By the joint effect of these features the light condition in the plant population at the ripening stage was improved and a comparatively high percentage of ripened grains was obtained even under the dense planting conditions. In Suweon258 the duration from transplanting time to heading time was roughly fixed at 80 days, during which the accumulated air temperature was also almost constant, about 2, 000°C. As the heading time progressed in parallel with movement of the transplanting time, it was easy to bring the ripening stage to the time of most favorable climate by choosing the transplanting time. Suweon258 was recognized as a high yielding cultivar, producing more than 800kg/10a in hulled grains. Early season transplanting and dense planting, both were the essential factors needed to realize the high yielding potential of the cultivar.

[学科分类] 农业科学（综合）

[关键词] Accumulated air temperature;移植期;High productivity;栽植密度;Japonica-Indica hybrid;水原258号;Planting density;積算気温;Solar radiation;多収性;Suweon258;日印交雑稲;Transplanting time;日射量