GROWTH AND YIELD OF JAPONICA-INDICA HYBRID RICE

Japonica-Indica hybrid rice lines produced tillers vigorously during t he 30-day period after transplanting and exhibited a high degree of he terosis in terms of crop growth rate (CGR). Though the degree of heter osis decreased thereafter, it rose again after heading, contributing t o the good characteristics of maturation in hybrid rice. High yield of hybrid rice lines was attained by the summation of the increase of ea ch yield component. Response of hybrid rice to fertilizer was distinct ive with the enhancement of both dry matter production and yield assoc iated with the large amount of fertilizer applied. Tolerance to unfavo rable environments such as low temperature and low light intensity was higher than that of the parental varieties at the vegetative stage, w hereas at the reproductive stage it was lower than that of Japonica va rieties. Thus, the Japonica-Indica hybrid rice lines appear to have th e potential to achieve a superhigh yield in the northern region of Jap an.