Growth and survival rate after maturity in Oryza sativa L. and O. glaberrima Steud

摘要

Ten cultivars of O. sativa (6 japonica, 2 indica and 2 japonica X indica) and 5 cultivars of O. glaberrima were grown in pots. Some plants of each cultivar were cut at 10 cm above the ground at maturity, and the others remained uncut. Both were grown under two different day-length conditions with a suitable temperature. The growth state at maturity, changes in the number of living tillers after maturity and survival rate after maturity were examined. Starch content of stems (stem + leaf sheath) ofO. sativa at maturity tended to be higher than that of O. glaberrima. Nodal root number and total leaf length of the tiller bud from the node of a stem section at maturity were greater in O. sativa than in O. glaberrima. New tillers appeared in both O. sativa and O. glaberrima after maturity. The number of living tillers after maturity was always greater in O. sativa than in O. glaberrima, although the relationship was reversed for some period in the long-day uncut plot because of the appearance of newtillers from higher nodes. Long-day and uncut conditions enhanced the survival of tillers. In O. glaberrima, the survival rate of all cultivars at 250 days after maturity was nil. In O. sativa, survival rate at 250 days after maturity was higher in japonica cultivars than in indica and including japonica X indica cultivars. All plants of some indica cultivars had died before 250 days after maturity. The long-day condition increased the survival rate. The continued appearance of new tillers in both O. sativa and O. glaberrima after maturity suggested that both O. sativa and O. glaberrima had potential perennial ability, although the perennial ability of O. glaberrima was very small compared with that of O. sativa.