Effects of Inabenfide 〔4'-chloro-2'-(α-hydroxybenzyl)-isonicotinanilide〕 on Growth, Lodging, and Yield Components of Rice

Abstract

In the field experiments from 1987 to 1992, the treatment with inabenfide at 0.20-0.24g a. i. m^-2 reduced the culm length by 4-14% of the control, and prevented breaking-type lodging. The dwarfing effect of inabenfide was evident especially at the lower internodes and at the upper three leaf blades. The yield, percentage of ripened grains and 1000 grain weight of rice plants treated with inabenfide were greater than those of control. Furthermore, we observed an increase in the percentage of ripened grains and the 1000 grain weight by the treatment with inabenfide under lodging-inhibiting conditions and in 1990 and 1992, when lodging was not so much influenced by inabenfide treatment. At 17-18 days after heading, the relative light intensity in the canopy of the inabenfide-treated plants was higher than in the canopy of the control plants, and light extinction coefficient (K) was lower in the former than in the latter. Although the number of grains per panicle was decreased, the number of panicles per hill and the leaf area per grain at early ripening stage were increased by the treatment with inabenfide. The starch content in leaf-sheaths and culms in the inabenfide-treated plants was significantly higher than that in the control from heading to maturity. It is suggested that : (1) Inabenfide promotes the ripening of rice.; (2) The effect is related not only to the direct effect on lodging but also to the "plant type", improved by the treatment with inabenfide.