Effects of enantiomers of inabenfide [4'-chloro-2'-(#alpha#-hydroxybenzyl)isonicotinanilide] on growth, lodging and yield components of rice (oryza sativa)

摘要

We examined the growth regulating activities of enantiomers of inabenfide [4'-chloro-2'-(#alpha#-hydroxybenzyl)isonicotinanilide, 82211-24-3 (CAS RN Number)], an inhibitor of gibberellin biosynthesis, on rice plants (Oryza sativa L. cv. Koshihikari) with pot and field experiments. The (S)-form of inabenfide was more effective in reducing culm length than the racemate, whereas the (R)-form showed little effect. In treatment during the tillering stage, the (S)-form was about two times as potent as inabenfide (racemate) in its dwarfing effects on culms but also reduced the spikelet density to a greater extent than did the recemate. In addition, in treatments near the heading stage, the (S)-form (0.06 g/m~2) reduced culm length, especially at the upper internodes, by 15% of the control and decreased the degree of lodging at maturity, whereas the racemate (0.24 g/m~2) showed a lesser dwarfing effect. We conclude that: (1) the (S)-form is the active ingredient of inabenfide in reducing the culm length and lodging of rice plants; (2) the (S)-form may be absorbed and translocated to elongating upper internodes more rapidly than inabenfide when applied near the heading state; and (3) treatment with the (S)-form near the heading stage will reduce the amount of ingredient required.