Effects of Leaf Movement on Dry Matter Production and Photoinhibition in Field Grown Soybean
Akihiro Isoda and Takashi Tomagae

Effects of leaf movement on dry matter production, yield and photosystem II (PSII) in soybean were examined. The leaves of the upper layers of the canopy were restrained by a net during the period from the flowering stage to the harvesting sage, as compared with non-restraining treatment of leaves. There was no significant difference in the growth parameters (crop growth rates, leaf area index and net assimilation rates) between the treatments during the treated period. Differences in the seed yield and yield components were not also found between the treatments. The leaf temperature in the plot of the restraining leaves was higher than the non-restraining treatment during daytime. Though the maximum difference was 5.5 ûC between the treatments on 16 Aug., the maximum leaf temperature of the treated plot was lower than 40ûC. There were not found significant differences between the treatments in quantum yield of photosystem II (ƒ³PSII)and non-photochemical quenching (NPQ) except 16 Aug., which are concerning with the efficiency and photoinhibition in PSII, respectively. A less gain in the leaf temperature by the treatment in Aug. and enough available water in the field in Sept. might not reduce the efficiency in PSII, consequently not decrease dry matter production.