Effects of Leaf Movement on Radiation Interception in Field Grown Leguminous Crops : III. Relation to leaf temperature and transpiration among soybean cultivars

Abstract

Varietal differences of leaf movement in soybean were examined in terms of radiation interception, leaf temperature and transpiration. Five cultivars (c.v. Tsurukogane, Nanbushirome, Enrei, Tachinagaha and Miyagishirome) were grown under field conditions. An attempt was made to restrain leaf movement in the upper layers of the canopy with a nylon net. In the pod tilling stage, intercepted radiation of each leaflet of two plants within the communities was measured by integrated solarimeter films for 2 days. Although intercepted radiation per unit ground area for each cultivar was not different between the control and the treatment, there was a large varietal difference in vertical distribution of mean intercepted radiation per unit leaf area. In the uppermost layer, Nanbushirome and Tsurukogane had larger values in the treatment, the other cultivars had smaller differences between the control and the treatment. A cultivar with smaller and thick leaflets tended to have larger intercepted radiation per unit leaf area. The effects of the treatment on Leaf temperature and transpiration ability differed among the cultivars. Leaf temperature was regulated by the combination of leaf movement and transpiration. The magnitudes of these two factors might differ among the cultivars ; leaf temperature was regulated mainly by leaf movement for Tsurukogane, Nanbushirome and Enrei and by both factors for Tachinagaha. Miyagishirome could not control leaf temperature in the day time on clear days, as compared to the other cultivars.