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 filling stage, intercepted
radiation of each leaflet of two plants within the canopy 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 leaflet 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 daytime on clear days, as
compared to the other cultivars.
Key words: Intercepted radiation, Leaf movement, Leaf temperature,
Soybean, Transpiration