1990 Volume 59 Issue 3 Pages 535-539
Responses of the leaflet movements in kidney bean plants (Phaseolus vulgaris L.) were examined to the change of artificial light intensity and air temperature. Using lateral leaflets of first trifoliolates in potted plants of two cultivars, 'Hime-tebo (Vertical type)' and 'Taisho-kintoki (Twisting type)', the change in the vertical and twisting angles of their leaflets were measured under respective four levels of the light and the temperature. Leaflet light angles (the angles between the leaflet normal at 60 min after light turned on and the incoming light) were less at any levels of the light intensity for Hime-tebo than Taisho-kintoki (Fig. 1). This difference resulted from a greater response of the vertical angle for the leaflet of Hime-tebo and the twisting angle for that of Taisho-kintoki (Fig. 2). Movements of the lateral leaflet in kidney bean plants seemed to functionally differentiate into the tracking and avoiding responses to the radiation with the vertical and twisting changes, respectively. Because a similarity of such a phenomenon was also recognized in the result due to change of the air temperature (Fig. 3 and 4), the increase of the twisting response appeared to be caused by change of the leaf temperature dependent on an intense light or a high air temperature. While the vertical response of Hime-tebo greatly responded even to a low light (Fig. 2), its leaflet movements were little influenced by the changes of radiations and air temperatures. But leaflet movements of Taisho-kintoki became larger particularly in the twisting response due to the increases of light intensity and air temperature. Accordingly, there would be differences in sensitivity to the light and in activity to the leaf temperature in leaflet movements between the kidney bean cultivars.
