Effect of Water Potnetial of Culture Medium on Geotropic Response of Primary Seminal Root in Japanese Wheat Cultivars.

Abstract

It has been observed that wheat has a shallow root system in wet soil and a deep root system in dry soil. However, the control mechanisms of root growth depending on soil water status remain unclear. Since root geotropic response seems to play an important role in the formation of the root system, the effect of water potential of culture medium on the geotropic response of the primary seminal root in Japanese wheat cultivars was examined. Agar medium with different concentrations of polyethylene glycol (PEG-6000) and vermiculite medium with different levels of water content were used. Growth angle of the primary seminal root in Minaminokomugi, which usually shows small root growth angle, became larger in low water potential media (-0.05 MPa) than in the control (O MPa). Effects of low water potential on root geotropic responses in the agar medium were also examined in 133 Japanese wheat cultivars. Minaminokomugi and 50 other cultivars showed large responses in the low water potential medium. It is considered that low water potential of the culture medium stimulates positive root geotropic responses in certain Japanese wheat cultivars.