Effects of arbuscular mycorrhizal fungi on the morphology of kidney bean root

The effects of arbuscular mycorrhizal fungus (Glomus R10) on the root morphology and physiology of kidney bean (Phaseolus vulgaris L.) have been investigated. Infection with arbuscular mycorrhizal fungi reduced the length and the number of tap roots, and the 1st and 2nd order lateral roots. However, the number of the 1st order lateral roots per unit length of tap root and that of the 2nd order lateral roots per unit length of the 1st order lateral root were not affected by the infection. Application of phosphorus fertilizer did not change the morphology of the roots. These findings suggest that infection with arbuscular mycorrhizal fungi alters the morphology of the root system of kidney bean. The infection also promoted the bleeding rate and triphenyl-tetrazoliumchloride (TTC)-reducing power per unit length of roots, but did not affect the bleeding rate per plant. It was unclear whether the increase in bleeding rate and TTC-reducing power was due to the physiological changes in the roots, or whether the increase in TTC-reducing power and water absorption by the arbuscular mycorrhizal fungi. Our results show that infection with arbuscular mycorrhizal fungi affects the morphology of kidney bean root; however, the effect on the physiology of roots remains to be examined further.