Effects of drought stress on carbon metabolism of bermudagrass (Cynodon dactylon L.)

The effect of drought stress on carbon metabolism in the leaves and roots of bermudagrass was investigated. Plants established in PVC tubes suffered from three water treatments for 10 days. C138 and Tifway (drought-tolerant) were found to have lower relative electrical conductivity and higher water use efficiency than C32 (drought-sensitive) under moderate drought by increasing carotenoid and soluble sugar content and rapidly decreasing leaf starch content. The sucrose synthase activity of leaves and roots, acid invertase and neutral invertase activity of C32 roots substantially decreased under severe drought, resulting in a slow sucrose decomposition rate and significantly lower fructose and glucose contents than C138 and Tifway. The activities of four carbon metabolism enzymes and sucrose content in the leaves were greater than those in the roots, while the fructose and glucose contents were on the contrary, indicating that bermudagrass transported fructose and glucose obtained from sucrose decomposition from leaves to roots under drought to reduce roots damage. The path analysis indicated that leaves neutral invertase activity, and roots soluble sugar content might be the key parameter of carbon metabolism in bermudagrass under drought.