[Effects of NaCl stress on seedling growth and IAA metabolism of sweet potato and its relation to salt-tolerance].

Seedlings of three sweet-potato (Ipomoea batatas) cultivars with different salt-tolerance were stressed with different concentrations of NaCl during the seedling stage. Plant growth, leaf area growth, and IAA content decreased with increasing NaCl concentration, while the activities of POD and IAA oxidase increased. The extent of plant growth, leaf area growth and IAA content decrease and the extent of POD and IAA oxidase activity increase were larger in sensitive cultivar than those in moderately tolerant and tolerant cultivars. In addition, the content of chlorogenic acid increased under NaCl stress. Chlorogenic acid content reached its peak value at 170 mmol.L-1 of NaCl in sensitive and moderately tolerant cultivars and 225 mmol.L-1 of NaCl in tolerant cultivar. Chlorogenic acid content decreased with increasing NaCl concentration, but it was higher than that of the control.