The aim of this study was to evaluate the drought stress responses of various forages and to select forage cultivars with high drought resistance. A pot experiment was carried out to study the effects of drought stress on the growth and physiology of Hemarthria compressa,Sudangrass( a Sorghum hybrid),and Dolichos lab lab. The drought responses,as measured using various physiological indices,differed among the three forages. The biomass of the three forages continuously decreased as the duration of the drought treatment extended. The maximum decrease in biomass under drought,as compared with their respective controls,was 18. 29% for H. compressa,31. 21% for Sudangrass,and 33. 55% for D. lab lab. Light and medium drought treatments had little effect on the root growth of H. compressa and Sudangrass,but increased their root: shoot ratios. The decrease in shoot biomass under drought reduced water consumption,and the increased root: shoot ratios increased the water and nutrition absorption capacity of the plants. The drought treatments damaged cell membranes and increased the malondialdehyde content,resulting in leakage of intracellular materials,increased relative electric conductivity,reduced chlorophyll content,and lower root activity,all of which inhibited growth of the three forages. Under drought stress,the proline content in tissues of the three forages was 1. 3- 8. 1 times that in their respective controls,and there were significant increases in soluble sugar content and soluble protein content,which aided osmotic adjustment. The drought treatments also promoted the activity of antioxidant enzymes( superoxide dismutase,peroxidase,and catalase) in the three forages. The increased antioxidant enzyme activities helped to eliminate free oxygen radicals to mitigate drought damage. A comprehensive evaluation of the drought resistance of the three forages using the membership function method ranked their drought resistance,from strongest to weakest,as follows: H.compressa > D. lab lab > Sudangrass.
Acta Prataculturae Sinica