Evaluation of biochemical responses to drought stress as possible screening methods for drought tolerance in potato

Abstract

Potato is gaining in importance as high value nutritional crop in developing countries. Since the potato is more sensitive to drought than most other crop species, an understanding of how water stress affects growth, yield and development is of great economic and social importance. Although all potato cultivars are affected by drought, there are cultivar differences in susceptibility. Breeding and selection procedures are complicated by a poor understanding of this complex phenomenon as well as by the interaction between heat and drought stress in field studies. It is thus of importance to develop a laboratory screening method for early detection of drought tolerance in an attempt to shorten the testing period in breeding programmes, Twelve potato cultivars ( 8 from South- Africa) with known growth periods and responses to drought in the field were grown in a glasshouse. Drought stress was induced three weeks after sprout emergence by the withholding of water. The physiological and biochemical assays evaluated as potential screening methods for drought tolerance included chlorophyll fluorescence, chlorophyll content, CuZn superoxide dismutase activity, glutathione reductase activity, ascorbate peroxidase activity, free proline concentrations, polyamine titres and 2,3,5-triphenyltetrazolium chloride (TTC) reduction which measures cell viability. (Abbreviation abstract}