The use of physiological parameters to identify drought tolerance in spring wheat cultivars

Wheat crops produced under dryland conditions in the winter rainfall region of South Africa often experience periods of water stress. It is, therefore, important to identify spring wheat cultivars that can withstand these conditions. The multitude of factors potentially involved in drought resistance make it unlikely that a single measurement will provide an all-encompassing test of drought tolerance. The aim of this study was to determine whether total ear water potential, relative water content (RWC), leaf diffusive resistance (LDR), transpiration rate and the accumulation of free proline could be used to distinguish between drought tolerant and drought sensitive spring wheat cultivars. The withholding of water and the use of polyethylene glycol (PEG) imposed stress at different physiological growth stages. It was shown in this study that these physiological parameters could be used to identify drought tolerance in spring wheat cultivars. Although genetic differences, as measured by the above-mentioned parameters, do exist between cultivars, the effect of water stress on plant growth and harvest data should also be taken into account in deciding whether these differences are of any commercial benefit.