Resistance to Drought and Salinity: Avenues for Improvement

Abstract

Various techniques for improving the resistance of plants to drought or salinity are discussed in relation to a notional spectrum ranging from rationality to random search. The rational end of the spectrum is exemplified by the control of phenology so that flowering occurs at an optimal time; the random end by wide crosses, such as that between wheat and Elytrigia, which give the remote hope that the high yield-potential of one will combine with the toughness of the other. Most of the techniques occupy the middle ground and involve selecting for characters whose protagonists have strong, but often poorly articulated, hunches that the characters will confer resistance to drought or salinity on the plants possessing them. For drought resistance of grain crops, the possible worth of many of these characters is discussed in relation to their likely impact on improving a crop's ability to (a) extract water from the soil, (b) produce dry matter given a limited water supply, and (c) convert dry matter into grain.