Model analysis of plant traits leading to prolonged crop survival during severe drought

Abstract

Plant survival of severe drought may be especially important in long-life crops such as pastures and rangelands, which might be subjected to prolonged water deficit at some time during their life cycles. While a number of plant traits have been discussed as being beneficial in increasing drought survival, there is virtually no quantitative evidence concerning the relative merits of these traits. This analysis was undertaken with a relatively simple model of plant water balance to calculate the duration of crop survival during exposure to severe water deficits. A low leaf epidermal conductance was an essential factor in prolonging plant survival under drought. The benefit of low epidermal conductance was greatest at a value of 0.10 mm s −1, which is less than has been typically reported for annual field crop species. Investigation of the variation and inheritance of epidermal conductance in crops that may be subjected to survival-threatening drought were identified as prime topics for future research. Once a low epidermal conductance has been achieved, additional increases in prolonging plant survival of severe drought can be obtained as a result of leaf shedding and a low lethal relative water content for leaves.