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

Plant survival of severe drought may be especially important in long-life c rops such as pastures and rangelands, which might be subjected to prolonged water deficit at some time during their life cycles. While a number of pla nt traits have been discussed as being beneficial in increasing drought sur vival, there is virtually no quantitative evidence concerning the relative merits of these traits. This analysis was undertaken with a relatively simp le 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 ben efit 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 specie s. investigation of the variation and inheritance of epidermal conductance in crops that may be subjected to survival-threatening drought were identif ied as prime topics for future research. Once a low epidermal conductance h as been achieved, additional increases in prolonging plant survival of seve re drought can be obtained as a result of leaf shedding and a low lethal re lative water content for leaves. Published by Elsevier Science B.V.