The Effects of Epicuticular Wax Cover on the Rate of Water Loss of Sorghum bicolor (L.) Moench

Abstract

Experiments were conducted to determine the role of epicuticular wax cover on the rate of water loss of sorghum plants. Relative Water Content (RWC), water potential ( ), transpiration rate, stomatal conductance and stomatal density were measured in 3 near-isogenic lines of sorghum variety ROKY62, bloom (BmBm), sparse-bloom (hh) and bloomless (bmbm) under different water conditions. Under drought conditions, bloomless sorghum exhibited more negative?? values than the bloom type, -1.70 Mpa as compared to -1.43 Mpa for the bloomless and bloom lines, respectively. Under normal water conditions, similar trend was observed in? , where the values were -1.62 and -1.21 Mpa for the bloomless and bloom lines, respectively. Data indicated that there is a positive relationship between wax cover and the internal water content of plants. The bloomless plants had higher stomatal conductance and transpiration rates than the bloom or sparse-bloom plants. Microscopic examinations revealed higher stomatal densities on the flag leaf than on the third leaf down in all 3 isogenic lines. We conclude that wax cover on sorghum leaves reduces the transpirational water loss and prevents a rapid decrease in plant water potential