Changes in cuticular transpiration, leaf wax and leaf wax crystals of barley genotypes in response to terminal drought stress

In order to evaluate the effect of terminal water deficit stress on leaf traits and their relations to grain yield in different barley genotypes (‘Yousof’، ‘Fajr30’، ‘Nosrat’، ‘PBYT-46’، ‘PBYT-97’ and ‘Morocco’)، two separated experiments were conducted in stress (water withholding from anthesis towards the end of growing season)، and non stress (normal irrigation) conditions based on RCBD with three replications in 2010-2011 at Yazd Agricultural Research Station. The results indicated that drought stress significantly reduced leaf area index، greeness and increased canopy temperature and leaf rolling. Also، drought stress significantly increased epicuticular wax content at 21 days after anthesis. Studying by Scanning Electron Microscope (SEM) confirmed the increased dispersal of leaf wax crystals in leaf surface in ‘Yousof’ and ‘PBYT-46’ genotypes. ‘Fajr30’ genotype with the highest amount of cuticular transpiration and canopy temperature had the highest reduction in grain yield and ‘Yousof’ and ‘PBYT-46’ genotypes with higher amount of wax crystals dispersal، lower amount of cuticular transpiration، canopy temperature and greeness reduction in stress condition، had the least reduction percentage in grain yield. According to the non significant correlation between leaf wax and grain yield in both conditions (stress and normal) and in stress condition، it seems that increased epicuticular wax crystals had a more effective role than the quantity of wax in drought tolerance of barley genotypes.