Carbon and nitrogen isotope composition and epicuticular wax of durum wheat (Triticum durum Desf.) plants exposed to water deficit at anthesis
Various morphological and physiological characters related to the water deficit were studied at five durum wheat (Triticum durum Desf.) genotypes under three water regimes (well-water, 60% PC and 30% PC). Stomatal resistance (Rs), cuticular transpiration (RWL), relative water content (RWC) were measured in the flag leaf just before harvest. Chlorophyll content, soluble sugar and the chemical composition of epicuticular waxes of flag leaf and spike were determined. Specific leaf dry weight (SLDW), shoot dry weight (SDW), root shoot ratio (RD/SD), δ15N, δ13C were evaluated. The results indicated that water deficit involves many changes in durum wheat genotypes resulting in decreased in SLDW, δ15N, RWL, RWC and chlorophyll content and increase in δ13C, total wax, soluble sugar, stomatal resistance (Rs). Negatives correlations were showed between carbon isotope composition and SLDW as well as with chlorophyll content. A positive correlation was found between carbon isotope composition and stomatal resistance. The results also showed that epicuticular waxes had similar compositions in both organs except for certain constituents. Acetates, hydrocarbons, fatty acids, alkanes, bicyclical alkanes, alkenes, alcohols, aldehydes, ketones, cholesterols, esters, ethers, heterocyclicals and triterpenes were the main determined compounds.