Effects of late Season Drought Stress on Grain Yield, Protein, Proline and ABA of Bread Wheat Varieties

An experiment was conducted in order to evaluate the effects of late season drought stress on yield, protein percentage, proline and abscisic acid content of bread wheat genotypes, in Varamin Agricultural Research Center in 2011-12. 20 wheat genotypes containing Sirwan (a new breeded variety), WS-82-9 (A promising lines) and 18 new wheat lines were evaluated at two normal irrigation and water stress in flowering stage conditions. two randomized complete block design with three replications were used. The results of combined analysis of variance showed that, grain yield and many of yield components significantly affected by drought stress on reproductive growth stage. Grain yield had significantly decreased from 6331 kg/hac in normal irrigation to 4384 kg/hac in drought stress condition (by 30.7%). non irrigation at flowering, significantly decreased spike length, no. of seed per spike, TKW, HI, biological yield and flag leaf area by 33.9%, 43.1%, 38.3%, 19.1%, 15.9% and 19.3% respectively. leaf Proline content significantly increased from 40.8 µmol/gr.fw in normal irrigation to 56 µmol/gr.fw in water stress treatment. Also, the stress treatment significantly increased seed protein percentage from 11.8% to 12.9%. In drought stress condition, abscisic acid hormone and proline amino acid increased by 56.3% and 37.2% respectively. The highest grain yield at drought stress treatment was obtained from WS-82-9 line and Sirwan by 6394 and 6065 kg/hac respectively. These two genotypes had the highest amounts of proline and abscisic acid at water stress condition, too.