Abd El Moneim, M. A., Cocks, P. S., Swedan, Y. 1988: Yieldstability of selected forage vetches ( Vicia sp.) under rainfed conditions in West Asia. Journal of Agricultural Science (Cambridge) , 111 , 295
The objective of current study was to look at the variable expression of antioxidant enzymes in wheat genotypes exposed to various water stress regimes. Further the malondialdehyde (MDA) content were measured as an indicative of membrane integrity. Tolerance indices were calculated which reinforce in distinguishing tolerant and susceptible genotypes. The experimental material consisted of thirteen genotypes obtained from different sources. Stress was imposed by withholding irrigation at three different growth stages of plant, i.e. tillering, anthesis and grain filling. Four resistance indices include stress susceptibility index (SSI), yield stability index (YSI), mean productivity (MP) and tolerance index (TOL) was calculated on the basis of grain yield. Water stress treatments had no significant effect on CAT activity. CIM-47, CIM-49 and NR-234 showed minimum MDA content with increased POX activity under three different irrigation conditions and are therefore considered as tolerant genotypes. Higher levels of MDA with decline activity of POX was found in CIM-51, DD-4 and NR-230 led to suggest them as susceptible genotypes. The variable response of genotypes in tolerance could be related to differences in antioxidant enzyme levels. Significant positive correlation was found between SSI and TOL values whereas negative and significant association was noted between SSI and YSI. Significant and negative correlation was observed between YSI and TOL values. These traits are recognized as beneficial water stress tolerance indicators for selecting a stress tolerant variety. The most outstanding tolerance capacity in terms of susceptibility indices was detected in CIM-47 and CIM-50 under all water stresses. They indicated lowest SSI, TOL and MP with high YSI values. It may, therefore, be concluded that these genotypes have the potential of stress tolerance.