Selection and introduction of early drought tolerant wheat genotypes

Drought stress is one of the most important abiotic stresses which influence crop plant production under dry and semi dry regions. There are many reports on how crop response specially wheat to the stress. While, drought stress along its solved and unsolved problems is at the top of agricultural research topics. Definition of drought stress concept is very difficult because of interference between climate and the stress severity in the given water storage. Base on this, climate change phenomenon has resulted in drought stress increasingly interact with heat stress. The positive interaction has negatively affected those results from researches on drought stress; therefore, direct and indirect effects of drought stress have been continuously through the time considered. The present study has been designed to assess response of wheat varieties and inbred lines to drought stress under two dryland farming and line source system conditions. With respect to that drought stress is a major component of salt stress, to comparative assessment of ionic and non-ionic drought stress an experiment was carried out at the salt affected areas of Iran. Therefore, dryland region, line source experiment, and salt affected area, respectively have been located in Zanjan (Ghidar), Karaj and Yazd. The results showed that the most important parameters that had the greatest role in production of sustain yield under drought (dryland and line source experiments) and saline conditions were total biological yield and harvest index. On the other word, the parameters can be translated from plant ability in production of photo assimilates and their mobilization to grains. The presented data revealed that there was the highest correlation between biological yield and ear length. Among the variant experimental results, seed color had an effective correlation with dry matter production and proper grain yield, so that increase in seed darkness accompanied with decrease in drought and salt tolerance and genotypes with more light color had more sustainable seed yield. In the research, a comprehensive report from mode of action and correlation amount between morpho-physiological characteristics and yield production under drought stress has been presented