مرکز منطقه ای اطلاع رساني علوم و فناوري - اثر تنش خشكي بر عملكرد و برخي خصوصيات فيزيولوژيك جو

چكيده لاتين :

Two exprimentes (a preliminary pot and a subsequent field one) were conducted in 2002 and 2003 to evaluate the effects of different levels of drought stress on some morpho physiological characteristics of barley genotypes. In pot experiment (first year) 15 genotypes of barley were investigated in a split-plot layout within a complete randomized design with three replications. Main plots consisted of four treatments of irrigation (100%, 70%, 40% and 10% of field capacity (FC) while sub plots being consistent of 15 improved lines. In the second year, three genotypes were selected from the preliminary experiment and investigated in a field test. A split-plot layout within randomized complete block design with three replications was employed. Main plots were composed of three irrigation treatments (100 , 75 and 50% of total net irrigation water requirement) while sub plots being three genotypes of barlry {Makuee (a bred variety), Bahtim7-Dl/79 (an improved line), and Walfajre / W1-2291(an improved line)}. The results of pot experiment showed that the maximum grain yield was obtained at 100% FC but, there was not a significant difference observed between this treatment and the 70% one. The two Bahtim7-DI/79 and Walfajre/Wl lines had significantly higher grain yields in drought stress conditions due to a higher WUE, FT/TT along with a shorter plant height. These two lines demonstrated to have a higher yield stability in drought stress conditions, in pot experiment, and may be considered as varieties that produce acceptable yields in drought stress conditions. Drought stress in field conditions also showed adverse effects (of water deficit) on many morphophysiological characteristics of barley genotypes. Difference between 100 and 50% irrigation treatments was significant, but this difference was not significant either between 100 and 75, or between 75 and 50% treatments. In th 50% treatment, many indices such as relative water content (RWC), flag leaf area and transpiration efficiency significantly decreased but this reduction was not significant for the 75% treatment. Path analysis of yield indicated that the factors incoming in regression equation in drought stress conditions (50%) were different from those in the normal conditions. This result was comparatively in accordance with that in pot experiment. Path analysis of WUE also (like in pot wexpriments) showed that the direct effect of HI on WUE was more than the effect resulting from ETE in either normal or drought stress conditions. Yield reduction was observed to be less in the case of Bahtim 7- DI/7 and Valfajre/ WI in drought stress conditions, indicating higher yield stability as compared with the third line, Makuee.