واكنش هاي فيزيولوژيك و مورفولوژيك علف هرز جو دره به سطوح مختلف تنش خشكي (Hordeum spontaneum C. Koch)

Wild Barley (Hordeum spontaneum C. Koch) Physiological and Morphological Responses to Different Levels of Drought Stress

Wild barley has severely infested many wheat fields in Fars province. Investigation on wild barley physiological and morphological characteristics under drought stress condition can help to identify the effective factors in this weedʹs survival. A greenhouse experiment was conducted in the form of factorial completely randomized design with three replicates in college of agriculture, Shiraz University. Four irrigation regimes including: 100%, 75%, 50% and 25% of field capacity (F.C.) were applied on a weight basis. Measurements were taken at two vegetative growth stages, before and after irrigation. Physiological characteristics were assessed through ADC, LCz photosynthesis meter. Such morphological characteristics as tiller number, plant height, spike number, biological yield as well as grain yield were evaluated at the end of plant growth period. Results indicated that maximum photosynthetic rate was obtained at 100% F.C. and tillering after irrigation while minimum photosynthetic rate at 25% F.C. and tillering before irrigation. Maximum rate of transpiration was obtained at 100% F.C. and tillering after irrigation as well as at stem elongation after irrigation while minimum transpiration rate at 25% F.C. and tillering before irrigation and of stem elongation before irrigation. Maximum stomatal conductance was obtained at 100% F.C. and stem elongation after irrigation, while minimum stomatal conductance at 25% F.C. and tillering before irrigation. Maximum intercellular C02 concentration was obtained at 25% F.C. and at tillering before irrigation, while minimum intercellular C02 concentration at 100% F.C. and tillering after irrigation. This trend indicated that, under stress conditions, absorbed CO2 by leaf could not be efficiently used in photosynthesis. Maximum biological yield and plant height were obtained at 100% and 75% F.C., while minimum at 25% F.C. Grain yield and spike number had the highest values at 100% F. C., and the lowest values at 25% F. C.