Effect of nitrogen source on bean growth under water deficit conditions
2015
Rashidi, S. | Ebadi, A. | Parmoon, G. | Jahanbakhsh, S. | Haghighat, Z.
The study investigated the effects of inorganic nitrogen on some physiological and biochemical traits of beans under water deficit stress. The experiment was arranged in factorial order based on completely randomized design with three replications in the greenhouse. Treatments included irrigation regimes at 30%, 55% and 80% of field capacity and different nitrogen sources as control or relying on nitrogen fixation, NH4 sup +, NO sub 3 sup - and NH sub 4 sup + NO sub 3 sup -. Chlorophyll a and b, total chlorophyll and carotenoid content decreased as a result of water stress. NO sub 3 sup -led to higher chlorophyll a and total chlorophyll content compared with other nitrogen sources, while NH sub 4 sup + consumption increased chlorophyll b and carotenoid content. Enhancing water stress reduced leaf soluble protein content and decreased the amount of soluble sugars. Changes in initial flourescence (F sub o) increased over time, but the maximum flourescence (F sub m) and variable flourescence (F sub v) decreased. The photochemical efficiency of photosystem 2 (F sub v/F sub m) decreased due to water deficit. Biomass and shoot length were reduced by increasing stress severity. Among treatments of nitrogen sources, NO sub 3 sup - significantly increased shoot dry weight. The lowest shoot dry weight was obtained in the nitrogen-fixing (control) plants.
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