Document Type : Research Paper
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Abstract
Deficit irrigation, as a limiting factor for growth, will affect physiological characteristics of plants. In order to investigate the effects of deficit irrigation on yield, chlorophyll fluorescence, dry weight of stems and leaves, and leaf area index of sunflower, this study was performed at the research farm of Agriculture and Natural Resources University of, Sari, Iran, in 2013. The experimental treatments were arranged as randomized complete block design with three replications. The irrigation regimes consisted of full irrigation (FI), regulated deficit (DI75, DI55), and partial root-zone drying irrigation (PRD75, PRD55). The results indicated that the effect of irrigation treatments on yield, photosynthetic efficiency, maximum fluorescence (Fm), minimum fluorescence (Fo), leaf area index, shoot dry weight, leaf dry weight, and head dry weight was significant. Comparison showed that water stress significantly decreased grain yield, photosynthetic efficiency index and maximum fluorescence (Fm), whereas the minimum fluorescence (Fo) was increased. The maximum seed yield (5148 kg ha-1) was attained in full irrigation treatment and had no difference with PRD75 treatment. The maximum leaf area index at the end of the growing season was 4.3 and recorded in FI and had no difference with PRD75, DI75 and PRD55. Overall, treatment PRD75 is recommended since it reduced water consumption by 16.8 percent relative to FI treatment and had no significant difference with full irrigation treatments (FI) in terms of seed yield, quantum yield, and other growth parameters.
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