Interaction of phosphorus concentration and soil moisture on photosynthetic traits in soybean plants
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DOI:10.7606/j.issn.1000-7601.2010.05.27
Key Words: soybean  P nutrition  drought stress  photosynthesis
Author NameAffiliation
WANG Xuming The Provincial Key Laboratory of the Resource Plant Biology in College of Life Sciences, Huaibei Normal University, Huaibei, Anhui 235000, China 
ZHANG Zheng The Provincial Key Laboratory of the Resource Plant Biology in College of Life Sciences, Huaibei Normal University, Huaibei, Anhui 235000, China 
SHI Gangrong The Provincial Key Laboratory of the Resource Plant Biology in College of Life Sciences, Huaibei Normal University, Huaibei, Anhui 235000, China 
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Abstract:
      The effects of phosphorus (P) nutrition and soil water availability (W) on the photosynthetic traits of soybean (Glycine max (L.) Merr.) plants were studied in pot experiments. Four levels of P supply (0.05, 0.5, 1.0 mmol/L and 2.0 mmol/L KH2PO4) were applied by nutrition solution. Before seedling establishment, the pots were kept near 100% of holding water capacity (HWC). Afterwards, the pots were maintained at 20%, 40%, 60%, and 80% HWC, respectively. The results were showed as follows: (1) Both the low P and drought stress resulted in a reduction of the leaf water content and shoot biomass, and an increase of the leaf water saturation deficit (WSD) and root/shoot ratio i n soybean plants. There was a significant P×W interaction on WSD, root/shoot ratio, leaf water content, specific leaf area, and shoot biomass. (2) The chlorophyll contents(Chl a, Chl b and Chl a+b) were significantly decreased in s eedlings under low P and/or drought stress, while chlorophyll a/b ratio was enhanced in P deficient plants, and it showed significant P×W interaction. (3) Drought stress and P deficient significantly reduced Fv/Fm and ΦPSⅡ, and a sig nificant P×W interaction was observed on Fv/Fm. (4) Both the low P and drought stress caused a decrease in the net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate, but an increase in the stomatal limitation (Ls) in soybean plants. A significant P×W interaction was observed on the water use efficiency and Ls.