Location: Adaptive Cropping Systems LaboratoryTitle: Interactive effects of temperature and phosphorus nutrition on soybean physiological traits: leaf photosynthesis, chlorophyll fluorescence, and nutrient efficiency
Submitted to: Photosynthetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2018
Publication Date: 12/7/2018
Citation: Singh, S.K., Reddy, V., Fleisher, D.H., Timlin, D.J. 2018. Interactive effects of temperature and phosphorus nutrition on soybean physiological traits: leaf photosynthesis, chlorophyll fluorescence, and nutrient efficiency. Photosynthetica. 57:248-257.
Interpretive Summary: Temperature stress often coincides with the phosphorus deficiency during soybean growth under the field condition. To investigate the interactive effects of temperature and phosphorus nutrition on plant physiological processes, soybean was grown at a range of temperature regimes under the sufficient and deficient phosphorus fertilization. Results showed a significant temperature × phosphorus interaction for the majority of physiological traits. The phosphorus deficiency adversely affected leaf photosynthesis rate mainly at and below the optimum temperature. However, under warmer temperature regimes, a sustained photosynthesis rate in phosphorus-deficient plants was observed, which was accompanied by the abundance of chlorophyll, increased photosynthetic efficiency, and greater phosphorus utilization efficiency. These results are useful to farmers and researchers to understand the plant physiological response of soybean under phosphorus and temperature interaction and highlighted that the warmer temperature might negate the decline in leaf photosynthesis rate caused by phosphorus deficiency.
Technical Abstract: An experiment was conducted to assess the interactive effects of temperature (22, 26, 30, and 34 °C daily mean T) and phosphorus fertilization (sufficient, 0.5 mM and deficient, 0.08 mM P) on soybean physiological traits. The P deficiency decreased leaf P concentration over approximately 50% across temperature regimes. However, a marked decrease in the physiological traits under P deficiency was primarily observed below (22 °C) and at the optimum temperature (26 °C, OT) but not at the warmer temperatures (30 °C and 34 °C). This resulted into a significant P × T interaction for the majority of the physiological traits including chlorophyll content, rate of photosynthesis (PN), stomatal conductance (gs), and chlorophyll fluorescence parameters such as efficiency and quantum yield of photosystem II (Fv’/Fm’ and 'PSII). At warmer temperatures in the P-deficient leaves, the PN was similar to the values observed under the P-sufficient condition, which was accompanied with the sustained chlorophyll content, gs, chlorophyll fluorescence parameters, photochemical quenching, and increased carboxylation capacity (VCmax) and nutrient utilization efficiencies. This study found that warmer temperatures compensated the decrease in soybean PN despite the >50% lower leaf P concentration in the P-deficient plants. Thus, the temperature response of PN and chlorophyll fluorescence parameters were modified under P deficiency and merits further investigations to understand the underlying molecular responses mechanisms.