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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #303446

Title: Combined effects of phosphorus nutrition and elevated carbon dioxide concentration on chlorophyll fluorescence, photosynthesis, and nutrient efficiency of cotton

Author
item SINGH, SHARDENDU - University Of Maryland Eastern Shore (UMES)
item Reddy, Vangimalla

Submitted to: Journal of Plant Nutrition and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2014
Publication Date: 10/21/2014
Citation: Singh, S.K., Reddy, V. 2014. Combined effects of phosphorus nutrition and elevated carbon dioxide concentration on chlorophyll fluorescence, photosynthesis, and nutrient efficiency of cotton. Journal of Plant Nutrition and Soil Science. 177:892-902.

Interpretive Summary: The atmospheric CO2 concentration is projected to be doubled by the end of the 21st century. In general, plant growth and productivity increases under high CO2 environment, but decreases under phosphorus deficiency. Plant mineral nutrients such as phosphorus may exert major control on the plant response to the rising atmospheric carbon dioxide (CO2) concentration. Therefore, it is important to study the combined effect of phosphorus deficiency under current and projected (doubled of the current CO2 of 400 µmol) CO2 concentrations on cotton physiology and nutrient use efficiency. Results showed that chlorophyll fluorescence parameters were significantly influenced by phosphorus deficiency and can be used as a measure of overall photosynthetic capacity in cotton. The beneficial effect of the elevated CO2 decreases as the phosphorus deficiency increased. Phosphorus and nitrogen utilization efficiency of cotton biomass production were highly reduced due to phosphorus deficiency. However, it was significantly stimulated by elevated CO2, especially under higher phosphorus nutrition. The study suggested a higher level of soil phosphorus is critical for elevated CO2 to increase nutrient utilization efficiency for optimum cotton growth and yield.

Technical Abstract: To examine the combined effects of phosphorus nutrition and CO2 on photosynthetic and chlorophyll fluorescence (CF) processes, and nutrient utilization and uptake, two controlled environment experiments were conducted using 0.20, 0.05 and 0.01 mM external phosphate (Pi) nutrition each at ambient and elevated CO2 (aCO2, 400 and eCO2, 800 µmol mol-1, respectively). On average, photosynthetic rate (Pnet) and stomatal conductance declined by 50-53% at 0.05 mM Pi and by 70-72% at 0.01 mM Pi as compared to the 0.20 mM Pi treatment. However, Pi-deficiency and eCO2 tended to increase the intrinsic water use efficiency. The CF parameters were affected more by Pi nutrition than CO2 treatment. Structural changes within the chloroplasts and photoinhibition of the photosystem II (PSII) were due to increased minimal CF while decreased maximal CF, efficiency of energy harvesting, electron transport rate (ETR), quantum yield of PSII ('PSII) and CO2 assimilation ('CO2), and overall photochemical quenching in the Pi deficient leaves. Higher 'PSII/'CO2 ratio and stimulation of photorespiration (ETR/Pnet) was found in Pi-deficiency, whereas opposite was the case under CO2 enrichment. In the Pi-deficient plants, the decline in the phosphorus (P) and nitrogen (N) utilization efficiency (up to 91%) of biomass production was mainly associated with greater reduction in the biomass relative to the tissue P concentration as the Pi supply was reduced. However, it was significantly stimulated by eCO2 especially at the two higher Pi supply treatments. A close association of the total biomass and photosynthesis with the P and N utilization or uptake efficiencies was found. The P utilization efficiency of Pnet appeared to be stable across a range of leaf P, whereas the N utilization efficiency markedly increased with leaf P and differed between CO2 levels. An apparent effect of both the treatments (Pi and CO2) on the nitrogen uptake and utilization efficiency indicated the alteration in N acquisition and assimilation in cotton plants.