Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/19/2012
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Two experiments were conducted in 2011 to study cotton response to varying phosphorus (P) supply under current and projected atmospheric CO2 concentrations. Cotton (cultivar deltapine 555) plants were grown in six growth chambers with three levels of P supply (0.2 (optimum), 0.05 and 0.01 mM) and two levels of CO2 (400 and 800 µmol mol-1) under optimum irrigation environment for 95 days. Several growth and physiological measurements were made during and at the end of both experiments. Irrespective of the CO2 concentrations, P deficient plants exhibited highly reduced leaf photosynthesis (Pnet) and were significantly shorter (45-55%) with decreased node numbers (20-25%) accompanied with reduced leaf area (80-90%) and total biomass (75-80%). Phosphorus deficiency caused greater decrease in Pnet at projected CO2 concentration (51-83%) than at current (35-67%). The stimulatory effect of elevated CO2 on Pnet was insignificant under P deficient conditions. Reduced rate of stem elongation, leaf area expansion caused primarily due to reduced cell elongation were the main cause of smaller size of the plants. In general, CO2 enrichment failed to alleviate the negative effect of P deficiency on photosynthesis and reproductive structure (flower, square, and boll). However, small stimulatory effects of elevated CO2 on plant height and total biomass were observed. Irrespective of the P supply, photosynthetic acclimations of cotton plants to CO2 enriched environments were evident from the reduced quantum yields and carboxylation efficiency of the photosynthetic processes. The results from this study clearly indicated that the amount of available soil P will affect cotton growth and development independent of atmospheric CO2 concentration. One of the aspects of the study was to develop numerical relationships of cotton tissue P content with growth and photosynthesis to derive P response algorithms in cotton to improve the predictability of cotton crop simulation model GOSSYM.