Response of cotton to varying carbon dioxide, irrigation, and nitrogen: Yield and growth
Kimball, B.A.; Mauney, J.R.
Agronomy Journal 85(3): 706-712
1993
ISSN/ISBN: 0002-1962 Accession: 009347589
The CO-2 concentration of the atmosphere is increasing and is expected in double sometime near the middle of the next century. To determine the effects of such a CO-2 increase on cotton (Gossypium hirsutum L.) growth and productivity, a series of experiments from 1983 through 1987 were conducted with open-top CO-2-enriched field chambers at ample as well as limited levels of water and N at Phoenix, AZ (Arizona, USA). Comparison with open-field plots showed that there was a significant chamber effect, amounting to a 30% average increase in growth inside, but under dry conditions in 1985, the situation was reversed. No significant effects of CO-2 on harvest index, root-shoot ratio, or lint percentage was found, so the primary effect of elevated CO-2 was to produce plants that were larger. Comparing the results of 500 and 650 mu-mol mol-1 CO-2 treatments, the increments of growth from ambient (about 350 mu-mol mol-1) to 500 mu-mol mol-1 were not significantly different from increments from 500 to 650 mu-mol mol-1. No statistically significant interactions were detected between CO-2 level and either irrigation or nitrogen level, even when these variables were sufficiently low enough to limit growth. However, under well-maintained water stress conditions, the growth response to CO-2 tended to be somewhat larger than under normal irrigation levels. Averaging over all the data available from these experiments, seed cotton yield (lint plus seed) and above-ground biomass were increased by 60 and 63%, respectively, by CO-2 enrichment to 650 mu-mol mol-1.