As the CO2 content of the air increases, cotton (Gossypium hirsutum L.) plants typically display enhanced rates of photosynthetic carbon uptake, as noted by Reddy et al. (1999), who reported that twice-ambient atmospheric CO2 concentrations boosted photosynthetic rates of cotton by 137 to 190% at growth temperatures ranging from 2°C below ambient to 7°C above ambient.
Elevated CO2 also enhances total plant biomass and harvestable yield. Reddy et al. (1998), for example, reported that plant biomass at 700 ppm CO2 was enhanced by 31 to 78% at growth temperatures ranging from 20 to 40°C, while boll production was increased by 40%. Similarly, Tischler et al. (2000) found that a doubling of the atmospheric CO2 concentration increased seedling biomass by at least 56%.
These results indicate that elevated CO2 concentrations tend to ameliorate the negative effects of heat stress on productivity and growth in cotton. In addition, Booker (2000) discovered that elevated CO2 reduced the deleterious effects of elevated ozone on leaf biomass and starch production.
Atmospheric CO2 enrichment can also induce changes in cotton leaf chemistry that tend to increase carbon sequestration in plant biolitter and soils. Booker et al. (2000), for example, observed that biolitter produced from cotton plants grown at 720 ppm CO2 decomposed at rates that were 10 to 14% slower than those displayed by ambiently-grown plants; and after three years of exposure to air containing 550 ppm CO2, Leavitt et al. (1994) reported that 10% of the organic carbon present in soils beneath CO2-enriched FACE plots resulted from the extra CO2 supplied to them.
In summary, as the CO2 content of the air increases, it would seem to be a good bet that cotton plants will display greater rates of photosynthesis and biomass production, which should lead to greater boll production in this important fiber crop, even under conditions of elevated air temperature and ozone concentration. In addition, carbon sequestration in fields planted to cotton should also increase with future increases in the air's CO2 content.
For more information on cotton growth responses to atmospheric CO2 enrichment see Plant Growth Data: Cotton (dry weight, photosynthesis).
References
Booker, F.L. 2000. Influence of carbon dioxide enrichment, ozone and nitrogen fertilization on cotton (Gossypium hirsutum L.) leaf and root composition. Plant, Cell and Environment 23: 573-583.
Booker, F.L., Shafer, S.R., Wei, C.-M. and Horton, S.J. 2000. Carbon dioxide enrichment and nitrogen fertilization effects on cotton (Gossypium hirsutum L.) plant residue chemistry and decomposition. Plant and Soil 220: 89-98.
Leavitt, S.W., Paul, E.A., Kimball, B.A., Hendrey, G.R., Mauney, J.R., Rauschkolb, R., Rogers, H., Lewin, K.F., Nagy, J., Pinter Jr., P.J. and Johnson, H.B. 1994. Carbon isotope dynamics of free-air CO2-enriched cotton and soils. Agricultural and Forest Meteorology 70: 87-101.
Reddy, K.K., Davidonis, G.H., Johnson, A.S. and Vinyard, B.T. 1999. Temperature regime and carbon dioxide enrichment alter cotton boll development and fiber properties. Agronomy Journal 91: 851-858.
Reddy, K.R., Robana, R.R., Hodges, H.F., Liu, X.J. and McKinion, J.M. 1998. Interactions of CO2 enrichment and temperature on cotton growth and leaf characteristics. Environmental and Experimental Botany 39: 117-129.
Tischler, C.R., Polley, H.W., Johnson, H.B. and Pennington, R.E. 2000. Seedling response to elevated CO2 in five epigeal species. International Journal of Plant Science 161: 779-783.