Interactive Effects of Low Temperature and Elevated Carbon Dioxide On Seedling Growth and Photosynthesis of Three Crops of Tropical Origin.

Projected increases in atmospheric carbon dioxide [CO₂] and extreme temperature events will have serious consequences on plants of tropical origin when grown under sub-tropical and temperate regions. Thus, it is important to quantify and understand the consequences of elevated [CO₂] and low temperature on crop growth to develop management practices and varieties. The objective of this experiment was to investigate the growth responses of three crops, cotton, groundnut, and sorghum grown under optimum (28/20°C, day/night) and low (18/10°C) temperatures and at ambient (380 ppm) and elevated (760 ppm) [CO₂] levels. Elevated [CO₂] increased photosynthesis, the response in sorghum was much less compared to cotton and groundnut. Low temperature suppressed rates of photosynthesis and electron transport, and showed more damage to cell membranes compared to optimum conditions. Elevated [CO₂] ameliorated the low temperature effects in cotton, but not in sorghum and groundnut. Therefore, the beneficial effects elevated [CO₂] on photosynthesis and growth appears to be species-dependent.