|Prasad, P. - UNIV. OF FLORIDA|
|Boote, K. - UNIV. OF FLORIDA|
|Thomas, J. - UNIV. OF FLORIDA|
Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2002
Publication Date: August 1, 2002
Citation: Prasad, P.V.V., Boote, K.J., Allen, L.H., Thomas, J.M.G. 2002. Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.). Global Change Biology, v. 8, p. 710-721 Interpretive Summary: Earlier research on important seed crops (e.g., rice, soybean, peanut) showed that reproductive development and yield were decreased by high temperature. Thus, global warming could have adverse effects on the World's food supply. USDA, ARS and University of Florida scientists at Gainesville tested another crop, red kidney bean (Montcalm), to determine the effects of elevated temperatures and carbon dioxide (CO2) on photosynthesis, pollen, and seed growth in the pod. Kidney bean was grown at daily maximum/minimum temperatures ranging from 82/64 to 104/86 degrees Fahrenheit (F) in 350 or 700 ppm CO2. Exposures above 28/18 degrees F at ambient and elevated CO2 decreased seed yield by about -0.6 & -0.8 grams per plant per degree F, respectively, and decreased seed set by -3.6% per degree F at both CO2 levels. Deleterious effects were due to decreased production and viability of pollen. Elevated CO2 increased photosynthesis and seed yield 50% and 24%, respectively. There was no interaction between CO2 and temperature, and high CO2 did not offset the negative effects of high temperature on yield. Thus, even with elevated CO2, yield losses due to high temperature are likely to occur if temperatures increase along with rising CO2.
Technical Abstract: Reproduction and yield of seed crops are decreased by high temperature. This research on kidney bean quantified the effects of elevated temperatures and CO2 on photosynthesis, pollen, and seed growth. Kidney bean cv Montcalm was grown at maximum/minimum temperatures ranging from 28/18 to 40/30C in 350 or 700 ppm CO2. Exposures above 28/18C decreased photosynthesis, seed number (slope -2.3 & -3.3 seed per plant per C), seed yield (-1.1 & -1.5 g per plant per C) at ambient and elevated CO2, respectively. Also, increasing temperature decreased seed set (-6.5% per C) and seed number (-0.34 seed per pod per C) at both CO2 levels. Deleterious effects were due mainly to decreased production and viability of pollen. Elevated CO2 did not affect seed size, but temperature above 31/21C reduced seed size 0.07 g per C. Elevated CO2 increased photosynthesis and seed yield 50% and 24%, respectively. There was no interaction of CO2 and temperature, and high CO2 did not offset the negative effects of high temperature on reproduction and yield. Thus, even with elevated CO2, yield losses due to high temperature (greater than 34/24C) are likely to occur especially if high temperatures coincide with sensitive stages of reproductive development.