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food supply. Curry et al. (1995) predicted decreased soybean yields in the southeastern USA associated with Climate change due to increased [CO 2 ] and elevated temperature a 5ЊC increase in temperature predicted by several may impact the composition of crop seed. This study was conducted to determine the potential effects of climate change on composition global climate change models. Allen and Boote (2000) and gene expression of soybean [Glycine max (L.) Merr. cv. 'Bragg'] reviewed the documented impacts of climate change on seed. Soybean plants were grown in sunlit, controlled environment soybean, including decreased yield and quality due to chambers under diel, sinusoidal temperatures of 28/18, 32/22, 36/26, higher growth temperature. Sunlit, controlled environ-40/30, and 44/34؇C (day/night, maximum/minimum), and two levels ment chambers have been used to examine the effects of [CO 2 ], 350 and 700 mol mol Ϫ1 , imposed during the entire life and interactions of increased [CO 2 ] and temperature cycle. The effect of temperature on mature seed composition and on plants (Pickering et al., 1994), revealing important transcripts in developing seed was pronounced, but there was no effect alterations of physiology, growth, and seed yield (Baker of [CO 2 ]. Total oil concentration was highest at 32/22؇C and decreased and Allen, 1993; Allen and Boote, 2000). with further increase in temperature. Oleic acid concentration in-The unique chemical composition of soybean has creased with increasing temperature whereas linolenic acid decreased. Concentrations of N and P increased with temperature to 40/30؇C, made it one of the most valuable agronomic crops worldthen decreased. Total nonstructural carbohydrates (TNC) decreased wide. Consumed for thousands of years in Asia, soybean as temperatures increased, and the proportion of soluble sugars to has steadily gained importance as food in the USA, and starch decreased. Transcripts of a gene that is downregulated by auxin many new products have been developed using soybean (ADR12) were dramatically downregulated by elevated temperature, seed as raw material (Liu, 1997). Oil and protein compossibly reflecting the altered course of seed development under enviprise ≈20 and 40%, respectively, of the dry weight of ronmental stress. Transcripts of ␤-glucosidase, a gene expressed dursoybean seed, and approximate values of other compoing normal soybean seed development, were detected in seed grownnents include carbohydrates (30%), crude fiber (5%), at 28/18؇C but not in seed grown at 40/30؇C, which also suggests and ash (5%) (Hymowitz et al., 1972). In addition, soythat normal programs affecting seed composition were perturbed by bean contains minerals such as Fe, Cu, Mn, Ca, Mg, elevated temperature. These results confirm previous studies indicating that high temperature alters soybean seed composition, and sug-Zn, Co, P, and K. Vitamins B 1 , B 2 , and B 6 , as well as gest possible mechanisms by which climate change may affect soybean isoflavones, are also available in soybean (A...

It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed‐set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol−1) or elevated (700 µmol mol−1) CO2 levels. There were strong negative relations between temperature over a range of 28/18–40/30 °C and seed‐set (slope, − 6.5% °C−1) and seed number per pod (− 0.34 °C−1) under both ambient and elevated CO2 levels. Exposure to temperature > 28/18 °C also reduced photosynthesis (− 0.3 and − 0.9 µmol m−2 s−1 °C−1), seed number (− 2.3 and − 3.3 °C−1) and seed yield (− 1.1 and − 1.5 g plant−1 °C−1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed‐set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature > 31/21 °C linearly reduced seed size by 0.07 g °C−1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development.

Continuing increases in atmospheric carbon dioxide concentration (CO2) will likely be accompanied by global warming. Our research objectives were (a) to determine the effects of season‐long exposure to daytime maximum/nighttime minimum temperatures of 32/22, 36/26, 40/30 and 44/34°C at ambient (350 μmol mol−1) and elevated (700 μmol mol−1) CO2 on reproductive processes and yield of peanut, and (b) to evaluate whether the higher photosynthetic rates and vegetative growth at elevated CO2 will negate the detrimental effects of high temperature on reproductive processes and yield. Doubling of CO2 increased leaf photosynthesis and seed yield by 27% and 30%, respectively, averaged across all temperatures. There were no effects of elevated CO2 on pollen viability, seed‐set, seed number per pod, seed size, harvest index or shelling percentage. At ambient CO2, seed yield decreased progressively by 14%, 59% and 90% as temperature increased from 32/22 to 36/26, 40/30 and 44/34°C, respectively. Similar percentage decreases in seed yield occurred at temperatures above 32/22°C at elevated CO2 despite greater photosynthesis and vegetative growth. Decreased seed yields at high temperature were a result of lower seed‐set due to poor pollen viability, and smaller seed size due to decreased seed growth rates and decreased shelling percentages. Seed harvest index decreased from 0.41 to 0.05 as temperature increased from 32/22 to 44/34°C under both ambient and elevated CO2. We conclude that there are no beneficial interactions between elevated CO2 and temperature, and that seed yield of peanut will decrease under future warmer climates, particularly in regions where present temperatures are near or above optimum.

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