Adverse high temperature effects on pollen viability, seed-set, seed yield and harvest index of grain-sorghum [ Sorghum bicolor (L.) Moench] are more severe at elevated carbon dioxide due to higher tissue temperatures

• Published in: Agricultural and forest meteorology 2006-10, Vol.139 (3), p.237-251
• Main Authors: Prasad, P.V. Vara, Boote, Kenneth J., Allen, L. Hartwell
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; air temperature; Biological and medical sciences; Carbon dioxide; Climate change; cultivars; elevated atmospheric gases; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Global warming; grain crops; grain sorghum; grain yield; harvest index; heat injury; heat stress; leaf temperature; plant reproduction; pollen; seed set; seed temperature; Sorghum; Sorghum bicolor; temperature; vegetative growth; viability; Yield; yield components
• ISSN: 0168-1923; 1873-2240
• DOI: 10.1016/j.agrformet.2006.07.003

Global climate change, especially, increases in carbon dioxide (CO 2) concentration and the associated increases in temperature will have significant impact on the crop production. Grain-sorghum [ Sorghum bicolor (L.) Moench] cultivar DeKalb 28E was grown at daytime maximum/nighttime minimum temperature regimes of 32/22, 36/26, 40/30 and 44/34 °C at ambient (350 μmol CO 2 mol −1) and elevated (700 μmol CO 2 mol −1) CO 2 from emergence to maturity in controlled environments to quantify the effects of temperature and CO 2 on the reproductive processes and yield. Growth temperatures of 40/30 and 44/34 °C inhibited panicle emergence. Growth temperatures ≥36/26 °C significantly decreased pollen production, pollen viability, seed-set, seed yield and harvest index when compared to 32/22 °C. Percentage decreases in pollen viability, seed-set, seed yield and harvest index due to elevated temperature were greater at elevated CO 2 when compared with ambient CO 2. Elevated CO 2 increased seed yield (26%) at 32/22 °C, but decreased seed yield (10%) at 36/26 °C. At high temperatures, elevated CO 2 increased vegetative growth but not seed yield, thus, leading to decreased harvest index. We conclude that the adverse effects of elevated temperature on reproductive processes and yield of grain-sorghum were more severe at elevated CO 2 than at ambient CO 2; and the beneficial effects of elevated CO 2 decreased with increasing temperature. The adverse temperature sensitivity of reproductive processes and yield at elevated CO 2 was attributed to higher canopy foliage and seed temperatures.