Genetic diversity for photosynthesis in wheat under heat-stressed environments and its relationships to productivity
1994
Delgado, M.I. | Reynolds, M.P. | Larque-Saaverda, A. | Nava Sanchez, T. (Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico, DF (Mexico). Wheat Program)
Genetic variation in photosynthetic rate, stomatal conductance, leaf chlorophyll content, and dark respiration was studied in 16 wheat genotypes (Triticum aestivum L.) grown under high-temperature field conditions in Central Mexico. Measurement was made on flag leaves in full sun light, at three different stages of plant development, and at different times of the day. Two experiments were conducted with sowing dates in December 1991 and March 1992. And the results compared with the grain yields of the experiment plots on which measurements was made. Photosynthetic rate was fairly stable during the day between 10:00 and 14:00, and cross experiments, despite differences in leaf temperature of up to 4 deg C. However, rates of photosynthesis fell noticeably at successively later stages of plant development, and showed a strong interaction with genotype. For both planting dates, there was a clear association among the parameters photosynthetic rates, stomatal conductance, leaf temperature, and chlorophyll content, and all of these parameters were correlated significantly with grain yield. Photosynthetic rate in the post anthesis period was strongly associated with chlorophyll loss after anthesis, which suggest that genetic variability in the onset of senescence may be an important variable determining the yield of wheat in hot environments
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