Photosynthetic Characteristics Of Different Wheat Genotypes Under Water Stress

Photosynthesis is the basis of plant productivity and crop yield, water stress is a important environmental factor inhibiting photosynthesis. In this thesis, under water stress conditions, using the pot experiment, we studied photosynthetic characteristics and some correlative physiological indexes, growth and yield indexes of 5 wheat genotypes, discussed the regulatory mechanisms and evolutionary trends of the effect of the water stress on wheat photosynthetic characteristics. The main results are as follows:1. The effect of water stress on wheat photosynthesis was different in the different wheat genotypes and growth stages. In jointing stage, under water stress, the decrease in photosynthetic rate of every wheat genotypes mainly due to stomata limitation. While in pre-anthesis and grain-filling stage, although water stress resulted in a decrease in wheat stomata conductance, the intercellular CO2 concentration was not decreased significantly, even increased, indicated that the decrease in wheat photosynthetic rate mainly due to non-stomata limitation in pre-anthesis and grain-filling stage.2. The difference in Fv/Fm value among different wheat genotypes were not significant in every growth stage, and the changes of Fv/Fm values were not significant under water stress, indicated that water stress didn't influenced the PSâ…¡primary photochemistry reaction; Under water stress, the Fv/Fo values of every wheat genotypes were not decreased in jointing stage, but decreased in pre-anthesis and grain-filling stage, indicated that the PSâ…¡activity was prone to restrained by water stress; Water stress result in a decrease in qP values of every wheat genotypes in pre-anthesis, the decrease extent of Shan253 and Changwu134 were more significant. In grain-filling stage, the qP values of evolutionary wheats decreased under water stress, while Shan253 and Changwu134 hadn't decreased, indicated that the effect of water stress on the re-oxidation in Q-A of modern wheat was slight, while before this stage, the electron transport from PSâ…¡to QA restrained by water stress was main factor of photosynthesis non-stomata limitation to modern wheat; The qNP values of hexaploid were higher than diploid and tetraploid wheat, indicated that the ability of using light energy...