The Study On Mechanism Of Nonstomatal Factors In Photosynthesis Of Maize Seedlings Under Water Stress

In the present study, the effect and mechanism of water stress (drought and flooding) on morphological, physiological and biochemical indexes of maize seedlings were examined using pot culture. Comparison of effect of a drought and flooding stress photosynthesis parameters, the activity of antioxidant enzymes, membrane permeability and the content of MDA on maize seedlings was analyzed. Especially, effect of nonstomatal factors on photosynthesis of maize seedling exposed to drought and flooding stress was investigated. The main results were as follows:1. Seven indexes, including the relative height, stem diameter, leaf area, shoot dry weight, root numbers, root dry weight and root/shoot ratio of maize seedlings exposed to drought and flooding stress were determined. The results showed that serious water stress (drought and flooding) restrained the plant growth (shoot and roots), decreased the relative height, leaf area and stem diameter, and reduced the accumulation of dry weight. However, the inhibition degrees were different as the water stress changed. Drought and flooding stress enhanced the growth of roots and shoot in the early days, respectively. But all the indexes decreased markedly if maize seedlings were exposed to serious drought and flooding stress for a long time and the growth of maize seedlings was almost stopped.2. In this study, physiological indexes, including the relative water content of leaves, root vigour, the chlorophyll content, solubile proteins and proline were measured. The results showed that, under the condition of both drought and flooding, the relative water content of leaves, the root activity, the chlorophyll content, solubile proteins of maize seedlings gradually decreased, but the proline content increased greatly. At the beginning of flooding stress, the water relative content of leaves changed slightly and decreased with time.