| In order to solve the contradiction between supply and demand in Hubei province, enrich cropping system, the development of maize is essential. However, waterlogging has disadvantage on the germination rate and development of maize in seedling stage, so it is difficult to set up the rational population structure, which affects the production of maize. All those above are main obstacles for further development of maize in Hubei. In the experiment we set up five soil water contents: the soil water content respectively reached34.3%±9.0%(WI),56.6%±8.6%(W2),73.1%±4.0%(W3),83.5%±3.8%(W4),91.7%±1.7%(W5) of the field water holding capacity. Two maize varieties:Yidan629, Denghai9. We can research the effect of changes on the morphology, physiological and biochemical metabolism, get the critical value and sensitive indicator under waterlogging. The main results were summarized as follows:(1) The height, stem diameter, leaf area, dry weight of shoot and total length, surface area, volume, dry weight of root in W4, W5decreased significantly compared with the W3. The biomass of waterlogging stressed plants was remarkably decreased.(2) Compared with W3, the malondialdehyde content of Yidan629and Denghai9in leaf of W4respectively increased248.28%and182.46%, and the root were226.20%and283.50%. The leaf and root of W5have more malondialdehyde than W4. The content of soluble protein and proline increased in order to maintain the balance the osmotic pressure of inside and outside of cells.(3)Compared with W3, from3leaf stage to5leaf stage, the activity of superoxide dismutase (SOD) in W4, W5was enhanced significantly by120.47%,111.13%,176.26%and175.70%,231.37%,87.02%, respectively. The activity of ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT) and guaiacol peroxidase (POD) in W4was also significantly higher than W3. But at six leaf stage, Compared with W3, Denghai9increased by15.45%in W4, which did not reach significant level, and the SOD activity of root was significantly reduced by37.10%. As the process of growth, the activity of antioxidant enzyme began to decrease, and broke the balance between the generation and eliminate of active oxygen species(AOS).(4) At six leaf stage, compared with W3, the SPAD value of Yidan629and Denghai9in W4significantly reduced27.45%and35.54%, respectively. At the same time, the net photosynthetic rate (Pn) and instantaneous water use efficiency (WUEI) were significantly decreased by35.18%,42.23%and32.18%,35.18%. Stomatal conductance decreased significantly by21.81%and36.73%, which is less than the net photosynthetic rate. The concentration of intercellular CO2was significantly increased by52.21%and13.96%, but the difference of transpiration rate (Tr) did not reach significant level.(5) The dry weight of root and total length, surface area, volume of root were significantly positively correlated, but the dry weight of root and the content of soluble protein, malondialdehydet and proline and the activity glutathione reductase and ascorbic acid peroxidase were negatively correlated. Dry weight of shoot and height, stem diameter, leaf area and SPAD value had significantly positive correlation, but dry weight of shoot and the activity of hydrogen peroxide, peroxidase, glutathione reductase, ascorbic acid peroxidase and the content of malondialdehyde, soluble protein, proline and water use efficiency were significantly negatively correlated.In a word, we deduced that W4, W5lead to the waterlogging, namely, the soil water content reached80%of the field water holding capacity, which is the critical value of waterlogging at seedling stage. The content of malondialdehyde (MDA) in W4, W5significantly decreased, compared with W1, W2, W3. Therefore MDA can be used as a sensitive indicator under waterlogging. |
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