A Study Over Thewater Stress Sensitivity And Water Suitability Of Summer Maize

In this study, summer maize Zhengdan 958 as tested materials, different developmental stages of the water control experiment was taken in Xiajin Shandong province and Yuncheng Shanxi province in the year of 2013 to 2014. Through analysing the different developmental stages of the physiological and ecological parameters in response to water stress of summer maize, the relative soil moisture index based on the suitability evaluation grades was determined. The quantitative relationship between soil moisture and precipitation in the different climate zones of Shandong was analysised, the precipitation suitability index was determined. Dividing precipitation suitability of the growth of summer maize in Shandong province. Aimed at evaluating the degree of summer maize water stress from the regional scale. The main conclusions were as follows:1. Water stress can lead to depression of summer maize photosynthetic rate, morphological indexes and yield formation, and the levels were not only depend on the degree of water stress, but also depend on the stress period. The photosynthetic rate was 47,1% lower than the contrast, under water stress in tasseling mature stage,decreased greatly. Compared with contrast, photosynthetic rate under water stress in emergence to jointing and jointing to tasseling stage decreased by 36.5% and 20% respectively. The emergence to jointing stage the largest decrease suffered from light drought, decreased by 41.9%. The seedling to jointing stage and jointing stage and tasseling stage after being affected by water stress, the yield was separately decreased by 37.5%,33.4%,44.1%, the maize yield was the most deep effection under the water stress in tasseling mature stage.2. Summer maize had the relative humidity of soil suitability index value at different growth stages.Seedling emergence to jointing, jointing, tasseling mature period of soil relative humidity optimal levels were 73%-91%,74%-92%,74%-92%. Optimal level threshold value of summer maize is similar, the upper limit ofdifference in each stage. The emergence to jointing stage, dry weight of summer maize critical value is 60% and waterlogging serious criticalvalue is 99%. Tasseling mature stage, dry weight of summer maize critical value is 66% and waterlogging serious criticalvalue is 99%. The emergence to jointing stage had the drought resistant, and Tasseling mature stage had the strong resistance.3. The condition of soil moisture in most areas of Shandong is suitable for cultivation of summer maize. The center and northwest of Shandong in the whole growth period of summer maize, soil relative humidity optimal grade probability of more than 70%, the most widely distributed in center of Shandong. Summer maize on soil moisture in the whole growth period in the southern of Shandong at suitable level frequency was higher, and the percentage was more than 20%. The local area, Shandong Peninsula, the interannual variation of rainfall duringmaize growth, large, soil relative humidity discomfort level more than 15% probability of occurrence frequency of large, prone to water stress, threatening the production.4. Summer maize had different precipitation suitability index at different growth stages in the regional climate zones. In seedling emergence to jointing stage, the precipitation optimum level index of upper limit and lower limit value in northwest of Shandong were 72.5mm, which is lower than other regions. From jointing stage to tasseling stage, tasseling stage to mature stage, the precipitation optimum level index range was larger, the difference between the upper and lower limits of precipitation were 101.2、115.8mm. The tasseling maturity, peninsula precipitation optimum range is smaller, on the contrary in the center of Shandong, the limit value were 94.4mm、117.6mm respectively5. Most regions of Central Shandong and Lunan in summer maize growth period, rainfall belong optimal suitability rating to meet the demands of summer precipitation growth process of Corn. Emergence - jointing period, most areas of ShandongBandao when suitability for secondary suitable, stress phenomenon will be happend easierly. Jointing - tassel and tassel -maturity period, northwest in Shandong Province occurred water stress easierly.