| The key to the development of agricultural production was that how to improve water use efficiency and fertilizer utilization in the west semiarid region of Heilongjiang province.the trival about effects of water and fertilizer on maize made in Gannan Country, Heilongjiang Province in 2007 and 2008.The text that researched the changing rules of soil water content at different growth period ,the relations between the yield and water requirement and net photosynthetic rate,transpiration rate and stomatal conductance under different water and fertilizer level.Also,the correlations between net photosynthetic rate and temperature,carbon dioxide,relative humidity,and relations between transpiration rate and stomatal conductance,yield.The main conclusions are the following:(1).Overal,the moisture content of soil quality appeared different at the different soil depth, significantly in 0～100cm.The variation of soil moisture was big in 60～90cm and minimum in 0～60cm. The moisture content of soil quality got the biggest under the condition of high-volume water and fertilizerand under the condition of low-rainfall, the moisture content of soil quality got the minimum. The moisture content of soil was higer at the silking stage than other stageand provide the sufficient water and nutrition for the late growth.(2).The water requirement was get the maximum in the high-volume of water and fertilizer,and get the minimum in the low-volume of fertilizer and high-volume water. It is shown from the correlation between the yield and water requirement that the high water level demand was priorer than the medium water level, the low water level,respectively.It was linked to the existence of corresponding between the yield and water requirement. The water-volume level would infullence the yield level,significantly.(3).The biological index were obviously of maize under different water and fertilizer level,such as height,base thickness,leaf area and dry matters. The biological index changed the same in the whole growing period.The biological index of high-volume of water and fertilizer were higher than those of volume of water and fertilizer. Low-volume of water and fertilizer were lower than those of volume of water and fertilizer under the condition of less precipitation. The biological index of high-volume of water was the largest and the low-volume of water's was the smallest. The filling stage was key to improve yield and improved the accumulation of dry matter could improve the yield obviously.The high-volume of water and fertilizer were higher than others on the yield. The low-volume of water and fertilizer were lower than others on the yield under the condition of low-rainfall.(4).The net photosynthetic rate's day changes curves exhibited a peaked curve and influenced by the temperature,carbon dioxide and relative humidity. etc. In the whole growing period, the net photosynthetic rate's changes curves almost the same and the index of net photosynthetic rate got the max at the silking stage. The net photosynthetic rate index of high-volume of water and fertilizer were higher than others in the day time and the growing period.We studied the changes in the transpiration rate,stomatal conductance and the water use efficiency of leaf.It was shown that the transpiration rate and stomatal conductance were changed by the meteorological factors and exhibited a single peaked curve. the effct of stomatal conductance, changes on the transpiration rate,s,significantly under the condition of high-volume of water.The correlation between water use efficiency of leaf and net photosynthetic rate in high-level demand of water level was better than that of in medium water level demand.The water use efficiency of leaf was heightened with the increasing of the net photosynthetic rate.There was direct correlation relationship between yield and the net photosynthetic rate.The yield was maximum under the condition of the high water level and minimum under the condition of the low water level.
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