| It is vitally important to expand winter wheat in Hexi oasis irrigation district ecologically. in order to set up perfect cultivation systems, Effects of different density, irrigation and fertilization on grain yield, grain filling properties, distribution of matter pre-anthesis, water use efficiency(WUE) and photosynthetic rate were studied in 2007 on the basis of experiment in 2005, 2006. The main results showed as following:In 2007, twelve planting densitie were setup in the density experiment , ranging from 225×104 basic plant/hm2 to 1050×104 basic plant/hm2. they were 225(A1), 300(A2), 375(A3), 450(A4), 525(A5), 600(A6), 675(A7), 750(A8), 825(A9), 900(A10), 975(A11), 1050(A12)×104 basic plant / hm2. The scope of grain yield among different density ranged from 4815.57 to 8510.15kg/hm2. Grain yield was the highest, which were planted by 675×104 basic plant/hm2. comprehensively analyzing the result in the past three years(2005～2007), the results showed that the most optimum density scope was 600～675 basic plant/hm2 in Hexi Oasis Area.Six treatments were setup in the fertilization experiment in 2007, according to the quantity of N + P2O5 (kg/hm2), they were 120+75 (D1), 165+105(D2), 165+165(D3), 225+165(D4), 300 +225kg/hm2(D5), 375+300(D6). The result showed that grain yield of D4 were the highest. The optimal scope of fertilization quantity was N165～225,P2O5105～165kg/hm2 in Hexi irrigation district.5 sowing date treatments were setup ranging from september 19th to november 15th in 2005, 2006. the results in the past two years showed that the safe and optimal sowing date was from september 17th to november 15th.Three treatments were setup in irrigation experiment in 2007. that was, W1 = 1500 (overwinter) + 1050( jointing) + 1050(heading) = 3600(m3/hm2); W2 = 1500 (overwinter) + 1500(jointing) + 1050(heading) + 1050(grain-filling) = 5100(m3/hm2); W3 = 1500(overwinter) + 675(jointing) + 600(heading) + 450(grain-filling) = 3225(m3/hm2). The results showed that high yield and WUE could be achieved by treatment W1. By compresensively analyzing the results in the past three years, another irrigation measurement could be adapted, which was 1800(overwinter) + 1650(jointing) = 3450 m3/hm2. it was most important to ensure ample water supply from jointing to heading stage in Hexi oasis area. Highest WUE couldn't be achieved when winter wheat was irrigated fully and water stressed excessively. 2) compared the variation degree of different cultivation factors(sowing date, irrigation, planting density, fertilization). In the cultivation factors, effect of sowing date on grain yield(GY) and spike number per hectare(SNH) , planting density on grain weight, irrigation on grain numbers per spikes(GNP) were the most significant. In components of yield, SNH was the most easily affected by cultivation environment. GNP was the next, and thousand-grain weight was the most stable. In density, fertilization, sowing date and irrigation experiment, There was commonly negative correlatonship between SNH and GNP(r=-0.67, -0.94**). However, the effect of restriction each other between SNH and GNP wasn't significant, and they could be improved simultaneously. There was negtive correlationship (r=-0.66, -0.70**) only in fertilization and sowing date experiment. when the two components (SNH, GNP) formed in early stage, it was the key to promote grain-filling, improve grain weight in order to obtain high yield and compensate the loss of grain yield in early stage.Grain-filling properties, distribution of dry matter, statistic change of soil moisture and change of photosynthetic traits in density and irrigation experiment were studied. The results showed that:The increasing of grain dry weight displayed"S"curve of"slow-rapid-slow", and could be well fitted by Richards equation in density experiment, in the contrary, by Logistic equation in irrigation experiment. there was significant or most significant positive correlationship between average grain filling rate and TGW in density and irrigation experiment. The effect of density and irrigation on average grain-filling rate was eminent. Average grain-filling rate of winter wheat couldn't decrease significantly even though that had been dry in grain-filling stage as long as that had been irrigated properly before heading. Effect of density on average grain-filling rate and maximum grain-filling rate was more significant than that of irrigation. Average and maximum grain-filling rate could be improved simultaneously in density experiment. in the contrary, in irrigation experiment. the duration of raipid increasing srage in density was about 15～18d, which contributed about 56～59% to grain weight. However, in irrigation experiment, that was about 18～21d, and about 70.17%～74.63%.In density and irrigation experiment, compared with transfering quantity, contribution ratio of dry matter stored in three organs(leaves, leaf sheath, stem) pre-anthesis, that was, stem>Leaf sheath>leaf, and that of stem was 2.0 and 2.7 times that of leaf sheath and leaf in density experiment , however, 3.6 and 7.1 times that of leaf sheath and leaf in irrigation experiment. as long as winter wheat had been irrigated fully before heading, drought in grain-filling stage benefited transfering of matter stored pre-anthesis. There was significant difference among different density and irrigation treatments, and high yield and WUE could be realized simultanenously in the two experiment.Soil water content in different soil layers were measured in different growth stage, and the results showed that the difference among treatments was significant, reflecting significant difference among defferent density population. Compared difference of soil water content among treatments in different growth stage, 60cm～150cm>20～60cm>0～20cm.Water consumption in deep layers played an important role in ensuring high yield and effective water use in winter wheat in Hexi oasis. It didn't benefit water use in deep layers when density population was too high or low. Soil water content below 30cm was the lowest at treatment A7 in heading, anthesis and grain-filling stage. And water use degree was the largest . especially below 60cm. There was close correlationship between water content in 30～90cm soil layers and transfering of matter stored pre-anthesis to grain. Trasfering of matter stored pre-anthesis could be accelarated when soil water content mention above decreased.Photosynthetic rate of flag leaf was measured in heading, anthesis and middle grain-filling. The results showed that cultivation condition affected photosynthetic rate significanly. Photosynthetic rate decreased step by step with growth stage at different density treatments and decreasing degree at high density was the most. In irrigation experiment, if winter wheat was irrigated fully from jointing to heading, photosynthetic rate couldn't be decreased significantly even though winter wheat wasn't irrigated in grain-filling stage. In density experiment, there was positive and stage correlationship between photosynthetic rate, average grain-filling rate and maximum grain-filling rate.There was significantly positive correlationship between photosynthetic rate in heading, anthesis and grain-filling stage in density experiment. however, in irrigation experiment, there was positive and stage correlationship between TGW and photosynthetic rate in late growth stage.
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