Studied On Coupling Effect Of Water And Nitrogen Fertilizer Of Wheat-corn Band Interplanting In Hexi Oasis Irrigation Area

The studies were conducted at ZhangYe experimental station of Gan Su Academy of Agricultural Sciences from March 2008 to October 2008.The cropping patterns of studies were wheat-corn band interplanting and studied photosynthetic characteristics,water use efficiency, crop water consumption and yield of change law in wheat-corn band interplanting during the conditions of water and fertilizer coupling.The main results were as follows:1.The results indicated that variations of water and fertilizer coupling had remarkable effect on photosynthetic characteristics of intercropped wheat and intercr0pped maize.The highest photosynthetic rate appeared on the flowering stage and filling stage of intercropped wheat,and then decreased,photosynthetic rate was lowest on mature period of intercropped wheat in the different treatments of water and fertilizer.The highest photosynthetic rate was 17.84μmolCO₂·m^-2·s^-1,which appeared in the treatment of irrigation water 5550m³/hm², nitrogen 630kg/hm².The highest transpiration rate appeared on the flowering stage,which appeared in the treatment of irrigation water 6570m³/hm²,nitrogen 420kg/hm².The change laws of stomatal conductance was the same with the change lows of photosynthetic rate.The highest photosynthetic rate of intercropped maize appeared on the flowering stage and then decreased in the different treatments of water and fertilizer.The highest photosynthetic rate appeared in the treatment of irrigation water 6750m³/hm²,nitrogen 630kg/hm².The change laws of transpiration rate was the same with the change lows of photosynthetic rate,and the lowest transpiration rate appeared in the treatments of irrigation water 5550m³/hm²,nitrogen 630kg/hm², which water saving effect was better than other treatments.The treatment of irrigation water 6750m³/hm²,nitrogen 630kg/hm² had remarkable effect on stomatal conductance of intercropped maize.2.The relationship between intercropped wheat yield and photosynthetic rate of filing stage was linear relationship,and r=0.8302.The regression analysis of intercropped wheat yield and photosynthetic rate of filing stage indicated that irrigation water 6750m³/hm²,nitrogen 420kg/hm² could gain higher photosynthetic productive efficiency and better coupling effect of water and fertilizer.The relationship between intercropped maize yield and photosynthetic rate of filing stage was linear relationship too,and r=0.91.The regression analysis of intercropped maize yield and photosynthetic rate of filing stage indicated that irrigation water 6750m³/hm² combined with proper treatment of nitrogen fertilizer could gain higher photosynthetic productive efficiency and better coupling effect of water and fertilizer.The highest of yield strip intercropping was 15069.65kg/hm²,which appeared in the treatments of irrigation water 6750m³/hm²,nitrogen 630kg/hm².The conditions of water and fertilizer had different effects on strip intercropping yield,and results of analysis showed that fertilizer effect＞effect of water-fertilizer interaction＞water effect.The variations of water and fertilizer coupling had remarkable effect on water use efficiency of strip intercropping,and results of analysis indicated that irrigation water 5550m³/hm², nitrogen 630kg/hm² could gain highest water use efficiency and water use efficiency of treatment of irrigation water 5550m³/hm²,nitrogen 210kg/hm² was lowest.The water use efficiency of strip intercropping increased with increasing nitrogen rate in the condition of middle irrigation amount or high irrigation amount.The water use efficiency of strip intercropping decreased with the increase of nitrogen rate in the condition of low irrigation amount.The water use efficiency of strip intercropping decreased first and increased afterwards with increasing irrigation amount in the condition of low nitrogen rate.The water use efficiency of strip intercropping increased first and decreased afterwards with increasing irrigation amount in the condition of middle nitrogen rate or high nitrogen rate.4.Different treatments of water and fertilizer had some effects on crop water consumption during main growth period.Crop water consumption of wheat in the filling period was highest and trileaf stage of wheat was lowest.Crop water consumption of strip intercropping had change lows on different conditions of water and fertilizer.The different treatments of water and fertilizer had different effects on the ratio between main growth stage and whole growth stage, and the results showed that growth period water consumption accounts for the percentage of water consumption in the whole growth period increased first and then decreased from trileaf stage of wheat to filling stage of maize.Crop water consumption of trileaf stage of wheat accounts for ratio of the whole growth stage was lowest and crop water consumption of filling stage of wheat accounts for ratio of the whole growth stage was highest.The analysis of daily crop water consumption in different treatment during main growth period indicated that daily crop water consumption of wheat in the filling period was highest and daily crop water consumption of trileaf stage of wheat was lowest.5.The relationship between strip intercropping yield and crop water consumption of whole growth stage was linear relationship,and r=0.7174.The regression analysis of strip intercropping yield and crop water consumption of whole growth stage indicated that nitrogen 630kg/hm² combined with proper treatment of irrigation amount could gain highest water use efficiency and better coupling effect of water and fertilizer.6.The analysis of relationship between intercropped wheat yield and leaf water use efficiency of wheat or relationship between intercropped maize yield and leaf water use efficiency of maize indicated that irrigation water 5550m³/hm²,nitrogen 420kg/hm² or irrigation water 5550m³/hm²,nitrogen 630kg/hm² could gain higher leaf water use efficiency of wheat, higher yield and better water saving effect.The leaf water use efficiency of wheat was in positive correlation with the intercropped wheat yield and r=0.7614.For the intercropped maize, irrigation water 5550m³/hm²,nitrogen 630kg/hm² could gain high yield and good water saving effect.