Effects Of The Interaction Of Nitrogen And Water On Physiological Characteristic And Grain Yield Of Wheat

The experiment was conducted in the Institute of Dryland Agriculture, Gansu Academy of Agriculture Sciences. Random block design method was adopted, two factors three levels, the three nitrogen levels were: no nitrogen (CK), didn't apply pure nitrogen; middle nitrogen (MN), applied pure nitrogen 0.4g per pot; high nitrogen (HN), applied pure nitrogen 1.5g per pot. the three water levels were: Serious dry, maintain 40 percent of saturated water content; Middle dry, maintain 60 percent of saturated water content; Normal Water, maintain 80 percent of saturated water content. There were totally nine treatments, repeated three times. The main conclusions of the study are summarized as follows:1,Nitrogen application could enhance the foliar photosynthetic rate(Pn), instantaneous water use efficiency (IWUE), stomatal conductance (Gs), the apparent photosynthetic electronic transport rate (ETR), overall photochemical quantum yield of PSⅡ(Yield) and photo-chemical quenching coefficient (qP), and decrease intracellular concentration of CO2(Ci). Under drought and well water conditions, the Pn, IWUE, Gs and ETR of high-nitrogen leaf was higher than the other nitrogen level. During Jointing and Ripening periods, the total PSⅡphoto Yield of high-nitrogen leaf which under drought condition were lower than the middle-nitrogen leaf and controls; During Heading and Ripening periods, the qP of high-nitrogen leaf that under middle middle-dry and well water condition were higher than middle-nitrogen leaf in wet and driest treatments. Under the condition of three nitrogen level, with the aggravated of water stress, the Chlorophyll content,carotenoid content,IWUE and Pn demonstrated a trend of increasing。Under the no nitrogen condition, with the aggravated of water stress, Gs,ETR and qP decreased, Ci increased. however, Under the middle and high nitrogen condition, the result was opposite.Correlation analysis showed that there were a significantly linear positive correlation between IWUE and Pn ,but negative with Tr,Ci,Gs. wheat leaves of Pn was positive correlation with Yield,qP,ETR, and reach highest point on the middle nitrogen level; The relationship between Pn and Gs, IWUE were different in different treatments, the results indicated that nitrogen application could improve the opening proportion of photosynthetic instruments, photos-catching ability and electronic transport rate, and then amended the efficiency of photosynthetic instruments; The effects of nitrogen application on gas exchange were different under different moisture condition, and then affected the water use efficiency, but the reduction of Pn and IWUE caused by drought could be compensated by supplying nitrogen fertilizer.2,nitrogen application could enhance the SOD,CAT of Function Leaf, decrease MDA. Under well water conditions, both the MDA of CK and MN treatment were higher than HN treatment during jointing stage, the others showed decrease with the increase of nitrogen application. Under three water conditions, the SOD of wheat leaf gradually increased from jointing stage to flowering stage, and increased with the inhance of nitrogen application. Under well water conditions, the CAT inhanced with the nitrogen increase. Under middle dry conditions, the CAT was increase during Jointing and flowering stage, MN treatment the CAT presented highest during Heading and Ripening stage. Under Serious dry conditions, CAT presented highest duringjointing and ripening stage. Under the condition of three nitrogen level, the more water, the higher MDA and SOD content in the wheat leaves. under the condition of no nitrogen, however, the CAT of the wheat leaves increased in low nitrogen, and it increased while applying nitrogen.3,Under well water and dry conditions ,from jointing stage to heading stage, the content of total nitrogen were HNW>MNW>CK1. Under serious dry conditions, the total tendency was gradually decrease from jointing to ripening stage. And the MND treatment was highest, however, the treatment HND was lowest .under well water conditions, the phosphorus content of nitrogen treatment was highest during flowering stage, middle dry and ck conditions were also highest. Under three water conditions the potassium content has had no significant difference. Correlation analysis showed that there was a twice negative correlation trend between NRA and wheat nitrogen content.4,The trial indicated that, under well and middle dry conditions, wheat height was highest in the middle nitrogen treatment during jointing stage, the others were highest in high nitrogen treatment, as well as 1000-grain weight,grain number per spike and grain weight per spike under three water conditions. Under the condition of three nitrogen level, the more water, the lower height,dry weight and spike number of wheat. Both 1000-grain weight and Spike grain weight per pot of wheat were highest under middle drought treatment.