Effect Of Water Supply On Crop Yeild And Physiological Characteristics With N Application

The semi-arid area which grows the crops have the characteristics of uneven and little rainfall.Crops have to endure the force of drought with different degree and different kinds,while suffering from the nutrient deficient,and so get a lower yield.The present paper through about four years pot experiment from 1997 to 2000,with the combination design of water and N supply in different growth stages,and the quadratic general spinning design(half acturalization),studied the effect of water and N supply on the yield and physiolgical characteristics of wheat and corn during the water-limited conditions,and established the mathematical models for the relationships among yield,yield constitutive factors and water and N supplying in different stages.These aimed to gain clues to increasing the crop yield in the arid-area agriculture.The main results showed as the following:Under water-limited conditions,the jointing stage is the sensitive stage of water for winter wheat,and enough water was preferred..The stages with most great effect upon water supply were the jointing stage and filling stage.With the enough water supply in jointing stage,winter wheat could be provided with less water in primary growth stage,and enough nitrogen supply.Under the conditions with or without N fertilizer supply,The yield effect of water supply and shortage in seedling,jointing and filling stage were studied.The results showed that these treatments significantly affected grian yield,biomass,the effective numbers of ears,the grain numbers of each ear and the 1000-grain weight.The jointing stage was very sensitive to the stress.With base N supply,the grain numbers of each ear and the 1000-grain weight significantly decreased(lower than the control)with water stress in jointing stage,while the grain yield were the lowest.The jointing stage was most sensitive to water deficit stress.On the other hand,the seedling stage was water effective compensation period of biomass;The jointing stage was highly effcitve water compensations period of biomass and also the effective compensation period of grian yield.Affected by the water status in seedling stage and filling stage and N supply,water supply in jointing stage have different effects.Without N supply,water supply sinificantly had compensation effect on the effective numbers of ears and the grain numbers of each ear.With base N supply,3 constitiuents of yield were significantly compensated by water supply,and the yield was the highest. The mulit-regression analysis on yield and yeild constituents revealed that,water treatment in three stages mainly affected the effective numbers of ears and the grain numbers of each ear,less affected the 1000-grain weight,and so determined the yield difference.The mathematical models for the relationships among wheat yield,yield constitutive factors and water applying stage with nitrogen fertilizer applied have been established with the quadratic general spinning design.The results showed as the following:the factors affecting the wheat yield followed the order:water supply in anthesis and filling stage>water supply in jointing stage>water supply in over-winter stage >water supply in seedling>nitrogen supplied.The factors affecting the above biomass of wheat followed the order:water supply in jointing stage > water apply in anthesis and filling stage> water supply in over-winter stage> water supply in seedling> nitrogen applicated. Water supply in jointing stage most signicantly affected the biomass;Water content in seedling stage and over-winter stage had a significantly interaction effct. It is beneficial to utilize enough nitrogen under water deficit.The photosynthesis was negatively related with the temperature difference between leaf and air in later growth stage of winter wheat.Nitrogen supply can effectively lower the leaf temperature,and enhanced the photosynthesis.Base nitrogen promoted the protective enzymes activities of leaf in jointing stage,with the least oxidative injure;Under water supply,with the increase of nitrogen fertilizer used,the...