Comparative Studies On Interaction Effects Between Water And Fertilizers To Wheat Under Three Soils

This study compares the interaction effect of water, nitrogen phosphorus and potassium (WNPK) to wheat grow, photosynthesis character, activity of leaf enzyme, yield and nutrient absorption character under different soil with potted plant method. The three kind of soil is fluro-aquic soil from Fengqiu Henan province, loessial soil from Changwu Shanxi province and red soil from Qiyang Hunan province which formed under different heat and water gradient. We can conclude that:(1) The results from fluro-aquic soil show that: the joint effect of WNPK were not so much to wheat growth at seedling period, after that, WPK promote wheat growth significantly, enhance photosynthesis, so lead to better plant height and leaf area. Water stress could improve MDA content significantly, but the synergistic effect of SOD, POD and CAT can decrease MDA accumulation. Amount of water and phosphorus were important to wheat yield. Rational applying ratio of WNP combined when soil water was deficient and rational applying ratio of NPK combined when soil water was sufficient were the guarantee of high production. The nitrogen and phosphorus content in plant becoming high but the potassium content deceases with higher P input. WNP have good synergistic effect.(2) The results from loessial soil show that: Water and nitrogen is two important factors affecting wheat growth. Water deficient was the key factor which affects photosynthesis. Phosphorus could enhance leaf photosynthesis significantly, dry material accumulation and resistance of plants under water stress. The substitute effect of water and phosphorus had been in evidence when there were no water stress. In the study, SOD and POD assorted with each other very well under adversity, MDA content had good correlation with leaf protection enzyme. The first factor affecting wheat yield was water, and then was P. the positive interaction effect of NPK to yield was base on certain water content. Different water and fertilizer ratio had bigger effect on yield. NPK could improve wheat yield when the water supply were good. The trend of yield was: middle level N＞high level N＞low level N. the higher P input could improve plant total N and total P content, but the effect to K were not so regular.(3) The results from red soil show that: due to the special character of red soil, water and overmuch PK content had less promoting effect to wheat yield, but K had opposite effect. Water were the main factor affecting photosynthesis. NPK had synergistic effect on photosynthesis under water stress, but it would change to antagonistic effect under no water stress condition. The activity of leaf protection enzyme would rise and MDA would decrease with Water and nutrition content rising, so it would improve resistance of wheat. The level of P content and distribution could directly affect protection enzyme activity and MDA content. In this study, using more NPK fertilizer under water stress and using more PK fertilizer under no water stress were the key method to improve wheat yield. Higher P content promoted N absorption of wheat.(4) We conclude from the result of three soils that: water was the dominant factor affecting wheat growth, water stress could lead to reduction of yield. On red soil this phenomena was much serious. The effect of NPK content under different soil and water content level had big different affect to wheat, so good application amount and ratio were the key technology to water and fertilizer saving.(5) The interaction effect of water and fertilizer to wheat different on three soils. Water was the key factor affecting interaction of fertilizers. N was the controlling factor of NP and NK interaction effect. P and K with N together showed synergistic effect to antagonistic effect on fluro-aquic soil, But it was not so distinct under water stress.and middle level N＞high level N＞low level N under no water stress on loessial soil. It was middle level N＞low level N＞high level N on red soil under both water condition. The interaction effect of PK under both water condition were similar on three soils. The main effect of P was significant.