Effects Of Exogenous Orangic Acids And Foliar Spraying On Phosphorus Uptake And Delveopment Of Maize (Zea Mays L.) Under P-limiting Soil

Effects of three exogenous organic acids (Citric acid, malic acid and oxalic acid) on rhizosphere properties of maize (Zhengdan958) and morphological and physiological characteristics (chlorophyll content, net photosynthetic rate, biomass, yield, root volume, root activity and acid phosphatase activity) of maize under P-limiting conditions were studied by pot experiment;discussed exogenous organic acids on nitrogen, phosphorus, potassium absorption cumulative effect of maize by using of automatic Kjeldahl apparatus, vanadium molybdenum yellow colorimetry and atomic absorption spectr ophoto -metry. The results were as follows:1 Three exogenous organic acids (citric acid, malic acid and oxalic acid) treatments significantly improved solid-state phosphorus dissolve and uptake in soil and promote the efficient use of phosphorus in maize. Three exogenous organic acids (citric acid, malic acid and oxalic acid) treatments significantly increased Olsen-P, available N and available K, and decreased soil pH (P<0.05) in the rhizosphere compared to treatment of organic acids (CKo). However, organic matter content, total nitrogen and total phosphorus in the rhizosphere were no significant difference (P> 0.05) compared to control (CKo). The results indicate that exogenous organic acids have a good ability to activate insoluble organic phosphorus in soil.2 The plant height, stem diameter, biomass, relative yield, root volume and root activity increased significantly, while the root surface acid phosphatase activity and root tissues acid phosphatase activity decreased under three of organic acids (citric acid, malic acid and oxalic acid) treatment conditions. The results suggest that organic acids promote activation of insoluble phosphorus in soil and improve P uptake and accumulation by maize.3 The chlorophyll content, net photosynthetic rate, N, P and K accumulation in individual maize plant and P utilization efficiency significantly enhanced in three organic acids treatments. This indicates that organic acids promote the N, P and K absorption and accumulation in maize plants under low P conditions and promote the growth and development of maize.4 Three organic acids (citric acid, malic acid and oxalic acid) treatments significantly improved the phosphorus activation and absorption, especially in Tca treatment and obviously increased the growth, development and yield of maize. The Tca treatment can best alleviate P deficiency and can be used as a substitute for part of the application of phosphate fertilizer in theory.Through the foliar spraying experiments, the foliar spraying four different concentrations of KH₂PO₄ (0%, 0.1%, 0.3% and 0.5%) on maize (Zhengdan 958) seedling growth characteristics and photosynthesis influence; discussed foliar spraying different concentrations of KH₂PO₄ on nitrogen, phosphorus, potassium absorption cumulative effect of maize by using of automatic Kjeldahl apparatus, vanadium molybdenum yellow colorimetry and atomic absorption spectrophotometry. The results were as follows:1 Foliar spraying different concentrations of KH₂PO₄were significantly increased seedling height, roots coarse and biomass of corn (P < 0.05), that the plants through blades with the nutrient absorption by the roots of similar, all as nutrition with plants use, they had the same effect on plant growth and development.2 Foliar spraying different concentrations of KH₂PO₄ could evidently improve the chlorophyll-a (Chla), chlorophyll b (Chlb),chlorophyll content (Chla + Chlb) and the net photosynthetic rate of corn. Foliar spraying Further proof KH₂PO₄ can effectively increase the corn seedling photosynthesis,growth and development of corn further improve nutrition and security foundation.3 When foliar spraying KH₂PO₄ with 0.3%, the plant height is higher,rhizome thick and relative are bigger,value biomass is the highest, with the treatment group of the corn has large green leaf area, strong net photosynthetic rate, larger N,P,K accumulation and so on. This shows the foliar spraying KH₂PO₄ with 0.3% to promote concentration processing of maize growth are best.