Effects of water and N supply on maize bleeding sap and its nutrient contents

A micro-plot field experiment was conducted under a rain-shelter condition to study the effects of water and nitrogen supply on bleeding sap and contents of ammonium N , nitrate N , free amino acid , P and K in the sap , and the nutrients absorbed by plant of maize .Four factors, soil surface treatment , irrigation , N rate and root growing space , were involved in this experiment .Determinations were carried out at an interval of certain time .Results show that under water- stress condition , water supply remarkably increased the bleed and content of nutrients in the sap of maize .The effects of N supply being depended on water supply by either irrigation or soil moisture retention .With better water supply , bleed- ing sap and nutrients contents were increased by N addition whereas under serious water stress condition , application of N reduced the bleeding sap and nutrients content in it .N , P and K absorbed by maize had almost the same trend as the bleeding sap .