Effect of Phosphorus on Protective Enzymes of Soybean Cultivars with Different Phosphorus Efficiencies

Soybean is sensitive to phosphorus in the whole growth stage.Our objective is to compare activity of SOD,POD,CAT,MDA content,and the relationships between them and yield in soybean cultivars with different phosphorus efficiencies under low phosphorus(0 kg·ha-1),medium phosphorus(82.5 kg·ha-1) and high phosphorus levels(165 kg·ha-1) in Shenyang from 2006-2007.The results showed that activities of SOD,POD,CAT of high phosphorus efficiency cultivars(HPEC) increased with the growth of soybean,and MDA content was lower under low-phosphorus stress.Medium and high phosphorus application had little influence on activities of SOD and POD of HPEC,and activity of CAT slowly declined in the late growth stage,and the activities of SOD and POD of low phosphorus efficiency cultivars(LPEC) increased in the late growth stage,and the decreasing time of CAT activity of LPEC was delayed to the seed filling stage.Compared to low phosphorus treatment,MDA content of HPEC declined by 10.0% and 4.8%,LPEC declined 20.9% and 17.9%,respectively,under medium phosphorus and high phosphorus levels.A strong ability of scavenging active oxygen and good membrane stability was one of reasons which soybean cultivars with high phosphorus efficiency resisted the stress of low phosphorus and had a higher yield.