Effect of Different Rate of Super Absorbent Polymer Specific Leaf Area and Photosynthesis of Medicago sativa

In order to improve output of Medicago sativa,the response of specific leaf area and photosynthesis of Medicago sativa under field environmental conditions with the super absorbent polymer SAP was studied.The SAP was added to the soil at the following rates:0,15 and 30 kg·hm-2.The result showed that the SAP had no significant effect on the SLA of Medicago sativa(P0.05),with significant effect on leaf chlorophyⅡ and the photosynthesis.Applied with 15 kg·hm-2 of SAP,Medicago sativa had higher pn,gs,Trand WUE than those of CK,but the pn,gsand Tr were significantly lower than those of the CK when applied with 30 kg·hm-2 of SAP,WUE had no change.The correlations betweenpnand gs,pnand Trof Medicago sativa applied with 30 kg·hm-2 of SAP were the most closely connected,while the correlations betweenpnand WUE applied with 15 kg·hm-2 of SAP were the most closely connected.Application of SAP still need deep study.