Effects of phosphorus rate on root phosphatase activities of different sugar beet genotypes

The effects of phosphorous application rate on the phosphatases activities of root in vivo,on the root surface and in the substrate were studied using liquid culture under sterile condition.The results showed that affecting degree of P supply level in nutrient solution on phosphatases of sugar beet root varied with the kinds of phosphatases,beet varieties and the spatial distribution places from the root in vivo to the substrate.The activities of acid and neutral endogenous phosphatases were significantly influenced by phosphorous rate.There was a statistically significant(5%) variation in enzyme activity between different P levels for all varieties,however,as to alkaline one,only the variety 6 and 12 reached 5% statistical level.P level had a stronger effect on neutral phosphatases derived from root exudation than on acid and alkaline one.All varieties,except variety 6,the effect on neutral phosphatase reached 5% or higher statistical significant level,however as to the acid and alkaline phosphatases,there were only 50% varieties reached significant level.In terms of special distribution,the reaction of acid phosphatase on the root surface was the most sensitive to P applying rate,and all the varieties showed a same tendency.Under low P condition,the acid phosphatase on the root surface increased significantly of all varieties.The effects of P on the correlation between all the 3 kinds of endogenous phosphatases and those in the substrate had the following order: alkaline phosphatase > neutral phosphatase > acid phosphatase.