Effects of P fertilizer application on nitrogen,phosphorus,potassium content as well as acid phosphatase and polyphenol oxidase activities in flue-cured tobacco

In order to elucidate the nutrition foundation in plant growth and development and physiological mechanism of leaf color formation by P fertilizer application,and further provide theoretical and practical basis for rational P fertilization in high quality flue-cured tobacco production,pot experiments were carried out to study the effects of different rates of phosphorus fertilizer on leaf nutrition( N,P,K) and polyphenols content as well as their relative enzymes activities of acid phosphates and polyphenol oxidase in flue-cured tobacco leaves using Qinyan 96. The results showed that,in rational range of P application rates from P2O50 to 5. 84 g / pot,N,P,K and polyphenol contents in tobacco leaves were all increased with increasing P rate resulting in significant positive correlations,but the negative effects were obtained due to excessive P rate. Acid phosphatase activity in tobacco leaves was continuously decreased with increasing P rate resulting in significant negative correlations. These results suggested that optimal P application rate could improve leaf nutrition,and increase polyphenols content and its oxidation level to be beneficial for leaf color formation of flue-cured tobacco leaves. Acid phosphates activity can be served as an efficient physiological indictor for evaluation of supply level of soil P.