[Effects of different application amount of N, P, K fertilizers on physiological characteristics, yield and kernel quality of peanut].

The field experiment was executed with peanut cv. Fenghua No. 1 from 2004 to 2005 in the experimental station of Shandong Agricultural University to study the effects of N, P, K fertilizers application amount on physiological characteristics, yield and kernel quality of peanut. The results showed that, compared with no fertilization, application N, P, K fertilizers increased the content of chlorophyll and soluble protein, enhanced photosynthetic rate and the activities of superoxide dismutase (SOD), peroxidase (POD) and catlase (CAT), and reduced malondialdeyde (MDA) accumulation amount in peanut leaves. The effects of applying N 300-450 kg x hm(-2), P5O2, 150-225 kg x hm(-2) and K2O 300-450 kg x hm(-2) treatments were the most significant. The improvement effect of N fertilizer on photosynthesis properties was mainly at early stage, and that of P was at middle-later stage, K was at whole stage. Applying N, P, K fertilizers increased the pod yield of peanut remarkably, and with the increasing of N application amount the pod yield enhanced, the pod yields were highest when P and K application were at middle amount rates (P5O2, 150 kg x hm(-2) K2O 300 kg x hm(-2)). The increasing effect on pod yield of K fertilizer was greater than that of N and P fertilizers. Applying a small amount of P and K fertilizers (P2O5 75 kg x hm(-2), K2O 150 kg x hm(-2)) could significantly increase the contents of fat and protein in peanut kernel, applying a small amount of N fertilizer (N 150 kg x hm(-2)) could significantly increase the content of protein in peanut kernel, but applying a large amount of N fertilizer (N 450 kg x hm(-2)) could significantly increase the content of fat in peanut kernel. Applying P fertilizer obviously increased fat and protein content, applying N fertilizer mainly enhanced protein content, and applying K fertilizer mainly raised the content of soluble sugar. In addition, the application of N, P and K fertilizers also increased the contents of lysine and methionine which were inadequate in the protein fractions of peanut kernel, enhanced the contents of oleic acid and linoleic acid, raised the ratio of oleic acid to linoleic acid, improved nutritional quality of peanut, and pronged the shelf life of peanut products.