[Soil microbial biomass and respiration rate under effects of different planting patterns of peanut].

A field experiment with randomized design was conducted to study the effects of six planting patterns of peanut, i.e., spring sowing and plastic film mulching, spring sowing and open cultivation, summer sowing and plastic film mulching, summer sowing and open cultivation, intercropped in wheat field, and control of intercropped in wheat field, on soil microbial biomass C, soil active microbial biomass, and soil respiration rate. The results showed that the growth stage and planting pattern of peanut had significant effects on soil microbial biomass and respiration rate. With the prolonged time after anthesis, soil microbial biomass C, active microbial biomass, and respiration rate increased gradually, peaked at pod-setting stage, and decreased then. Open cultivation enhanced soil microbial biomass C and respiration rate but reduced soil active microbial biomass, being unfavorable to soil nutrient transformation and nutrient availability, while plastic film mulching increased soil active microbial biomass, and consequently, promoted soil nutrient transformation and nutrient availability. Comparing with intercropped in wheat field and open cultivation, intercropped in wheat field and plastic film mulching increased soil microbial biomass C, active microbial biomass, and respiration rate, which immobilized more soil nutrients and was not conducive to peanut growth.

[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.