[Application effects of biogas slurry partly substituting for chemical fertilizer on autumn tomato production in winter-solar greenhouse]. / æ²¼æ¶²éƒ¨åˆ†æ›¿ä»£åŒ–è‚¥åœ¨æ—¥å ‰æ¸©å®¤ç§‹ç•ªèŒ„ä¸Šçš„åº”ç”¨æ•ˆæžœ.

To explore the effects of biogas slurry coordinating chemical fertilizer on growth promotion of tomato, we used three kinds of typical biogas slurry as concentrated nutrient solution, respectively fermented from raw duck manure, pig manure, cow dung, while urea, monocalcium phosphate and potassium sulphate as auxiliary nutrition to balance the nutrient difference between different dilution ratios of biogas slurry. The results showed the biogas slurry partially substituting chemical fertilizer could significantly improve soil fertility, including available nitrogen, phospho-rus, and potassium. As for water soluble calcium, magnesium, iron, manganese and zinc in soil, biogas slurry application could activate their availability, with the magnitude of such effects depended on the fermentation level of raw materials and dilution ratio. Compared with chemical fertilizer, coordinating biogas liquid fertilizer significantly promoted the growth of tomato, with the yield increased by 55.9%-232.8% and the chemical fertilizer dosage decreased by 18.2%-85.0%. Furthermore, such effects became more prominent along with prolonged time. The fruit quality was significantly improved with the increases of lycopene, ascorbic acid and total sugar, and the decreases of acidity and nitrite concentration, and the decrease of NO2- by 35.6%-90.3%. In addition, the taste flavor of fruits was 7.0%-20.3% higher than that of chemical fertilizer treatment. The yield and quality of tomato took on nonlinear synchronization, and the relation between taste flavor and sugar/acid showed significantly positive correlation, which was affected by fertilizer type. Biogas slurry partly substituting chemical fertilizer could achieve the goals of high yield, high quality, environmental protection, efficient utilization of agricultural resources in tomato production.

Exogenous NO mediated the detoxification pathway of tomato seedlings under different stress of Cu and Cd.

Nitric oxide (NO) is a well-known signaling molecular that plays a significant role in stress tolerance of plants to heavy metals. However, the detoxification mechanism of NO has not been well studied. Here, we examined the absorbing and transporting characteristics of copper (Cu) and cadmium (Cd) in tomato seedlings through nutrient solution culture and its response to exogenous NO under Cu and/or Cd stress. Results showed that Cu and Cd with the concentration of 50 &Mgr;mol·L-1 greatly inhibited plant growth, with Cd having a higher inhibiting effect than Cu. Under single or dual stresses of Cu and Cd, their contents in both tomato roots and leaves were significantly increased. However, tomato roots showed preference to essential element Cu with a luxury uptake and strictly against Cd through cell plasma membrane in which the content of Cd was only one tenth of Cu in plants. These metal stresses, especially Cd stress, could be alleviated by application of exogenous NO. Tomato plants detoxify these passively-absorbed elements through similar mechanisms, including chelation with glutathione, phytochelatin or metallothionein, as well as vascular compartmentalization. Exogenous NO could alleviate these stresses through regulating the oxidation-reduction condition of GSH-GSSH, controlling the metabolism of GSH-PCs, as well as promoting the vascular compartmentalization of excessive Cu and Cd. In addition, NO could induce higher expression of chelators, such as MTs, GSH and PCs, in both roots and shoots, which showed additive effects to other responses and might be another important detoxification pathway mediated through NO for the responses of tomato plants to Cu and Cd stresses.

[Effects of long-term fertilization on soil fertility in yellow fluvo-aquic soil]. / 长期不同施肥方式对黄潮土肥力特征的影响.

Based on the long-term field fertilization experiment in yellow fluvo-aquic soil, this study selected 2 types of soil physical, 8 items of soil chemical, and 5 soil biological properties for principal component-cluster analysis to valuate comprehensively effects of long-term fertilization on soil fertility. Results showed that significant differences of soil properties were found among the fertilization treatments. Compared with no organic manure treatment (NPK), all treatments of organic manure (M) or its combination with inorganic fertilizers (MN, MNP, MNPK) significantly reduced soil bulk density, and increased soil total porosity, the contents of soil organic carbon, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, microbial biomass, and activities of catalase, urease, alkaline phosphatase and invertase. Two principal components that could reflect 85.5% of the original information quantity without losing any original variables were extracted from the initial 15 indices. Within the primary group of principal components, bulk density, total porosity, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, total phosphorous, available phosphorus, available potassium,microbial biomass, catalase, urease, alkaline phosphatase and inver-tase were the major contributors, while among the secondary group of principal components, total potassium and pH were the major ones. Hierarchical cluster analysis of the new indices extracted based on scores of the two principal components revealed the effects of different patterns of long-term fertilization displayed an order of MNPK＞MNP＞M, MN＞NPK＞N, NP＞CK. In conclusion, organic fertilizer has the positive effect on improving soil fertility, and combined application of organic and N, P, K fertilizer is the best fertilizing model.

[Effects of exogenous tetracycline on rape soil enzyme activity and rape quality].

This paper studied the effects of applying different concentration (0, 0.30, 0.60, and 0.90 mg x kg(-1)) tetracycline on the soil enzyme activities and rape quality. The results showed that soil urease activity after applied 0.30, 0.60, and 0.90 mg x kg(-1) of tetracycline and soil suerase activity after applied 0.90 mg x kg(-1) of tetracycline were inhibited in the whole cultivating period, while the soil sucrase activity after applied 0.30 and 0.60 mg x kg(-1) of tetracycline showed a trend of activation-inhibition-activation. Soil proteinase activity showed a trend of inhibition-activation, and the extent and duration of the inhibition and activation had significant positive correlations with tetracycline concentration (r = 0.950 * *). Soil catalase activity showed activation first and turned to irregular then. The action duration of tetracycline on the activities of soil urease, catalase, sucrase and proteinase were 7 weeks, 6-8 weeks, 7 weeks, and 6-7 weeks, respectively. At harvest time, the soluble sugar contents in rape leaves after applying 0.30, 0.60, and 0.90 mg x kg(-1) of tetracycline decreased dramatically by 91.99%, 87.92%, 90.12%, while the soluble protein content increased by 26.47%, 28.13%, and 23.22%, respectively, compared to the control.