城市污泥腐殖土中活性物质分离及作用机理研究

生活污水处理产生的城市污泥经腐熟后形成腐殖土可作为土壤有机质来源,是生活污水处理后污泥合理循环应用重要方式。采用培养皿法研究污泥腐殖土粗提取物对种子萌发影响,利用硅胶柱分离和红外光谱法鉴定粗提物抑制种子萌发的活性物质并研究其作用机理。结果表明,污泥腐殖土粗提取物浓度增加,水萝卜、小白菜种子萌发率降低,种子萌发受抑制时间延长,玉米幼苗中SOD、POD活性升高。鉴定腐殖土中活性化合物结构为3-羟基苯甲酸,该化合物对水稻种子α-淀粉酶活性具有显著抑制作用,导致水稻种子发芽率显著降低。腐殖土严重抑制种子萌发,分离该腐殖土中活性物质并研究其作用机理,可为污泥再利用提供理论基础。     

Effects of Bacillus coagulans supplementation on the growth performance and gut health of broiler chickens with Clostridium perfringens-induced necrotic enteritis

Background: The poultry industry is in need of effective antibiotic alternatives to control outbreaks of necrotic enteritis(NE) due to Clostridium perfringens.Methods: This study was conducted to investigate the effects of feeding Bacil us coagulans on the growth performance and gut health of broiler chickens with C. perfringens-induced NE. Two hundred and forty 1-day-old broiler chicks were randomly assigned to a 2 × 2 factorial arrangement with two dietary B. coagulans levels(0 or 4 × 109 CFU/kg of diet) and two disease chal enge statuses(control or NE chal enged).Results: NE-induced reduction in body weight gain was relieved by the addition of B. coagulans into broiler diets compared with the NE-infected birds. NE infection damaged intestinal morphological structure, promoted intestinal C.perfringens growth and liver invasion, and enhanced anti-C. perfringens specific sI gA concentrations in the gut and specific IgG levels in serum compared with the uninfected birds. NE infection significantly(P 0.05) decreased mucin-2(at 14 d post-infection(DPI), tol-like receptor 2(TLR2, at 7 and 14 DPI), TLR4(at 7 and 14 DPI), tumor necrosis factor super family15(TNFSF15, at 7 and 14 DPI), lysozyme(LYZ, at 14 DPI) and fowlicidin-2(at 7 and 14 DPI) mR NA levels, whereas it dramatical y(P = 0.001) increased IFN-γ mR NA levels at 7 DPI. However, chal enged birds fed diets supplemented with B.coagulans showed a significant(P 0.01) decrease in gut lesion scores, decreased C. perfringens numbers in the cecum and liver, and an increase in fowlicidin-2 mR NA levels in compared with the uninfected birds. In addition, compared with the non-supplemented group, dietary inclusion of B. coagulans improved intestinal barrier structure, further increased specific sI gA levels and alkaline phosphatase(IAP) activity in the jejunum, enhanced the expression of jejunum lysozyme mR NA, and inhibited the growth, colonization, and invasion of C. perfringens; in contrast, it reduced serum-specific IgG concentrations and jejunum IFN-γ mR NA levels.Conclusion: These results indicated that dietary B. coagulans supplementation appeared to be effective in preventing the occurrence and reducing the severity of C. perfringens-induced NE in broiler chickens.     

FOLIAR APPLICATION OF ZINC INFLUENCES THE LEAF MINERAL STATUS,VEGETATIVE AND REPRODUCTIVE GROWTH,YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN

Deficiency of zinc (Zn) is widespread in many citrus orchards of Pakistan, consequently hampering fruit yield. Effects of foliar applications of zinc sulfate on tree nutrition, growth, productivity and fruit quality were studied on ‘Kinnow’ mandarin. Leaf nitrogen (N), calcium (Ca), and manganese (Mn) were highest for trees sprayed with 0.2% zinc sulfate, while phosphorus (P) and iron (Fe) were highest with 0.6% zinc sulfate and potassium (K) and Zn were highest with 0.8% Zn sulfate applications. Trees sprayed with 0.6% zinc sulfate exhibited highest increase in height, crown width and stem girth, fruit diameter, fruit weight, ascorbic acid contents, and total phenolics compared to all other treatments. Pre-harvest fruit drop was lowest and total number and weight of fruit per tree was highest at harvest with 0.4% zinc sulfate application. In conclusion, foliar application of zinc sulfate up to 0.6% improved tree mineral nutrients, growth, and productivity with better fruit quality in ‘Kinnow’ mandarin.     

Nutrient management and submergence-tolerant varieties antecedently enhances the productivity and profitability of rice in flood-prone regions

Abstract

Poor productivity of rice in rainfed lowlands is due to complete submergence as it is a major abiotic stress of these regions. For enhancing the rice productivity of these areas, better nutrient management options are required and results may even better when combined with stress tolerant cultivars, even when tested under natural conditions of farmers’ field. For supporting the above statement, the effect of nitrogen and phosphorus in graded doses was evaluated for submergence tolerance in controlled conditions and the results obtained were tested and validated at farmers’ field in Cuttack, Odisha, India. Shoot elongation, leaf senescence and lodging were lowest with the application of higher phosphorus (60?kg ha^?1). Highest dose i.e. 100-60-40 NPK kg ha^?1 resulted in higher plant survival of all the varieties by 90–170% over no nutrient application, it was also reflected in the higher growth after recovery, leaf greenness, leaf and stem growth, chlorophyll and carbohydrate concentrations and ultimately higher grain yield. At farmers’ field, application of basal P, K and post-flood N management practice resulted in overall better performance of Swarna and Swarna-Sub1 showing higher yield attributes leading to 65.7 and 37.9% higher grain yield, over conventional practices followed by farmers. Apart from that results were more positive if post-flood nitrogen was applied as urea foliar spray might be due to quick absorption of N by plant leaves and also spraying helps in removing the silt of flood water sticking to the leaf surface and facilitated the plants to photosynthesize and survive after desubmergence. These cost-effective management options may enhance the productivity and profitability of rice in the flood-prone areas where farmers hesitate to apply nutrients.     

Zinc bioavailability response curvature in wheat grains under incremental zinc applications

Zinc application is generally recommended to enrich wheat grains with Zn; however, its influence on Zn bioavailability to humans has not received appreciable attention from scientists. In this pot experiment, seven Zn rates (from 0 to 18 mg kg^?1 soil) were applied to two wheat cultivars (Shafaq-2006 and Auqab-2000). Application of Zn significantly increased grain yield, grain Zn concentration and estimated Zn bioavailability, and significantly decreased grain phytate concentration and [phytate]:[Zn] ratio in wheat grains. The response of grain yield to Zn application was quadratic, whereas maximum grain yield was estimated to be achieved at 10.8 mg Zn kg^?1 soil for Shafaq-2006 and 7.4 mg Zn kg^?1 soil for Auqab-2000. These estimated Zn rates were suitable for increasing grain Zn concentration and Zn bioavailability (>2.9 mg Zn in 300 g grains) to optimum levels required for better human nutrition. Conclusively, Zn fertilization for Zn biofortification may be practiced on the bases of response curve studies aimed at maximizing grain yield and optimum Zn bioavailability. Moreover, additive Zn application progressively reduced the grain Fe concentration and increased the grain [phytate]:[Fe] ratio. However, a medium Zn application rate increased grain Ca concentration and decreased the grain [phytate]:[Ca] ratio. Hence, rate of Zn application for mineral biofortification needs to be carefully selected.     

Functional identification of G. hirsutum genes for their role in normal plant development and resistance against Verticillium dahliae using virus-induced gene silencing

European Journal of Plant Pathology - Virus-induced gene silencing (VIGS) is a reverse genetic tool used to identify the function of individual genes by reducing their expression. Here VIGS was...     

High Sodium in Irrigation Water Caused B Toxicity at Low Soil Solution and Shoot B Concentration in Maize (Zea mays L.)

Sodium (Na) and calcium (Ca) in brackish water differentially affects boron (B) nutrition of plants grown on calcareous and salt-affected soils. A glasshouse experiment was conducted to evaluate the effect of brackish irrigation water with different sodium adsorption ratio (SAR_iw) [distilled-water control, 8, and 16 (mmol_c L^?1)^1/2] on B nutrition of maize. Plants were grown for 40 days with 5 levels of B (0, 1.29, 2.30, 3.22, and 4.46 mg kg^?1 soil). Boron application significantly improved plant growth at lower rates. High B rates and application of high SAR_iw decreased plant growth independently, and the reduction in growth was further aggravated due to combined effect of both B and high SAR_iw. Decreased growth was attributed mainly to increased shoot B and Na concentration, while decreased Ca concentration. These ionic changes also altered internal and external B requirements. Yield decrease was observed at lower B concentration in soil solution B and plants shoot grown with high SAR_iw than in plants grown with distilled water and low B application rates.     

Improving the Performance of Wheat by Seed Priming Under Saline Conditions

Salinity is one of a major threat in harvesting good wheat stand on sustained basis. In this study, potential of seed priming techniques to improve the performance of wheat varieties (SARC‐1 and MH‐97) in a saline field was tested. For priming, wheat seeds were soaked in aerated solution of ascorbate (50 mg l^?1; ascorbate priming), salicylic acid (50 mg l^?1; salicylicate priming), kinetin (50 mg l^?1; kinetin priming) and CaCl₂ (50 mg l^?1; osmopriming) for 12 h. For comparison, seeds were also soaked in simple water (hydropriming); in addition, untreated seeds were also taken as control. Seed priming treatments substantially improved the stand establishment; osmopriming (with CaCl₂) was at the top however. Likewise maximum fertile tillers, grains per spike, 1000‐grain weight, grain yield and harvest index were observed in plants raised from seeds osmoprimed (with CaCl₂) followed by ascorbate priming in both the varieties tested. As an index of salinity tolerance, seed priming treatments also improved the leaf K⁺ contents with simultaneous decrease in Na⁺ concentration, osmopriming being the best treatment. Similarly, maximum total phenolic contents, total soluble proteins (TSP), α‐amylase and protease activities were observed in osmoprimed (with CaCl₂) seeds followed by ascorbate priming. Economic analysis also indicated that osmopriming is more viable with maximum net return and benefit‐to‐cost ratio. In conclusion, different seed priming treatments in wheat seeds improved the salinity tolerance nonetheless osmopriming (with CaCl₂) was the most effective treatments to get higher grain yield and net return in both wheat varieties whereas kinetin was the least effective.     

MODULATION OF NITROGEN-UTILIZATION EFFICIENCY IN WHEAT GENOTYPES DIFFERING IN NITRATE REDUCTASE ACTIVITY

The plants growing in natural field conditions do not express their full genetic potential of nitrogen (N) utilization due to a limiting availability of N at later stages of growth. Their full potential is likely to manifest under non-limiting nitrogen supply wherein the high nitrate reductase (HNR) and the low nitrate reductase (LNR) genotypes should differ significantly in their N-utilization efficiencies. In a sand culture experiment, using IC 321157 (HNR) and C 306 (LNR) genotypes of Triticum aestivum L. under controlled conditions, 15-day-old plants were collected in triplicate and analyzed for nitrate content, N-metabolizing enzymes and N harvest. Kinetic studies were conducted to obtain the Km and Vmax values for enzymes. The values for nitrate content, activities of the nitrate- and the ammonium- assimilating enzymes, biomass and N harvest were higher in the HNR than in the LNR genotype. The higher affinities of enzymes to their substrates in the HNR genotype indicated a greater potential of this genotype for N utilization under non-limiting N supply with a well-coordinated system of N uptake and assimilation. The study suggests that the N-utilization efficiency of plants can be improved by exploiting their full genetic potential under non-limiting N supply, which may be achieved by synchronizing the supply with demand during late stages of plant growth. It also shows that the enzymes responsible for N assimilation act in a coordinated way, thus necessitating the need of a holistic approach for the study of the N-metabolic pathways.