Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress

Two experiments were conducted to elucidate the possible effects of dietary L‐tryptophan (TRP) in Labeo rohita based on growth performance and physio‐biochemical responses. In the experiment I, a 60‐day feeding trial was carried out to elucidate the effects of dietary TRP enrichment on growth performance and physio‐biochemical responses. In the experiment II, the TRP pre‐fed L. rohita, from experiment I, was exposed to temperature and salinity stress to evaluate stress‐mitigating efficacy of TRP. In L. rohita, dietary supplementation of TRP showed significant effect on weight gain percentage and feed conversion ratio but not on blood glucose. A significant increase in RNA content and RNA/DNA ratio upon TRP supplementation was observed and was positively correlated with growth performance. The results of experiment II indicated that weight gain percentage, serum T3 and T4 levels were significantly reduced in groups that were exposed to temperature and salinity stress and fed diets without TRP supplementation. However, dietary supplementation of TRP significantly augmented weight gain percentage in stress‐exposed groups. Tryptophan supplementation helped in bringing back T3 and T4 levels comparable with control. A significant increase in superoxide dismutase, catalase, Adenosine triphosphatase, blood glucose and serum cortisol was observed in temperature‐ and salinity‐exposed groups fed without TRP‐supplemented diets. However, TRP supplementation was found to be effective in restoring the above parameters. The results of these experiments suggest that dietary TRP supplementation augments growth, lowers energy demand and helps in mitigating thermal and salinity stress in L. rohita.     

Straw mulching with fertilizer nitrogen: An approach for improving crop yield,soil nutrients and enzyme activities

Field experiments were conducted to study soil properties, soil enzymes activities, water use efficiency (WUE) and crop productivity after six years of soya bean straw mulching in the semi‐arid conditions of China. The experiment included four treatments: CK (Control), N (240 kg N ha^‐1), H (soya bean straw mulching at half rate 700 kg ha^‐1 with 240 kg N ha^‐1) and F (soya bean straw mulching at full rate 1,400 kg ha^‐1 with 240 kg N ha^‐1). Soil organic carbon (SOC), soil labile organic carbon (LOC), soil available N (AN), available P (AP) and enzyme activities were analysed after wheat harvesting in 2016 and 2017. Results show that straw amounts had positive effects on the soil fertility indices being higher for treatment F. The SOC, LOC, AN, AP and enzyme activities (i.e. saccharase, urease and alkaline phosphatase) were in the order of F > H > N > CK. High wheat grain yield and WUE were observed for F treatment. A total of six years mulching along with 240 kg ha^‐1 nitrogen fertilizer application is sufficient for wheat yield stability and improving soil properties except urease activities in the semi‐arid condition of China. However, the straw mulching amount should be further studied with minimum nitrogen fertilizer for an environment‐friendly and effective approach for improving the soil biological properties with adequate crop production on a sustainable basis in the semi‐arid region of China.     

Effect of neem cake on persistence of diazinon and endosulfan in paddy soil

Experiments were carried out to study the influence of two types of neem cake (solvent-extracted, NC-I and expeller-extracted, NC-II) on the persistence in soil of diazinon and endosulfan applied as commercial formulations. It was found that both types of neem cake applied at 10, 20 or 30 g ha^-1 prolonged the period of degradation as compared with soils without neem cake amendment, and hence increased the persistence of the insecticides. There was little difference in the effect of the two types of neem cake. Treatment of the soil with insecticide 10 days after amendment with neem cake did not lead to any increase in persistence; for a good response, treatment of soil with insecticide and with neem cake must be done at the same time. © 1998 SCI.     

Natural products as pesticides: Two examples of stereoselective synthesis

The strategy and synthetic efforts leading to efficient stereoselective syntheses of thiangazole, a tris-thiazolinyl-oxazole metabolite isolated from Polyangium spp., and of hydantocidin, a spironucleoside metabolite isolated from Streptomyces hygroscopicus, are discussed.     

Transformations of Phosphorus and Other Plant Nutrients in Poultry Litter Composted with Sugarcane and Cabbage Wastes

Poultry litter (PL) is a significant source of nutrients, but a suitable amount of carbon needs to be added as a bulking agent during its composting to a stable nutrient source. Here, we characterized the transformation of phosphorus and other plant nutrients during aerobic composting of PL with sugarcane (SW) and cabbage waste (CW) for 120 d. Periodic samples were collected during composting and analyzed for total C, P (and its fractions), K, Ca, Mg, Cu, Fe, Zn, Mn, EC and pH. At the initial stage of composting (20 d), the P fractions varied in the order: water soluble P > NaHCO₃-P (readily plant-available) > HCl-P (Ca+Mg-bound) > residual-P > NaOH-P (Fe+Al-bound). After 120 d, the order was HCl-P > residual-P > water-P > NaHCO₃-P > NaOH-P. These variations suggested a transformation of labile Pi to more recalcitrant forms during composting. Water soluble P was the dominant fraction during the initial composting period. This declined progressively with time of composting, while the HCl-P increased, confirming the transformation of the more vulnerable water soluble P to the more recalcitrant HCl-extractable P. This indicated that the composting could be a useful way of managing manure for P stabilization and reducing its losses in runoff water following land application. The total C varied directly with the ratio of sugarcane and cabbage wastes in the manure but was inversely related to the duration of composting. Extractable K, Ca, Mg, and Na increased whereas trace elements concentrations decreased with time of composting. The higher availability of basic plant nutrients and reduced availability of heavy metals in the mature compost are valuable attributes for safe use in sustainable agricultural production.     

Determination of the role of salicylic acid and Benzothiadiazole on physico-chemical alterations caused by <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> in tomato

Shoe-string disease caused by Cucumber mosaic virus (CMV) is one of the major threats to tomato production worldwide. The alteration in some biochemical parameters in leaves of the susceptible tomato genotype (Nagina) associated with CMV infection and the effect of exogenous application of salicylic acid (SA) and benzothiadiazole (BTH) were studied in this paper. Results showed that exogenous treatment with SA and BTH not only led to plants which gave significantly more yield than diseased controls (DC), but also delayed symptom expression and reduced disease severity. Analysis of biochemical parameters indicated that exogenous application of elicitors and viral infection, significantly affected the activity of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Compared to the DC plants, minimum disease severity and maximum number of fruit were recorded after a single dose of SA + BTH. Maximum plant height was recorded after weekly application of SA and maximum fruit yield per plant was gained with single dose of SA. Moreover, the activity of POD was significantly elicited many-fold after weekly application of SA + BTH, while higher amount of SOD was recorded with single dose of SA. The activity of CAT was also significantly accelerated after weekly application of SA + BTH while increased level of APX was noticed with single dose of BTH. In conclusion, the combined application of SA and BTH played an important role in induction of defense mechanism against CMV infection and can be useful in tomato disease management programs.     

New report of Cycas revoluta leaf necrosis by Phoma herbarum from Pakistan

Journal of Plant Diseases and Protection - Necrosis on Cycas revoluta leaves was observed on trees growing in a local garden in Lahore, Punjab, Pakistan. Phoma herbarum was isolated and identified...     

Effect of Fruiting Branch/Square Removal on Growth and Quality of Bt Cotton under Different Potassium Rates

Removal of early fruiting branches with greater potassium doses caused more source and no sink at early stages of growth, leading to improved yield, yield components, and fiber quality traits in Bt cotton. The study used manual alteration of plant architecture (F₁, no branch removal; F₂, removal of first fruiting branch; F₃, removal of first and second fruiting branches; F₄, removal of all squares from first fruiting branch; F₅, removal of all squares from first and second fruiting branches) and potassium rates (50, 100, and 150 kg ha^?1) in a randomized complete block design and was repeated for 2 years (2011 and 2012). Increasing potassium application increased total bolls per plant and cotton yield to the greatest levels in F₃ and F₅, against lowest level in the control. Ginning out turn, fiber length, seed oil, and seed protein content were influenced by fruiting branch or square removal but the difference was less. Increasing potassium improved seed and fiber quality.     

Genetic Variation in Cadmium Accumulation and Tolerance among Wheat Cultivars at the Seedling Stage

Exploitation of genetic differences to select wheat cultivars’ pollution-safe from cadmium (Cd) contamination requires better understanding of Cd uptake and translocation patterns. For this purpose, 15 wheat cultivars were grown in nutrient solution and exposed to four levels of Cd, i.e., 0, 15, 30, and 45 µM. The plants were harvested after 2 weeks of Cd exposure. Root and shoot relative dry matter (DM) was decreased in most of the cultivars, but some cultivars did not exhibit any toxic symptoms. The lowest Cd concentration in shoots was recorded for Lasani-2008 and Iqbal-2000 while the highest for Sehar-2006 and Inqlab-91. Both root absorption and translocation accounted for regulating Cd concentration in shoots. There was no relationship between relative DM and Cd concentrations in roots and shoots. The results suggest that wheat cultivars with low shoot Cd concentration but higher tolerance, i.e. Lasani-2008 and Iqbal-2000, could be used in breading programs for low Cd wheat.