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排序方式: 共有675条查询结果,搜索用时 15 毫秒
1.
The plant pathogenic oomycete, Phytophthora infestans, is the causal agent of late blight disease in tomato and potato. For characterizing Egyptian P. infestans isolates by DNA marker analysis, 40 isolates of P. infestans were collected from different locations in Egypt during two growing seasons (2012/2013 and 2013/2014). The 40 isolates were grouped into seven genotypes, in which 24 alleles were detected. The identified genotypes were not completely associated with geographic location and sample collection years. These results provide genetic and geographical information for developing a program to manage late blight disease.  相似文献   
2.
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.  相似文献   
3.
The research work was carried out to synthesize a series of novel chitosan based water dispersible polyurethanes (CS-WDPUs). The three step synthesis involves the formation of end capped PU-prepolymer was formed through the reaction between polyethylene glycol (PEG) (Mn=600 g/mole, dimethylolpropionic acid (DMPA) and isophorone diisocyanate (IPDI) followed by the preparation of neutralized NCO terminated PU-prepolymer, which lead to the chain extension by using the chitosan. The dispersion of the obtained product was carried out by adding proper proportion of water. The synthesized CS-WDPUs were applied onto the different qualities of plain weave poly-cotton printed and dyed textile swatches by employing pad-dry-cure procedures. The textile assets of the treated and untreated textile swatches were assessed, as color fastness, pilling resistance, tear and tensile strength. The results showed that the chitosan incorporation into PU backbone has significant effect on the assets of treated textiles. These synthesized CS-WDPUs are eco-friendly bio-based finishes with potential applications for polyester/cotton textiles.  相似文献   
4.
An understanding of variation in fruit quality in relation to tree age can help understand the issue of poor fruit quality in young orchards; however, limited information is available on the citrus fruit. In this study, the endogenous nutritional status in rind, rag, and leaves; pectin status in rind and rag; and anatomical fruit growth parameter in rind tissues were studied in ‘Kinnow’ mandarins fruit during their development on trees from three age (6-, 18-, and 35-year-old) groups. In older (35-year-old) trees, rind, rag, and leaf nitrogen (N), phosphorus (P), and potassium (K) concentrations were superior. In fruit from all tree age groups, total pectin and protopectin reduced; however water-soluble pectin (WSP) improved. In rind tissues harvested from young (6-year-old) trees, cell density was more while cell size was less. In all tree age groups, cell density in rind tissues correlated negatively with rind WSP.  相似文献   
5.
The present research was designed to investigate the growth promoting and immunostimulating properties of Moringa oleferia leaf meal (MLM) in grass carp. Juvenile grass carp (22.03 g ± 1.164) were fed with diets supplemented with 0, 50, 100 and 150 g/kg MLM for 48 days. At the end of feeding trial, skin mucus was used for analysis of lysozyme, protease, antiprotease and peroxidase activity. Head kidney was used for expression analysis of tumour necrosis factor‐alpha, interleukin‐8 and interferon‐γ. The obtained results showed that fish fed with 100 and 150 g/kg MLM had significant increase in weight gain and specific growth rate (p < .05). However, condition factor was not altered. The MLM (50 and 100 g/kg) inclusion resulted in higher mucus lysozyme and protease activity (p < .05), while peroxidase activity increased only in fish fed with 100 g/kg MLM and antiprotease activity was not altered. Expression of tnf‐α increased in a dose‐dependent manner, and significant (p < .05) increase was recorded in fish fed with 150 g/kg MLM. The expression of il‐8 and ifn‐γ increased in fish fed with 50 and 150 g/kg MLM; however, the increase was not significant (p > .05). In conclusion, supplementing juvenile grass carp feed with MLM up to 150 g/kg has growth promoting and immunostimulating effects.  相似文献   
6.
Outbreaks of an infectious disease affecting cultured white sturgeon (Acipenser transmontanus) were investigated. Clinical signs included erratic swimming, arching of the back and mortality. Necropsy findings included poorly demarcated yellow to dark-red and friable lesions in the epaxial muscle, ulcerative skin lesions and haemorrhages in the swim bladder and coelomic wall. Histological evaluation revealed areas of necrotizing and heterophilic myositis with aggregates of bacterial cocci. The lumen of blood vessels in the dermis, under ulcerated areas, and in the posterior kidney, was occluded by fibrin thrombi. Aggregates of Gram-positive cocci were observed in the muscle lesions and within the fibrin thrombi in the dermis and kidney. Genetically homogeneous Streptococcus iniae strains were recovered from affected fish from different outbreaks. The isolates shared high degree of similarity at gene locus (gyrB) with previously characterized S. iniae from cultured fish in California, confirming the emergence of this particular strain of S. iniae in US aquaculture.  相似文献   
7.
In the past five decades, constant research has been directed towards yield improvement in pigeonpea resulting in the deployment of several commercially acceptable cultivars in India. Though, the genesis of hybrid technology, the biggest breakthrough, enigma of stagnant productivity still remains unsolved. To sort this productivity disparity, genomic research along with conventional breeding was successfully initiated at ICRISAT. It endowed ample genomic resource providing insight in the pigeonpea genome combating production constraints in a precise and speedy manner. The availability of the draft genome sequence with a large‐scale marker resource, oriented the research towards trait mapping for flowering time, determinacy, fertility restoration, yield attributing traits and photo‐insensitivity. Defined core and mini‐core collection, still eased the pigeonpea breeding being accessible for existing genetic diversity and developing stress resistance. Modern genomic tools like next‐generation sequencing, genome‐wide selection helping in the appraisal of selection efficiency is leading towards next‐generation breeding, an awaited milestone in pigeonpea genetic enhancement. This paper emphasizes the ongoing genetic improvement in pigeonpea with an amalgam of conventional breeding as well as genomic research.  相似文献   
8.
The authors analysed epidemiological data of the Hungarian tick-borne encephalitis epidemic from the past seven decades. A total of 911 meningitis serosa cases were described from 1930-1950 s by local hospital physicians, indicating that the virus had been present in the country decades before its official identification in 1952. The virus spread freely in the 1950s–1960s, occupying almost all habitats where ticks occurred in large numbers. The increasing number of cases drove authorities to classify this illness as a notifiable disease in 1977 and to organize the first measures to stop the epidemic. Statistical analysis revealed that the large-scale vaccination launched from the 1990s was responsible for the sharp decrease in the number of human cases from 1997. A significant negative correlation was found between the number of vaccine doses sold and human cases 6 years later. The TBEV endemic area covers 16.57% of the territory and 16.65% of the population of the country. In the last 10 years, 186,000 vaccine doses/year in average were enough to keep the incidence of human TBEV infections between 0.45 and 0.06/100,000 persons. A 20-year-long study found evidence for easing clinical signs in TBEV-infected hospitalized patients. Statistics found a sharp decrease in the number of samples sent for TBEV diagnosis after 1989. Male dominance of patients was characteristic of the epidemics since the 1940s, but now analysis of detailed data from the 1981–2021 period (60.5%–87.5%) proved the statistical significance of this dominance. Obviously, the voluntary vaccination programme was the tool which broke the spread of the epidemic. Widespread public awareness of the disease and the tick vector, probable evolutionary spread of less pathogenic virus strains supplemented with the vaccination campaign led to a negligible level of human TBE cases in Hungary in the last years.  相似文献   
9.
A study was conducted to determine the effect of macronutrients (NPK) in alleviating the adverse effects of simulated acid rain (SAR) on sunflower (Helianthus annuus L.). In addition to control (T0), three different treatments, i.e., SAR (HNO3) of pH 3 (T1), NPK (T2), and SAR + NPK (T3), were applied on two sunflower cultivars, i.e., FH-37 and FH-385. The experiment was set up in CRD (completely randomized design) with four replicates of each treatment. Chlorophyll a, b, total chlorophyll, carotenoids, ion contents (NPK), and gas exchange characters were determined. Acid rain remarkably reduced the chlorophyll pigments, NPK ionic content, photosynthetic rate, transpiration rate, and stomatal conductance, while an increase in internal CO2 concentration and water use efficiency was noted in both the cultivars. The mixture of NPK with SAR exhibited positive impact to lessen the toxicity caused by acid. Among cultivars, FH-385 showed better performance as compared to FH-37.  相似文献   
10.
Effects of repeated application of urea (UN) and calcium nitrate (CN) singly and together with crop straw biochars on soil acidity and maize growth were investigated with greenhouse pot experiments for two consecutive seasons. Canola straw biochar (CB), peanut straw biochar (PB) and wheat straw biochar (WB) were applied at 1% of dried soil weight in the first season. N fertilizers were applied at 200 mg N kg?1. In UN treatments, an initial rise in pH was subjected to proton consumption through urea hydrolysis, afterwards nitrification of NH4+ caused drastic reductions in pH as single UN had soil pH of 3.70, even lower than control (4.27) after the 2nd crop season. Post-harvest soil analyses indicated that soil pH, soil exchangeable acidity, NH4+, NO3? and total base cations showed highly significant variation under N and biochar types (< 0.05). Articulated growth of plants under combined application with biochars was expressed by 22.7%, 22.5%, and 35.7% higher root and 25.6%, 23.8%, and 35.9% higher shoot biomass by CB, PB and WB combined with CN over UN, respectively. Therefore, CN combined with biochars is a better choice to correct soil acidity and improve maize growth than UN combined with biochars.  相似文献   
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