In field control of Botrytis cinerea by synergistic action of a fungicide and organic sanitizer

A new Integrated Pest Management program based on the combination of synthetic pesticide with a GRAS(generally recognized as safe)-classified sanitizer for the control of Botrytis cinerea in field conditions was described. The aim behind this research was to determine whether the use of this mixture would enhance the efficiency of pesticides while decreasing the recommended dose. Naturally infected tomato plants, grown in the greenhouse, were treated with two commonly used fungicides SWITCH(Syngenta, Switzerland) and SIGNUM(BASF, Germany) each alone or combined with a commercially available organic sanitizer PERACLEAN?5(Evonik Industries, Germany). A total of 27 treatments were tested consisting of three concentrations of synthetic fungicide(×1, ×1/2 and ×1/4 of the recommended dose) either applied separately or combined with three concentrations of the tested sanitizer(0.5, 1 and 1.5%). The control efficacy achieved by the fungicides applied alone ranged between 0 and 66.7% while all fungicide-sanitizer mixtures resulted in up to 70% control of grey mould. The treatment that provides the maximum control of B. cinerea was the result mixture of ×1/4 of the recommended concentration of SWITCH(15 g L~(–1)) with 0.5% of PERACLEAN~?5. This combination suppressed 85% of grey mold infections while decreasing the usually used amount of this pesticide by 75%, reducing therefore the well known negative impacts of chemical pesticides on environment and consumers health.     

Effect of altering the steric hindrance of the nitrogen atom in 2,5-bis(pyridin-n-yl)-1,3,4 thiadiazole isomers on their ability to elicit tomato defense responses against Verticillium wilt and crown gall diseases

Three isomers of the ligand 2,5-bis(pyridinyl)-1,3,4-thiadiazole, with the N atom of pyridine group in position 2, 3 or 4, named respectively, L2, L3 and L4 were compared for their use as plant defense activators. They were examined for their ability to protect tomato plants from Verticillium dahliae and Agrobacterium tumefaciens in the greenhouse, to induce reactive oxygen species and to activate plant defenses, including antioxidant enzymes. The three ligand isomers exhibited in vitro only slight inhibition of radial growth of V. dahliae, while no significant inhibition was observed for phytopathogenic bacteria. In the greenhouse, the three ligand isomers statistically reduced the severity of Verticillium wilt and crown gall on tomato plants, and the isomers L3 and L4 were the most efficient to control Verticillium wilt. This superiority was reflected in their differential ability to activate H₂O₂ accumulation, antioxidant enzymes including catalase and ascorbate peroxidase and other defense-related enzymes such as guaiacol peroxidase and polyphenol oxidase. These results demonstrated that the presence of the N atom within the two pyridinyl groups in the position 3 or 4 highly enhanced the activity of plant defense and antioxidant responses as well as their ability to reduce the severity of symptoms caused by V. dahliae on tomato.     

An Optimized Covalent Immobilization of Glucamine on Electrospun Nanofibrous Poly(vinylidene fluoride) Sheets Grafted with Oxirane Groups for Higher Boron Adsorption

Nanofibrous poly(vinylidene fluoride) (PVDF) sheets were produced by electrospinning and grafted with oxirane groups using radiation induced grafting of glycidyl methacrylate (GMA) followed by treatment with N-methyl-D-glucamine (NMDG). The NMDG density in the nanofibers was tuned by optimization of the immobilisation reaction variables using response surface methodology (RSM). The various properties of NMDG-containing nanofibers were evaluated using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The NMDG-containing nanofibers were tested for boron selective removal from solutions. A maximum glucamine density yield of 2.2 mmol/g was obtained at 15 wt%, 87 oC, 64.7 min and 150 % for NMDG concentration, temperature, time and degree of grafting (DG), respectively. The applied procedure incorporating RSM was found to be highly effective in the optimization of covalently immobilised glucamine on the oxirane modified PVDF based-nanofibrous structure and in imparting an excellent combination of physico-chemical and boron retention properties. A complete boron removal was achieved in 100 mg/l boron solution adsorbent with a dosage of 0.6 g at pH 7 in 2 h time. This was accompanied by a promising reusability suitable for boron removal from solutions.     

Modeling Dissolved Ozone and Bromate Ion Formation in Ozone Contactors

Many drinking water utilities that use source waters with significant bromide ion levels are currently seeking disinfection regimes that will minimize the formation of brominated disinfection byproducts while providing adequate disinfection. While ozonation appears to be a promising option for achieving these goals, the uncertainty of future drinking water regulations has developed a need for predicting actual disinfection byproduct formation prior to the costly investment for upgrading existing treatment facilities. The models developed in this paper provide comparisons of ozonation application methods, providing a basis for minimizing bromate and aiding in future design considerations. Theoretical and empirical models for the determination of ozone transferred, dissolved ozone concentrations, and bromate formation have been derived and compared with pilot-scale and full-scale data; a good agreement has been observed between the actual data and the predicted data, showing the validity of these models. True-batch bromate formation more closely simulated pilot-scale and full-scale data. Bromate formation in one stage vs two stage ozone contactors and different reactor configurations have been compared. Ozone gas phase concentration appears to have an effect on bromate formation as well.     

Identification and characterization of salt- and thermo-tolerant Leucaena-nodulating Rhizobium strains

 Rhizobium-legume symbioses are important for their nitrogen input, but salinity and elevated temperature in arid and semi-arid areas limit their effectiveness, and therefore plant growth and productivity. Sixteen Rhizobium strains isolated from root nodules of Leucaena trees grown in different geographical areas of Egypt varied in their degree of tolerance to salinity and in their symbiotic effectiveness with Leucaena leucocephala under saline conditions. Three strains were tolerant to >3% NaCl. L. leucocephala grown in the greenhouse at concentrations of NaCl up to 1.0% and inoculated either with strain DS 78 or strain DS 158 displayed significantly better growth than those plants grown at the same levels of salinity and inoculated with reference strain TAL 583. Although nine of the Rhizobium strains grew at 42  °C, their mean generation times were lengthened two- to fourfold. When daylight growth temperatures were elevated from 30  °C to 42  °C, nodule number and mass, nitrogenase activities and shoot top dry weight of plants inoculated with strains DS 78, DS 157 and DS 158 significantly increased, whereas these parameters decreased in plants inoculated with strain TAL 583. Rhizobium strains that effectively nodulate Leucaena under adverse saline conditions and at high temperatures were thus isolated, identified and characterized. Received: 12 September 1997     

Mobilization of phosphorus contributes to positive rotational effects of leguminous cover crops on maize grown on soils from northern Nigeria

Previous research has demonstrated a positive rotational effect of tropical leguminous cover crops on maize growth on a luvisol from Nigeria. This effect could not be explained by a better N supply. The objective of the present work was to further clarify whether improved P nutrition has been a contributing factor. Nine cover crops and maize were studied in nutrient solution‐culture with 1 and 20 μM P and with NO₃‐N as N source for root physiological parameters that may affect P mobilization. Zea mays, Lablab purpureus, and Centrosema pubescens responded to P deficiency by higher rates of proton excretion. Clitoria ternatea excreted OH^— with only small differences due to P nutrition. At low P supply, Chamaecrista rotundifolia, Clitoria, and Centrosema had the highest exudation rates of organic acid anions, especially citrate and malate. A major difference between plant species was found in root‐surface acid phosphatase activity. Cajanus cajan expressed the highest phosphatase activity. V_max of P uptake increased markedly under P deficiency, particularly for maize. Compared to the other plant species Cajanus, Chamaecrista, and Clitoria were characterized by a greater capability to absorb P at low external P concentrations. The nine cover crops and maize were also grown in pot experiments using two soils from northern Nigeria low in available P. The ultisol from Jos had a high P fixation capacity and was more acidic than the alfisol from Zaria. All plant species were precultured in the first season at 100 (Zaria) and 250 (Jos) mg P per pot. In the subsequent season, maize was uniformly seeded into all pots containing the remaining roots and the incorporated shoot dry mass (according to 15 mg P per pot) of the pre‐crop. No P and 250 (Zaria) or 500 (Jos) mg P per pot were freshly applied. Maize growth and P uptake were enhanced after legumes in Zaria soil. Cajanus showed the highest residual effect, and also Clitoria, Chamaecrista, and Lablab showed effects superior to the mean. In Jos soil, Clitoria, Cajanus, and Lablab enhanced maize growth above average. Also, a highly significant positive correlation between P uptake and biomass production was obtained. These results indicate that enhancement of maize growth after leguminous cover crops, at the low P supply of the soil used, mainly depends on P mobilization capacity of the cover crop.     

Identification and partial characterization of selected proteolytic enzymes in the digestive system of giant freshwater Prawn Macrobrachium rosenbergii (De Man) Postlarvae

Biochemical assays and substrate SDS-PAGE were conducted to partially characterize and identify various types of proteases present in the digestive tract of PL₁₅ giant freshwater prawn ( Macrobrachium rosenbergii ). Casein hydrolytic assay of the enzyme extracts showed major proteolytic activities at pH 3.0, 6.0 and 9.0, while assay of preincubated enzyme extracts with phenylmethylsulphonyl fluoride (PMSF), a serine protease inhibitor produced a 33.17% reduction in alkaline protease activity. When specific inhibitors tosyl-lysine chloromethyl ketone and tosyl-phenylalanine chloromethyl ketone were used, they resulted in a reduction in activity of proteases in the enzyme extracts by 82.41% and 55.03%, respectively, confirming the presence of trypsin and chymotrypsin, while ethylenediamine tetraacetic acid produced protease activity reduction in 33.92% showing the presence of metalloproteases in the digestive tract of the prawn. Further characterization of the alkaline proteases using SDS-PAGE technique, after incubating the extract in the presence or absence of specific inhibitors, produced six bands corresponding to molecular masses of between 13.48 and 136.1 kDa; two trypsin bands of 13.48 and 36.4 kDa, three chymotrypsin bands in the range of 23.0–73.4 kDa and one for metalloprotease of 136.1 kDa, all of which were identified from a zymogram. This study suggests that protein digestion in M. rosenbergii is initiated by an acid protease followed by a combination of action of alkaline proteases: trypsin, chymotrypsin and metalloproteases.     

Identification of a mannose‐binding lectin‐like protein recognized by the anti‐CD25 antibody in haemocytes from Cherax quadricarinatus

The crustacean haemolymph contains three main cell populations; however, it is not clear which mechanisms participate in the regulation of cells related to innate immunity. This work aimed to identify potential interleukin‐like receptors that could regulate cellular responses in Cherax quadricarinatus. By histochemical analysis with murine anti‐CD25 staining (targeting the α‐chain of the IL‐2 receptor), we identified that this antibody recognizes cytoplasmic granules in semigranular and granular haemocytes. In haemocytes stimulated with phorbol myristate acetate (PMA), increased fluorescence was observed in these cytoplasmic granules, whereas staining with a human IL‐2 antibody after stimulation with 1–10 ng/ml PMA revealed no overexpression of the receptor or oxidative burst in haemocytes. Two‐dimensional Western blot analysis of haemocyte lysates showed that anti‐CD25 identified a 27.4‐kDa protein with an isoelectric point (pI) of 7.7 and a 46‐kDa protein with a pI of 6.9. De novo sequencing of these proteins identified that they had 32% homology with a mannose‐binding lectin (MBL) from Pacifastacus leniusculus. Our results indicate that a mannose‐binding lectin‐like protein could exert a protective effect that prevents damage from other activated immune responses.     

Genetic parameters of survival in four generations of Indian white shrimp (Fenneropeneaus indicus)

This study evaluated the genetic variance for survival at harvest of Indian white shrimp (Fenneropenaeus indicus) using a pedigreed synthetic population generated upon collecting broodstock from different fishery grounds in Egypt. The estimated heritabilities (h² ± SE) of survival from generations G₀ to G₃ ranged from 0.144 ± 0.026 to 0.008 ± 0.030 using a model that included the common environmental effect (c²). Low heritability (0.014 ± 0.015) was estimated across generations with the inclusion of common environmental effect (c²). However, the h² of survival from G₀ to G₁ ranged from 0.569 ± 0.071 to 0.410 ± 0.011 when c² was not included. The genetic correlation for survival between different ponds from G₀ to G₃ was moderate to high (0.79 ± 0.042 to 0.83 ± 0.012) but significantly different (P < 0.05). There were low correlation coefficients (?0.237 ± 0.089 to 0.316 ± 0.073) between body weight estimated breeding value (EBV) and survival EBV of families in four generations.     

Effect of growth stage on the content and composition of the essential oil and phenolic fraction of sweet marjoram (Origanum majorana L.)

The variation in the content and composition of Origanum majorana L. essential oil has been studied. Plant material has been harvested at four phenological stages (early vegetative, late vegetative, budding and full-flowering). Essential oil yield varied from 0.04 to 0.09% reached during the full-flowering stage. Analysis of the essential oils by GC and GC/MS revealed the presence of 38 components represented mainly by oxygenated monoterpenes (64.01–71.4%), monoterpene hydrocarbons (21.73–29.92%) and sesquiterpene hydrocarbons (1.47–4.05%). The main components were terpinen-4-ol (29.13–32.57%), cis-sabinene hydrate (19.9–29.27%), trans-sabinene hydrate (3.5–11.61%), γ-terpinene (2.11–8.20%), bornyl acetate (1.52–2.94%) and linalool (1.05–1.39%). On the other hand, phenolic contents varied from 2.706 to 6.834 mg/g of dry weight obtained during the later vegetative stage. RP-HPLC analysis of the methanolic extract of O. majorana L. dried aerial parts showed the predominance of phenolic acids during the early vegetative stage whereas flavonoids predominate during the other stages of growth. The main phenolic acids identified were trans-2-hydroxycinnamic, rosmarinic, vanillic, chlorogenic, gallic and cinnamic whereas the main flavonoids were amentoflavone, apigenin, quercetin, luteolin, coumarin and rutin. Results obtained showed that later vegetative stage is characterized by the highest contents of bioactive compounds and therefore it could be considered as the best stage for harvesting marjoram plants.