Field study of the interaction between Orobanche crenata Forsk. and some new lines of Vicia faba L. in Egypt

In Egypt, some newly derived lines of faba bean (Vicia faba L.) as well as Giza 402, all of which had shown a certain resistance against the parasitic weed Orobanche crenata Forsk., were tested in the field. For reasons of comparison, the susceptible cultivars Giza 3 and Reina Blanca were included in this test. Faba bean plants and Orobanche attachments were regularly harvested and examined. The susceptible cultivars completely collapsed before the end of the growing season, whereas others, particularly line 402/294, remained alive until pod formation was completed. It appeared that fewer Orobanche spikes emerged on the new lines and Giza 402. Evidence is given that this was not due to avoidance mechanisms, such as smaller root mass, a deeper root system or lack of germination stimulants. Numbers of Orobanche attachments per unit of lateral root length were found to be low. Hence, it could be concluded that these lines are partially resistant; this resistance must be due to some defence mechanism in their roots. The few Orobanche plants attached grew very fast so that final Orobanche dry weight was similar in resistant and susceptible host plants. Further experiments, including broomrape-free controls, are required to study whether some tolerance mechanism might be involved.     

Effects of mycorrhiza inoculation on cucumber growth irrigated with saline water

This experiment was conducted as a factorial based on complete randomized design (CRD) to study the effects of mycorrhiza inoculation density on cucumber cv. Super N3 irrigated with different salinity sodium chloride (NaCl) levels. Treatments were mycorrhiza inoculations; M1 (non mycorrhizal plant), M2 and M3 (mycorrhiza inoculations with 1000 and 2000 spores) and saline water was provided by S1, S2, S3, and S4 (control, 50, 75, and 100 mM NaCl) with 4 replications. The results showed that saline water reduced root, shoot, and fruit weights, and increased proline and electrolyte leakage. Photosynthesis rate, stomata and mesophyll conductance significantly decreased with increased NaCl concentrations. Mycorrhiza inoculation with 2000 spores increased fruit fresh and dry weights, proline and electrolyte leakage, and both mycorrhiza inoculations increased root and shoot dry weights, photosynthesis and stomata conductance. Root volume increased by mycorrhiza inoculation with 2000 spores under non-stress condition, and root length was stimulated by both mycorrhiza inoculations at all saline water levels. Fruit fresh and dry weights were enhanced by mycorrhiza inoculation with 1000 spores at all saline water levels. Photosynthesis rate was reduced by saline water stress and mycorrhiza inoculation stimulated photosynthesis rate. Mycorrhiza inoculation with 2000 spores increased transpiration under saline and non-saline conditions. Proline content of cucumber leaves increased under saline water application. Electrolyte leakage increased by saline water and mycorrhiza inoculation could not improve it. Both mycorrhiza inoculations (1000 and 2000 spores) at all salinity levels, and mycorrhiza inoculation with 1000 spores at 100 mM NaCl enhanced fruit weight, photosynthesis, and proline content of the cucumber leaves.     

Sex steroid level and sexual dimorphism expression of genes in gonads of the great sturgeon Huso huso Linneaus, 1758 during maturity developmental stages

Little is known about molecular mechanisms involved in gonad differentiation in sturgeon species. In non‐mammalian vertebrates, sox9, dmrt1, cyp17a1 and ar are male specific genes in testicular differentiation and are highly conserved. In order to understand the mechanism underlying testicular development in sturgeon, we investigated sex steroids level of 11‐ketotestosterone (KT) and testosterone (T) and relative expression of sox9, dmrt1, cyp17a1 and ar in great sturgeon gonads during different stages of sexual maturity. The results showed all studied genes had dimorphic patterns in males. In immature gonads (stage I), only cyp17a1 expressed in male gonads, while other genes did not express, and KT and T levels were low. Dmrt1 showed dimorphic expression pattern in male gonads at maturity stage II, III and IV. Furthermore, sox9 and ar mRNA presented significant dimorphic expression pattern in male gonads only at maturity stage 4. Plasma androgens levels were significantly higher in males compared to females during maturity stages II, III and IV. The results showed that among these four genes, only cyp17a1 expressed in male gonads at maturity stage I (immature), suggesting that this gene may be applicable as a sex marker in recently differentiated male great sturgeon. Sexually dimorphic patterns in other studied genes (sox9, dmrt1 and ar) suggesting that these genes may be important for testicular development and differentiation in premature great sturgeon. The obtained results provide a foundation for further research on sex differentiation and developing strategies for the sexing of sturgeon for aquaculture.     

Population density and feeding duration of cabbage looper larvae on tomato plants alter the levels of plant volatile emissions

BACKGROUND: As part of their indirect defense, plants under herbivore attack release volatile chemicals that attract natural enemies of the herbivore. This is a very well-documented phenomenon. However, relatively few studies have investigated the response of plants to different population levels of herbivores and their feeding duration. RESULTS: Working with larvae of the cabbage looper, Trichoplusia ni (Hübner), and tomato plants, Lycopersicon esculentum Mill cv. clarence, and using an ultrafast gas chromatograph (the zNose™) for volatile analyses, the authors studied the effect of larval density and feeding duration on levels of plant volatile emissions. Intense herbivory caused higher emission levels of the herbivore-induced plant volatiles (HIPVs) (Z)-3-hexenyl acetate, (E)-β-ocimene and β-caryophyllene than those caused by moderate herbivory. When herbivory had ceased following 12–24 h of larval feeding, plants kept releasing HIPVs at a high level for a longer period of time than they did following only 6 h of larval feeding. The plants' slow adjustment in their volatile emissions following prolonged larval feeding might be strategic, as such feeding is more likely to have ceased just temporarily. CONCLUSION: This information may help in the development of a pest monitoring system that is based on herbivore-induced plant volatiles. Copyright © 2011 Society of Chemical Industry     

Comparative toxicity of Rosmarinus officinalis L. essential oil and blends of its major constituents against Tetranychus urticae Koch (Acari: Tetranychidae) on two different host plants

Bioassays of Rosmarinus officinalis L. essential oil and blends of its major constituents were conducted using host-specific strains of the two-spotted spider mite, Tetranychus urticae Koch, on bean and tomato plants. Two constituents tested individually against a bean host strain and five constituents tested individually against a tomato host strain accounted for most of the toxicity of the natural oil. Other constituents were relatively inactive when tested individually. Toxicity of blends of selected constituents indicated a synergistic effect among the active and inactive constituents, with the presence of all constituents necessary to equal the toxicity of the natural oil.     

A Modified DMT-HFO Technique for Investigating the Kinetics of Phosphorus Desorption from Calcareous Soils and its Relationship with Maize Growth

In this research, phosphorus (P) desorption was investigated using DMT-HFO as an “infinite” sink for 10 calcareous soils over a period of 1–35 days and the kinetic data was related to soil properties and P uptake by maize (Zea mays L.). First- and second-order, and simple Elovich equations adequately described P desorption kinetics, however parabolic, exponential and zero order equations provided the best fits to the data. A systematic relationship exists between the second order rate parameter (k₂) and the clay content of the soils. There are positive relationships between P desorption rate constants (for zero order, Elovich and parabolic equations), and both dry matter and P content of maize shoots and also for roots. These relationships indicate that P desorption rate may be a limiting factor for maize growth in these soils. The DMT-HFO technique may be used to assess the long-term availability of P to plants.     

Chitinolytic <Emphasis Type="Italic">Streptomyces griseorubens</Emphasis> E44G enhances the biocontrol efficacy against <Emphasis Type="Italic">Fusarium</Emphasis> wilt disease of tomato

Streptomyces griseorubens E44G is a chitinolytic bacterium isolated from cultivated soil in Saudi Arabia (a hot, arid climatic region). In vitro, antifungal potential of S. griseorubens E44G was assessed against the phytopathogenic fungus, Fusarium oxysporum f. sp. lycopersici (the causative agent of the Fusarium wilt disease of tomato). An inhibition zone of 24 mm was recorded. The chitinolytic activity of S. griseorubens E44G was proved when the colloidal chitin agar plate method was used. A thermostable chitinase enzyme of 45 kDa molecular weight was purified using gel filtration chromatography. The optimum activity was obtained at 60 °C and pH 5.5. The purified enzyme has shown a very pronounced activity against the phytopathogenic fungus, F. oxysporum. The molecular characterization of the chitinase gene indicated that it consists of 1218 bp encoding 407 amino acids. The phylogentic analysis based on the nucleotide DNA sequence and the deduced amino acids sequence showed high similarity percentages with other chitinases isolated from different Streptomyces species. In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent.     

Lethal and sublethal effects of buprofezin and imidacloprid on Bemisia tabaci (Hemiptera: Aleyrodidae)

The sweetpotato whitefly, Bemisia tabaci (Gennadius), has become a major threat to agriculture worldwide. The development of insecticide resistance in B. tabaci has necessitated the exploration of new management tactics. The toxicity of imidacloprid and buprofezin to various life stages of B. tabaci was determined in the laboratory. Also, the sublethal effects of both insecticides were studied on demographic and biological parameters of B. tabaci. Both insecticides were very toxic against first stage larvae of the pest with LC₅₀ values of 1.0 and 19.3 ppm for buprofezin and imidacloprid, respectively. Toxicities decreased between successive stages (LC₅₀ values ranging from 1.0 to 2854.0 ppm). The LC₅₀ values of imidacloprid for adult males, females and eggs were 11.8, 71.6 and 151.0 ppm, respectively. Buprofezin had no significant effect on adults and eggs. The sublethal concentration of imidacloprid had no significant effect on demographic and biological parameters of B. tabaci but the maximal value for the mean generation time (T) (18.8 day) was observed in imidacloprid treatment. Buprofezin significantly decreased stable population and biological parameters of B. tabaci except it did not decrease the rate of population increase or the sex ratio of offspring.     

Physiochemical Processes Affecting the Geochemistry of Carbonate Aquifer of Southeastern Al-Ain Area, United Arab Emirates (UAE)

Detailed hydrogeochemical analyses were carried out in order to delineate the physiochemical processes and paleohydrogeological regime of groundwater flow of southeastern Al-Ain area and its surrounding desert fringes. Groundwater composition and salinization could be a result of integrated cycles of successive physiochemical processes of mixing of seawater, salt dissolution, and flushing by recharge water from the infiltration of rainfall in the interdune areas and gravel plains and also from Jabal Hafit lying to the southeast, and sewage effluent water from the residence areas to the northwest. In addition to that, ion exchange upon flushing, salt sieving from deep aquifers, and evaporation and accumulation along the wetland zones are factors affecting the groundwater of the area. Human and anthropogenic activities might have negative impact on the quality of groundwater in the region. Both Zn and Fe are the most detectable heavy metals in the analyzed samples, and they reach as maximum as 2,277 ??g/l and 2,902.6 ??g/l for Zn and Fe, respectively, along the north western localities. The source of these metals is most probably due to contamination threats by the sewage effluent or industrial wastes in these localities. Reducing environment releases the toxic and heavy metals in soluble compounds in case of high organic matters. A strong relationship appears between Fe and Zn ion concentrations in groundwater and the type of well construction materials (casings and screens). Also, a positive correlation is observed between the concentrations of Zn in water wells and in plants surrounding the wells. The increase of chromium concentrations is observed in the north of the study area, and this increase might be ascribed to the weathering of olivine and pyroxence of Oman Mountain in the northeast and might be possibly due to using the manure or animal wastes for agriculture activities.     

Yield Attributes and Oil Safety in the Hyperaccumulator Canola Plant Grown in a Bioremediated Sewaged Soil

A field experiment was carried out at Abu-Rawash sewage farm to appraise the effect of certain novel remediative amendments on the quality of oil as well as the vegetative parameters and yield criteria of canola plant used as hyperaccumulator for the remediation of sewaged soils. The treatments included fallow soil （irrigated without growing canola）, soil cultivated with canola （Brassica napus L.） and inoculated with arbuscular mycorrhiza （AM）, soil inoculation with Thiobacillus sp. （a mixture of Thiobacillus ferrooxidans and Thiobacillus thiooxidant）, soil treated with a mixture of 250 mg bentonite plus 250 mg rock phosphate/kg soil and inoculated with phosphate dissolving bacteria （PDB）, and soil treated with all the aforementioned remediative amendments. Results indicated that the vegetative parameters and yield criteria of canola plant did not exhibit any serious adverse impact under all treatments applied. The concentrations of Zn and Cu in canola oil extracted from plants grown in soil inoculated with AM and/or Thiobacillus sp. far exceeded the safe permissible levels. On the other hand, the content of both PTEs in the oil extracted from canola plants grown in soil treated with either probentonite or with mixture of all remediative amendments followed the permissible safe levels.