Results 1 - 10 of 85
Results 1 - 10 of 85. Search took: 0.019 seconds
|Sort by: date | relevance|
[en] The molecular epigenetic relationship between DNA methylation and hybrid vigor using different sources of cytoplasmic male sterility of sunflower (six A-lines, three R-lines, and their 18 F1's) has been investigated. Molecular analysis of DNA methylation using methylation-sensitive amplification polymorphism (MSAP), revealed that the used four primers succeeded in characterizing a total of 36 specific loci, 35 out of these loci found to be methylation-susceptible (MSL). Meanwhile, only 27 loci were polymorphic achieving were 77% polymorphism percentage of 77%. Differently methylated regions (DMRs indicated a large convergence between A-lines and single hybrid populations, whereby the percentage of unmethylated state reached 23% and 22% in both populations, respectively. The highest percentage of non-methylated state (31%) was detected in R-lines, whereas the hybrids gave the highest percentage of hemimethylated state (13%) against their sterile maternal lines (Alines) and fertility restorer lines (R-lines) which were 10% and 8%, respectively. A-lines showed the minimum percentage of the internal cytosine methylation (10%), where as, the parental testers and the resulted hybrids gained a slightly higher different percentage (14% and 13%, respectively). The epigenetic distinctness of sterile A-lines was clear as they showed the highest value for full methylation state (57%) against testers and diallel hybrids (46% and 50% respectively). Hybrids like A3XR2 showed a unique methylation pattern to occupy a single cluster. Hybrids with higher hybrid vigor (A2XR1, A4XR2, and A6XR1) gave the highest positive heterosis values for plant yield. (author)
[en] Microbial formulations prepared from entomopathogenic fungi emerging as the effective alternate of chemical pesticides against different crop pests. They cause lethal infections and regulate insects and mites population in nature by epizootics and considered as primary candidates for mycoinsecticides. In this study, we evaluated five species of entomopathogenic fungi such as Beauveria bassiana, Metarhizium anisopliae, Isaria farinosa, Paecilomyces lilacinus and Verticillium lecanii against Phenacoccus solenopsis on okra crop. Three concentrations calculated on the basis of previous study (LD50, ten times higher and ten times lower than LD50) of each fungal biocontrol agent were applied to okra plants infested with mealybugs. In the pot experiment, the higher dose of M. anisopliae (7.063×108) and B. bassiana (1.37×108) followed by P. lilacinus (6.615×107) were highly effective in controlling the pest population, they brought 83.7, 80 and 78.7% reduction, respectively. Second most effective treatments were a higher dose of V. lecanii (1.69×107) and a medium dose of P. lilacinus (6.615×106), brought 69.4 and 53% reduction in mealybugs. Among all entomopathogenic fungi, I. farinosa was the least effective; its lower, medium and higher doses caused only 20.7, 48.5 and 51.6% reduction, respectively. In field trial, higher doses of all biocontrol agents were more effective than their medium and lower doses. Whereas, maximum yield was recorded in the higher (7.063×108) and medium dose of (7.063×107) of M. anisopliae followed by a higher (1.37×108) and medium (1.37×107) dose of B. bassiana. This study provides new opportunities for effective and eco-friendly control measures of mealybugs. (author)
[en] Fruit quality improvement of date palm has always been an issue that can be resolved by using different approaches, and one of them is the application of chemical fertilizers. Potassium is the least used nutrients by the growers in this part of the world although it is a major nutrient necessary to improve the yield and fruit quality of date palm. Keeping in view the importance of potassium, the objective of the present research was performed to investigate the role of potassium in improving yield and quality of ‘Dhakki’ date palm. For this purpose, seven different treatments were used for the experiment including:(i) Control (distilled water spray); (ii) KNO3 at 1%; (iii) KNO3 at 1% + urea at 2%; (iv) KNO3 at 2%; (v) KNO3 at 2% + urea at 2%; (vi) KNO3 at 3%; (vii) KNO3 at 3% + urea at 2%. The application of KNO3 was performed at ‘Kimri’ stage of fruit development. The randomized complete block design was used including three replications. Pre and post-harvest physicochemical parameters were evaluated that included fruit drop, fruit length, diameter, fruit weight, percent pulp, bunch weight, total soluble solids, reducing, non-reducing and total sugars in the fruits. The results revealed that during both seasons of study, KNO3 alone and mixed with urea significantly showed better results however the application of KNO3 at 2% is found to be more effective in minimizing fruit drop (46.99% and 50.05%) and enhancing other variables i.e. fruit length (54.41mm and 53.46mm), diameter (43.15mm and 41.31mm), fruit weight (13.69g and 13.53g), percent pulp (90.99% and 93.59%), bunch weight (8.21kg and 8.11 kg) and total soluble solids (76.07 and 76.83 °Brix) during both seasons of study hence resulting in improved yield and fruit quality of ‘Dhakki’ date palm. (author)
[en] The current research study was designed to evaluate the impact assessment of Better Management Practices of cotton by comparing the performance of both the adopters and non-adopters of BMPs. The present quantitative (cross-sectional) study was conducted in the Southern region of the Punjab province of Pakistan. A sample of 160 farmers constituting equal number of adopters and non-adopters of BMPs of cotton was drawn from district Khanewal which was purposively selected from the Southern Punjab. Data were collected by the utilization of a well-structured interview schedule. The results of the logit model revealed that education and farming experience had a significant influence on the adoption of BMPs. Furthermore, it was found that the adoption of BMPs was mainly affected by the area under cotton cultivation, land ownership status, age, and family size of the cotton grower, but the probability of these variables was not found statistically significant. The frequency analysis of the collected data revealed that the average number of irrigations applied by both the adopters and non-adopters was 16.0 and 21.0, respectively. Mean numbers of fertilizer (Urea, DAP, Potassium Nitrate, etc.) bags and pesticide applications applied by the adaptors and non-adopters were 3.5 and 4.2 bags, 3.8 and 7.7 applications, respectively. Child labor was exploited by 11.3% of adopters and 78.8% of non-adopters. Health and safety measures were highly considered by 75.0% of the adopters and 42.5% of the non-adopters. It was concluded that BMPs on cotton had significant impact not only on the productivity but also on the environmental safety and sustainability of the cotton crop. (author)
[en] The short range atmospheric dispersion exercise was executed by eight participants using eight models. These included: - Atmospheric Dispersion and Dose Analysis Method (ADDAM); - Canadian Standards Association (CSA-ERM) code; -Computational Fluid Dynamics (CFD) code; - CLMM; - HOTSPOT 2.07.1; - LASAIR; - RDDMMC; and - University of Seville Model (USev). Descriptions of each of these models and their assumptions are provided in the sections that follow.
[en] This work demonstrates an analytical protocol for high precision Sm isotope analysis by thermal ionization mass spectrometry (TIMS) using a Pt activator. The method permits precise measurements of small aliquots (1-20 ng) of Sm on single Re filament using a modified static-total evaporation technique. This study represents the first attempt to use such protocols for Sm isotope analyses while reducing the loading size of Sm for TIMS. The method could potentially be deployed to study geological, meteorites and lunar samples containing low Sm concentrations, to monitor neutron irradiation exposure based on 149,150Sm, or to measure Sm isotopic composition in other types of nuclear samples. (author)
[en] Spermidine (Spd) and wood vinegar are widely reported for its positive role to ameliorate plants under abiotic stress. In this study, the protective roles of Spd and wood vinegar in salt-sensitive rice cultivars ‘Khao Dawk Mali 105 (KDML105)’ and ‘RD6’ exposed to salinity stress were investigated under greenhouse and field conditions by dividing into two experiments. Under the greenhouse condition, three concentrations of Spd (0.1, 0.5 and 1.0 mM) were sprayed daily to 60-dold ‘KDML105’ plants (booting stage) grown in soil for 7 d ahead of watering the plants with tap water (control) or 30 mM NaCl (salt stress). The results showed that spraying 0.5 mM Spd was most effective in improving the salt tolerance of ‘KDML105’ as evidenced by an increase in the development of flag leaves, SPAD values, yield and yield components. To reduce crop production cost, the second experiment was conducted. The concentration of Spd used was based on the greenhouse experiment. Exogenous Spd (0.5 mM) was applied in comparison with wood vinegar (1:300 and 1:500) under field condition. Rice ‘KDML105’ and ‘RD6’ were grown under low (EC = 3 dS m-1) and high (EC = 10 dS m-1) saline fields. At the booting stage, Spd or wood vinegar were sprayed daily for 7 d. In both saline field sites, both rice cultivars sprayed with Spd and/or wood vinegar at all tested ratios showed a marked increase in yield and yield components, with better results observed for ‘KDML105’. The findings suggest that Spd and wood vinegar could be applied for alleviating the effects of salt stress on rice production. (author)
[en] A chemical methodology has been selected to isolate and concentrate select trace fission product (FP) elements from separated Pu for nuclear forensics. The methodology employs several different resins and eluents to chromatographically separate U and the FP elements of interest into their own fractions. The U, rare-earth element, Cs, and Ba fractions were isolated with relative yields of ≥ 73.8%, ≥ 80.7%, ≥ 98.5%, and ≥ 98.0%, respectively. The methodology was able to successively isolate select FP elements on the order of 10-10 g out of much larger samples of Pu. (author)
[en] High night temperature periods have reduced rice crop yields in recent years in Colombia. One of the strategies used to address this situation has been selecting tolerant genotypes and identifying physiological variables that serve as selection criteria in breeding programs. The aim of this study was to determine the effect of two-night temperatures (24°C vs. 30°C) on the physiological and agronomic performance of seven rice genotypes (Fedearroz 50 (F50), Fedearroz 60 (F60), IR 1561, FLO 2764, LV447-1, CT19021 and LV1401). At milk growth stage, a group of six plants of each genotype was placed in a growth chamber between 18:00 and 24:00 h at 30°C for a period of eight days (stressed plants). Meanwhile, another group of rice plants sorted by genetic material was kept under normal growth conditions (24°C) in a shade house (Control Plants). Results showed that rice genotype F50 plants showed a lower rate of spikelet fertility compared to the other genotypes studied at 30°C (p≤0.05). Leaf photosynthetic pigments and chlorophyll α fluorescence parameters (Y(II), Y(NPQ), Y(NO) and Fv/Fm ratio) showed no differences between night temperatures; however, significance differences were found among genotypes. The above results suggest that Y(II), Y(NPQ), Y(NO) and Fv/Fm in rice plants at advanced phenological stages (milk stage) are not an effective tool to quantify the physiological behavior of rice genotypes under a high night temperature condition. (author)
[en] An overview of high-temperature gas-cooled reactor (HTR)fission product chemistry and its influence on source terms in core heatup accidents is given. These accidents are risk-dominating for medium-sized HTRs and are characterized by maximum core temperatures of —2500°C (2773 K) and a late-starting, slowly proceeding fission product release from the fuel particles. In these accidents, the number of chemical reactions in the core and primary circuit is limited by the low oxygen potential and preferential release of metal from the fuel. The graphite in the core acts as a very powerful barrier to metallic fission products because of its chemisorption action. Cesium iodide (Csl) formation can reduce this sorptive retention for cesium when there is a high cesium burden on the graphite. This is not necessarily expected for small HTRs, which have much lower maximum accident temperatures (1600°C = 1873 K) and a much lower fractional release of fission products from coated particles. In the primary circuit, less efficient chemisorption of fission products on metals occurs. The fission product chemistry in the HTR reactor building is similar to that for other reactor types. Conservatisms in handling fission product chemistry in HTR safety analyses are identified. This leads to the conclusion that, especially for metallic fission products, a significant potential for reduction of the actual core heatup source terms exists. In modern medium-sized HTRs, these source terms are of the order of<1% of the core inventory for cesium, iodine, and noble gases and <0.1% for strontium. For small HTRs, these source terms remain several orders of magnitude smaller.