In vitro storage of fish oocytes: effect of storage temperature,media conditions and storage duration on fertilization and larval hatchability of Indian major carp,rohu (Labeo rohita)

The viability of matured oocytes stored in vitro were assessed using carp ovarian fluid (OF) and artificial carp ovarian fluid (ACOF) under different temperature regimes (4, 24, 26, 28 and 30°C) for different storage durations (0, 60, 120, 150 and 180 min). Significantly higher fertilization (74%) was achieved when the oocytes were stored using ACOF and 65% in OF after 180 min at 28°C. Similarly the hatching rates of larvae were significantly higher in the ACOF and OF, that is, 64% and 47%, respectively, after 180 min of storage. The oocytes kept in the storage containers with ACOF having 65% moisture level showed a significantly higher fertilization rate than the 59% moisture level. This study demonstrated that unfertilized matured oocytes (eggs) of rohu can be stored in vitro for 180 min without compromising the viability (fertilization and hatching) to a great extent in OF and ACOF.     

Boron and zinc fertilizer applications are essential in emerging vegetable‐based crop rotations in Nepal

Background : Since recently, the traditional rice–wheat rotation systems in Nepal are subject to drastic changes. Progressing urbanisation and shifting consumer preferences drive a replacement of wheat by high‐value vegetables during the cold dry season, particularly in the peri‐urban fringes, while emerging water shortages prevent permanent soil flooding during the monsoon season, leading to partial substitution of lowland rice by less water‐consuming upland crops. Associated changes in soil aeration status affect soil nutrient availability while particularly vegetables enhance the demand for the critically limiting micronutrients boron (B) and zinc (Zn). Aim : In both rice‐ (anaerobic) and maize‐based (aerobic) systems we assessed the differential response of traditional winter wheat in comparison to cauliflower and tomato to applied B and Zn fertilizers. Methods : Experiments were conducted (1) in a pot trial with two contrasting soil types (Acrisol vs. Fluvisol) and (2) in field validation trials at two contrasting sites (representing lowland vs. mid‐hills) in Nepal. Results : The on‐going shift from flooded rice to aerobic maize during the wet season negatively affected dry matter accumulation and grain yield of the dry season wheat, but not of cauliflower and tomato. While Zn application tended to increase wheat yields under field conditions, B application induced no significant effect, irrespective of the soil or production site. However, low to moderate applications of B (2.0–4.4 kg ha^?1) and Zn (3.3–4.4 kg ha^?1) nearly doubled biomass accumulation and nutrient uptake of vegetables and increased the economic yields of cauliflower and tomato between 8 and > 100%. These responses were generally more pronounced in the Fluvisol than the Acrisol. While overall yields of wheat and temperate vegetables were higher in the cool mid‐hills the relative yield responses to applied B were more pronounced in the lowland than the mid‐hill sites. On average, the partial factor productivities of applied fertilizer were low to moderate in wheat, with 1 and 8 € increase in net revenue per € of investment in B and Zn, respectively. In the vegetables, this partial factor productivity increased to about 4 € €^?1 investment with Zn, and reached about 43 € €^?1 investment in B, irrespective of the production site. Conclusions : While the application of Zn fertilizers can moderately improve the performance of traditional rice–wheat rotations, B and to a lesser extent Zn application become essential and highly profitable when shifting towards vegetable cropping. The demand for B and Zn fertilizers is foreseen to dramatically increase with progressing urbanisation and the associated shifts in production systems of Nepal.     

Sexual activity patterns in rams.

Behaviour was measured in reproductively experienced rams from three crossbred strains and two pure breeds (Suffolk and Finnish Landrace) in an attempt to develop a method for rapid screening of sexually aggressive rams and to measure breed differences in sexual activity. A set sequential pattern of activity need not occur in sexually experienced rams, and components of their sexual behaviour may be influenced by the estrual status of the ewe. The data indicate that the number of attempted mounts is an acceptable selection tool, with a mount following a short period of investigation most likely to be followed by coitus. Two sequential ten minute periods are sufficient for rapid screening of rams for short-term sexual activity levels.     

Biodegradation of Toluene Under Seasonal and Diurnal Fluctuations of Soil-Water Temperature

An increasing interest in bioremediation of hydrocarbon polluted sites raises the question of the influence of seasonal and diurnal changes on soil-water temperature on biodegradation of BTEX, a widespread group of (sub)-surface contaminants. Therefore, we investigated the impact of a wide range of varying soil-water temperature on biodegradation of toluene under aerobic conditions. To see the seasonal impact of temperature, three sets of batch experiments were conducted at three different constant temperatures: 10°C, 21°C, and 30°C. These conditions were considered to represent (1) winter, (2) spring and/or autumn, and (3) summer seasons, respectively, at many polluted sites. Three additional sets of batch experiments were performed under fluctuating soil-water temperature cases (21<>10°C, 30<>21°C, and 10<>30°C) to mimic the day-night temperature patterns expected during the year. The batches were put at two different temperatures alternatively to represent the day (high-temperature) and night (low-temperature) times. The results of constant- and fluctuating-temperature experiments show that toluene degradation is strongly dependent on soil-water temperature level. An almost two-fold increase in toluene degradation time was observed for every 10°C decrease in temperature for constant-temperature cases. Under fluctuating-temperature conditions, toluene degraders were able to overcome the temperature stress and continued thriving during all considered weather scenarios. However, a slightly longer time was taken compared to the corresponding time at daily mean temperature conditions. The findings of this study are directly useful for bioremediation of hydrocarbon-polluted sites having significant diurnal and seasonal variations of soil-water temperature.     

Mitigating soil erosion through farm-level adoption of soil and water conservation measures in Samanalawewa Watershed,Sri Lanka

Abstract

Soil erosion by water is currently one of the most notable types of land degradation in Samanalawewa Watershed in Sri Lanka, creating copious environmental and socioeconomic impacts. Thus, with the aim of detecting and mapping the rates of human-induced soil erosion in the watershed, remote sensing and geographic information system based modelling and field experiments were carried out. The results of the assessment disclosed that the present rate of human-induced soil erosion varies from 0 to 289 t ha^?1 yr^?1 with the majority of the area exceeding the natural rate of soil erosion by 14 to 33 times at present. However, the average rate of human-induced soil erosion has declined dramatically from 19.8 to 4.3 t ha^?1 yr^?1 from 1986 to 2008. In order to analyse the significant determinants of farm-level adoption of soil and water conservation measures, binary logistic regression procedure was applied using the data collected through a household survey (n = 201). The most significant (p<0.01) variables of the study were the farmers’ perceptions of soil erosion problems, gender of the household head, training on soil and water conservation, and ascertained advice from agricultural extension officers while the variables regarding past awareness about soil conservation technologies and off-farm income were significant at p<0.05. Furthermore, the study revealed that the majority (60.2%) of the farmers in the study area had been adopting different types of soil and water conservation measures for a prolonged period of time. Therefore, owing to the current decreasing rate of soil erosion, the soil and water conservation costs and the ratios of human-induced soil erosion vs natural soil erosion had declined significantly while the productivity of their lands had gone up.     

PCR-based sensitive and specific detection of Pectobacterium atrosepticum using primers based on Rhs family gene sequences

A sensitive and specific assay was developed to detect potato blackleg caused by Pectobacterium atrosepticum in potato. Primers PEAF and PEAR from the Rhs family gene homologous to RhsA (cell envelope biogenesis – outer membrane) were used to amplify a 904 bp DNA fragment. PCR was used to detect the pathogen in artificially inoculated potato seed tubers. The PCR product was only produced from 12 isolates of P. atrosepticum from various countries among 36 isolates of other species of Pectobacterium , Pseudomonas , Xanthomonas , as well as Escherichia coli and the soilborne fungus Fusarium oxysporum f.sp. dianthi .     

Phylogenetic relationships and virulence assays of Fusarium secorum from sugar beet suggest a new look at species designations

Fusarium spp. are responsible for significant yield losses in sugar beet (Beta vulgaris) with Fusarium oxysporum f. sp. betae most often reported as the primary causal agent. Recently, a new species, F. secorum, was reported to cause disease in sugar beet but little is known on the range of virulence within F. secorum or how this compares to the virulence and phylogenetic relationships previously reported for Fusarium pathogens of sugar beet. To initiate this study, partial translation elongation factor 1-α (TEF1) sequences from seven isolates of F. secorum were obtained and the data were added to a previously published phylogenetic tree that includes F. oxysporum f. sp. betae. Unexpectedly, the F. secorum strains nested into a distinct group that included isolates previously reported as F. oxysporum f. sp. betae. These results prompted an expanded phylogenetic analysis of TEF1 sequences from genomes of publicly available Fusarium spp., resulting in the additional discovery that some isolates previously reported as F. oxysporum f. sp. betae are F. commune, a species that is not known to be a sugar beet pathogen. Inoculation of sugar beet with differing genetic backgrounds demonstrated that all Fusarium strains have a significant range in virulence depending on cultivar. Taken together, the data suggest that F. secorum is more widespread than previously thought. Consequently, future screening for disease resistance should rely on isolates representing the full diversity of the Fusarium population that impacts sugar beet.