Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

The allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.     

Heat stress and effect of shade materials on hormonal and behavior response of dairy cattle: a review

In tropical countries, at high temperatures, several physiological rearrangements occur in cows as they attempt to facilitate heat dissipation and/or reduce metabolic heat production. Following exposure to heat, cattle appear to acclimatize within 2–7 weeks. The failure of homeostasis at high temperatures may lead to reduced productivity or even death. The situation is even worse when humidity adds to high temperature. Livestock with elevated body temperature exhibit lower DMI and growth with less efficiency, reducing profitability for dairy farms in hot and humid climates. Shading of feed and water also offers production advantages. Although several elaborate methods for reducing heat stress in cows have been reported, simple shade materials appear to be the most cost-effective methods that are currently applicable to tropical developing countries. Different materials are being used to provide shade during warm weather. The shade material determines the microclimate—it should be light, strong, durable, weatherproof, good looking and a bad conductor of heat, and free from tendency to condense moisture inside. This review discusses various shade materials and their advantages and disadvantages in different situations.     

银合欢落叶层对苗圃生长的森林一农田作物的他感作用(英文)

利用随机区组试验评估了孟加拉国吉大港大学苗圃内的银合欢落叶对森林作物种白格、黄金檀和农田作物种长豇豆、鹰嘴豆和木豆的他感作用。结果表明,凋落叶诱导抑制作物的萌发和生长,该抑制作用依赖于萃取物浓度、凋落物及受体物种类型。萃取物浓度越高则他感作用越强。受体植物的生长响应随应用的凋落叶而变化。低浓度(10g·m-2)凋落叶对农田作物嫩芽生长有促进作用,而其他浓度的凋落叶则呈现明显的抑制作用,施用的凋落叶浓度越大抑制作用也越大。但是不同处理所表现出的抑制趋势并不均一,根系生长受到的影响大于嫩芽。图3表4参34。     

Prevalence of bluetongue virus antibodies and associated risk factors among cattle in East Darfur State,Western Sudan

Background

Bluetongue virus (BTV) is an insect-transmitted virus, which causes bluetongue disease (BT) in sheep and a fatal hemorrhagic infection in North American white-tailed deer. However, in cattle the disease is typically asymptomatic and no overt clinical signs of disease appear to be associated with BTV infection. Serological evidence and isolation of different BTV serotypes have been reported in Sudan, however, no information is currently available in regard to previous exposure of Sudanese livestock to BTV infection in East Darfur State, Sudan.

Aims

To determine the prevalence of BTV antibodies and to identify the potential risk factors associated with BTV infection among cattle in East Darfur State, Sudan.

Methods

A total of 224 blood samples were collected randomly from five localities in East Darfur State, Sudan. The serum samples were screened for detection of BTV-specific immunoglobulin G (IgG) antibodies using a competitive enzyme-linked immunosorbent assay (c-ELISA).

Results

Serological evidence of BTV infection was observed in 150 out of 224 animals accounting for a 67% prevalence rate among cattle in East Darfur State. Older cattle (>2 years of age) were six times more likely to be infected with BTV (OR = 6.62, CI = 2.87-15.26, p-value = 0.01). Regarding animal source (contact with other herds) as a risk factor, it was shown that cattle purchased from market or introduced from other herds were 3 times at higher risk of being infected with BTV (OR = 3.87, CI = 1.07-13.87, p value = 0.03). Exposure of cattle to the insect vector increased the risk of contracting BTV infection by six times compared to non-exposed cattle (OR = 6.44, CI = 1.53-27.08, p value = 0.01).

Conclusion

The present study indicated that age, animal source and the intensity of the insect vector are influential risk factors for BTV infection in cattle in the Darfur region. Surveillance for BTV infection should be extended to include other susceptible ruminants and to study the distribution of the insect vectors to better predict and respond to a possible BTV outbreak in the State of East Darfur, Sudan.     

Introduction of aromatic fragrance into cultivated tomato from the peruvianum complex'

This study was performed to introduce the distinct aromatic fragrance of Lycopersicon peruvianum LA 1554 into the cultivated tomato, Lycopersicon esculentum. The strong breeding barriers existing between these two distantly related species were circumvented by the ovule selection and culture method. A large BC₁F₁ population was developed and among 127 plants, 36 were self‐compatible and yielded fruits. Fruits of some of these selected plants were found to be enriched with a sweet aromatic flavour. Sensory evaluation of the fruit aroma of these selected plants was performed by a panel of 12 members against one of the best consumer‐rated Japanese commercial tomato cultivars, ‘Momotaro’. Although extensive variation was observed in fruit‐aroma in the BC₁F₁ population, panel opinion on ‘flavour‐desirability’ significantly favoured the BC₁F₁ fruits of some selected plants over the cv. ‘Momotaro’. Therefore, it can be concluded that the aromatic fragrance of a ‘L. peruvianum’ accession has successfully been introduced into the cultivated tomato gene pool.     

Fusarium wilt of chickpea: physiological specialization, genetics of resistance and resistance gene tagging

Chickpea wilt caused by Fusarium oxysporum f. sp. ciceris is one of the major yield limiting factors in chickpea. The disease causes 10–90% yield losses annually in chickpea. Eight physiological races of the pathogen (0, 1A, 1B/C, 2, 3, 4, 5 and 6) are reported so far whereas additional races are suspected from India. The distribution pattern of these races in different parts of the world indicates regional specificity for their occurrence leading to the perception that F. oxysporum f. sp. ciceris evolved independently in different regions. Pathogen isolates also exhibit differences in disease symptoms. Races 0 and 1B/C cause yellowing syndrome whereas 1A, 2, 3, 4, 5 and 6 lead to wilting syndrome. Genetics of resistance to two races (1B/C and 6) is yet to be determined, however, for other races resistance is governed either by monogenes or oligogenes. The individual genes of oligogenic resistance mechanism delay onset of disease symptoms, a phenomenon called as late wilting. Slow wilting, i.e., slow development of disease after onset of disease symptoms also occurs in reaction to pathogen; however, its genetics are not known. Mapping of wilt resistance genes in chickpea is difficult because of minimal polymorphism; however, it has been facilitated to great extent by the development of sequence tagged microsatellite site (STMS) markers that have revealed significant interspecific and intraspecific polymorphism. Markers linked to six genes governing resistance to six races (0, 1A, 2, 3, 4 and 5) of the pathogen have been identified and their position on chickpea linkage maps elucidated. These genes lie in two separate clusters on two different chickpea linkage groups. While the gene for resistance to race 0 is situated on LG 5 of Winter et al. (Theoretical and Applied Genetics 101:1155–1163, 2000) those governing resistance to races 1A, 2, 3, 4 and 5 spanned a region of 8.2 cM on LG 2. The cluster of five resistance genes was further subdivided into two sub clusters of 2.8 cM and 2.0 cM, respectively. Map-based cloning can be used to isolate the six genes mapped so far; however, the region containing these genes needs additional markers to facilitate their isolation. Cloning of wilt resistance genes is desirable to study their evolution, mechanisms of resistance and their exploitation in wilt resistance breeding and wilt management.     

Characterizing Groundwater Dynamics Based on Impact of Pulp and Paper Mill Effluent Irrigation and Climate Variability

Automated synoptic weather typing and robust orthogonal stepwise regression analysis (via principal components analysis) were applied together to develop within-weather-type air pollution prediction models for a variety of pollutants (specifically, carbon monoxide – CO, nitrogen dioxide – NO₂, ozone – O₃, sulphur dioxide – SO₂, and suspended particles – SP) for the period 1974–2000 in south-central Canada. The SAS robust regression procedure was used to limit the influence of outliers on air pollution prediction algorithms. Six-hourly Environment Canada surface observed meteorological data and 6-hourly US National Centers for Environmental Prediction (NCEP) reanalysis data of various weather elements were used in the analysis. The models were developed using two-thirds of the total years for meteorological and air pollution data; the remaining one-third (randomly selected) was used for model validation. Robust stepwise regression analysis was performed to analytically determine the meteorological variables that might be used to predict air pollution concentrations. There was a significant correlation between observed daily mean air pollution concentrations and model predictions. About 20, 50, and 80% of the 80 prediction models across the study area possessed R ² values ≥ 0.7, 0.6, and 0.5, respectively. The results of model validation were similar to those of model development, with slightly smaller model R ² values.     

In situ imaging of the endogenous CD8 T cell response to infection

Mounting a protective immune response is critically dependent on the orchestrated movement of cells within lymphoid organs. We report here the visualization, using major histocompatability complex class I tetramers, of the CD8-positive (CD8) T cell response in the spleens of mice to Listeria monocytogenes infection. A multistage pathway was revealed that included initial activation at the borders of the B and T cell zones followed by cluster formation with antigenpresenting cells leading to CD8 T cell exit to the red pulp via bridging channels. Strikingly, many memory CD8 T cells localized to the B cell zones and, when challenged, underwent rapid migration to the T cell zones where proliferation occurred, followed by egress via bridging channels in parallel with the primary response. Thus, the ability to track endogenous immune responses has uncovered both distinct and overlapping mechanisms and anatomical locations driving primary and secondary immune responses.