Yield components,light interception and marker compound accumulation of stevia (Stevia rebaudiana Bertoni) affected by planting material and plant density under western Himalayan conditions

A field experiment was conducted to study the effect of planting material and plant density on stevia (Stevia rebaudiana Bertoni) under western Himalayan conditions during 2011 and 2012. The experiment conducted in a split plot design consisted of two types of planting material (rooted slips and fresh seedlings) in the main plot and five inter- and intra-row spacing in subplots with three replications. Yield attributes and dry leaf biomass yield of stevia were not affected by the type of planting material; however, plant density significantly influenced the yield attributes and leaf and stem dry biomass. Although the wider spacing (60 × 45 cm) gave more leaves, higher leaf area index, higher leaf dry mass per plant as compared to closer spacing, it resulted in lower values of these attributes per unit area. Plants spaced in 30 × 30 cm accumulated 41.2% and 42.8% more total biomass than 60 × 45 cm. Steviol glycoside content did not change due to different planting materials and plant densities; however, closer plant spacing (30 × 30 cm) recorded 114.8% and 70.0% higher steviol glycoside accumulation compared to wider row spacing (60 × 45 cm) in 2011 and 2012, respectively.     

Potential of Eisenia foetida for Sustainable and Efficient Vermicomposting of Fly Ash

Vermicomposting of fly ash has been attempted, using red earthworm, Eisenia foetida. Fly ash, which was obtained from thermal power station, was mixed with cowdung in different proportions (20, 40, 60 and 80%). These mixtures were used as feed for earthworms, and after 30 days, vermicast recovery, worm zoomass and numbers of juveniles produced were recorded. A total of six runs each of 30 days were conducted during the whole study. Concentrations of heavy metals in different mixtures of fly ash–cowdung, before and after vermicomposting and in the earthworms used in the study were also estimated. Results show maximum output of vermicasts and maximum number of juveniles produced was in reactors with 40% fly ash while maximum weight gain by earthworm was in 20% fly ash vermireactors. Performance of vermireactors up to 60% fly ash was more or less similar but at 80% fly ash, there is a marked reduction in overall performance of the reactors. Chemical analysis of different samples of fly ash–cowdung mixtures prior to vermicomposting revealed high concentrations of zinc, chromium, lead, nickel and copper. Chemical analysis of vermicomposted samples showed 30–50% reduction in heavy metals up to 60% fly ash and 10–30% reduction in 80% fly ash. Metal analysis of earthworms revealed considerable bioaccumulation of heavy metals in their body. The Present study indicates the feasibility of E. foetida for mitigating the toxicity of metals and up to 60% fly ash–cowdung mixtures can be used for sustainable and efficient vermicomposting.     

Trends and advances in the diagnosis and control of paratuberculosis in domestic livestock

Paratuberculosis (pTB) is a chronic granulomatous enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP) in a wide variety of domestic and wild animals. Control of pTB is difficult due to the lack of sensitive, efficacious and cost-effective diagnostics and marker vaccines. Microscopy, culture, and PCR have been used for the screening of MAP infection in animals for quite a long time. Besides, giving variable sensitivity and specificity, these tests have not been considered ideal for large-scale screening of domestic livestock. Serological tests like ELISA easily detects anti-MAP antibodies. However, it cannot differentiate between the vaccinated and infected animals. Nanotechnology-based diagnostic tests are underway to improve the sensitivity and specificity. Newer generation diagnostic tests based on recombinant MAP secretory proteins would open new paradigm for the differentiation between infected and vaccinated animals and for early detection of the infection. Due to higher seroreactivity of secretory proteins vis-à-vis cellular proteins, the secretory proteins may be used as marker vaccine, which may aid in the control of pTB infection in animals. Secretory proteins can be potentially used to develop future diagnostics, surveillance and monitoring of the disease progression in animals and the marker vaccine for the control and eradication of pTB.     

Impacts of Bioinoculants Pseudomonas jesenii MP1 and Rhodococcus qingshengii S10107 on Chickpea (Cicer arietinum L.) Yield and Soil Nitrogen Status

Cold-adapted bioinoculants are considered as harbingers of sustainable hill agriculture. Therefore, two previously characterized psychrotolerant diazotrophs, Pseudomonas jesenii MP1 and Rhodococcus qingshengii S10107, were evaluated for their plant growthpromoting potential for chickpea (Cicer arietinum L.) grown under natural field conditions. Comparative analysis of agronomical and biochemical crop parameters revealed the irrelevance of chemical fertilizers for chickpea production; the diazotrophs alone were sufficient to fulfil the crop''s nutritional requirement. However, the integrated use of bacterial strains in combination with urea at 20 kg N ha^-1 as urea was being recommended for higher crop yield and better soil nitrogen status. Quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE)-based soil bacterial dynamics unveiled the persistence of both diazotrophs until the end of the crop maturation period without affecting the native micro-flora. Therefore, these bioinoculants can be explored as natural nitrogen resource, and an additional incentive in their bio-formulation will be a step towards agricultural sustainability.     

Nanoclay polymer composites loaded with urea and nitrification inhibitors for controlling nitrification in soil

Nanoclay polymer composites (NCPCs) were synthesized with partially neutralized acrylic acid and bentonites and loaded with urea and nitrification inhibitors (NIs) to act as a slow release carrier of nitrogen (N). The resulting product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD of NCPCs revealed that the bentonite layers were completely exfoliated and dispersed in the composite after the polymerization. The water absorbency of pure polymer (Acrylic acid + Acrylamide) was 197.53 g g^?1 and 137.75 g g^?1 by nanocomposite (8% nanobentonite) in distilled water. The nitrification inhibition ability of these NCPCs was evaluated by incubation study for 60 days in laboratory at 28°C and 50% water-holding capacity. The Schiff base -NCPCs were most effective at inhibiting nitrification (30–87%) compared to dicyandiamide and Neem oil. A column study was performed to know the movement of NH₄-N and NO₃-N at three different depths. Result showed that the Schiff base -NCPC decreased nitrate movement by 78.5% at the depth of 5 cm in soil column. The slow release of nitrogen and good water retention capacity confirmed that these NCPCs can be viably exploited for application in agriculture.     

Mycobacterium avium subspecies paratuberculosis – an important food borne pathogen of high public health significance with special reference to India: an update

This review underlines the public health significance of ‘Indian Bison Type’ of Mycobacterium avium subspecies paratuberculosis (MAP) and also its potential as ‘zoonotic infection’. In the absence of control programs, bio-load of MAP is increasing and if we take total population of animals (500 million plus) and human beings (1.23 billion plus) into account, the number of infected animals and human beings will run into millions in India. Our research on screening of over 26,000 domestic livestock for MAP infection using 4 different diagnostic tests (microscopy, culture, ELISA and PCR), during last 31 years has shown that the average bio-load of MAP in the livestock population of India is very high (cattle 43%, buffaloes 36%, goats 23% and sheep 41%). ‘Mass screening’ of 28,291 human samples between 2008–2016 revealed also high bio-load of MAP. It has been proved that MAP is not in-activated during pasteurization and therefore live bacilli are continuously reaching human population by consumption of even pasteurized milk and other milk products. Live bacilli have also been recovered from meat products and the environment thus illustrating the potential of MAP as pathogen of public health concern. However, at present, there is inadequate scientific evidence to confirm a conclusive link between MAP infection and Johne's disease in ruminants and some cases of Crohn's disease in human beings.     

Influence of foliar application of mineral nutrients at different growth stages of guava

Foliar application of nutrients enhances efficient use along with quick response. The experiment was undertaken to study the effect of foliar application of mineral nutrients viz., boron (B), zinc (Zn), calcium (Ca), and potassium (K) sprayed at different growth stages viz., at fruit set and at two weeks after fruit set of guava (Psidium guajava L.). Increase in plant canopy and minimum seed index was in Zn (0.03%) sprayed at fruit set. Fruit size, sugar: acid, and organoleptic score were better in K (0.5%) sprayed at two weeks after fruit set. Increased yield in Zn (0.01%) and pectin enhancement with B (0.03%) was found at two weeks after fruit set, respectively. Minimum physiological loss in weight of fruits was with Ca (0.5%) sprayed at two weeks after fruit set. In general, for most of the desirable characters 0.5% potassium (K) spray at 2 weeks after fruit set had better results.     

Plant growth promoting potential of psychrotolerant Dyadobacter sp. for pulses and finger millet and impact of inoculation on soil chemical properties and diazotrophic abundance

Western Indian Himalaya is very rich in biodiversity. Being a cold climatic region, it possesses various psychrotolerant and psychrophilic microorganisms. Psychrotolerant bacterium Dyadobacter sp. was isolated from this region and studied for its plant growth promoting potential against four legumes and finger millet. This bacterium was able to grow at nitrogen (N) deficient medium at both 10°C and 28°C and gave positive nifH amplification that confirms the psychrotolerant and diazotrophic nature of this bacterium. Pot trial-based study showed that this bacterium was able to promote plant growth by fixing atmospheric nitrogen (N₂) and making it available to plants. Agronomical parameters, leaf nitrate reductase activity, and total chlorophyll content were recorded at 30, 45, 60, and 90 days after sowing and found to be increased over their respective controls. The 16S rDNA and nifH genes were quantified by q-PCR to study the dynamics of total bacterial and diazotrophic abundance due to inoculation of Dyadobacter sp. in soil. Soil chemical properties related to soil fertility were also studied at different time intervals after sowing. We found positive correlation among soil pH, soil nifH gene abundance, soil nitrate concentration, and plant leaf nitrate reductase activity. PCR-DGGE was performed to study persistence of Dyadobacter sp. in soil after inoculation, which showed good persistence of plant growth promoting rhizobacteria (PGPR). Hence, it is concluded that Dyadobacter sp. has potential to promote plant growth by fixing atmospheric N₂ and making it available to plant. Further, psychrotolerant nature of this bacterium can be exploited to enhance plant growth in cold climate agriculture due to its ability to fix atmospheric N₂ at low temperature.     

Multilocus sequence analysis revealed a high genotypic diversity of Aeromonas hydrophila infecting fish in Uganda

A multilocus sequence analysis (MLSA) was carried out to delineate Aeromonas hydrophila from fish in Uganda. Five housekeeping genes including recA, gyrB, metG, gltA and pps; and the 16S rRNA gene were amplified and sequenced from a total of nine A. hydrophila isolates. The obtained sequences were edited, and consensus sequences generated for each gene locus. The housekeeping gene sequences were concatenated and phylogenetic analysis performed in MEGA version 7.0.2. Pairwise distances ranged from 0.000 to 0.118, highest within the gltA gene locus and lowest within the 16S rRNA gene. The average evolutionary diversity within isolates from the same source ranged between 0.002 and 0.037, and it was 0.033 between the different sources. Similar tree topologies were obtained from the different gene loci with recA, metG and gyrB being more consistent in discriminating isolates according to sources while the 16S rRNA gene had the lowest resolution. The concatenated tree had the highest discriminatory power. This study revealed that A. hydrophila strains infecting fish in Uganda are of diverse genotypes suggesting different sources of infection in a given outbreak. Efforts to minimize spread of the bacteria across sources should be emphasized to control infections of mixed genotypes.