Fingerprinting in cucumber and melon (<Emphasis Type="Italic">Cucumis</Emphasis> spp.) Genotypes using morphological and ISSR markers

In the present investigation, 13 Cucumis genotypes from different geographical areas of India were screened for genetic diversity using 19 morphological traits and 15 ISSR primers. The analysis of morphological traits grouped the accessions into six clusters. Cluster V contained the maximum number of genotypes namely Kanivellari, Long Green, Andaman Local, Perundurai Local, and Sempatti Local. Clusters I and VI contained the minimum number of genotypes. Among all the characters, the highest mean value was observed in fruit length (23.38) and the lowest mean value was observed in stripes on the blossom end (1.31). The 15 ISSR primers generated 109 polymorphic alleles. The average number of ISSR alleles generated was 8.3 per primer and the level of polymorphism was 87.20%. The ISSR primer UBC 825 was highly informative with a PIC value of 0.8934. The 13 genotypes were grouped into six clusters based on ISSR markers. Cluster III contained the maximum number of genotypes, namely Kanivellari, Sankagiri Local, Perundurai Local, Long Melon, and Sempatti Local, while Clusters I, II, IV, and V (Karur Local, Andaman Local, Edapaddi Local, and N 78, respectively) contained the minimum number of genotypes. The ISSR profile generated genotypes specific allele namely, UBC 812_700bp and UBC 812_1000bp for Cluster VI which contained Cucumis genotypes collected from the northern part of India. Similarly, UBC 808 produced specific allele UBC 808_650bp formed in Cluster III which contained genotypes collected from Tamil Nadu and Kerala.     

Agro-biodiversity and ethnobotany of Lakshadweep Islands of India

The Lakshadweep is a tiny landmass of 32 km² area (8^o–12^oN, 71^o–74^oE) constituted by a group of 27 small atolls located in the Indian territory of Arabian Sea of Indian Ocean. Studies on crop genetic diversity including wild relatives of crop plants of the region are little known except for coconut palm. This report deals with 106 collections assembled in two exploration and collection missions comprising 46 plant species under 35 genera belonging to 24 families. The plant germplasm collected during the trips are mostly useful as vegetable, fibre, medicinal plant, dye, edible tuber, timber and ecosystem service provider. The crop wild relatives collected during the study include that of sunnhemp, melon, yam, jute, pigeon pea, sugarcane, etc. A set of germplasm accessions was sent to national research institutes for regeneration. Out of the total collection, 64 accessions were assigned with national identity (Indigenous Collection or IC numbers: IC 0572014 to IC 0572077), and conserved in long term storage at National Gene Bank or in the field gene bank of ICAR-NBPGR, New Delhi. The important germplasm assembled from the islands include highly pungent betel leaf and a large fruited noni. Plants of Cajanus scarabaeoides (L.) Thouars, bitter less Cucumis melo L. var. agrestis Naudin saline tolerant Canavalia cathartica Thouars, Vigna marina (Burm.) Merr. and Corchorus trilocularis L. were the unique wild relatives collected. The current report is the first of its kind on the exploration and collection of plant genetic resources (other than coconut) from Lakshadweep Islands. Wild melon accessions collected are currently employed in distant hybridization programs. During the survey, ethnobotanic information of 23 plants for medicinal and other uses was also documented. Novel uses of the native plant species in the islands indicate their potential for exploitation in other coastal ecosystems. This report aims to highlight the potential plant resources of the region for direct human use and in future breeding programs.     

Effects of calorie restriction on the expression of manganese superoxide dismutase and catalase under oxidative stress conditions in the rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis>

Calorie restriction (CR) in the rotifer Brachionus plicatilis extends its lifespan, as it enhances the expression of antioxidant enzymes such as manganese superoxide dismutase (Mn SOD) and catalase. Here we show that CR also increased the mRNA levels of these antioxidant enzymes upon exposure to oxidative stress. Rotifers cultured under CR showed a higher survival rate than those fed ad libitum (AL) upon exposure to 0.05–0.2 μM juglone, an oxidative stress inducer. The relative mRNA levels of Mn SOD and catalase before exposure to juglone were slightly higher in the CR rotifers than in their AL counterparts, although these differences were not statistically significant. AL rotifers showed no apparent upregulation of the mRNA levels of these antioxidant enzymes upon exposure to 0.025 and 0.05 μM juglone. In contrast, the CR rotifers increased the mRNA levels of Mn SOD and catalase by up to 5.4-fold and 4.2-fold, respectively, resulting in significant differences between their levels in AL and CR rotifers under oxidative stress conditions. Furthermore, the protein level of catalase was clearly higher in CR than in AL rotifers 6 h after exposure to oxidative stress. These results suggest that the upregulation of Mn SOD and catalase genes is involved in CR-induced resistance to oxidative stress in the rotifer.     

Influence of conservation tillage on soil physicochemical properties in a tropical rainfed agricultural system of northeast India

In agricultural systems, especially where the soils are highly erodible, there is always a need for a better synchronization of nutrient release and nutrient demand by the growing crops. Management practices, such as conservation tillage could serve as a viable alternative to the mounting crisis and could enhance SOM besides other physicochemical properties. A field study was conducted in the rainfed agricultural system of northeast India with variedly tilled implements (indigenous spade, Country Plough, Bose Plough and Mouldboard Plough) from 2006 to 2007 to study the effect of these implements on the soils’ physiochemical properties during different growth phases of Oryza sativa in a rainfed valley agricultural system. A marked change in the bulk density values was observed up to 15–20 cm depth only in the Mouldboard Plough tilled plots. Over all, bulk density showed a significant positive correlation only with total N (r = 0.263, n = 30, p < 0.01). In all the study sites, a significant variation (p < 0.01) of soil moisture content with respect to time duration, tillage type and soil depth was observed. In Sites I and II, pH showed significant variation (p < 0.01) with time duration (F = 6.6, 3.0, d.f. = 5) and tillage type (F = 73.0, 48.5, d.f. = 4), respectively. Amongst all the study sites, Site II had comparatively higher value for soil organic matter followed by Sites III and I. Total N too showed variation with duration, tillage type and soil depth with ANOVA for the factors showing significant variation between and amongst them across the sites. Available P of the soil too varied remarkably along the crop's growing duration, its depth and upon the tillage method followed. Thus, our results suggest that conservation tillage, especially no-tillage, could serve as an effective tool with respect to increasing soil C and N sequestration in the subtropical agroecosystem of northeast India.     

Dynamics of soil microbial biomass C, N and P in disturbed and undisturbed stands of a tropical wet-evergreen forest

To understand the spatial and temporal dynamics of soil microbial biomass and its role in soil organic matter and nutrient flux in disturbed tropical wet-evergreen forests, we determined soil microbial biomass C, N and P at two soil depths (0–15 and 15–30 cm), along a disturbance gradient in Arunachal Pradesh, northeastern India. Disturbance resulted in considerable increase in air temperature and light intensity in the forest and decline in the soil nutrients concentration, which affected the growth of microbial populations and soil microbial biomass. There were significant correlations between bacterial and fungal populations and microbial biomass C, N and P. Soil microbial population was higher in the undisturbed (UD) forest stand than the disturbed forest stands during post-monsoon and less during rainy season due to heavy rainfall. Greater demand for nutrients by plants during rainy season limited the availability of nutrients to soil microbes and therefore, low microbial biomass C, N and P. Microbial biomass was negatively correlated with soil temperature and pH in all the forest stands. However, there were significant positive relationships among microbial biomass C, N and P. Percentage contribution of microbial C to soil organic C was higher in UD forest, whereas percentage contribution of microbial biomass N and P to total N and total P was higher in the moderately disturbed site than in the highly disturbed (HD) site. These results reveal that the nutrient retention by soil microbial biomass was greater in the selective logged stand and would help in the regeneration of the forest upon protection. On the other hand, the cultivated site (HD) that had the lowest labile fractions of soil organic matter may recover at a slower phase. Further, minimum and maximum microbial biomass C, N and P during rainy and winter seasons suggest the synchronization between nutrient demand for plant growth and nutrient retention in microbial biomass that would help in ecosystem recovery following disturbance.     

Biophysical Factors and Canopy Coupling Control Ecosystem Water and Carbon Fluxes of Semiarid Sagebrush Ecosystems

The sagebrush-steppe ecosystem covers much of western North America, and its productivity is sensitive to warming and increasingly variable precipitation. Interannual variation in precipitation has been shown to be the most significant factor controlling biogeochemical cycling while both soil and atmospheric drought are dominant factors of ecosystem fluxes. We show that plant canopies can also act to limit water losses through stomatal and aerodynamic control. We use 4 data-yr from 2 sites (2 069 and 2 469 m above sea level elevation, respectively) to evaluate control of carbon and water fluxes and to calculate the degree to which the ecosystem canopy and atmosphere are decoupled. Environmental conditions were similar between the two sites, although the lower elevation site was slightly warmer (1.8°C higher temperature) and drier (0.2 kPa higher vapor pressure deficit). Ecosystem responses of net ecosystem exchange (NEE) and evapotranspiration (ET) to environmental drivers were similar between sites and years, with the wet site-yr 2009 having the largest ET and NEE fluxes. Canopy leaf area led to divergent behavior of the canopy-atmosphere decoupling parameter under high (> 11% by volume) soil moisture conditions. During low (< 11%) soil moisture periods, both sites had tight ecosystem stomatal control on ET with little NEE activity. This study highlights how semiarid ecosystems can alter their canopy leaf area in order to control how decoupled semi-arid canopies are to the atmosphere, potentially moderating impacts of climate change.     

Dry matter accumulation and nutrient uptake patterns of onion seed crop

Abstract

Dry matter accumulation and nutrient uptake patterns of crops must be determined to optimize fertilizer scheduling. This study assesses the dry matter accumulation and nutrient uptake patterns of onion seed crop. Plant samples were collected between 0 and 120?days after planting, and their nutrient content was analyzed to determine the dry matter accumulation and nutrient uptake patterns. The quantity and period of nutrient uptake and the mobility of nutrients within the plant parts varied for different nutrients. The absorption of nitrogen (N) and potassium (K) was the highest during vegetative stage, whereas phosphorus (P) and sulfur (S) uptake was the highest during flower initiation stage. N, P, K, and S, which had accumulated in the vegetative parts, moved from the senesced vegetative parts to the inflorescence during the reproductive stages owing to their high mobility in the phloem. The onion plants continued to absorb zinc, copper, manganese, and iron throughout their growth owing to the immobility of these elements in plant system. The result of this study may facilitate efficient scheduling of fertilizer application to increase nutrient uptake and yield.     

Comparison of organic and conventional farming for onion yield,biochemical quality,soil organic carbon,and microbial population

In an ongoing field experiment, organic and conventional farming (control) were compared for onion bulb yield, biochemical quality, soil organic carbon (SOC), and microbial activity after the sixth cropping cycle. The treatments used for organic production were farmyard manure (FYM, 20,000 kg ha^?1), poultry manure (PM, 10,000 kg ha^?1), vermicompost (VC, 10,000 kg ha^?1), neem cake (NC, 5000 kg ha^?1), and a combination of FYM (5000 kg ha^?1), PM (2500 kg ha^?1), VC (2500 kg ha^?1), and NC (1250 kg ha^?1); all treatments were compared with the control. Organic treatments produced 24.6–43.6% lower yield consistently for 6 years than the control treatment. No significant difference was observed between PM, FYM, and VC treatments for the bulb yield. Bulb analysis during the sixth year indicated that plants that received FYM, PM, or VC had higher levels of total phenol, total flavonoid, ascorbic acid, and quercetin-3-glucoside than the control plants. All the five organically treated sets had significantly higher values of SOC, microbial population, fungal-to-bacterial ratio, and dehydrogenase activity than the control and the initial values in each treated set. The results indicate that FYM, PM, or VC application enhances biochemical quality and organic farming is more sustainable than conventional farming.     

An outbreak of Shiga toxin‐producing Escherichia coli O157:H7 linked to a mud‐based obstacle course,England, August 2018

In August 2018, Public Health England (PHE) was made aware of five probable cases of Shiga toxin‐producing Escherichia coli (STEC) O157:H7 among individuals reporting participation in a mud‐based obstacle race. An additional four cases, identified via routine whole‐genome sequencing, were subsequently linked to the same event. Two of the nine cases were due to secondary household transmission. Despite an agreement between the event organizers and the local authority, to ensure that all livestock were removed from the site 28 days before the event, sheep were observed grazing on some of the routes taken by the runners 2 days prior to the race taking place. A retrospective review of incidents reported to PHE between 2015 and 2018 identified 41 cases of gastroenteritis associated with muddy assault course events. Of these, 25 cases were due to infection with STEC O157:H7, of which all but one were associated with outbreaks. Due to the environment in which such events take place, it is impossible to entirely remove the risk of exposure to potentially pathogenic zoonoses. However, race organizers should ensure that livestock are removed from the course 28 days before the event. They should also ensure that participants are made aware of the risk of contracting gastrointestinal disease from the environment, and to stress the importance of hand hygiene post‐event and the risk of secondary transmission, particularly to children who are at risk of developing haemolytic uraemic syndrome.     

Effects of Bacillus subtilis metabolites on larval Aedes aegypti L

The culture supernatant of a strain of Bacillus subtilis isolated from soil samples killed larvae of the mosquito Aedes aegypti. The metabolites produced by B. subtilis were characterized using high performance liquid chromatography (HPLC). Mortality rate was dose-dependent for all larval instars of A. aegypti. Log probit analysis (95% confidence level) revealed an LC₅₀ of 1.73 and an LC₉₀ 3.71 μg/ml. Molecular weights/masses of B. subtilis metabolites were confirmed using SDS–PAGE analysis. B. subtilis metabolites were confirmed using HPLC analysis. We demonstrate that secondary metabolites from B. subtilis have larvicidal activity against A. aegypti and may be suitable for the control of this and other mosquito vectors of human disease. The larvae to the metabolites, significant reduction in the activities of acetylcholinesterse, α-carboxylesterase, and acid phosphatases were recorded.