Tropical Region Of India Research Articles

Comparative analysis of HEC-HMS and SWAT hydrological models for simulating the streamflow in sub-humid tropical region in India.

Assessment of water availability in sub-humid regions is important due to distinct climatic and environmental conditions. In this study, Soil and Water Assessment Tool (SWAT) and Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) models have been assessed in simulating streamflows in the sub-humid tropical Kabini basin in Kerala, India, spanning 1260 km2. Calibration and validation utilized daily weather data from 1997 to 2015 from the Muthankera gauging station. The study investigated the impact of routing methods on runoff simulation in the ArcSWAT, exploring Muskingum and Variable Storage methods. Evaluation metrics encompassed Nash-Sutcliffe Efïciency (NSE), Coefficient of Determination (R2), Percent bias (PBIAS), RMSE-observations standard deviation ratio (RSR), and Peak Percent Threshold Statistics (PPTS) approach for high-flow values. The result indicates that HEC-HMS outperforms SWAT concerning R2 and NSE values during daily calibration and validation. Monthly simulations showed HEC-HMS closely aligning with SWAT (Variable storage), outperforming SWAT (Muskingum). The PPTS approach proved effective in simulating high-flow values. Both models exhibited proficiency in streamflow analysis within the study area, promising predictive potential for future hydrological studies in sub-humid regions.

Enumeration, Identification and characterization of endophytic bacteria isolated from sugar beet (Beta vulgaris L.) root for ethanol production

The bioethanol production from sugar beet is regulated by endophytic bacteria. Thus, the present investigation is aimed to isolate, identify and characterize endophytic bacteria from different varieties of sugar beet roots. The presence of specific bacteria in sugar beet roots plays vital role in bioethanol production. The ability to produce bioethanol through fermentation with the help of various microbes present in roots was studied in different varieties of sugar beet at Indian Institute of Sugarcane Research, Lucknow sub tropical regions of India. A total of 16 microbial isolates comprising of 12 bacterial and 4 fungal strains were studied for their potential to produce bioethanol from sugar beet root. Among them only 2 bacteria were more effective as fermenting agents. These isolated endophytic bacteria were characterised by molecular sequencing and were identified as Enterobacter hormaechei and Enterobacter cloacae. These isolates may also act as a good alternative agent for the bioethanol production.

A Review on Areca Catechu

Abstract: Areca catechu L.is a species of palm which grows much of tropical pacific, Asia & parts of Africa, The palm is believed to have originated in the philippines and is widely cultivated in several south Asian and Southeast Asian countries. In the present article, it Haa been describe about usefulness of Arecanut as an herbal drug and it's therapeutic application prospect Arecacatechu, commonly known as supari, consists of dried ripe nuts that came under Arecaceae family, which is cultivated in the tropical region of India and Southeast Asia. It is a prevalent traditional herbal medicine that is chewed to separate collected fluid in the alimentary canal and for killing worms. Areca catechu seed contains alkaloids (arecoline, arecaine, arecaidine, guvacoline, guvacine, and choline), tannin, gallic acid, gum, and various minerals such as copper, calcium, phosphorus, and iron. The chemical constituents of this plant have been used as antidiabetic, stomatitis, bleeding gums, gingivitis, conjunctivitis, glaucoma, leucorrhoea, urinary disorders, anorexia, diarrhea, blood pressure regulating activity, antiulcerogenic, antioxidant activity, anticonvulsant activity, central nervous system stimulant activity, antifertility, oxytocic activity, antiviral activity, anthelmintic, and making it more popular than chewing gum ,but not as popular as Tobacco.

Synergistic Effect of Herbals and Nanoparticles - Zinc Oxide on Silkworm Pathogens

Acalypha indica L. is an annual herbaceous weed and widely distributed throughout the tropical region of India. It has been wound healing activity, antibacterial activity and antiurolithiatic activity. The herbal plant Murrayakoenigii have been used as analgescis, astringents, antidysenterics or febrifuges in folk medicine in China and other Asian countries. The antibacterial responses of Zinc oxide (ZnO) against Staphylococcus sp. SA 3were investigated. The acetone, ethyl acetate and methanol extracts of A. indica showed minimum inhibitory activity4 ±0.31mm, 10±0.18 mm and 6±0.23 mm respectively and maximum inhibitory activity 8±0.15 mm, 20±0.37 mm and 12±0.14mm at different concentration (0.5, 1.0, 1.5 and 2.0 µl) against the bacterial pathogen Staphylococcus sp. SA 3. The acetone and methanol extracts of M. koenigii showed minimum inhibitory activity 6±0.25 mm and 6±0.25 mm and maximum inhibitory activity 10± 0.18 mm and 8±0.15 mm. The ethyl acetate extract of M. koenigii did not showed inhibitory activity. In the combined effect of acetone, ethyl acetate and methanol extracts of A. indica and ZnO showed minimum inhibitory activity 4±0.31 mm, 10±0.13 mm and 4±0.31 mm respectively and maximum inhibitory activity 10± 0.13 mm, 22± 0.30 mm and 8±0.15 mm respectively. The combined effect of acetone, ethyl acetate and methanol extracts of M. koenigii and ZnO showed minimum inhibitory activity 16±0.08 mm and 6± 0.23 mm. The ethyl acetate extract of M. koenigii showed no inhibitory activity and maximum inhibitory 20± 0.37 mm, 2± 0.04 mm and 10± 0.13 mm respectively. The GC-MS analysis of methanol extract of A. indica showed the presence of 8 phytoconstituents and the nanoparticle ZnO impregnated ethyl acetate extract of A. indica showed the presence of 11 phytoconstituents.

Diverse type I and type II methanotrophs cultivated from an Indian freshwater wetland habitat.

Wetlands are the main natural sources of methane emissions, which make up a significant portion of greenhouse gas emissions. Such wetland patches serve as rich habitats for aerobic methanotrophs. Limited knowledge of methanotrophs from tropical wetlands widens the scope of study from these habitats. In the present study, a freshwater wetland in a tropical region in India was sampled and serially diluted to obtain methanotrophs in culture. This was followed by the isolation of methanotrophs on agarose-containing plates, incubated under methane: air atmosphere. Methanotrophs are difficult to cultivate, and very few cultures of methanotrophs are available from tropical wetlands. Our current study reports the cultivation of a diverse community of methanotrophs from six genera, namely, Methylomonas, Methylococcus, Methylomagnum, Methylocucumis (type I methanotrophs) along with Methylocystis, Methylosinus (type II methanotrophs). A high abundance of methanotrophs (106-1010 methanotrophs/g fresh weight) was observed in the samples. A Methylococcus strain could represent a putative novel species that was also isolated. Cultures of Methylomagnum and Methylocucumis, two newly described type I methanotrophs exclusively found in rice fields, were obtained. A large number of Methylomonas koyamae strains were cultured. Our study is pioneering in the documentation of culturable methanotrophs from a typical tropical wetland patch. The isolated methanotrophs can act as models for studying methanotroph-based methane mitigation from wetland habitats and can be used for various mitigation and valorization applications.

TENOSPORA CORDIFOLIA: PHYTOCHEMICAL and PHARMACOLOGICAL REVIEW

Tinospora cordifolia is a climbing deciduous shrub. It can be found all over the tropical region of India, as well as in China, Bangladesh, Myanmar, and Sri Lanka. This plant is a member of the Menispermaceae family. It is a well-known medicinal plant that is used in many traditional remedies to treat a wide range of illnesses. Amrita and Guduchi are the common names. It has been used to cure a variety of illnesses, including diabetes, leprosy, skin conditions, diarrhoea, and fever, and is regarded as an essential medicinal plant in the Indian system of medicine (ISM). Alkaloids, Terpenoids, Lignans, Steroids, and other chemical compounds have been documented to be present in the plant, establishing the phytochemistry and pharmacological action of Tinospora cordifolia. Additionally, it exhibits hepatoprotective, antioxidant, anti hyperglycemic, and anti-neoplastic properties.

Influence of canopy architecture on photosynthetic parameters and fruit quality of mango in tropical region of India

Influence of canopy architecture on photosynthetic parameters and fruit quality of mango in tropical region of India

Evaluation of anti-inflammatory activity of Garcinia indica, a wild edible fruit by inhibiting secretory phospholipase A2 group IIA enzyme from human pleural fluid

Introduction and Aim: Garcinia indica is a wild edible fruit plant distributed in tropical regions of India. Fruits of G. indica were traditionally used to treat chronic inflammatory diseases like rheumatoid arthritis, gastrointestinal disorders, etc., But the basis of anti-inflammatory function of the fruit is not understood. Therefore, this study aims to evaluate the anti-inflammatory function of G. indica. Initially phytochemical screening of G. indica was carried out, tested antioxidant potency of G. indica fruit and evaluated its anti-inflammatory function by inhibition of secretory phospholipase A2 IIA (sPLA2IIA) enzyme. Methodology: The Soxhlet extraction method was used for the preparation of extracts of G. indica fruit. DPPH and phosphomolybdenum assays were carried out to estimate the antioxidant activities of G. indica fruit. The inhibition of sPLA2IIA, modulating indirect hemolytic and edema inducing activity and protein denaturation assays were done to evaluate the anti-inflammatory function. Results: Aqueous and solvent extracts of G. indica fruit showed a wide variety of phytochemicals. The ethanol extract of G. indica fruit showed greater antioxidant activity (79.12 % ±1.2) and reduction power (68.14% ± 4.4). The extract showed sPLA2IIA inhibition to a greater extent (50%), neutralized sPLA2IIA induced indirect hemolysis (IC50 45.518 µg/mL) and mouse paw edema (119.35% ± 2.74) with the IC50 value of 45.12 ±1.36µg. Conclusion: The extracts of G. indica contain a wide variety of phytochemicals. The ethanol extract of G. indica fruit exhibited a greater antioxidant activity and anti-inflammatory activity. Thus, the results defended the traditional usage of the G. indica fruit in the indigenous system of medicine.

Hornet pests of honey bees in the Indian Himalayas and a low cost trapping device for their eco-friendly management

Honey bees suffer from a cosmic array of biotic and abiotic stress during their life cycle. The insect pests like wax moths and Dermestid beetles contribute immensely to the damage of bee colonies and reduction in honey yield in tropical regions of India. While, the bee colonies in temperate regions of Indian Himalayas, face an entirely different set of hitches that include predation of forager bees by three hornet species (Vespa mandarinia, Vespa velutina nigrithorax and Vespa tropica). The attacks on bee colonies by these hornet species compel the bees to desert the colony and swarm away to a new habitat thus, causing severe economic losses to bee keepers. Considering the severe setbacks enforced by hornets, a low-cost hornet trap was designed. The bait ingredients and their trapping efficiency against targeted hornet species are presented herewith. It was observed that green colored bottles attracted 34 hornets of three species in 10 days, while transparent bottles attracted only seven hornets at bait proportions of 1:2:2 (Apple cedar Vinegar: orange juice: water). Moreover, to reduce the attraction of honey bees into the trap, supplementary ingredients like rotten fruits and market honey were used, which enhanced the trapping efficiency of hornets. The benefit-cost ratio of 12.30:1 was recorded after the installation of the trap, which was significantly superior to traditional method (1.64:1) of manual swatting of hornets in the apiary. The farmers are currently trained to design and use these traps for the management of hornet pests in the Indian Himalayas.

Assessment of Cytotoxic, Antioxidant, Thrombolytic, Anti Inflammatory and Antimicrobial Activity of Curcuma longa Linn, Cissus quadrangularis and Boerhaavia diffusa Herbal Mixture - An In vitro Study

Background and Aim: Plants play an important role in drug research, and the pharmaceutical industry is heavily reliant on natural products for new drug development. Curcumin, a natural compound contained in the rhizomes of the plant Curcuma longa Linn., has been shown to have anti-inflammatory properties in scientific studies. Cissus quadrangularis L. is a fleshy plant that can be found all over the world, especially in Asia, Africa, and a few other warm tropical areas. Boerhaavia diffusa L. (Nyctaginaceae) is present in the tropical regions of India, South America, and Africa. B. diffusa roots are commonly used in Ayurveda to treat various ailments. The aim of the study is to assess the cytotoxic, antioxidant and thrombolytic, antiinflammatory and antimicrobial properties of the aqua-alcoholic extract of the herbal mixture (Curcuma longa Linn +Cissus quadrangularis +Boerhaavia diffusa )
 Methods: Aqua-alcoholic extract of mixture of Curcuma longa Linn, Cissus quadrangularis and Boerhaavia diffusa was prepared. Phytochemical in-vitro studies were done using the CCB mixture cytotoxicity by brine shrimp lethality assay, antioxidant activity by DPPH assay, anti inflammatory activity by albumin denaturation assay, antimicrobial activity against Staphylococcus aureus, Streptococcus mutans, Escherichia coli and Candida albicans by agar well diffusion method, thrombolytic activity by clot lysis assay.
 Results: The CCB mixture showed good cytotoxic activity at varying concentration in brine shrimp lethality assay, increasing antioxidant activity with DPPH assay, increasing thrombolytic activity, increasing anti inflammatory activity with increasing concentration, the anti microbial activity was not efficient as positive controls.
 Conclusion: In this in-vitro study the CCB mixture shows improved cytotoxic, antioxidant, thrombolytic, anti-inflammatory and antimicrobial activity. Further studies on invivo animal and human clinical trials needs to be done.

Areca catechu: A phytopharmacological legwork

AbstractArecacatechu, commonly known as supari, consists of dried ripe nuts that came under Arecaceae family, which is cultivated in the tropical region of India and Southeast Asia. It is a prevalent traditional herbal medicine that is chewed to separate collected fluid in the alimentary canal and for killing worms.Areca catechuseed contains alkaloids (arecoline, arecaine, arecaidine, guvacoline, guvacine, and choline), tannin, gallic acid, gum, and various minerals such as copper, calcium, phosphorus, and iron. The chemical constituents of this plant have been used as antidiabetic, stomatitis, bleeding gums, gingivitis, conjunctivitis, glaucoma, leucorrhoea, urinary disorders, anorexia, diarrhea, blood pressure regulating activity, antiulcerogenic, antioxidant activity, anticonvulsant activity, central nervous system stimulant activity, antifertility, oxytocic activity, antiviral activity, anthelmintic, and foul breath. It showed a dose‐dependent toxicity profile, and various research has been done regarding its safety analysis and it would be considered safe when administered in the prescribed dose. The purpose of the present paper is to make available an up‐to‐date review on the ethnic, traditional description, morphology, phytochemistry, and the pharmacological and toxicological profile of this plant. Furthermore, the possible advances, trends, and a perspective for forthcoming research of this plant have also conversed.

Long-Term Climate Variability and Drought Characteristics in Tropical Region of India

AbstractThis work reports climate change signals and long-term trend analysis of climate variables, meteorological drought, and extreme climate indexes over the tropical state of Kerala in India. T...

Genetic divergence studies in green fruited brinjal (Solanum melongena L.)

Brinjal (Solanum melongena L.) is widely cultivated as one of the most important vegetables in both subtropical and tropical regions of India. It is a popular vegetable in India, China, Turkey, Japan, Syria, Egypt, Indonesia, Philippines, Thailand, France, Italy and USA. It is an important source of fibre (1.3 g/100g), protein (1.4 g/ 100g), vitamin-A (124 I.U) and potassium (200 mg/ 100g) and it is recommended even for patients with diabetes, asthma, cholera and bronchitis. Being primary centre of origin, India has accumulated wide range of variability in this crop. In spite of large number of varieties available in India, only few are promising

Assessment of impacts of potential climate change on meteorological drought characteristics at regional scales

AbstractDrought patterns are better understood by analysing the joint dependence among long‐term drought characteristics: severity, duration, and frequency. Changes in these drought characteristics are also likely due to potential climate change, for instance, increased drought severity and duration, increased frequency of drought events, and increased spatial extent of drought impacts. In this study, we performed a regional‐scale analysis of potential changes in meteorological drought characteristics in a tropical region in India under a warming future climate scenario. The meteorological drought characteristics were computed using the Standardized Precipitation Index. The Coordinated Regional Downscaling Experiment South Asia Regional Climate Model future precipitation simulation under the RCP 4.5 scenario was bias‐corrected and utilized for future drought frequency analysis. Regionalization of meteorological drought characteristics was performed using the simple k‐means clustering technique to identify the homogeneous regions for baseline and future periods. Bivariate copula was utilized to model the dependence among the drought characteristics in order to develop the S‐D‐F curves. The changes in regionalization and regional S‐D‐F curves under future potential climate change were then investigated. The results of the study suggest an increase in drought severity by 2–3% for long‐term droughts (duration more than 5 months) in the future as indicated by upward shift and changes in the slope of the regional S‐D‐F curves. There is a projected increase in the occurrence of long‐term droughts in the future when compared to short‐term (duration of 1 to 3 months) droughts. We also observed a considerable spatial shift of drought hotspots, the severe drought‐prone regions lie in the eastern part of the study region in the future. Future projections of regional S‐D‐F curves and Spatio‐temporal drought characteristics obtained from the proposed framework may be utilized for devising drought mitigation strategies.

Impact of Drip Fertigation on Weed Population, Dry Weight and Yield of Onion in Semiarid Tropical Region of India

Field demonstrations were conducted during rabi season for two years in seven locations of Tiruppur District, Tamil Nadu state to study the weed density under drip fertigation and conventional method of cultivation (Farmer’s practice). Nine weed species emerged with a frequency of more than 50% irrespective of the locations. Drip fertigation with recommended dose of fertilizers (RDF) produced the highest bulb yield of onion when compared with the conventional method of cultivation. Total population of weeds and weed dry weight were minimum under drip fertigation.

Assessment of growth, physiological, and yield attributes of wheat cultivar HD 2967 under elevated ozone exposure adopting timely and delayed sowing conditions.

The present study was conducted to assess the impact of elevated levels of O3 and shifting of crop calendar practice, singly, and in combination on Triticum aestivum cv. HD 2967 on its growth, gas exchange parameters, and yield attributes in open-top chambers (OTCs). Two sowing dates were considered: timely sown and late sown. Late sowing was delayed by 20days from the timely sowing date. The result revealed that wheat plants under elevated O3 and timely sown conditions (ET) showed reductions in growth parameters, while such effects were synergistic when plants were exposed to elevated O3 under late sown conditions (EL). Photosynthetic rate, stomatal conductance, and water use efficiency reduced significantly under EL followed by ET and AL as compared with AT (ambient O3 + timely sown) whereas transpiration rate showed maximum increment under EL. Grain yield reduced by 45.3% in EL as compared with AT and 16.2% in ET as compared with AT. The growth parameters and yield attributes obtained from the present experiment revealed that (i) O3 is affecting the growth and productivity of the wheat and (ii) late sowing practice has not proved to be a feasible adaptation strategy for the wheat cultivation against O3-induced production losses under the prevailing conditions of Indo-Gangetic Plain. This is the first report documenting the shifting of crop calendar practice at the present and future scenario of O3 concentration under agro-ecological conditions in the tropical region of India.

Silicon enhances yield and nitrogen use efficiency of tropical low land rice

AbstractHigh nitrogen (N) rate often leads to low yield of rice due to lodging and mutual shading. This study was conducted to ascertain whether silicon (Si) could enhance yield response of rice to higher N rate by enhancing rigidity of plant parts and improving photosynthesis. The effects of Si and N on crop growth, photosynthesis, N use efficiencies and yield of rice were investigated during wet season (June to November) in sub‐humid tropical region of India. An increasing trend in crop growth rate with Si at all levels of N was observed. Silicon reduced the flag leaf angle making the leaf more upright and enhanced flag leaf N content. Leaf chlorophyll concentration and single leaf photosynthesis rate were higher with Si compared to without Si at flowering stage. Both N and Si significantly affected panicle number and grain filling. Application of 200 kg SiO2 ha−1 and 100 kg N ha−1 produced the highest number of panicle per square meter, filled grain per panicle and yield. Significant yield increases ranging from 8.2–16.9% were observed with Si compared to without Si. Both N and Si treatments had significant effects on N uptake and N use efficiency. Agronomic N use efficiency and N recovery efficiency were higher with Si compared to without Si. The highest physiological N use efficiency was recorded with 200 kg SiO2 ha−1 and 80 kg N ha−1. Silicon may enhance yield response of rice to higher N rate by improving source (photosynthetic) capacity and sink (reproductive organ) strength.

Determining Factor/s of Window Glazing Regarding Reduction in Electrical Energy Consumption

Abstract Among all building envelops, windows are typically the weakest barrier to heat ingress. The building energy consumption of any conditioned building located in the tropical country is deeply governed by the amount of heat gain inside the building because heating ventilation and air-conditioning (HVAC) system is a major energy consumer. Hence, it can be easily inferred that the energy consumption of a building can be reduced through judicial selection of window glasses. This paper illustrated the importance of thermal transmittance (U-value) and solar heat gain coefficient (SHGC) value of window glazing in detail and also demonstrated the energy savings potential of various types of commercially available windowpanes. The electric energy savings potential of various types of windowpanes such as tinted, reflective, single glazing, and double glazing glasses have been analyzed through eQUEST energy simulation software for a building, situated in the tropical region of India. Building architectural data and all other information regarding HVAC, lighting, etc. have been collected during the energy audit and trained in the eQUEST simulation for further analysis. The calibration of simulation model has been done using actual monthly electricity consumption data of the case building. This study depicts the percentage decrease in electrical energy consumption due to retrofitting of various commercially available window glasses compared with base building. The study also compares the importance of main two determining factor(s) U and SHGC value behind the judicial selection of proper window glazing.

Incidence of rhizome rot of ginger in some selected areas of Bangladesh and the causal pathogens associated with the disease

Ginger (ZingiberofficinaleL.) belongs to family Zingiberaceae is an important oriental spice crop. Ginger is high value crop which grows well in warm and humid climate and is cultivated from sea level to an altitude of 1500 meters above sea level (Kandinnan, et al. 1996). It has special significance for tropical countries where it is produced and consumed in large quantities (Islam, 2017; BARI, 2012, 2013 and 2014). The aromatic rhizomes are used as spice and medicine. Major producers of ginger in the world are India, Jamaica, Sierra Leone, Nigeria, China, Japan, Taiwan and Australia (Rana and Sharma, 1998). Ginger is much more used in Bangladesh as a spice and is cultivated more or less all over the country. In the country produced only 74380 metric tons of ginger from 9120 ha of land and the yield per hectare was 8.15 kg (BBS, 2011). But average yield is low as compared to other ginger growing countries of the world. The production is not enough to fulfill the annual requirement of the country. So every year a good amount of ginger is imported in exchange of foreign currency. Like many countries diseases are the major limiting factors for ginger cultivation in Bangladesh. Among the diseases, rhizome rot is the most devastating one caused by Pythium aphanidermatum, Fusariumoxysporum, Sclerotiumrolfsiiand Ralstoniasolanacearumthroughout the world (Chauhan and Patel, 1990; Dohrooet al. 1987 and Iyer, 1987). The pathogens involved decide the nature of the damage and symptom expression .The major pathogens involved with rhizome rot are viz., species of Pythium causing soft rot, Fusariumspp. causing yellows or wilt and Ralstoniasolanacearumcausing bacterial wilt (Elliot, 2003). Basal rot caused by Sclerotiumrolfsiiwhich appears later in the season in some cases. All these pathogens are known to form complexes with nematodes leading to synergistic effect on the severity of the disease. They predispose the crops to secondary pathogens (Sarma, 1994).Loss due to rhizome rot is estimated in many countries and the main pathogens associated with rhizome rot are the fungi such as Pythium spp. and Fusariumspp, bacteria like Ralstoniasolanacearumand nematode (Elliot, 2003). It may cause losses to the extent of 50% or more due to soft rot ((Islam, 2017; BARI, 2012, 2013 and 2014; Joshi and Sharma, 1982) and sometimes total failure of the crops in the tropical regions of India (Fageriaet al, 2006); 70% rhizomeproduction is reduced due to the infection caused by Pythium spp. and Fusariumspp. in Nepal (Anon., 2012) and 5-30% losses occurred in Fiji and Australia by Pythium myriotylum(Stirlinget al., 2009). Soil, water and infected planting materials are the main source of perpetuation of these pathogens (Dohroo, 2005). Pythium spp. is able to persist in soil over decay by means of encysted zoospores, oospores and sporangia. Pythium spp also can survive in air dry muck soil for up to 12 years (Hoppe, 1966). Pythium spread via infested rhizomes (Trujillo, 1964) and as oospores surviving in debris in the soil (Dohroo, 2005). Infection started from contaminated planting materials, saprophytically living fungus in the soil or on trash of previous ginger crops. The soft rot pathogen generally have quite a wide host range and can survive on other host plants so this makes it difficult to control in the field. In the past Pythium aphanidermatumwas known as the sole causal agent of rhizome rot of ginger and was successfully controlled by the technology developed by Plant Pathology Division, BARI. But during the last few years that technology was not working well and it was noticed that some other fungal and bacterial association were involved with such rot. As the crop is cash crop so it is prime need to identify the causal agents of rhizome rot through intensive survey which will help to modify the existing technology for managing the disease in future. The present research work was undertaken to determine the incidence of rhizome rot of ginger and its causal agents.Bangladesh J. Agril. Res. 44(3): 569-576, September 2019

Genetic variation and survival of Erysiphe necator in tropical India

The heterothallic, biotrophic fungus Erysiphe necator causes powdery mildew on grapes which impacts the yield and quality of fruits and their processed products. Two genetic groups, A and B, have been described which overwinter either as flag shoots or chasmothecia. The genetic structure of the Indian isolates and their oversummering mode in tropical regions is not known. In this study, population genetic analysis of 26 and 134 E. necator isolates from temperate and tropical regions of India, respectively, was performed. PCR analysis showed presence of both genetic groups A and B in temperate regions and only genetic group B in tropical regions. Flag shoots were not observed in tropical region. Weather data analysis and temperature sensitivity of E. necator conidia indicate the possibility of the pathogen oversummering as conidia on bark. Sequence analysis of ITS (Internal Transcribed Spacer), IGS (Intergenic Spacer), TUB2 (Beta-Tubulin) and EF1-α (Translation Elongation Factor 1-α) genes covering 1762 nucleotides from 22 isolates showed the presence of four haplotypes, A-IN1, B-IN1, B-IN2 and B-IN3 in temperate regions and only haplotype B-IN3 in tropical regions. Haplotypes A-IN1 and B-IN1 were similar to haplotypes of group A and B, respectively, reported from USA, Europe and Australia. The other two haplotypes, B-IN2 and B-IN3 grouped with haplotypes from USA and are new reports from India. The diversity and haplotype structure suggest that powdery mildew was introduced in north India and then moved to tropical regions corroborating historical reports of the introduction of grapevines in India. Occurrence of a genetic group with lower fungicide sensitivity and greater aggressiveness might explain the difficulties to manage this disease in Maharashtra, India.