Antagonistic potential of Trichoderma hamatum against Alternaria porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis

Alternaria porri causing purple blotch disease of onion is a destructive phytopathogen which causes severe loss in productivity. The present study aimed to unravel the antagonistic potential and efficacy of volatile organic compounds produced by various Trichoderma spp. against A. porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis. Ten isolates of Trichoderma species were isolated from the rhizospheric soil of healthy onion plants. Upon paired plate technique, the in vitro efficacy of ten Trichoderma isolates were tested against virulent isolate of Alternaria porri isolated from purple blotch disease infected onion plants. The Trichoderma isolate TIM2 showed 76.29 per cent inhibition on mycelial growth of pathogen. The effective Trichoderma isolate was identified as Trichoderma hamatum through the analysis of the rDNA of internal transcribed spacers (ITS) region and it was subjected to GC-MS analysis.  The result of GCMS analysis indicated the highest peak area and retention time with major antimicrobial bioactive compounds like Tetradecane, 2,6,10-trimethy (20.327), (1.22) and Dodecane, 2-cyclohexyl (20.079), (2.14), Heptadecane (21.222), (9.50), Octadecane (22.379), (3.58), Eicosane, 9-cyclohexyl (22.578), (1.84), 2-Propenoic acid, pentadecyl ester (23.400), (10.37), 2,6,10,14-tetramethyl (23.567), (10.37), Eicosane (27.311), (2.34), Hexadecanoic acid, methyl ester (27.918), (4.43), n-Hexadecanoic acid (29.156), (3.59) and  Tetrapentacontane, 1,54-dibromo (31.906), (3.33). These bioactive compounds identified through GCMS analysis from the crude extracts of Trichoderma hamatum exhibited a stronger antifungal activity against A. porri. Hence the application of T. hamatum for the management of purple blotch disease highly supress growth of the pathogen and reduce the disease incidence.    

Climate nutrient management for various sources and levels of fertilizers on soil nutrients, growth and yield of maize (Zea mays l.) in Madurai district, Tamil Nadu, India

Global climate change is expected to soil processes and properties, which are important for restoring soil fertility and low productivity. The field experiment was conducted at Research Farm, Agricultural College, and Research Institute, Madurai district, Tamil Nadu, during Kharif season 2021 to study of various sources and fertilizers' levels to influence under deficit and excess water conditions on soil fertility, growth, and yield of maize (Zea mays). The study revealed that excess and deficit water condition in moisture regime irrigations at Irrigation water / Cumulative Pan Evaporation (IW/CPE) ratio of 1.0 along with nutrient management practices (N8) 125 % Soil Test Crop Response (STCR) - NPK soil application by 1 % foliar spray of micronutrient mixture. Significantly higher of mean values available nitrogen (225 kg ha-1), available phosphorous (20.81 kg ha-1), available potassium (351 kg ha-1), dry matter production (DMP) (16,404 kg ha-1), plant height (250 cm) and yield (9,030 kg ha-1) and was comparable with IW/CPE ratio of 0.8, 0.6 along with others nutrient management practices at 100 % and 75 % STCR - NPK followed by foliar sprays 2 % NPK (19:19:19) and Pink-pigmented facultative methylotrophs (PPFM) 1 %. Hence, under a normal water availability situation, irrigation at an IW/CPE ratio of 0.8 was good enough to produce a higher yield, while under deficit and excess water conditions IW/CPE ratio of 1.0 along with125 % STCR-NPK by foliar spray of micronutrient mixture of 1 % was suitable for obtaining optimum nutrient management for enhancing soil fertility, growth and yield of maize

Non-Destructive Testing of Magnetically Impelled Arc Butt Welding of Mild Steel Tubes

This paper presents the results of Non-Destructive Testing on Magnetically Impelled Arc Butt (MIAB) welded mild steel tubes of 27mm OD and 1.5mm thickness. As part of this work, the tests covered were radiography, liquid penetrant, and magnetic particle testing. The testing results indicate that porosity, penetration levels and the defects found are within acceptable limits as per standard. For this experimental work, the selection of parameters was based on trial and error adopted in preliminary trials. The irregularities found in the non-destructive testing samples have enabled the fine-tuning of process parameters. The optimum values of hydraulic pressure, weld time and weld current are assessed to be 30-35bar, 5.5s and 150 A, respectively 270 A for this dimension of tubes. This work focuses on the experimental observations of MIAB welding and Non-destructive testing results for MS tubes of the selected dimension, which have not been reported in the existing literature. The achieved input forms the database for the parametric study of this process. The optimum parametric ranges obtained from the results can be extrapolated to be used for joining tubes of different dimensions and can also form the inputs for reaching parameter and response dependency equations

Isolation and Characterization of Bacteria from the Gut of Bombyx mori that Degrade Cellulose, Xylan, Pectin and Starch and Their Impact on Digestion

Bombyx mori L. (Lepidoptera: Bombycidae) have been domesticated and widely used for silk production. It feeds on mulberry leaves. Mulberry leaves are mainly composed of pectin, xylan, cellulose and starch. Some of the digestive enzymes that degrade these carbohydrates might be produced by gut bacteria. Eleven isolates were obtained from the digestive tract of B. mori, including the Gram positive Bacillus circulans and Gram negative Proteus vulgaris, Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Serratia liquefaciens, Enterobacter sp., Pseudomonas fluorescens, P. aeruginosa, Aeromonas sp., and Erwinia sp.. Three of these isolates, P. vulgaris, K. pneumoniae, C. freundii, were cellulolytic and xylanolytic, P. fluorescens and Erwinia sp., were pectinolytic and K. pneumoniae degraded starch. Aeromonas sp. was able to utilize the CMcellulose and xylan. S. liquefaciens was able to utilize three polysaccharides including CMcellulose, xylan and pectin. B. circulans was able to utilize all four polysaccharides with different efficacy. The gut of B. mori has an alkaline pH and all of the isolated bacterial strains were found to grow and degrade polysaccharides at alkaline pH. The number of cellulolytic bacteria increases with each instar

Efficacy of Herbicides on Nutrient Uptake of Crop, Weed and Its Impact on Soil Microflora of Irrigated Maize (Zea mays L.)

Aim: Field experiment was conducted to study the suitable weed management methods to check the nutrient depletion by weeds, check the dynamics of microbial population and in relation to improve the biomass stover yield of maize (Zea mays L.). Study Design: This experiment laid out in a randomized block design and 8 different weed management treatments with three replications. Place and Duration of Study: Field experiment was conducted at Agricultural College and Research Institute, Madurai, Tamil Nadu Agricultural University, Tamil Nadu in kharif 2019. Methodology: TNAU maize hybrid CO-6 was used for this experiment. Treatments were application of pre-emergence herbicide atrazine at 0.25 kg/ha or pendimethalin 1 kg/ha applied singly on 3 days after sowing and in combination with post-emergence herbicide tembotrione 120 g/ha or halosulfuron methyl 90 g/ha on 25 DAS, weed free check, unweeded check in maize crop. Weed nutrient depletion and microbial population was analysed in laboratory. Results: The application of pre-emergence atrazine 0.25 kg/ha followed by post-emergence tembotrione 120 g/ha effective in controlling of grasses and BLW and enhance the nutrient uptake of maize. The stover maize yield increased with application of herbicides and sequential application of herbicides achieved 88% improved stover yield over unweeded check. Sequential application of herbicides initially reduce the population of soil microflora but the population gradually build up in all the herbicide applied plots at 60 days after application. Conclusion: Based on the results of the experiment, it was concluded that pre-emergence atrazine 0.25 kg/ha followed by post emergence tembotrione 120 g/ha effective in controlling of weeds and enhance the nutrient uptake and stover yield of maize without much adverse impact on soil microbial population

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato