Partial characterization of toxins associated with stem end rot of mango caused by Lasiodiplodia theobromae

In this study, the toxicity of liquid culture media from different isolates of Lasiodiplodia theobromae was characterized and some properties of the toxic metabolites were distinguished. In this work toxin producing ability of L. theobromae was revealed by studying the physical parameters viz., osmotic potential, toxin concentration, pH, temperature and biological parameter like host specificity and wilting index. The obtained results showed that the optimal toxin-production conditions for L. theobromae in potato dextrose broth under pH 6.0, at 25-35°C for 7 days. The liquid culture from all isolates were toxic to mango plants and induced the rapid wilting. The toxin obtained from the liquid culture has thermal, acid base stability and a broad range of toxicity to main host and non-host plants. Moreover, the direct bioassay for two components of the liquid filtrates precipitated by ethanol showed that the active ingredient of the toxin is a kind of non protein substance, which was further endorsed by the papain hydrolysis analysis. Our results confirmed the chemical nature of toxic compound elucidating the favorable environmental conditions for toxin production of L. theobromae and proved potential role of toxic metabolites in the mechanism of disease development

Improved techniques to enhance the yield of paddy straw mushroom (Volvariella volvacea) for commercial cultivation

Cultivation of Volvariella volvacea in circular compact bed method recorded maximum yield of 972.8 g/bed (biological efficiency of 23.8%). Seeding the beds with 15 and 20 days old spawn with well developed chlamydospores contributed for significantly higher yields. Oil palm bunch waste in combination with rice straw or alone recorded significantly higher yields of 876.3 and 832 g/bed, and cotton waste, in combination with rice straw or alone, recorded 841.6 g and 778 g/bed, respectively. In vitro evaluation of the micronutrient based boosters VVB1 (CaCO3 400 ppm + CaCl2 50 ppm + KH2PO4 50 ppm + NaCl 50 ppm + Na2HPO4 50 ppm) and VVB2 (CaCl2 400 ppm + Na2HPO4 100 ppm) produced profuse mycelium with aerial silky strands, early chlamydospore formation (20.8 and 21.8 days) and increased chlamydospore density (7.8 × 102 and 7.2 × 102 spores/ml). Yields of 960 g/bed with more number of sturdy fruiting bodies were observed in beds sprayed with VVB1. V. volvacea can be successfully cultivated from March to September with 18 to 20% biological efficiency. Storage of V. volvacea at egg stage in air tight plastic box at deep freeze (-20°C) conditions remained intact until 36 h without spoilage.Keywords: Paddy straw mushroom, Volvariella volvacea, boosters, bed methods, cultivation technique

Detection of banana streak virus (BSV) Tamil Nadu isolate (India) and its serological relationship with other badna viruses

Banana streak virus (BSV) is of quarantine significance since Musa is a vegetatively propagated crop. Diagnosis by symptomatology is unreliable because the symptoms are variable or absent. Hence, reliable and sensitive diagnostic tests are of major significance. Such sensitive diagnostic tests are also required for virus indexing of germplasm collections. Hence, attempts were made for diagnosis of BSV and to study the serological relationship with other badna viruses. BSV particles were purified from BSV infected plants, collected from the locality of Tamil Nadu, India. Immunosorbent electron microscopy studies revealed bacilliform viral particles with a size of 120 x 30 nm. Polyclonal antiserum raised against BSV reacted with the rice tungro bacilliform virus and sugarcane bacilliform virus in TAS ELISA. In PCR assays, the primers designed to amplify DNA of BSV Onne isolate amplified DNA of BSV Tamil Nadu isolate producing amplicons of about 644 bp in size. The primers used in PCR to amplify the BSV did not amplify other badna viruses tested such as Rice tungro bacilliform virus and Sugarcane bacilliform virus. Our results suggest that the BSV isolate from Tamil Nadu is closely related to Nigerian BSV (Onne) isolate.Keywords: Triple Antibody sandwich Enzyme linked immunosorbent Assay (TAS ELISA), banana streak virus (BSV), polymerase chain reaction (PCR), polyclonal antiseru

Seasonal variation of paddy straw mushroom performance under different microclimate environments

Maize is an important base crop in intensive irrigated cereal based cropping system because of its wider climatic acclimatization. In contrast, a certain microclimate is needed for commercial mushroom production. Favourable microclimatic condition that prevails in maize field created a greater opportunity to grow the warm loving Paddy Straw Mushroom “Volvariella volvacea” as intercrop. In this context, a comparative study was taken up at Tamil Nadu Agricultural University to determine the performance of paddy straw mushroom as intercrop under different microclimate created in irrigated maize and polyhouse during summer and kharif 2022. Study concluded that the microclimate variables during kharif season was more favourable for obtaining higher straw mushroom yield as maize intercrop, but the summer season was also an economically viable one. The study found that the most ideal limits of microclimate variables such as morning and afternoon temperature, morning and afternoon RH for paddy straw mushroom was 26 to 29oC, 29 to 33oC, 80 to 98 per cent and 66 to 88 per cent, respectively. The polyhouse showed its superiority in providing controlled favourable microclimate for paddy straw mushroom than the fluctuating microclimate under maize canopy, however the higher infrastructural investment in polyhouse farming is not affordable for the small and marginal farmers. The microclimate prevailed in between maize rows could support paddy straw mushroom intercropping as a viable system, which had Land Equivalent Ratio of more than 1.6 and double the time of Crop Equivalent Yield when compare to sole cropped maize

Effect of Microclimate Modulation on the Growth and Yield of Straw Mushroom as a Intercrop in Maize Field during Summer

A field experiment was carried out during the summer season to study the effect of microclimate modification on growth and yield of paddy straw mushroom under outdoor cultivation as maize intercrop. A Randomised Complete Block Design (RCBD) with eight treatments comprising the combination of spacing (60 x 25 cm, 45 x 25 cm, paired row 45/75 x 25 cm, and paired row 30/60 x 25 cm) and mulching (with or without application), in three replications was used for this study. The study concluded that maximum average yield was obtained in normal spacing 45x25 cm coupled with mulching (578 g bed-1) with high biological efficiency of 19.3 per cent. The results inferred that both the afternoon (14.22 hours) microclimate variables viz., temperature (low) and relative humidity (high) had played major role for higher yield and Biological Efficiency (BE) of paddy straw mushroom as maize intercrop. Normal row spacing (45 x 25 cm) with or without mulch and paired row spacing (30/60 x 25 cm) with mulch provided favourable microclimate during summer for faster growth, higher yield and biological efficiency for paddy straw mushroom intercropped maize which in turn might be adopted by the farmers for the outdoor cultivation of paddy straw mushroom

Antifungal Volatilomes Mediated Defense Mechanism against Fusarium oxysporum f. sp. lycopersici, the Incitant of Tomato Wilt

In this study, the volatilomes of naturally growing plant leaves were immobilized in a suitable substrate to enhance vapors’ diffusion in the soil to eradicate the Fusarium wilt pathogens in Tomato. Volatilomes produced by Mentha spicata leaves immobilized in vermiculite ball was found to be effective and exhibit 92.35 percent inhibition on the mycelial growth of Fusarium oxysporum f. sp. lycopersici (FOL). Moreover, the volatilomes of M. spicata immobilized vermiculite balls were tested based on the distance traveled by the diffused volatilomes from the ball and revealed that the volatilomes of M. spicata traveled up to 20 cm distance from the center of PVC (Polyvinly chloride) chamber showed maximum reduction in colony growth of FOL at 12th day after inoculation. Tomato plants inoculated with FOL revealed increased expressions of defense gene, pathogenesis related protein (PR1) with 2.63-fold after 72 h and the gene, transcription factor (WRKY) increased with 2.5-fold after 48 h on exposure to the volatilomes of M. spicata vermiculite balls. To the best of our knowledge, this is the first report on development of volatilomes based vermiculite ball formulations. This result indicated that the volatilomes of M. spicata are promising phyto-fumigants for management of Tomato Fusarial wilt