Phytostimulation and growth promotion activities of Trichoderma spp. on groundnut (Arachis hypogaea L.) crop

Groundnut (Arachis hypogaea L.) suffers from many soil borne pathogens that deteriorate the quality of the seeds and are responsible for high yield loss. Practically Trichoderma sp. is used for seed treatment, it minimizes the seed and soil borne pathogens and supports plant growth promotion activities. In the present study, five different isolates of Trichoderma spp. were isolated from groundnut (A. hypogaea ) rhizosphere soil. All the five isolates were confirmed by morphological methods and using molecular tools through Polymerase Chain Reaction (PCR) amplification of Internal Transcribed Spacer (ITS) region of Trichoderma sp. and DNA gets amplified in 650 bp to 700 bp. Trichoderma spp. were molecularly identified as T(SP)-20 (Trichoderma longibrachiatum), T(AR)-10 (T. asperellum), T(VT)-3 (T. hamatum), T(BI)-16 (T. longibrachiatum), T(TK)-23 (T. citrinoviride). Phytostimulation activities of all the six isolates viz., phosphate solubilization, Ammonia production, IAA production, and Siderophore production, were evaluated. Among the six isolates, T(SP)-20, T(AR)-10, and TNAU-TA showed higher phytostimulation activities. The growth promotion of Trichoderma spp. on groundnut was assessed through the roll towel method. The isolate T(SP)-20 (T. longibrachiatum) produced the highest germination percentage of 93.33 and vigor index of 2246.2. This work developed a new isolate of T. longibrachiatum (T(SP)-20) which is a native isolate having significant  phytostimulation and growth promotion activities and it could be exploited for other soil borne disease managing successfully

Cropping duration and non-rhizomorphic mycelial phenotype of Pleurotus djamor woody1 co-segregate in the hybrid progenies

Crop duration of the cultivated Pleurotus spp. is 45 to 50 days. P. djamor isolate woody-1 was collected as natural selection and was found to be short cropping duration variety with total cropping duration of 30 days but it is less palatable. It produced very thin, loose and non-rhizomorphic mycelia appearing light white color. Whereas, other commercial Pleurotus varieties such as P. florida and P. djamor MDU1 are long crop duration varieties and palatable producing thick, compact and rhizomorphic mycelia with bright white color. Co-segregation of non-rhizomorphic mycelial phenotype and short cropping duration trait of P. djamor woody- 1 in hybrid progenies was evaluated. Hybrid strains viz., H2W12 and H2W14 have thin, loose and non-rhizomorphic mycelium and they produced primordia in 9-10 days after spawning with total cropping duration of 29-32 days. Whereas, hybrid strain namely Pf1W2 has thick, compact and rhizomorphic mycelial phenotype and it produced primordia in 20 days after spawning with the total cropping duration of 47 days. This study indicated that genes governing short cropping duration and non-rhizomorphic mycelial pattern were tightly linked and co-segregated in the progenies. Thus, non-rhizomorphic mycelial phenotype of P. djamor woody1 can be used as a phenotypic marker for selection of hybrid cultivar having short cropping duration with other desired agronomic traits in future breeding strategy

Survey and surveillance on rice false smut disease severity in Tamil Nadu and the influence of wind velocity on disease progression under field conditions

The false smut disease of rice incited by Ustilaginoidea virens is a major constraint on rice production. The main aim of the present study was to ascertain the false smut disease severity in both delta and non-delta districts of Tamil Nadu through survey and surveillance and assess the correlation between the disease severity and wind velocity for the past three years, 2019, 2020 and 2021. Moreover, the present study addressed the disease distribution pattern of false smut diseases under field conditions.  The results obtained from survey results revealed that the maximum disease severity was recorded in Nagapattinam district (Nagapattinam block) with 27.45% and the minimum disease severity was recorded in the district Theni (Bodinayakanur block) with 8% in 2021. Similarly in 2019 and 2020 maximum disease severity was recorded in the following districts Thanjavur district (Orathanadu block) with 19.91% and Thanjavur district (Peravurani block) with 18.54% and the minimum disease severity was recorded in the following districts Madurai district (Madurai north block) with 4.78% and Madurai district (Usilampatti block) with 4.78% respectively. The obtained R2 values through regression analysis were 0.70, 0.79 and 0.76 in the following years, 2019, 2020 and 2021, respectively. Besides the relationship between the false smut disease development, the pattern wind direction was also assessed. By assessing the false smut disease distribution pattern under field conditions, more disease distribution was observed around the surrounding area of the paddy field as well as the diagonal path of the field which clearly revealed that wind direction influences the disease development