lal s kAjay2019-02-252019-02-252018http://krishikosh.egranth.ac.in/handle/1/5810096850t-9954A study was done to evaluate the potential of bioagents in enhancing seed quality of carry over and fresh seed lots of two varieties of onion viz. Pusa Red and Pusa Riddhi stored in cloth bags and aluminum foil packets. Freshly harvested (2015-16) and carry over seeds (2014-15) of onion cultivars of Pusa Red and Pusa Riddhi were collected from IARI R.S. Karnal and Seed Production Unit, IARI, New Delhi. The seeds were treated with Trichoderma harzianum, Pseudomonas fluorescens, Bacillus pumilus and Bacillus subtilis as well as fungicides viz. Thiram and Bavistin as per the recommended dosage and stored under ambient conditions for six months. The seed quality parameters were analysed at an interval of two months. The fungicides and bioagents were evaluated for their efficacy against Purple blotch pathogen (Alternaria porri) through Inhibition zone technique and Poisoned food technique. The seeds stored in aluminum foil packets showed lower seed moisture content than seeds stored in cloth bags throughout the storage period. The treated seeds were effective in maintaining the seed quality parameters viz. Germination per cent, Vigour indices, SOG, MGT and seed health as compared to control. Amongst chemical seed treatments, the seeds treated with Bavistin were found to be most effective. The seeds treated with B. pumilus exhibited better seed quality as compared to other bioagents. The fresh seed lot of cv. Pusa Red maintained better seed quality among all seed lots whereas the carry over seed lot of cv. Pusa Riddhi was characterised with maximum seed deterioration throughout the storage period. The seeds stored in aluminum foil packets maintained better seed quality parameters as compared to seeds stored in cloth bags among the four seed lots. The treated seeds showed better storability up to six months of storage as compared to control. Seed health tests revealed that the seeds treated with Thiram and Bavistin showed better control of seed borne fungi than other seed treatments, followed by B. pumilus. Field emergence of treated seeds showed a similar trend of germination capacity (as recorded in standard germination test), maximum being in the fresh seed lots of Pusa Red treated with Bavistin. The maximum inhibition of mycelial growth was recorded in case of Thiram + Bavistin, followed by Thiram in the efficacy tests of fungicides against purple blotch pathogen. Among bioagents, the maximum inhibition of mycelial growth of Alternaria porri was exhibited by Trichoderma harzianum, followed by Pseudomonas fluorescens.en-USnullThesis