Seed biopriming with antagonistic microbes and their defense activity against damping-off disease in solanaceous vegetable crops

Damping-off disease caused by various soil and seed borne pathogens is of prime concern in nursery raised solanaceous vegetable crops. Use of chemicals for its management is quite an effective strategy, however, due to environmental concerns chemical application is reduced. Seed biopriming is a novel green approach that can be employed in mitigating the incidence of damping-off disease. Present study was performed to analyze the potential of antagonistic microbes as seed biopriming treatments and their efficacy in managing the disease along with their ability to induce defense activity. Fungal and bacterial antagonists were firstly screened for their efficacy against the pathogens and later seeds of tomato (Solanum lycopersicum L.), chilli (Capsicum annuum var. annuum L.) and capsicum (Capsicum annuum var. grossum L.) were bioprimed with effective antagonists. The enzyme activity of seedlings grown from bioprimed seeds of tomato, chilli and capsicum and sown in organic extract amended soil was estimated under in vitro conditions. Among the different bio-inoculants tested against damping-off pathogens, highest inhibition of mycelial growth of Pythium was recorded by Trichoderma virens Pers. (88.70%) followed by Trichoderma harzianum Rifai (83.85%). Mycelial growth of Fusarium oxysporum Schlecht. was also significantly inhibited by T. harzianum (86.55%). Biopriming of tomato and chilli seeds with Trichoderma virens recorded disease suppression of 57.87 and 54.71%, respectively. However, in capsicum seed biopriming with Trichoderma atroviride Pers. recorded 55.51% reduction in seedling mortality as compared to control. Enzyme activity in terms of PPO, PO, TPC and PAL was recorded which is significant in tomato, chilli and capsicum seeds bioprimed with T. harzianum, T. atroviride and Pseudomonas fluorescens Migula in combination with NSKE. These results marked the potential of seed biopriming with native isolates of Trichoderma that possesses enhanced enzyme activity in seedlings and this strategy can be used as an eco-friendly alternative of synthetic chemicals in disease management.