Evaluation of maize seed mycoflora and its impact on seed health and transmissibility to next generation crop

Maize (Zea mays L.) has a wide adaption to almost all the agro ecological zones of India and is the third most important cereal crop. The crop is afflicted by a number of fungi at pre-harvesting and post-harvesting stages. Maize seed samples were examined from forty five locations in nine districts from Delhi, Haryana and Uttar Pradesh to evaluate the post harvest seed mycoflora. Two hundred and seventy seeds were analyzed from each location to identify the seed colonizing fungi and their transmissibility to next generation crop. Maximum fungal invasion was recorded in samples from Ghaziabad district (37.1%) and minimum in Faridabad district (22.6%). Twenty two fungi representing sixteen genera were isolated out of which four species viz., Bipolaris sorokiana, Botryodiplodia theobromae, Exserohilum rostratum and Alternaria solani were not reported earlier from maize seeds in India. Fusarium spp. showed a wide spread occurrence in all the samples tested. Out of the twenty two fungal species only eight fungi, viz., Phoma spp. Colletotrichum graminicola, Exserohilum rostratum, Penicillium spp. Rhizopus spp. Aspergillus niger, A. flavus and Trichoderma spp. were not transmitted to seedlings, however, their occurrence formed the post harvest storage mycoflora. Exserohilum rostratum, Aspergillus spp. and Fusarium spp. severely affected the seedling growth. Seed vigor was recorded as minimum for Fusarium moniliforme (353.6) and F. verticilloides (332.8). The study revealed that field samples have widespread occurrence of Fusarium spp., Aspergillus spp. and Penicillium spp. as dominant mycoflora along with other fungi which should be a concern for seed health certification. Regular biodiversity monitoring for soil mycoflora in field is must to monitor the emerging and re emerging pathogens which may affect the next generation crop and hence the crop productivity.