Authors : M. N. Bhajbhuje
Page Nos : 24-34
Description :
The phytoalexins involvement in disease resistance against virulent pathogens is being widely
realizing in different plant system. The salts of heavy metals, well-known phytoalexin inducers,
were used at dilute concentrations in different treatments to control Alternaria leaf spot
infection in Vigna mungo (L.) Hepper seedlings caused by necrotrophic fungal pathogen
Alternaria alternata Keissler. Seed soaking for 24 h induced significant to moderate protection
to seedlings, at different stages of growth after treatment, against artificial inoculation of spore
suspension of Alternaria alternata Keissler an isolate of virulent pathogen and mostly induced
significant reduction in symptoms. Seed soaking in aqueous dilute solutions of test chemicals
comparatively seemed to provide the most effective and durable protection. Wet seed treatment
with barium, mercury and ferric chloride were proved most effective in reducing the infection
and lesion expression significantly. The fungitoxicity in leaf diffusate was recorded decline with
age in treated artificially inoculated seedlings. Little fungitoxicity appeared in leaf diffusates
from 4-wk old seedlings that had been treated uninoculated and moderate toxicity in that from
untreated, inoculated seedlings. However, treated seedlings inoculated at 3-and 4-wk stage
produced leaf diffusates with significantly greater toxicities which were in proportion to their
abilities to resist attack.
