Abstract:
Nine organic substrates viz., rice grains, sorghum grains, wheat grains, millet grains,
wheat straw, rice husk, cow dung, sawdust, and poultry manure were used for mass
multiplication of Trichoderma harzianum. Of these, sorghum grains followed by millet
grains were the best substrates. The poultry manure appeared to be the most unsuitable
substrate, whereas rice grains, wheat grains, wheat straw, and rice husk performed
moderately well. Sucrose was the best carbon source and supported the highest colony
growth of T. harzianum on Czapek’s Agar plates. Similarly, ammonium nitrate at 3,000
ppm appeared to be the most suitable nitrogen source and produced the highest colony
growth as well as abundant conidia. A combined use of sucrose at 30,000 ppm as carbon
source, and ammonium nitrate at 3,000 ppm as nitrogen source significantly enhanced the
mycelial growth and conidial production by T. harzianum in wheat straw, rice husk, and
millet grains, whereas, in sorghum grains and rice grains, the addition of carbon and
nitrogen sources showed negative effect on sporulation of T. harzianum. Studies on shelf
life of the inocula multiplied on various substrates showed that the populations of T.
harzianum on all the substrates achieved the peak at 60-75 days incubation period and
declined gradually thereafter. However, even after 330 days, the populations were greater
than the population at 0-day. At 345-360 days interval, population was found to be less
than the initial population at 0-day.
Keywords: Biocontrol agent, Mass multiplication, Shelf life, Trichoderma harzianum.
