BIOFERTILIZERS AND BIOPESTICIDES DR Mrs REKHA GULVE ASSO

BIOFERTILIZERS AND BIOPESTICIDES DR. Mrs. REKHA GULVE ASSO. PROF. MICROBIOLOGY MRS. K. COLLEGE, BEED.

BIOFERTILIZERS • Definition: • Biofertilizers can be defined as a live microbial preparation, when applied to seed , root or soil, colonizes the rhizosphere or the interior of the plant, and promotes growth and releasing growth promoting substances by increasing the availability of primary nutrients. • Biofertilizers also called ‘Microbial Inoculants’. • E. g. - Rhizofertilizer, Azofertilizers, Azospirillum fertilizers, Azolla fertilizers.

Advantages of Biofertilizers are cost effective. They are eco-friendly. Increase crop yield by 20 -30%. Improve soil texture and water holding capacity and restore natural soil fertility. • Add nutrients to soil and make nutrients available to crop. • Supplement to fertilizers, replace chemical nitrogen and phosphorous by 25%. • •

Groups Examples N 2 fixing Biofertilizers 1. Free-living 2. Symbiotic 3. Associative Symbiotic P Solubilizing Biofertilizers 1. Bacteria 2. Fungi P Mobilizing Biofertilizers Azotobacter, Beijerinkia, Clostridium, Klebsiella, Anabaena, Nostoc, Rhizobium, Frankia, Anabaena , Azollae Azospirillum Bacillus megaterium var. phosphaticum, Bacillus subtilis Bacillus circulans, Pseudomonas striata Penicillium sp, Aspergillus awamori 1. Arbuscular mycorrhiza Glomus sp. , Gigaspora sp. , Acaulospora sp. , Scutellospora sp. & Sclerocystis sp. 2. Ectomycorrhiza Laccaria sp. , Pisolithus sp. , Boletus sp. , Amanita sp. 3. Ericoid mycorrhizae Pezizella ericae 4. Orchid mycorrhiza Biofertilizers for Micro nutrients 1. Rhizoctonia solani Silicate and Zinc solubilizers Bacillus sp. Plant Growth Promoting Rhizobacteria 1. Pseudomonas fluorescens

1) Rhizofertilizers : Rhizofertilizers contain different species belonging to Rhizobium genus. Rhizobia are Gram negative, motile rods, aerobic in nature, present in soil. They form root nodules in leguminous plants and fix nitrogen symbiotically. Effective nodules are large, pink, and firm and contain Rhizobia as bacteroids. Pink color of root nodules is because of leghemoglobin. Bacteroids Growth of Rhizobium on Congored yest extract mannitol agar

Pea Plant R. leguminosarum nodules Pink color is leghaemoglobin a protein that carries oxygen to the bacteroids

Nodulation Process: The bacteria enter in the root nodule through root hairs, the interaction is highly specific and result in nodule formation. Inside the nodules many bacteria are presents in bacteroid form (undividing stage) which produce ‘nitrogenase enzyme’. The enzyme reduces the atmospheric nitrogen into ammonia this processes is called nitrogen fixation. The Rhizobium species are host specific means one Rhizobial species able to nodulate or infect a group of specific leguminous plant species, is called ‘cross inoculation group’. For ex. Rhizobium leguminosarum biovar viciae infect or form nodule in pea group. The species of Rhizobium are differ in their ability to fix nitrogen. Screening is essential to select the efficient nitrogen fixing species for preparation of biofertilizers. The estimated nitrogen fixation by Rhizobium species is 50 to 150 Kg/Ha or even more nitrogen in field trial in India. 10 to 15% crop yield increase when rhizofertilizers use.

Host Group Rhizobium Species Soybean group Rhizobium leguminosarum R. japonicum Lupini Group R. lupine orinthopus Pea group Alfafa grp. Group Beans group Clover group Crops Green pea, Lentil Soybean Lupinus R. melliloti. Medicago Melilotus Trigonella R. phaseoli Phaseoli R. trifoli Trifolium Cowpea group R. species Moong, Redgram, Cowpea, Groundnut Cicer group R. species Bengal gram

Isolation of Rhizobium Strain • An undamaged pink colored root nodule is selected • The nodule is surface sterilized with 10% Hg. Cl 2 For few minutes. • The nodule is washed with sterile distilled water. • The washed nodules are crushed in physiological saline. • The suspension is streaked on Congored yest extract mannitol agar( CRYEMA) plates. • The plates are incubated at 270 C for 3 -7 days.

Starter culture of a Rhizobial inoculant • A colony of efficient Rhizobial isolate is transferred to sterile YEM broth in the 250 ml capacity flask. • The flask is incubated on rotary shaker at 28 -30 0 C for 4 -5 days. • The culture is called starter culture or mother culture. • The starter culture attains a cell density of 10 5 - 106 cells/ml, this is called ‘seed’ and is used for charging large fermenters.

Mass production of Rhizobial Inoculant • For mass production jacketed stainless steel fermentor equipped with various control devices is used. • In fermentor YEM broth is used. • Various parameters controlled during fermentation include : Aeration(1 lit gas/min/20 lit medium); agitation, temperature(28 -30 0 C) and p. H 5 -7. • 1% inoculum is used. A population density of 5 x 10 9 /ml will be obtained in 96 hours. • Broth is taken out from the fermentor and mixed with suitable carrier.