03-01-2013, 11:09 AM
Factual evidences on amelioration of PGPR
Factual evidences on amelioration of PGPR.docx (Size: 239.94 KB / Downloads: 52)
Abstract
Neem cake is the residue obtained while extracting neem oil from neem seed kernels by varied extraction processes. It has an adequate quantity of NPK in organic form & other essential micro nutrients for plant growth. It is rich in both sulphur compounds and bitter limonoids. The high Azadirachtin content helps to protect plant roots from nematodes, soil grubs and white ants. It is used as good organic manure and best soil conditioner in agriculture as it seems to make soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas and prolongs the availability of nitrogen to crops, thus renders a remarkable improvement to plant immunity. The dual activity of Neem cake as fertilizer and pest repellent has made it a preferential input. The present investigation focuses on to ascertain the effect of aqueous neem cake extract on PGPR. It was found that Neem cake amendment in soil at 1-5% had no adverse effect on the population of free living nitrogen fixing bacteria Azotobacter chroococcum, Azotobacter vinelandii, & symbiotic Rhizobium species viz. Rhizobium japanicum, Rhizobium leguminosarum & phosphate solubilising Pseudomonas striata,Aspergillus awamorii,Penicillium digitatum & biofungicide Trichoderma viridae. The antimicrobial activity of aqueous Neem extract in the concentration range of 1-5% was evaluated against above mentioned PGPR by Kirby-Bauer method. Further, the effect of the same was assessed on auxin production & phosphate solubilising capacity. The general observation drawn with these findings that as neem cake extract did not show any inhibitory activity against these PGPR., the perspective studies would be on amalgamation of Neem cake with these Biofertilizer consortium & could be used for controlled slow release of nitrogen to the plants which reduces alkalinity in soil, as it produces organic acids on decomposition. As neem cake is compatible with soil microbes, ensures fertility, improves the organic matter content, helps improvement in soil texture, water holding capacity & soil aeration for better root development.
Key Words: PGPR (Plant Growth promoting rhizobacteria), Phosphate solubilizing bacteria, Neem Cake, Biofetilizers.
Introduction
Neem (Azadirachta indica), a fast-growing tree that can reach a height of 15–20 metres. It is native to India, Pakistan, and Bangladesh growing in tropical and semi-tropical regions. Neem trees also grow in islands in the southern part of Iran where it is called "Cherish". Neem cake is obtained from fruits and seeds of Neem tree. Neem cake organic manure is the by-product obtained in the process of cold pressing of Neem tree fruits and kernels, and the solvent extraction process for neem oil cake. It is a potential source of organic manure under the Bureau of Indian Standards, Specification No. 8558. Neem has also demonstrated considerable potential as a fertilizer. For this purpose, neem cake and neem leaves are especially promising. Neem Cake has adequate quantity of NPK in organic form for plant growth. Being a totally botanical product it contains 100% natural NPK content and other essential micro nutrients as N(Nitrogen 2.0% to 5.0%), P(Phosphorus 0.5% to 1.0%), K(Potassium 1.0% to 2.0%), Ca(Calcium 0.5% to 3.0%), Mg(Magnesium 0.3% to 1.0%), S(Sulphur 0.2% to 3.0%), Zn(Zinc 15 ppm to 60 ppm), Cu(Copper 4 ppm to 20 ppm), Fe (Iron 500 ppm to 1200 ppm), Mn (Manganese 20 ppm to 60 ppm). It is rich in both sulphur compounds and bitter limonoids. It was evident that residue of neem cake increased plant yield (Sharma et al,1981). The treatment of combined application of Azotobacter, Azospirillum together with neem cake and 100% recommended dose of nitrogen recorded higher yield and better parasitic nematode control in chilli(Zehra Khan et al,2011). Application of vermicompost along with neem cake resulted in higher seedling vigour index as compared to customary doses (Saumyaet al,2006).
Neem cake organic manure protects plant roots from nematodes and white ants probably due to its residual limonoid content. It also acts as a natural fertilizer with pesticidal properties. Neem cake is effective in the management of insects and pests (Sharma et al, 1981).The cake contains salannin, nimbin, azadirachtin and azadiradione as the major components. Of these, azadirachtin and meliantriol are used as locust antifeedants while salannin is used as an antifeedant for the housefly.
Nitrification inhibitor increases the efficiency of N fertilizer applied (Mishra et al, 1975). When ammonium ions are added to the soil, it is subjected to a process called nitrification by soil bacteria called Nitrosomonas Spp. which convert the ammonium ion to nitrate ions. Nitrate is lost from the soil due to leaching primarily on sandy soil and due to denitrification, leading to loss of nitrogen. Neem cake make soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas. It is a nitrification inhibitor and prolongs the availability of nitrogen to both short duration and long duration crops (Puri H.S., 1999).It has been reported that neem cake and alcoholic extract of neem-seed slowed down nitrification rate (Sahrawat et al, 1975)
Neem coated chemical fertilizers are also available now a days in market. Use of neem coated chemical fertilizers (Urea, DAP) reduced their requirement (Atriet al, 1981).It was evident that formulations of neem coated urea significantly increased grain yield. The use of cost-effective neem fractions and the combined water management is a better strategy for farmers, who are already aware of the benefits of the use of neem-coated urea, and of water management (Rao et al,2008)
Use of organic manure alone or along with chemical fertilizers helps in proper nutrition of crop plants and helps to maintain soil fertility. The increasing demand for nitrogen fertilizers can be fulfilled by integrating the use of organic and mineral fertilizers (hussain et al,1988). Considering all the beneficial properties of neem cake as efficient fertilizer & effective pest manager, the present investigation is carried out to check its compatibility with plant growth promoting rhizobacteria.
Material and Methods
Neem Seed Cake
The residue left after the extraction of oil from neem seed is known as neem cake. Neem cake used for the experiment was obtained from Neem Research & Technology Development Center,Gondkhairi,Nagpur.
Neem Seed Cake Aqueous Extract
1%,2% and 5% aqueous neem extract was prepared in sterilized distilled water, it was soaked overnight, filtered and refrigerated at 4°C .
Microbial Cultures
Cultures of Azotobacter chroococcum, Rhizobium sp., Pseudomonas striata, Trichoderma viridae, Aspergillus awamorii ,Penicillium digittatum isolated by Rajiv Gandhi Biotechnology Center,R.T.M.Nagpur University,Nagpur were used for the experiments. Azotobacter sp., Rhizobium sp.,Pseudomonas sp., were maintained on Jensen’s medium(JN),Yeast extract mannitol Agar(YEMA),Nutrient Agar(NA)respectively under standard optimal conditions of light ,temperature etc. Fungal cultures of Trichoderma virodae,Aspergillus awamorii,Penicillium digittatum were maintained on Potato Dextrose Agar(PDA) also under optimum conditions.
Antimicrobial Activity of Neem Cake Aqueous Exctract against PGPR
Broth cultures of Azotobacter chroococcum, Pseudomons sp. ,Rhizobium sp., Trichoderma viridae, Aspergillus awamorii,Penicillium digittatum were incubated. Aqueous neem-cake extract was assessed for antimicrobial activity against PGPR by Kirby Bauer method. Plates were observed for zone of inhibition.
Abstract
Neem cake is the residue obtained while extracting neem oil from neem seed kernels by varied extraction processes. It has an adequate quantity of NPK in organic form & other essential micro nutrients for plant growth. It is rich in both sulphur compounds and bitter limonoids. The high Azadirachtin content helps to protect plant roots from nematodes, soil grubs and white ants. It is used as good organic manure and best soil conditioner in agriculture as it seems to make soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas and prolongs the availability of nitrogen to crops, thus renders a remarkable improvement to plant immunity. The dual activity of Neem cake as fertilizer and pest repellent has made it a preferential input. The present investigation focuses on to ascertain the effect of aqueous neem cake extract on PGPR. It was found that Neem cake amendment in soil at 1-5% had no adverse effect on the population of free living nitrogen fixing bacteria Azotobacter chroococcum, Azotobacter vinelandii, & symbiotic Rhizobium species viz. Rhizobium japanicum, Rhizobium leguminosarum & phosphate solubilising Pseudomonas striata,Aspergillus awamorii,Penicillium digitatum & biofungicide Trichoderma viridae. The antimicrobial activity of aqueous Neem extract in the concentration range of 1-5% was evaluated against above mentioned PGPR by Kirby-Bauer method. Further, the effect of the same was assessed on auxin production & phosphate solubilising capacity. The general observation drawn with these findings that as neem cake extract did not show any inhibitory activity against these PGPR., the perspective studies would be on amalgamation of Neem cake with these Biofertilizer consortium & could be used for controlled slow release of nitrogen to the plants which reduces alkalinity in soil, as it produces organic acids on decomposition. As neem cake is compatible with soil microbes, ensures fertility, improves the organic matter content, helps improvement in soil texture, water holding capacity & soil aeration for better root development.
Key Words: PGPR (Plant Growth promoting rhizobacteria), Phosphate solubilizing bacteria, Neem Cake, Biofetilizers.
Introduction
Neem (Azadirachta indica), a fast-growing tree that can reach a height of 15–20 metres. It is native to India, Pakistan, and Bangladesh growing in tropical and semi-tropical regions. Neem trees also grow in islands in the southern part of Iran where it is called "Cherish". Neem cake is obtained from fruits and seeds of Neem tree. Neem cake organic manure is the by-product obtained in the process of cold pressing of Neem tree fruits and kernels, and the solvent extraction process for neem oil cake. It is a potential source of organic manure under the Bureau of Indian Standards, Specification No. 8558. Neem has also demonstrated considerable potential as a fertilizer. For this purpose, neem cake and neem leaves are especially promising. Neem Cake has adequate quantity of NPK in organic form for plant growth. Being a totally botanical product it contains 100% natural NPK content and other essential micro nutrients as N(Nitrogen 2.0% to 5.0%), P(Phosphorus 0.5% to 1.0%), K(Potassium 1.0% to 2.0%), Ca(Calcium 0.5% to 3.0%), Mg(Magnesium 0.3% to 1.0%), S(Sulphur 0.2% to 3.0%), Zn(Zinc 15 ppm to 60 ppm), Cu(Copper 4 ppm to 20 ppm), Fe (Iron 500 ppm to 1200 ppm), Mn (Manganese 20 ppm to 60 ppm). It is rich in both sulphur compounds and bitter limonoids. It was evident that residue of neem cake increased plant yield (Sharma et al,1981). The treatment of combined application of Azotobacter, Azospirillum together with neem cake and 100% recommended dose of nitrogen recorded higher yield and better parasitic nematode control in chilli(Zehra Khan et al,2011). Application of vermicompost along with neem cake resulted in higher seedling vigour index as compared to customary doses (Saumyaet al,2006).
Neem cake organic manure protects plant roots from nematodes and white ants probably due to its residual limonoid content. It also acts as a natural fertilizer with pesticidal properties. Neem cake is effective in the management of insects and pests (Sharma et al, 1981).The cake contains salannin, nimbin, azadirachtin and azadiradione as the major components. Of these, azadirachtin and meliantriol are used as locust antifeedants while salannin is used as an antifeedant for the housefly.
Nitrification inhibitor increases the efficiency of N fertilizer applied (Mishra et al, 1975). When ammonium ions are added to the soil, it is subjected to a process called nitrification by soil bacteria called Nitrosomonas Spp. which convert the ammonium ion to nitrate ions. Nitrate is lost from the soil due to leaching primarily on sandy soil and due to denitrification, leading to loss of nitrogen. Neem cake make soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas. It is a nitrification inhibitor and prolongs the availability of nitrogen to both short duration and long duration crops (Puri H.S., 1999).It has been reported that neem cake and alcoholic extract of neem-seed slowed down nitrification rate (Sahrawat et al, 1975)
Neem coated chemical fertilizers are also available now a days in market. Use of neem coated chemical fertilizers (Urea, DAP) reduced their requirement (Atriet al, 1981).It was evident that formulations of neem coated urea significantly increased grain yield. The use of cost-effective neem fractions and the combined water management is a better strategy for farmers, who are already aware of the benefits of the use of neem-coated urea, and of water management (Rao et al,2008)
Use of organic manure alone or along with chemical fertilizers helps in proper nutrition of crop plants and helps to maintain soil fertility. The increasing demand for nitrogen fertilizers can be fulfilled by integrating the use of organic and mineral fertilizers (hussain et al,1988). Considering all the beneficial properties of neem cake as efficient fertilizer & effective pest manager, the present investigation is carried out to check its compatibility with plant growth promoting rhizobacteria.
Material and Methods
Neem Seed Cake
The residue left after the extraction of oil from neem seed is known as neem cake. Neem cake used for the experiment was obtained from Neem Research & Technology Development Center,Gondkhairi,Nagpur.
Neem Seed Cake Aqueous Extract
1%,2% and 5% aqueous neem extract was prepared in sterilized distilled water, it was soaked overnight, filtered and refrigerated at 4°C .
Microbial Cultures
Cultures of Azotobacter chroococcum, Rhizobium sp., Pseudomonas striata, Trichoderma viridae, Aspergillus awamorii ,Penicillium digittatum isolated by Rajiv Gandhi Biotechnology Center,R.T.M.Nagpur University,Nagpur were used for the experiments. Azotobacter sp., Rhizobium sp.,Pseudomonas sp., were maintained on Jensen’s medium(JN),Yeast extract mannitol Agar(YEMA),Nutrient Agar(NA)respectively under standard optimal conditions of light ,temperature etc. Fungal cultures of Trichoderma virodae,Aspergillus awamorii,Penicillium digittatum were maintained on Potato Dextrose Agar(PDA) also under optimum conditions.
Antimicrobial Activity of Neem Cake Aqueous Exctract against PGPR
Broth cultures of Azotobacter chroococcum, Pseudomons sp. ,Rhizobium sp., Trichoderma viridae, Aspergillus awamorii,Penicillium digittatum were incubated. Aqueous neem-cake extract was assessed for antimicrobial activity against PGPR by Kirby Bauer method. Plates were observed for zone of inhibition.