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Molecular characterization of plant growth promoting rhizobacteria to develop efficient biofertilizer for pigeon pea (Cajanus cajan)

Posted by | February 21, 2021

Principal investigators:

  • Dr. Jay Prakash Verma

Associated with: 

  • Institute of  Environment & Sustainable Development, Banaras Hindu University, Varanasi 221005, UP, India

Project Summary:

The green revolution brought impressive gains in food production but with insufficient concern for sustainability. In India the availability and affordability of fossil fuel based chemical fertilizers at the farm level have been ensured only through imports and subsidies. Dependence on chemical fertilizers for future agricultural growth would mean further loss in soil quality, possibilities of water contamination and unsustainable burden on the fiscal system. Intensive farming practices that achieve high yield require chemical fertilizers, which are not costly but may also create environmental problems. The extensive use of chemical fertilizers in agriculture is currently under debate due to environmental concern and fear for consumer health. Consequently, there has recently been growing level of interest in environmentally friendly sustainable agricultural practices and organic farming system.  Organic farming system is not new in India and is being followed from ancient time. It is a method of farming system which primarily aimed at cultivating the land and raising crops in such a way as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm waste, aquatic waste) and other biological material along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco-friendly and pollution free environment. The Government of India has been trying to promote an improved practice involving use of bio- fertilizers along with fertilizers. These inputs have multiple beneficial impacts on the soil and can be relatively cheap and convenient for use. Consistent with current outlook, the government aims not only to encourage their use in agriculture but also to promote private initiative and commercial viability of production.

Plant growth-promoting rhizobacteria, a term first used by Kloepper and Schroth (1978), can directly or indirectly promote plant growth. PGPR inoculant currently commercialized as new and novel solution for plant growth enhancements through at least one mechanism, suppression of plant disease (term bioprotectants), improved nutrient acquisition (term biofertilizers) or phytohormone production (term biostimulants). Indirect mechanism used by PGPR include antibiotic protection against pathogenic bacteria, reduction of iron available to phytopathogen in the rhizosphere, synthesis of fungal cell wall-lysis enzyme  and  competition with detrimental microorganism for sites on plant root. Direct mechanism of plant growth  by PGPR include the provision of bioavailable  phosphorus for plant uptake nitrogen–fixation for plant use sequestration of iron for plant by siderophores, production of plant hormones like auxins, cytokinin and gibberellins and lowering of plant ethylene level (Glick 1995). PGPR ( Pseudomonas, Azospirillum, Azotobacter, Klebsiella, Enterobacter, Alcaligenes, Arthrobacter, Burkholderia, Bacillus and Serratia) have reported to enhance plant growth (Glick, 1995).

Red gram (Cajanus cajan) is a important pulse crop of India. It is commonly known as pigeon pea Gandule bean tropical green pea, kadios, Congo pea, gungo pea etc. it is a perennial member of the  fabaceae  family.  Pigeon peas are an important legume crop of rainfed agriculture in the semiarid tropics. The Indian subcontinent, eastern Africa and central America, in that order, are the world’s three main pigeon pea-producing regions. Pigeon peas are cultivated in more than 25 tropical and subtropical countries, either as a sole crop or intermixed with cereal, such as sorghum (Sorghum bicolor), pearl millet (Pennisetium glaucum), or maize (Zea mays), or with other legumes, such as peanuts (Arachis hypogaea). Being a legume, the pigeon pea enriches soil through symbiotic nitrogen fixation.  Pigeon peas are an important food in developing tropical countries. An excellent source of protein, the seeds (and sometimes the pods) are eaten as a vegetable, as a flour additive to other foods, in soups, and with rice (Center for New Crops and Plants Products 2002).  Although they vary slightly, typical nutritional values for seeds are: moisture, 10.1 percent, protein 19.2 percent, fat, 1.5 percent, carbohydrates, 57.3 percent, fiber 8.1 percent, and ash, 3.8 percent (Smartt 1976). About 3.4 million ha were under ultivation in 1978-1988 period, 88 percent of it in India (Nene and Sheila 1990). They contain high levels of protein and the important amino acids methionine, lysine, and tryptophan. In combination with cereals, pigeon peas make a well-balanced human food.  Application of some PGPR strains to seeds or seedlings has also been found to enhance the plant growth and yield as well as induced systemic resistance in the treated plant against phytopathogen. In addition to improvement of plant growth, PGPR are directly involved in increased uptake of nitrogen, synthesis of phytohormones, solubilization of minerals such as phosphorus, and production of siderophores that chelate iron and make it available to the plant root (Gyaneshwar et al., 1998). It has also been reported that PGPR is able to solubilize inorganic and organic phosphates in soil. Pigeon pea, the most important staple food in several developing countries and as a fertilizer, is the most important input required for cultivation. The high yielding variety has resulted in and increases in the production but requires large amounts of chemical fertilizers leading to health hazards and environmental pollution. In order to make cultivation sustainable and less dependent on chemical fertilizers, it is important to know how to use PGPR that can biologically fix nitrogen, solubilize phosphorus and induce some substances like indole acetic acid (IAA) that can contribute to the improvement of pigeon pea (Filip, 2001). Recently, there has been growing interest in PGPR due to their efficacy as biological control and growth promoting agents in many crops. There is very little information regarding the use of PGPR as biofertilizer (Elliott et al., 1996). Therefore, this project has been designed to screen the PGPR strains from rhizosphere soils that are compatible biofertilizer for pigeon pea (Cajanus cajan)  production . PGPR have shown positive effects in plants on parameters such as germination rate, tolerance to drought, weight of shoots and roots, yield and plant growth. Another major advantage of PGPR is that it produces antibacterial compounds that are effective against certain plant pathogens and pests (Raju et al., 1999). The objective of this project is to screen out rhizobacteria with maximum PGPR traits like IAA production, phosphate solubilization, 1-amino-cyclopropane-1-carboxylate (ACC) deaminase producing ability, siderophore producing ability, antagonism to plant pathogens like Fusarium udum and Macrophomina phaseolina and also enhance the pigeon pea production under sustainable agriculture.

Significance of the study:

Our research theme will be better for sustainable development in an eco-friendly and pollution free environment to provide healthy food and fiber for human and animals. By this work we have developed effective biofertilizer which enhanced red gram production without using chemical fertilizer. It is cost effective and provides cheaper rate of pulses to human being because pulse purchasing cost is much more higher by this poor people are not getting pulse in own diet. Then our target is enhanced the red gram production at low cost which is environmentally friendly. PGPR is an effective biofertilizer to enhanced sustainable agricultural production in India. The increased use of chemical fertilizers in agricultural system for increasing agricultural yield in response to the ever increasing food demand has adversely affecting soil system. Therefore, agricultural productions based on organic farming technologies are very essential. In this context, sustainable agriculture will enhances environmental and food quality, soil fertility status, soil health and the resource base on which agriculture depends. It also provides for basic human food and fiber needs; is economically viable; and enhances the quality of life for farmers and society as a whole.


  1. Molecular characterization of soil microorganism from rhizosphere soil of red gram and other crops.
  2. Studies of plant growth promoting activities of microbes for nitrogen fixer
  3. To select effective strains of indigenous Rhizobiaum, plant growth promoting rhizobacteria (PGPR) and plant growth promoting fungi (PGPF) for red gram under in vitro condition.
  4. To studies of bioformulation of different PGPR and PGPF to develop noble biofertilizer of multiple uses for the growth and yield of Red gram (Cajanus cajan) under field condition.
  5. To study the effect of Rhizobium, PGPR and PGPF formulation on growth, yield and nutrient uptake by chickpea and their impact on physico-chemical and biological properties of soil.