EFFECT OF PLANT GROWTH PROMOTING RHIZOBACTERIA AT VARYING LEVELS OF N AND P ON CAULIFLOWER (Brassica oleracea var. botrytis L.)
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Date
2011
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Abstract
The present investigations entitled “Effect of plant growth promoting rhizobacteria at varying levels of N and P on cauliflower (Brassica oleracea var. botrytis L.)” were conducted at Research Farm, Soil Microbiology Laboratory of Department of Soil Science and Water Management and RHRS-Bajaura, Kullu, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh during the years 20082010 to develop an effective inoculum of PGPR with multifarious plant growth promoting activities (Psolubilization, N- fixation, IAA, Siderophore, HCN production and antagonism against soil borne pathogens) to overcome problems of deficiencies of nitrogen, low availability of phosphorus and sensitivity of the crop to soil borne pathogens. Among a sub-sample of 60 isolates of PGPR isolated from the rhizosphere/ endorhizosphere of cauliflower from three (Bilaspur, Hamirpur and Kangra districts) naturally growing agro-climatic zones of Himachal Pradesh, only five efficient isolates were selected and characterized after a series of successful experiments under in vitro and net house conditions at varying levels of N and P fertilizers. The selected isolates were found positive towards majority of selected multifarious plant growth promoting traits and also had effective control against black rot, stalk rot and leaf spot diseases of cauliflower. On the basis of morphological, physiological and biochemical characteristics, isolates was presumptively identified as Bacillus spp. Thereafter, molecular characterization of the best native isolate was carried out with specific primers by taking genomic DNA and based on the 16S rRNA gene sequence the said isolate was identified as Bacillus pumilus. The application of selected isolate (MK5) at 75% recommended dose of N and P fertilizers level not only registered significant increase in yields by 26% (average of both the locations i.e. Kullu and Solan) over uninoculated control (recommended doses of NPK fertilizers) but also a saving of 25% N and 25% P fertilizers. The results of multilocations trials conducted (by taking the best treatment at both the locations i.e. MK5 + 75%NP) at three locations viz. RHRS-Bajaura, Kullu; UHF-Nauni, Solan and RHRS-Jachh, Kangra clearly depicts an increase of 8% (average of three locations) in curd yields over recommended levels of NPK fertilizers. The present studies, therefore suggests that PGPR are able to induce the production of IAA, solubilization of phosphorus and resistance to soil borne pathogens, thereby improving growth of plants. The conjoint use of PGPR inoculants with optimum doses of chemical fertilizers seems to be an efficient approach to reduce the use of chemical inputs (fertilizers and pesticides) for enhanced growth and yield without impairing the soil health for sustainable cauliflower cultivation in Himachal Pradesh.
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bacteria, planting, biological development, fungi, fertilizers, curd, productivity, nutrients, yields, inorganic acid salts, cauliflower (Brassica oleracea var. botrytis L.),rhizobacteria