SELECTION AND CHARACTERIZATION OF ENDOPHYTIC AND RHIZOSPHERIC MICROORGANISMS OF CHRYSANTHEMUM (Dendranthema grandiflora Tzvelve)
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2009
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ABSTRACT
An array of microbes are present in just a spoonful of soil found in close association with roots and capable of stimulating the plant growth by different mechanisms of action are referred to as plant growth-promoting rhizobacteria (PGPR). The use of these organisms in agricultural crop production can reduce the use of chemical inputs and sustain soil health. The present investigations were carried out to characterize and evaluate the effects of locally isolated PGPR from rhizosphere and roots of two cultivars ‗Ajay‘ and ‗Purnima‘ of chrysanthemum, a commercial flower crop of Himachal Pradesh. Out of 23 purified isolates, four isolates viz. KS1, KS5, KS6 and KS9 were selected on the basis of their efficacy to have maximum attributes like P-solubilization, growth on nitrogen free medium, siderophore, auxin, HCN production and antagonism against Pythium ultimum, Rhizoctonia solani and Fusarium oxysporum under laboratory conditions. On the basis of morphological, physiological and biochemical characteristics of the isolates, they were identified as Bacillus spp. The optimum pH and temperature for their growth, in general, were 7 and 35oC, respectively. The isolates were capable of hydrolyzing tri-calcium phosphate in solid and liquid PVK medium. The experiment on their efficacy was conducted in the net house and artificial short day photoperiod was provided after 45 days of planting to induce flowering. The application of selected isolates, as single or consortium of synergistic isolates, significantly improved shoot/root length, plant biomass, flower diameter, number of flowers per plant, available nutrients and microbial populations in the rhizosphere. The application of consortium of KS5 and KS6 isolates increased the plant height by 118 and 107 per cent, plant biomass by 603 and 575 per cent in ‗Ajay‘ and ‗Purnima‘, respectively over uninoculated control. The application of consortium, in general, has also reduced the number of days taken to flowering by 27 days over uninoculated control. There was an increase of 23, 38 and 28 per cent in available NPK content over uninoculated control. Thus, the consortium of KS5 and KS6 has good prospects to be used as PGPR inoculants not only for enhanced growth and flowering but also to sustain soil health under mid hill conditions of Himachal Pradesh.