The Classification Of Rhizospheric Micro-Organisms

Studies have evidently proved that the rhizospheric micro flora include both deleterious and beneficial elements which have the potential to influence both plant growth and crop yields significantly (Kleopper, 1994; Adesmoye and Kloepper, 2009). Rhizospheric micro-organisms were classified as beneficial (symbiotic) or harmful (pathogenic) or having no effect on the plant. The zone adjacent to root also provides a site for studying microbial interactions under natural conditions in a specific environment, due to the perennial nature of tea (Pandey and Palni, 2004).

Different microbial growth is stimulated in the zone adjacent to root of young and other perennial plants (Pandey and Palni, 2004). It is reported that younger tea plantations contain higher microbial dynamics than that of the older ones the zone of soil adjacent to root. The Burkholderia tuberum isolate was first discovered from Aspalathus (Rooibos tea plant) nodules in South Africa and latter described as Bradyrhizobium aspalati in the original publication. Isolation and identification of “the zone of soil adjacent to root” soil bacteria from Tea gardens of Barack valley Assam 16SrDNA analysis of has been carried out by Bhattacharjee et al., 2014).

Biomanures

The idea of biomanures was originated when Dobereiner and Day (1976) discover N fixing bacteria Azospirillum and Pikovskaya (1948) phosphate solubilizing bacteria. Their population level naturally varies with soil and agroclimatic zones. Further, the population level most often may not be enough to bring out significant contribution to the plant nutrition as their efficiency varies with isolates. Biomanures are most useful and they are not yet explored much in tea (Baby, 2002). N fixers, phosphate solubilizers, phosphate immobilizers and plant growth promoting rhizobacteria are falling under the biofertilizer (Jayaraj et al., 2004).

Since most of the plantation crops are long duration crops use of biomanures may have some limitations. For example, in plantation crops biomanures could be used more effectively during the plant establishment phase either in the nursery or field to increase the health of the planting stock to enable subsequent successful establishment in the field. In most of the plantation crops, initial experimentation has been carried out to explore the possibilities to use biomanures, including manures/composts, for enhancing growth and productivity. Performance has been either equally good or better than inorganic manures. Nautiyal 2006 stated that the, arbuscular mycorhizal fungus, mineral mobilizer has been found to be quite effective for growth, improvement and saving in phosphorus nutrition (25%) of plantation crops and spices such as pepper, cardamom, cashew, coconut, ginger and turmeric under field conditions.

It is reported that the application of P-solubilizing bacteria, Bacillus megaterium along with inorganic phosphate improved phosphate nutrition of cashew plants. Verma et al., 2001, reported in tea the effect of efficient isolates of microbial inoculants in N fixing, phosphate solubilising. In recent times biomanures are recognized as a as supplement to the organic manures or it can be integrated with manures, other than organic or biomanure to reduce the cost of production and conserving the soil health in the tea plantation. Despite of initial research on biomanures, there are several reports in tea appeared on microbes in relation to manure, pest and disease management (Ajay et al., 2005 and 2007; Ponmurugan and Baby, 2005).