International Journal of Plant & Soil Science

The present study assessed the population of nitrogen fixers and phosphate solubilizers in the rhizosphere, and suppression of leaf blotch disease caused by Taphrina maculans (Order: Taphrinales, Family: Taphrinaceae) in turmeric plants in response to chitosan application. Leaf blotch disease caused by Taphrina maculans has recorded upto 37.60 % to 52.90 % yield loss in turmeric. Hence, control measures have to be adopted. Chitosan is a biopolymer derived from chitin, which could evoke defense responses in plants. The treatments for this study included, foliar spray of chitosan 2 g L^-1 at monthly intervals (F₁), foliar spray of chitosan 4 g L^-1 at bimonthly intervals (F₂), soil drenching of chitosan 2 g L^-1 at monthly interval (S₁) and soil drenching of chitosan 4 g L^-1 at bimonthly interval (S₂). The untreated plants served as the control. The population of beneficial soil microbes were assessed and soil application of chitosan was observed to have better effect over foliar application with respect to the population of nitrogen fixing bacteria. More population of nitrogen fixing bacteria was recorded in the soil where chitosan 4 g L^-1 was applied as soil drenching at bimonthly interval (S₂).  The population of phosphate solubilizers were significantly higher over the control in all the chitosan treatments irrespective of the mode of application. However, the higher population of phosphate solubilizers were observed, when chitosan 2 g L^-1 was given as foliar spray at monthly intervals (F₁). The chitosan treated plants were also observed to have significantly lower incidence of leaf blotch disease compared to control plants. The use of chitosan as a plant biostimulant protects the plant from soil borne pathogens and increases the population of beneficial soil microflora, which have a role in improving the nutrient uptake by plants thereby enhancing the plant growth and yield.