Vol. 12, Issue 7 (2023)

Author(s):
Narayan Prasad Verma and Tapas Chowdhury

Abstract:
Sugarcane is highly nitrogen requiring crop, as it requires about 250 kg of elemental nitrogen to grow successfully over a hectare of land. Cropping with the use of only inorganic fertilizers has led to depletion of biological fertility of the soil and posing threat to long term soil productivity. To stop the continuous decline in biological soil fertility it is important to use Bio-fertilizers in combination with chemical fertilizers. At present no suitable bio-fertilizer for sugarcane crop is available in Chhattisgarh state of India which is made up of indigenous strains of N-fixing bacteria. In this present study 110 bacterial isolates were isolated directly from field grown sugarcane plants and screened out 46 isolates on the basis of their N-fixing capacity in-vitro. Out of 46, 39 isolates were found capable to fix considerable amount of nitrogen (3.52 to 24.41 mg N/g of carbon). Highest quantity of nitrogen (24.41 mg) was fixed by isolate K-74 in semi solid agar medium. On the basis of colony characters and nitrogen fixation behavior the above 39 isolates were initially considered as Nitrogen fixing bacteria and four best performed isolates were further characterized morphologically by observing their growth on different media and physiologically by measuring growth at different temperature, pH, sucrose levels, and sensitivity towards antibiotics, IAA production ability and through other biochemical tests for confirmation. Further, these promising isolates were evaluated under field conditions to find out their efficacy on the growth performance and yield of sugarcane crop (Var. Co-085), compared with two national standard checks. Yield attributing characteristics of sugarcane crop viz. plant height, number of tillers, cane girth, number of nodes, brix% and yield were found to be significantly increased by isolate K-74 with 75% RDN. Maximum population density of the tested organism in soil (7.12 x10⁷ cfu/gm), leaf tissue (4.4 x10⁷ cfu/gm) and cane juice (20.2 x10⁷ cfu/ml) was attributed to set inoculation of isolate K-74 with application of 75% RDN. Even it was found significantly superior over 75% RDN. It is concluded from the study that inoculation with indigenous isolate of K-74 can save more than 25% elemental nitrogen in sugarcane cultivation and could be an ideal bio-fertilizer for sugarcane in Chhattisgarh and other sugarcane growing states of India.