Increase in Seedling Emergence and Dry Weight of Pigeon Pea in the Field with Chitin-supplemented Formulations of Bacillus subtilis AF 1

Abstract

Different formulations of a chitinolytic plant growth-promoting rhizobacterium, Bacillus subtilis AF 1, were evaluated for growth promotion of pigeon pea in the field. Alginate, peat, chitin/Aspergillus niger mycelium-supplemented peat, and spent compost formulations of B. subtilis AF 1 effectively increased the seedling emergence, plant height and dry weight in the field, with chitin-supplemented peat formulation being the most effective in two different cropping seasons viz., ‘kharif’ and ‘rabi’. As a seed treatment, chitin-supplemented peat formulation of B. subtilis AF 1 increased the emergence and dry weight of pigeon pea seedlings by 29 and 33%, in comparison to an increase of 21 and 30%, respectively by mid-exponential phase cells of B. subtilis AF 1. Colonization of the root system was assessed by the recovery of introduced ampicillin-resistant and chitin-degrading B. subtilis AF 1, on media containing ampicillin and colloidal chitin, from the rhizoplane during the cropping period.