Biofertilizer formulation from Azotobacter and Azospirillum regional isolates and its effect on sugar cane (Saccharum officinarum) in greenhouse

Abstract

The anthropogenic activity has damaged the ecological niches of all agricultural regions. Culiacan Valley in Sinaloa, México, is not an exception; it has more than one million agricultural hectares. This soil has a high salt index and is susceptible to erosion, which reduces the amount of the microbiota responsible for processes of oxidation-reduction and conversion of essential nutrients for plant nutrition. The global trend in agriculture is to develop alternatives of biological origin, for example plant growth promoting bacteria (PGPB), especially nitrogen-fixing and phytohormone producers genera. In this study, indigenous isolates of Azotobacter and Azospirillum from Sinaloa were characterized and compared against four nitrogen-fixing collection strains, in order to create a formulate that could prevent or decrease the need of mineral fertilizers applications, to enhance sustainable production of sugarcane (Saccharum officinarum). Ten isolates and four reference strains with biofertilization potential were evaluated, showing genotypic and phenotypic characteristics proper of their genera. The acetylene reduction assays showed that all strains and isolates reduce in vitro acetylene to ethylene by nitrogenase enzyme. Greenhouse tests with nitrogen fixing bacteria showed adaptation of bacteria to the sugar cane rhizosphere, suggesting that these isolates are eligible to develop biofertilizers.