Effect of plant growth-promoting rhizobacteria at varying levels of N and P fertilizers on growth and yield of cauliflower in mid hills of Himachal Pradesh

The use of plant growth promoting rhizobacteria (PGPR) is steadily increasing in agriculture and offers an attractive way to supplement chemical fertilizers and pesticides by a wide variety of mechanisms. The indigenous isolates of PGPR were isolated from cauliflower rhizosphere soil in different agro-climatic zones of Himachal Pradesh. Five efficient isolates designated as MK2, MK4, MK5, MK7 and MK9 were selected and characterized after successful experiments under in vitro and net house conditions at varying levels of N and P on the growth and yield of cauliflower. All the isolates induced the production of indole acetic acid (IAA) and were able to solubilize phosphorus. The conjoint use of PGPR and N and P fertilizers resulted in a significant increase in number of nonwrapper leaves, curd diameter, curd depth and curd weight of cauliflower. Furthermore, PGPR isolates remarkably increased the yield of cauliflower. Among the five isolates, three isolates were selected for field trials on the basis of the results obtained from net house studies in which MK5 with 100 per cent N and P proved better in all aspects of cauliflower wrt increase in growth, yield, IAA production and phosphate solubilization. The present study, therefore, suggested that the use of PGPR isolate MK5 with 100 per cent N and P as inoculant biofertilizer was beneficial for cauliflower cultivation as it enhanced growth of cauliflower, and induced IAA production and phosphorus solubilization.