Plant growth-promoting rhizobacteria: Effects on growth and nitrogen fixation of lentil ( Lens esculenta moench) and pea ( Pisum sativum L.)

Abstract

The potential of a number of putative plant growth-promoting rhizobacterial strains to enhance the growth and nitrogen fixation of western Canadian cultivars of lentil ( Lens esculenta Moench) and pea ( Pisum sativum L.) was assessed in field and laboratory studies. Nine strains were tested on a single cultivar of lentil (Eston) and pea (Trapper) in the field. None of the strains had any effect on growth of pea in the field, but in lentil inoculated with one or more of the rhizobacterial strains, there were significant increases in emergence, vigor, nodulation, C 2H 2 reduction activity and root weight. Further laboratory studies conducted with the two best strains, G2-8 and G11-32 and lentil cv. Eston used four in vitro cultivation systems to determine the optimal conditions for plant growth enhancement. There was variation among experiments and cultivation systems but growth stimulation similar to that in the field was observed in trials with a sand column system. The best plant growth-promoting strain for Eston under in vitro conditions, G2-8, was then tested with lentil cv. Laird and plants inoculated with G2-8 had higher root and shoot dry weights and greater acetylene reduction than control plants in pot and sand column systems. Leonard jar and growth pouch systems were not satisfactory methods for observing growth enhancement of lentil by these bacterial strains, probably due to the slow growth rate of plants and watering method in the former system and the large seed size and short assay time in the latter. Results from these experiments suggest that strains such as G2-8 and G11-32 may be of value as adjunct inoculants for lentil, but effects are dependent on the cultivar and cultivation system used.