Varieties of lima bean shows different growth responses when inoculated with Bacillus sp., a plant growth-promoting bacteria

Evanielle Fernandes Lima,Janete Magali De Araujo,Vicente Paulo Da Costa Neto,Aurenivia Bonifacio,Francisco De Alcantara Neto,Artenisa Cerqueira Rodrigues

doi:10.14393/bj-v32n5a2016-32932

Abstract

Plant growth-promoting bacteria (PGPB) comprise of soil microorganisms that cause positive effects on plant growth. The hypothesis according to which the inoculation of lima bean with PGPB Bacillus stimulates vegetative growth, which may result in a higher plant productivity, was tested. Thus, this study aimed to evaluate the effects of inoculation of two varieties of lima bean (branca and boca de moca) with Bacillus sp., UFPEDA 472 strain, based on plant growth responses. The experiment was conducted in a greenhouse using a completely randomized design. Three treatments were applied separately to each lima bean variety: the first used inoculation with Bacillus , one was submitted to nitrogen supplementation, and one was the absolute control (non-inoculated plants). The following variables were evaluated: absolute and relative growth rate, root length, stem diameter, fresh and dry mass of shoots and roots, shoot:root ratio and total chlorophyll. The results showed that lima bean displayed better growth responses when inoculated with Bacillus sp. UFPEDA 472 in relation to the treatment with nitrogen and/or non-inoculated plants. When inoculated with PGPB Bacillus , the lima bean var. branca was superior to boca de moca in terms of root length and root dry mass. The lima bean var. boca de moca inoculated with Bacillus sp. UFPEDA 472 was superior to branca in terms of absolute growth rate, stem diameter, fresh and dry mass of shoot, shoot:root ratio and total chlorophyll. In general, the lima bean var. boca de moca inoculated with Bacillus shows a better growth performance. Our results suggest that growth responses of lima bean varieties branca and boca de moca are related with a positive interaction with the PGPB Bacillus .

Highlights

Plant growth-promoting bacteria (PGPB) are beneficial microorganisms inhabiting the rhizosphere (FIGUEIREDO et al, 2011)
PGPB may directly facilitate the supply of nutrients, produce siderophores and control phytohormone levels, indole acetic acid (IAA), and reduce the negative effects of environmental stress (DUCA et al, 2014; GLICK, 2014; GROBELAK et al, 2015)
The hypothesis according to which the inoculation of lima bean with PGPB Bacillus stimulates vegetative growth, which may result in a higher plant productivity, was tested in this study

Summary

Introduction

Plant growth-promoting bacteria (PGPB) are beneficial microorganisms inhabiting the rhizosphere (FIGUEIREDO et al, 2011). They stimulate plant growth through by acting as biofertilizers and bio-stimulants, increasing the ability of the plant to resist stressful situations (GLICK, 2014; HUANG et al, 2014). Bacillus species have other important mechanisms promoting plant growth such as the ability to fix nitrogen and solubilize phosphate and potassium (GROBELAK et al, 2015; PII et al, 2015). The inoculation with Bacillus results in a significant increase in the absorption of potassium, calcium and Received: 20/01/16 Accepted: 06/06/16

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