Plant growth-promoting endophytic bacteria on maize and sorghum1

João Pedro Alves De Aquino,Francisco Barbosa De Macedo Junior,Ademir Sérgio Ferreira De Araujo,Marcia Do Vale Barreto Figueiredo,Jadson Emanuel Lopes Antunes,Francisco De Alcântara Neto

doi:10.1590/1983-40632019v4956241

João Pedro Alves De Aquino, Francisco Barbosa De Macedo Junior + Show 4 more

Open Access

https://doi.org/10.1590/1983-40632019v4956241

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Abstract

ABSTRACT Plant growth-promoting bacteria (PGPB) are found in plant tissues and promote plant growth by secretion of hormones and enzymes, or by facilitating the nutrient uptake. This study assessed forty PGPB isolates to determine their effects on maize and sorghum growth. These isolates were also compared with uninoculated plants, as negative (-N; without N fertilization) and positive (+N; with N fertilization) controls. Plant height, stem diameter, shoot and root dry mass, leaf N accumulation and chlorophyll content were evaluated. For both the maize and sorghum, the height, stem diameter and shoot dry mass in plants inoculated with PGPB were similar to those of uninoculated plants supplied with N, and the responses for root mass were higher than in plants supplied with N. However, the PGPB isolates did not promote N accumulation and chlorophyll content similar to those of uninoculated plants supplied with N. The IPACC26 and IPACC30 isolates, both identified as Bacillus subtilis, resulted in better responses for plant growth and N accumulation than the other isolates.

Highlights

Plant growth-promoting bacteria (PGPB) are microorganisms that can improve the plant performance in many different ways (Palacios et al 2014)
The PGPB isolates had similar or higher growth effects on maize and sorghum, if compared to the growth of uninoculated plants supplied with N
17 PGPB isolates promoted a higher stem diameter in maize than in uninoculated maize plants supplied with N (Figure 2)

Summary

INTRODUCTION

Plant growth-promoting bacteria (PGPB) are microorganisms that can improve the plant performance in many different ways (Palacios et al 2014). These bacteria directly or indirectly promote the plant growth by secretion of hormones and enzymes, or by facilitating the uptake and accumulation of nutrients such as nitrogen (N) and phosphorus (P) (Ahemad & Kibret 2014). They can protect plants from pathogens, improve the soil structure and degrade pollutants (Hayat et al 2010). Bacillus and Pseudomonas influence the plant growth mainly by the synthesis of plant hormones (e.g., auxin, cytokinin and gibberellins) and production of siderophores and

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MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS