Nanozinc and plant growth-promoting bacteria improve biochemical and metabolic attributes of maize in tropical Cerrado

Arshad Jalal; Carlos Eduardo da Silva Oliveira; Andréa de Castro Bastos; Guilherme Carlos Fernandes; Bruno Horschut de Lima; Enes Furlani Junior; Pedro Henrique Gomes de Carvalho; Fernando Shintate Galindo; Isabela Martins Bueno Gato; Marcelo Carvalho Minhoto Teixeira Filho

doi:10.3389/fpls.2022.1046642

Nanozinc and plant growth-promoting bacteria improve biochemical and metabolic attributes of maize in tropical Cerrado

Front Plant Sci. 2023 Jan 12:13:1046642. doi: 10.3389/fpls.2022.1046642. eCollection 2022.

Affiliations

¹ Department of Plant Protection, Rural Engineering and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira, Brazil.
² Department of Plant Science, Food Technology and Socio-Economics, São Paulo State University (UNESP), Ilha Solteira, Brazil.
³ Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil.

Abstract

Introduction: Plant growth-promoting bacteria (PGPBs) could be developed as a sustainable strategy to promote plant growth and yield to feed the ever-growing global population with nutritious food. Foliar application of nano-zinc oxide (ZnO) is an environmentally safe strategy that alleviates zinc (Zn) malnutrition by improving biochemical attributes and storage proteins of grain.

Methods: In this context, the current study aimed to investigate the combined effect of seed inoculation with PGPBs and foliar nano-ZnO application on the growth, biochemical attributes, nutrient metabolism, and yield of maize in the tropical savannah of Brazil. The treatments consisted of four PGPB inoculations [i.e., without inoculation, Azospirillum brasilense (A. brasilense), Bacillus subtilis (B. subtilis), Pseudomonas fluorescens (P. fluorescens), which was applied on the seeds] and two doses of Zn (i.e., 0 and 3 kg ha^-1, applied from nano-ZnO in two splits on the leaf).

Results: Inoculation of B. subtilis with foliar ZnO application increased shoot dry matter (7.3 and 9.8%) and grain yield (17.1 and 16.7%) in 2019-20 and 2020-2021 crop seasons respectively. Inoculation with A. brasilense increased 100-grains weight by 9.5% in both crop seasons. Shoot Zn accumulation was improved by 30 and 51% with inoculation of P. fluorescens in 2019-20 and 2020-2021 crop seasons. Whereas grain Zn accumulation was improved by 49 and 50.7% with inoculation of B. subtilis and P. fluorescens respectively. In addition, biochemical attributes (chlorophyll a, b and total, carotenoids, total soluble sugar and amino acids) were improved with inoculation of B. subtilis along with foliar nano ZnO application as compared to other treatments. Co-application of P. fluorescens with foliar ZnO improved concentration of grains albumin (20 and 13%) and globulin (39 and 30%). Also, co-application of B. subtilis and foliar ZnO improved concentration of grains glutelin (8.8 and 8.7%) and prolamin (15 and 21%) in first and second seasons.

Discussion: Therefore, inoculation of B. subtilis and P. fluorescens with foliar nano-ZnO application is considered a sustainable and environmentally safe strategy for improving the biochemical, metabolic, nutritional, and productivity attributes of maize in tropical Savannah regions.

Keywords: PGPB (plant growth-promoting bacteria); amino acids; grain yield; nutrient uptake; photosynthesis; plant growth; storage proteins; zinc fertilization.

Grants and funding

This research received funding from The World Academy of Science (TWAS) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), first author’s doctoral fellowship (CNPq/TWAS grant number: 166331/2018-0, and productivity research grant (award number 311308/2020-1) of corresponding author.