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

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1046642

DOI=10.3389/fpls.2022.1046642

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>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.</p></sec><sec><title>Methods</title><p>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<italic>, Azospirillum brasilense</italic> (<italic>A. brasilense</italic>)<italic>, Bacillus subtilis</italic> (<italic>B. subtilis</italic>)<italic>, Pseudomonas fluorescens</italic> (<italic>P. fluorescens</italic>), which was applied on the seeds] and two doses of Zn (i.e., 0 and 3 kg ha<sup>−1</sup>, applied from nano-ZnO in two splits on the leaf). </p></sec><sec><title>Results</title><p>Inoculation of <italic>B. subtilis</italic> 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 <italic>B. subtilis</italic> 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 <italic>B. subtilis</italic> 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 <italic>B. subtilis</italic> and foliar ZnO improved concentration of grains glutelin (8.8 and 8.7%) and prolamin (15 and 21%) in first and second seasons.</p></sec><sec><title>Discussion</title><p>Therefore, inoculation of <italic>B. subtilis</italic> and <italic>P. fluorescens</italic> 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.</p></sec>