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.
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Claims 11
Claim · model-written summary
Bacillus subtilis with zinc oxide increased shoot dry matter in both seasons.
- Treatment
- Inoculation of B. subtilis with foliar ZnO applicatione0
- Outcome
- shoot dry mattere0
- Direction
- increasede0
- Value
- 7.3 and 9.8%e0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“maize”
Claim · model-written summary
Bacillus subtilis with zinc oxide increased grain yield in both seasons.
- Treatment
- Inoculation of B. subtilis with foliar ZnO applicatione0
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 17.1 and 16.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“maize”
Claim · model-written summary
Azospirillum brasilense increased hundred grain weight.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation with A. brasilense increased 100-grains weight by 9.5% in both crop seasons.”
t0“maize”
Claim · model-written summary
Pseudomonas fluorescens increased shoot zinc accumulation.
- Treatment
- inoculation of P. fluorescense0
- Outcome
- Shoot Zn accumulatione0
- Direction
- improvede0
- Value
- 30 and 51%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot Zn accumulation was improved by 30 and 51% with inoculation of P. fluorescens in 2019-20 and 2020-2021 crop seasons.”
t0“maize”
Claim · model-written summary
Bacillus subtilis improved grain zinc accumulation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain Zn accumulation was improved by 49 and 50.7% with inoculation of B. subtilis and P. fluorescens respectively.”
t0“maize”
Claim · model-written summary
Pseudomonas fluorescens improved grain zinc accumulation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain Zn accumulation was improved by 49 and 50.7% with inoculation of B. subtilis and P. fluorescens respectively.”
t0“maize”
Claim · model-written summary
Bacillus subtilis and nanozinc improved chlorophyll and carotenoids.
- Treatment
- inoculation of B. subtilis along with foliar nano ZnO applicatione0
- Outcome
- chlorophyll a, b and total, carotenoidse0
- Direction
- improvede0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“maize”
Claim · model-written summary
Pseudomonas fluorescens and zinc oxide improved grain albumin and globulin.
- Treatment
- Co-application of P. fluorescens with foliar ZnOe0
- Outcome
- grains albumine0
- Direction
- improvede0
- Value
- 20 and 13%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Co-application of P. fluorescens with foliar ZnO improved concentration of grains albumin (20 and 13%) and globulin (39 and 30%).”
t0“maize”
Claim · model-written summary
Pseudomonas fluorescens and zinc oxide improved grain globulin.
- Treatment
- Co-application of P. fluorescens with foliar ZnOe0
- Outcome
- globuline0
- Direction
- improvede0
- Value
- 39 and 30%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Co-application of P. fluorescens with foliar ZnO improved concentration of grains albumin (20 and 13%) and globulin (39 and 30%).”
t0“maize”
Claim · model-written summary
Bacillus subtilis and zinc oxide improved grain glutelin.
- Treatment
- co-application of B. subtilis and foliar ZnOe0
- Outcome
- grains gluteline0
- Direction
- improvede0
- Value
- 8.8 and 8.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“maize”
Claim · model-written summary
Bacillus subtilis and zinc oxide improved grain prolamin.
- Treatment
- co-application of B. subtilis and foliar ZnOe0
- Outcome
- prolamine0
- Direction
- improvede0
- Value
- 15 and 21%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“maize”
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See all 7 papers →8 of 20 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.