Agronomic biofortification of grain crops with zinc in association with plant growth-promoting bacteria

• Autor(a) principal: Jalal, Arshad
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/238501
• topic: Phaseolus vulgaris L.; Triticum aestivum L.; Zea mays L.; Zinc fertilization; Zinc uptake; Zinc use efficiency; Zinc partitioning; Productivity; Zinc nutrition; Inoculation; Fertilização com zinco; Absorção de zinco; Eficiência de uso do zinco; Partição de zinco; Produtividade; Nutrição de zinco; Inoculação

The intensive cropping system to pursue high grain production and feed the fast-growing global population has disturbed agricultural sustainability and nutritious security due to the imbalance use of chemical fertilizers. There is an urgent need to understand soil micronutrients deficiency and their impact on crop nutrition and productivity. Micronutrient fertilizer management especially zinc (Zn) through the soil and foliar application is crucial agronomic approach for improving agronomic biofortification of staple grains crops. The intervention of plant growth-promoting bacteria (PGPBs) could be one of the sustainable and safe strategies to improve nutrient acquisition and uptake in edible tissues of wheat-maize and common beans to combat Zn malnutrition and hidden hunger in human beings. In this context, this research was developed to understand the interactive effect of inoculation/ co-inoculation with PGPBs and Zn fertilization via soil and foliar to enhance growth performance, yield, and nutrition of wheat-maize and common bean crops for better biofortification of grains under field conditions of tropical savannah. A total of six experiments were performed in a randomized complete block design in Rhodic Haplustox soil under no-tillage system. Experiment 1 with common bean was conducted in 7 × 2, co-inoculation with PGPBs (no inoculation, Rhizobium tropici, R. tropici + Azospirillum brasilense, R. tropici + Bacillus subtilis, R. tropici + Pseudomonas fluorescens, R. tropici + A. brasilense + B. subtilis, and R. tropici + A. brasilense + P. fluorescens) in association with soil Zn application (without and 8 kg ha−1, applied from zinc sulphate) during 2019 and 2020 (May-August). Experiment 2 with common beans was conducted in 7 × 3 factorial scheme, co-inoculation with PGPBs (no inoculation, Rhizobium tropici, R. tropici + Azospirillum brasilense, R. tropici + Bacillus subtilis, R. tropici + Pseudomonas fluorescens, R. tropici + A. brasilense + B. subtilis, and R. tropici + A. brasilense + P. fluorescens) in association foliar nano-Zn doses (0, 1.5 and 3.0 kg ha-1, applied from zinc oxide) during 2019 and 2020 (May-August). Exeriment 3 with wheat was conducted in 4 × 2 factorial scheme, inoculations with PGPBs (no inoculation - control, A. brasilense, B. subtilis and P. fluorescence) in association with soil Zn application (0 and 8 kg ha−1) during 2019 and 2020 (May-September). Experiment 4 with wheat was conducted in 4 × 5 factorial scheme, inoculations with PGPBs (no inoculation - control, A. brasilense, B. subtilis and P. fluorescence) in association with five foliar nano-Zn doses (0, 0.75, 1.5, 3.0 and 6.0 kg ha−1) during 2019 and 2020 (May-September). Experiment 5 with maize was performed in 4 × 2 factorial scheme, inoculations with PGPBs (no inoculation - control, A. brasilense, B. subtilis and P. fluorescence) in association with soil Zn application (0 and 8 kg ha−1) during 2019–2020 and 2020–2021 (November-March). Experiment 6 with maize was also performed 4 × 2 factorial scheme, inoculations with PGPBs (no inoculation - control, A. brasilense, B. subtilis and P. fluorescence) in association with two foliar nano-Zn doses (0 and 3 kg ha−1) during 2019–2020 and 2020–2021 (November-March). Co-inoculation with R. tropici + B. subtilis and R. tropici + P. fluorescens along with soil and foliar Zn application improve plant growth, grain yield and nitrogen (N), phosphorous (P) and Zn concentrations in shoot and grains of common bean. Zinc use efficiency, applied Zn recovery, and utilization were also increased with co-inoculation of R. tropici + B. subtilis along with soil Zn application and foliar nano-Zn application at a dose of 1.5 kg ha−1 whereas agro-physiological efficiency was increased with triple co-inoculation of R. tropici + A. brasilense + P. fluorescens. Inoculation with B. subtilis improved maize grain yield (14-17%), while inoculation with P. fluorescens improve Zn accumulation in shoot (33-51%) and grains (37-50.7%) of maize under residual Zn and nano-Zn foliar fertilization in wheat-maize succession. In addition, biochemical attributes (chlorophyll a, b and total, carotenoids, total soluble sugar and amino acids) and Zn use efficiency were also increased with inoculation B. subtilis and P. fluorescens in combination with soil and nano-Zn foliar application. Inoculation with B. subtilis and P. fluorescens along with soil Zn and nano-Zn foliar application improved Zn concentration of shoot (18-31%) and grains (16-34%), N concentration of shoot (10-24%) and grains (16-20%), P concentration of shoot (26-32%) and grains (18-26%), and grain yield (4-20.6%) of wheat in tropical savannah. Also, inoculation of P. fluorescence with soil and foliar Zn application improved zinc use efficiency and utilization efficiency that increased Zn partitioning to edible grains for higher estimated Zn intake in with daily wheat consumption. Therefore, inoculation of B. subtilis and P. fluorescens with soil and foliar nano-Zn application is considered one of the most effective, sustainable and environmentally safe strategy for improving biochemical, nutritional and productivity attributes of common beans, maize and wheat cropping system. Hence, it is recommended that seed inoculation with B. subtilis and P. fluorescens along with Zn fertilization via soil or foliar nano-Zn at a dose 3 kg ha-1 could be an effective mechanism to improve plant nutrients acquisition and use efficiencies particularly Zn, leading to sustainable production and biofortification of common beans, wheat and maize under tropical savannah regions of Brazil.