Abstract
The use of plant growth-promoting rhizobacteria (PGPR) is an important and promising tool for sustainable agriculture. The objective of this study was to evaluate the morphophysiological responses and nutrient uptake of maize plants inoculated with A. brasilense under two water conditions. The experiment was carried out in a greenhouse with ten treatments: five A. brasilense inoculants (Control, Az1, Az2, Az3 and Az4) inoculated in the seed and two water conditions - irrigated and water deficit. Treatments with water deficit were imposed at the V6 stage for a period of 15 days. The phytotechnical characteristics, gas exchange, root morphology, shoot, root and total dry matter, as well as nutrient analysis, were evaluated after water deficit. Azospirillum brasilense (Az1, Az2, Az3 and Az4) yielded higher growth, increased gas exchange and nutrient uptake under irrigation conditions. Inoculation by Az1 and Az3 benefited the root architecture of maize plants, with a greater exploitation of the soil profile by these roots. Water deficit caused a reduction in the development of maize plants. Inoculation by Az1, Az2 and Az3 can improve plant growth, nutrient uptake and mitigate the effects of water deficit in the development of maize plants.
Highlights
Throughout their development, plants can be exposed to various environmental stresses
The benefits arising from the association of this bacteria with plants are the synthesis of various growth regulating substances, such as phytohormones (Barnawal et al, 2019); biological fixation of nitrogen (Revolti et al, 2018); phosphate and iron solubilization (Galindo et al, 2016; Revolti et al, 2018); biocontrol of phytopathogens (Cassán & DiazZorita, 2016) and plant protection against abiotic stress (Dar et al, 2018; Kaushal, 2019)
The same pattern was observed for shoot dry matter, with inoculants increasing in Az1 (22%), Az2 (16%), Az3 (29%) and Az4 (15%) and higher total dry matter(Az1-21%, Az2-16%, Az3-29% and Az4-15%), when compared to uninoculated control plants (Fig. 1ef)
Summary
Throughout their development, plants can be exposed to various environmental stresses. The tolerance of maize plants to water deficit from drought needs to be improved in order to meet the food demand in areas with limited availability of water resources. In this context, the search for technological research that aligns water availability with soil management is gaining importance in the current global scenario. PGPR offers an economically attractive and ecologically correct alternative to increase water and nutrient availability (Prasad et al, 2019) Due to their huge genetic pool, these microorganisms are the source of biochemical reactions that recycle nutrients for plant growth (Tkacz & Poole, 2015). Inoculation may induce hormone signaling from root to shoot, regulating leaf growth and other plant physiological
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