Abstract
Plant-growth-promoting bacteria (PGPB) are gaining attention as a sustainable alternative to current agrochemicals. This study evaluated the impact of three Bacillus spp. (5PB1, 1PB1, FV46) and one Brevibacillus sp. (C9F) on the important crop tomato (Solanum lycopersicum) using the model cv. ‘MicroTom’. The effects of these isolates were assessed on (a) seedlings’ growth and vigor, and (b) adult potted plants. In potted plants, several photosynthetic parameters (chlorophylls (a and b), carotenoids and anthocyanins contents, transpiration rate, stomatal conductance, net CO2 photosynthetic rate, and intercellular CO2 concentration, and on chlorophyll fluorescence yields of light- and dark-adapted leaves)), as well as soluble sugars and starch contents, were quantified. Additionally, the effects on redox status were evaluated. While the growth of seedlings was, overall, not influenced by the strains, some effects were observed on adult plants. The Bacillus safensis FV46 stimulated the content of pigments, compared to C9F. Bacillus zhangzhouensis 5PB1 increased starch levels and was positively correlated with some parameters of the photophosphorylation and the gas exchange phases. Interestingly, Bacillus megaterium 1PB1 decreased superoxide (O2−) content, and B. safensis FV46 promoted non-enzymatic antioxidant defenses, increasing total phenol content levels. These results, conducted on a model cultivar, support the theory that these isolates differently act on tomato plant physiology, and that their activity depends on the age of the plant, and may differently influence photosynthesis. It would now be interesting to analyze the influence of these bacteria using commercial cultivars.
Highlights
Increasing global food demand has made agricultural practices extensively dependent on chemical fertilizers and pesticides
Our results are in line with Cabra et al [40], who demonstrated that B. subtilis GIBI 200 had little effect on the shoot and root length and biomass of treated tomato plants
Gowtham et al [41] showed that inoculation of tomato plants with several plant-growth-promoting bacteria (PGPB) strains did not lead to changes in shoot and root length in plants grown under controlled conditions, but induced some increases in these parameters in plants growing under greenhouse conditions
Summary
Increasing global food demand has made agricultural practices extensively dependent on chemical fertilizers and pesticides. These agrochemicals are of extreme importance to food security, but contaminate the environment (e.g., water pollution and soil degradation), affecting entire ecosystems and human health [1,2]. The sustainability of food production became a priority, increasing the interest in new environmentally friendly tools to replace synthetic agrochemicals or, at least, reduce their impact [3]. One of the proposed alternatives to traditional agrochemicals is the use of plant-growth-promoting bacteria (PGPB) [4,5]. PGPB can improve plant growth and health in several ways. Direct benefits affect the plant metabolism, including the levels of phytohormone-like indole acetic acid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
