Pseudomonas fluorescens and Azospirillum brasilense Increase Yield and Fruit Quality of Tomato Under Field Conditions

Abstract

Crop inoculation with plant growth-promoting rhizobacteria (PGPR) is a sustainable alternative to diminish the excessive use of chemical fertilizers in agriculture. However, there is little information about PGPR inoculation effects under field conditions and even less on industrial tomato production. We aimed to study the effects of a sole inoculation at seedling stage with Pseudomonas fluorescens Rt6M10, Azospirillum brasilense Az39, and their combination on growth and yield of two industrial tomato varieties UCO 14 (UCO) and Harris Moran 3861 (HM). We compared these PGPR inoculation treatments with chemically fertilized and nonfertilized (control) seedlings under field conditions. We found that inoculation with Rt6M10, Az39, and their combination increased seedling root dry weight by 62%, 41%, and 23%, respectively and shoot dry weight by 29%, 23%, and 2%, respectively compared with non-inoculated control, improving tolerance to transplant stress. Inoculation with Rt6M10, Az39, and their combination increased stem diameter by 15%, 16%, and 13%, respectively, while Rt6M10 and the combination treatments increased leaf chlorophyll and carotenoid levels compared with non-inoculated plants. Az39 increased fruit number (35%) and fruit weight (38%) per plant in HM, whereas in UCO variety, the increase was the highest (48% and 49%, respectively). Seedling inoculation increase fruit firmness and equatorial and polar fruit diameter by 24%, 10%, and 12%, respectively in HM and by 21%, 14%, and 14%, respectively in UCO. Overall, bio-inoculation with Rt6M10 and/or Az39 was beneficial for tomato seedlings at transplanting and supported fruit yield and quality (total soluble solid content, pH, and titratable acidity) equally or better than chemically fertilized seedlings.

The Azospirillum genus and the cultivation of vegetables. A review

“…For tomato, it is verified that the inoculation of plants with A. brasilense improves the physiological activities of photosynthesis, accumulation of pigments, and antioxidant compounds (Lade et al, 2018;Pérez-Rodriguez et al, 2020). These changes increase vegetative development, yield (Escalante et al, 2015;Esquivel-Cote et al, 2017;Lima et al, 2018), and quality of the fruits (Caradonia et al, 2020).…”

“…Greater production of total fresh lettuce mass was obtained with the use of Azospirillum associated with increasing N doses, possibly due to the optimization of the use of N (Lima et al, 2017), due to its ability to promote greater root development of plants (Lade et al, 2018;Pérez-Rodriguez et al, 2020).…”

“…The role of bacteria of the Azospirillum genus as promoters of root development, through stimuli related to the increase of endogenous levels of phytohormones, accumulation of reserves, promotion of photosynthesis, and absorption of nutrients (Mangmang et al, 2016;Lade et al, 2018;Pérez-Rodriguez et al, 2020) justifies its exploitation in crops producing roots and tubers (Table 3). Also, the induction to mitigate the effects of environmental factors, such as water scarcity and toxicity due to the presence of elements such as aluminium (Cássan & Diaz-Zorita, 2016;Sahu et al, 2017;Silva et al, 2019).…”

Fruit collapse incidence and quality of pineapple as affected by biopesticides based on Pseudomonas fluorescens and Trichoderma harzianum

“…Evidently, due to the more severe infection generated by the inject method, the fruit as a protection mechanism could have promoted the increase in the uptake of calcium and magnesium to maintain the cell wall structure, encouraging more molecular ions assimilation and enzyme activities (Ca +2 , CDPKs, respectively). Besides, T. harzianum and P. fluorescens have been associated with a more remarkable assimilation of mineral nutrients content in terms of N, P, K, Ca and Mg in plants and fruits (Pérez-Rodriguez et al, 2020;Sood et al, 2020). These facts make clearer that the biopesticides may have an influence on the plant and fruit defense mechanism when a certain high degree of affectation is reached, in this case, triggering the respective calcium and magnesium increase.…”

Nitrogen-fixing bacteria and nitrogen fertilization on economic feasibility of tomato

“…According to Pérez-Rodriguez et al (2020), tomato seed inoculation with A. brasilense (Az39) enhanced seedlings growth, which in turn could avoid the need of supplemental fertilization during greenhouse production. These same authors related that plant growth-promoting rhizobacteria inoculation allowed producing high-quality seedlings that likely suffered less transplant stress in the field, increasing yield and quality of tomatoes.…”