Efeitos de bioinoculantes com bactérias que promovem o crescimento de plantas (BPCP) em três variedades de tomate (Lycopersicum esculentum, MILL)

Abstract

Tomato is one of the main vegetables cultivated in Brazil, with significant economic and social importance, contributing a substantial part of the national agricultural (45,1%) PIB. To increase production and ensure the global food demand, modern agricultural practices rely on chemical fertilizers, which have negative consequences for human health and the environment. However, agriculture faces a crucial challenge: to develop precision tools to enhance crop growth and productivity without these negative impacts. The use of bioinoculants based on PGPB is an important biotechnological alternative to reduce the excessive use of chemical nitrogen fertilizers. Thus, associations between beneficial bacteria and non-leguminous plants, such as tomatoes, can provide essential information for improving tomato cultivation in Brazil and worldwide. The main objective of this work is to investigate the effects of three bioinoculants composed of PGPB in three tomato varieties, aiming to identify the best associations to optimize growth, seeking the development of sustainable and easy-to-manage technologies. Inoculation experiments were conducted in a greenhouse, where plants were inoculated at 7 days after sowing (DAS) with Azospirillum baldaniorum Sp245, Herbaspirillum seropedicae HRC54, and the commercial bioinoculant Biofree, in addition to a control group (mock). Samples were collected at 14 DAS (7 DAI) and 37 DAS (30 DAI) for phenotypic analyses, performed during the vegetative growth of tomato plants. The results of inoculation experiments with the three tomato varieties (Cereja, Rasteiro Rio Grande and Microtom) in a greenhouse indicate that the efficacy of bioinoculants varies according to the combination between the variety and the bacteria used. The strain A. baldaniorum Sp245 stood out in the Cereja variety, promoting significant increases in plant height and biomass. In the Rasteiro Rio Grande variety, H. seropedicae HRC54 was more effective, especially at 30 days after inoculation, increasing the height and weight of the shoots and roots. For the Microtom variety, the three inoculation treatments were effective in increasing biomass, both of the shoots and roots, in tomato plants. Inoculation with SP245 and Biofree, in particular, showed promise, promoting a more robust development of this variety. To evaluate the best combination of tomato variety and bioinoculant under field conditions, the Cherry tomato variety was selected, as it showed good responsiveness to bioinoculants in the greenhouse. The selected bioinoculants were A. baldaniorum Sp245 and Biofree. The study was carried out in urban cultivation, through a partnership with the Hortas Cariocas Project. In this study, analyses were performed during the vegetative growth of the tomato plant. Fruiting was analyzed in another PhD thesis work. The results of the field experiment with the Cherry tomato variety, inoculation with A. baldaniorum Sp245 resulted in significant increases in plant height, fresh and dry weight of the shoot and roots. In addition, both Sp245 and the commercial bioinoculant Biofree significantly increased the levels of chlorophyll a, b, total and carotenoids in the plants, indicating improvements in the photosynthetic capacity. These findings highlight the promising potential of combining the Cereja variety with the bioinoculants Sp245 and Biofree to improve the development and physiological efficiency of tomato plants under field conditions. The findings reinforce the potential of bioinoculants in promoting tomato growth, highlighting the importance of selecting specific combinations between genotypes and bacteria to optimize agricultural productivity and sustainability. In addition, increased efficiency in the plant-bacteria association may contribute to reducing fertilizer and water consumption, promoting more sustainable agricultural practices.