Promoção de crescimento vegetal e melhoramento de parâmetros bioquímicos em Gossypium hirsutum L. por bactérias e quitosanas

Abstract

Plant Growth Promoting Bacteria (PGPB) are a group of microorganisms capable of improving plant growth. And chitosan is a biopolymer widely spread in nature with particular beneficial properties that are extremely useful in plant development. The use of these “green” products in agriculture has proven to be a sustainable and viable alternative, as they are effective in improving crops and do not harm the environment. Therefore, the present study aimed to evaluate the effect of inoculation with three species of PGPB (Bacillus subtilis, Priestia megaterium and Priestia aryabhattai) and the application of chitosan via seed on the morphological and biochemical aspects of Gossypium hirsutum L. (cotton). Two distinct experiments were carried out. In the first, cotton seeds were inoculated separately with bacterial suspensions of B. subtilis, P. megaterium and P. aryabhattai. The seeds were sown and plant growth was monitored for 60 days in a greenhouse. Finally, the plants were collected and analyzed for morphological and biochemical aspects. In the second experiment, native and modified chitosan preparations, of different molecular masses, were used to soak the seeds, which were also sown in a greenhouse and the same steps as in the first experiment were followed for morphological and biochemical analyses. The results found in the first experiment showed that seeds inoculated with P. aryabhattai showed significant improvements in the parameters of fresh mass, plant height, stem diameter and number of leaves and in the contents of chlorophyll (a, b and total), nitrogen (N) and proteins in relation to plants in the control treatment. Plants treated with P. megaterium also achieved improvements in fresh mass, stem diameter and N and protein content. These results indicate that these BPCP are capable of promoting the growth of cotton plants, demonstrating a potential for use in the processing of this crop in the agricultural sector, and can be used in the preparation of biostimulants. The results found in the experiment with chitosans showed that this biopolymer has the ability to benefit cotton plants, improving morphological parameters of growth of the shoot, root and stem diameter. Showing that chitosans can also be used to benefit this crop.