Arroz puitá inta CL cultivado na planície costeira do Rio Grande do Sul: comunidades bacterianas, características físico-químicas dos solos e valor nutricional

Abstract

Bacteria has a key role in maintaining the life and balance of ecosystems. Rice crops suffer microbial actions, including interactions between plants and micro-organisms. The agro-ecosystems are composed of several micro-habitats and allow the adaptation of a great microbial diversity. Rice crop management promotes changes in the physical and chemical characteristics of the water and due to changes in pH, turbidity, temperature, radiation and organic matter, may be related to the dynamics of the microbial communities present in the soil. The objective of this project was to evaluate the bacteriological communities present in the soil of the Puitá Inta CL rice, sowed in two rice regions, in the 2013/14 and 2014/15, with different soil types (Internal Coastal Plain / PCI and External Coastal Plain / PCE). In this study, we identified heterotrophic bacteria that can assist plants in their development and in the production of more nutritious grains and in the analysis of the physical and chemical elements of the soils, as well as the determination of the nutritional composition of the Puitá Inta CL rice grains, brown and Polished, produced in each region of study. The data of this research were presented in four chapters that correspond to the publications in the form of scientific articles. The results revealed a total of 29 bacterial species, of which 27 were recorded in PCE and 22 were PCI, in the different phenological phases of Oryza sativa. The abundance of Colony Forming Units (CFUs), the PCE region obtained 18.5% of the species in before sowing, 22.3% in the vegetative phase, 22.3% in the reproductive phase and 36, 9% during seed maturation (F1.9 = 7.84, p <0.05). The diversity estimated by the Shannon index was higher at maturity (M = 3.901) compared to the values obtained in the soil of other phenological phase (M = 2.97). The abundance of CFU in the PCI was 23.9% in before sowing, 21.7% in the vegetative phase, 20.7% in the reproductive phase and 33.7% during seed maturation (F1.9 = 7.03, P <0.05). The estimated diversity was higher in maturation (M = 3.801) compared to the values obtained in the soil of the other phenological phases (M = 2.46). Evenness index indicates that species distribution was similar in both regions (PCE and PCI) during maturation (E = 0.988 and 0.967). The high values obtained in the CCA analysis explain the variation observed in the three axes: for the first agricultural year they explain 67% of the variation of the species and for the second agricultural year they explain 86.5%. These data indicate that the maturation stage of plants to the diversity of bacterial species is predominant. The results of the PCA show that the first three axes explain 74.19%: axis 1 (47,12%) includes the variables Clay, pH and Hydrogen + Aluminum; The second axis (15.79%) includes Phosphorus, Electron exchange capacity pH 7 and Magnesium; And the third axis (11,28%) Aluminum, Organic Matter and Index of analysis and correction of acidity. The spatial result pattern shows a significant difference between the soils of each region, which can be verified by MANOVA (Wilk’s Lambda: 0.008, p <0.0001 and F = 61.6). Rice nutritional value, phenolic content and antioxidant content were tested by the Mann Whitney method, which reveals the difference between, brown and polished rice from each rice region (p<0,001), it is not temporal difference (p>0,05) between them (2013/14 and 2014/15).