Rizobactérias e silício na intensificação da mitigação do arroz de terras altas ao déficit hídrico e à brusone
Nenhuma Miniatura disponível
Data
2021-02-24
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
Rice (Oryza sativa L.) is the only cereal that feeds approximately 2,4 billion people in the world per day. The productivity of the highland farming system is challenged by the occurrence of blast (Magnaporthe oryzae) and water deficit. Plant growth-promoting rhizobacteria (PGPRs), as well as silicon, as they have multiple bioactivity, have the potential to mitigate water deficit and the effects of blast.The objective was to characterize nine rhizobacteria isolates, select the ones that are most resistant to high osmotic potentials combined with monosilicic acid, evaluate the effect of the best combinations in the development of rice seedling roots in vitro and in the mitigation of water deficit and blast leaf in rice plants, in vivo. Five sequential tests were performed. 1) Nine rhizobacteria isolates (Burkholderia pyrrocinia (BRM 32113) two Serratia sp. isolates (BRM 32114 and BRM 63522) and two Serratia marcescens (BRM 63521 and BRM 63523); Bacillus thuringiensis (BRM 32110), Bacillus cereus (BRM 32109), Pseudomonas fluorescens (BRM 32111) and Pseudomonas sp. (BRM 32112)) were characterized for the production of extracellular enzymes, siderophores, biofilm, ACC deaminase enzyme, indolacetic acid (AIA) and phosphatase, in a completely randomized design, and three repetitions. 2) The nine isolated PGPRs were grown in liquid culture medium supplemented with seven different concentrations of PEG-6000 combined with monosilicic acid, in a completely randomized design, and twelve replications. The growth rate was determined and viable cells were quantified. 3) The best isolates were used to treat the seeds of the cultivar BRS Esmeralda of upland rice. The seeds were sown in culture medium containing the seven concentrations of PEG-6000 combined with monosilicic acid, in a completely randomized design, with six replications. The root development of seedlings was evaluated with the aid of a scanner and the program WinRhizo Pro 2012b. 4) The best isolates were tested as antagonists to M. oryzae, in Petri dishes containing culture medium enriched with seven different concentrations of PEG-6000 combined with monosilicic acid, in a completely randomized design, in three replications. The colony diameter of each treatment was determined. 5) In greenhouse conditions, seeds of the cultivar BRS Esmeralda, treated with the isolate BRM 32111, were sown in plastic trays containing 3 kg of soil fertilized with calcium and magnesium silicate (9 g tray-1). At 15 days after planting, the leaves were sprayed with the same isolate and at 21 days they were subjected to four days of water deficit. Gas exchanges were evaluated at the end of this period. At 26 days, the plants were inoculated with a conidia suspension of M. oryzae. The progress of the disease was assessed for seven days. The isolates BRM 32110, BRM 3211 and BRM 63523 were the most resistant to high osmotic pressure, in addition to being producers of extracellular enzymes, siderophores, biofilm, ACC deaminase enzyme, AIA and phosphate solubilizers. And the isolate BRM 32111 was the one that most inhibited (78,36%) the mycelial growth of M. oryzae in the presence of monosilicic acid. In the development of seedlings in vitro, the same three isolates combined with monosilicic acid, were promising under high osmotic pressure, increased the length and area of roots and even more of root hair due to the expansion of very thin roots, mitigating the effects of water deficit in seedlings. Comparing the control with the highest osmotic potential, within the parameters length and total root surface area, the isolate BRM 32111 showed an increase of 93,26 and 77,32%, the isolate BRM 32110 of 203,65 and 110,24% and the isolate BRM 63523 of 139,67 and 170,13%. In the parameter length and area of very thin roots, this increase in treatments with osmotic pressures was up to 109,29 and 194,00%, (BRM 32111), 44,06 and 90,49% (BRM 32110) and 34,31 and 36,17% (BRM 63525). In a greenhouse, BRM 32111 in combination with calcium and magnesium silicate, in all treatments, an increase in transpiration and photosynthetic rates, water use efficiency, stomatal conductance, internal carbon concentration and carboxylation efficiency, in addition to reducing leaf blast severity. The nine isolates in synergism with silicon showed potential for mitigating damage caused by water deficit and blast suppression and among them BRM 32111 stood out in mitigating damage to upland rice plants in greenhouse, in vitro and in vivo.
Descrição
Palavras-chave
Citação
FARIA, D. R. Rizobactérias e silício na intensificação da mitigação do arroz de terras altas ao déficit hídrico e à brusone. 2021. 117 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2021.