Commercial formulations of Bacillus spp. for sugarcane pineapple disease control and growth promotion

Abstract

The objective of this work was to evaluate the commercial formulations of Bacillus subtilis QST-713 and Bacillus pumilus QST-2808 on mycelial growth inhibition of Thielaviopsis paradoxa, for the control of the pineapple disease and growth promotion in sugarcane. The inhibition of mycelial growth was evaluated in paired culture tests. Bacillus isolates were transferred to Petri dishes 48 hours before the pathogen, and the zone of inhibition was determined. The direct effect of the autoclaved commercial formulations at 0, 0.001, 0.01, 0.1, 1.0, and 10.0% on the inhibition of pathogen mycelial growth was evaluated. Bacillus spp. potential in controlling the disease and promoting plant growth was evaluated in assays on plant development and disease severity, both under controlled conditions and in the field. Bacillus isolates inhibited pathogen mycelial growth; however, the isolates did not control the disease effectively in the growth chamber and in the field. In the field assay without infestation by the pathogen, all treatments with biocontrol agents and fungicide increased the yield of cane stalks and sugar per hectare, compared with the control. In the assay with infestation by the pathogen, the B. pumilus-based product (2.0 L ha-1) and fungicide differed from the control only for the variable number of tillers.

Plant Growth-Promoting Bacteria Enhance Survival, Growth, and Nutritional Content of Sugarcane Propagated through Pre-Sprouted Seedlings under Water Deficit

“…Our results show that inoculation increased the stalk height (SH) at 63 DAT, similar to that found by Brandi et al [41], who reported that the association of two bacteria of the Bacillus genus increased the sugarcane height. In contrast, individual inoculation of each species did not raise this parameter [41].…”

“…Inoculation of B. licheniformis and B. subtilis can be a promising approach to improving plant growth, as the particularities of each species allow for a greater action spectrum on signaling pathways, nutrient solubilization, and phytohormone production [38,41,42,72]. Our results show that inoculation increased the stalk height (SH) at 63 DAT, similar to that found by Brandi et al [41], who reported that the association of two bacteria of the Bacillus genus increased the sugarcane height. In contrast, individual inoculation of each species did not raise this parameter [41].…”

“…The number of tillers per meter is a component of productivity that acts as a strong indicator of drought tolerance in sugarcane [109], showing that the increase obtained from PGPB under the 33% water regime demonstrates the tolerance-promoting potential of these species. Other studies have also reported an increase in the number of tillers under inoculation with species of the genus Bacillus [36,41,94,110].…”

“…The association of two Bacillus species is a promising approach to improving plant growth, given the particularities present in each species and the increased spectrum of action and specificity [41,42]. However, there are still no studies involving the association of B. licheniformis and B. subtilis in sugarcane propagated by PSS in the field; both are known and reported to be effective in promoting tolerance to water deficits.…”

Bacterial volatile organic compounds induce adverse ultrastructural changes and DNA damage to the sugarcane pathogenic fungus Thielaviopsis ethacetica

“…The treatment used to reduce the impacts caused by the disease typically consists of fast‐growing varieties and chemical treatment with fungicides (Bhuiyan et al ., 2014; Borges et al ., 2019). Many studies have reported the efficiency of phenylpyridylamine and triazole‐based fungicides in the control of pineapple sett rot (Bhuiyan et al ., 2014; Brandi et al ., 2018); however, these chemicals have a high cost, and continuous application may compromise their effectiveness due to the emergence of resistance that reduces disease control (Lucas et al ., 2015). In addition, and maybe more importantly, one of the crucial aspects for modern agriculture is to reduce the use of chemical fertilizers and pesticides, which generate negative impacts on human health and in the environment, harming soil health and fertility and causing water resource contamination and air pollution (de Souza et al ., 2015; Carvalho, 2017).…”