Bacillus cereus Improves Performance of Brazilian Green Dwarf Coconut Palms Seedlings With Reduced Chemical Fertilization.

Coconut production in the Amazon requires the knowledge and development of sustainable technologies to alleviate the detrimental effects of inorganic chemical fertilizers and intensive farming practices. In this study, we investigated the effects of plant growth-promoting rhizobacteria (PGPR) isolated from coconut seedlings on nutrient use efficiency (NUE) and physiological mechanisms related to biomass accumulation of seedlings grown with reduced inorganic fertilizer levels. Of the 96 PGPR isolates tested on rice plants, the isolate Bacillus cereus (UFRABC40) was selected, as it resulted in the most significant gain in growth variables. In a commercial coconut tree nursery, we subjected seedlings to two treatments, both with seven replications: control 100% NPK chemical fertilizer (CF) and B. cereus + 50% NPK CF. The results indicated that the inoculation increased phytohormone levels [190% indole acetic acid (IAA), 31% gibberellic acid GA3, and 17% gibberellic acid GA4] and leaf gas exchange [48% by assimilation of CO2 (A), 35% stomatal conductance to water vapor (gs), 33% transpiration, and 57% instantaneous carboxylation efficiency] in leaves. Furthermore, growth parameters (shoot, root, and total dry weight, height, and diameter) and macro- and micronutrient levels (95% N, 44% P, 92% K, 103 Ca, 46% Fe, 84% B) were improved. Our results show the potential ability of strain Bacillus cereus UFRABC40 to promote the growth performance of coconut seedlings under decreased application of inorganic fertilizers. The application of microbial-based products in coconut seedling production systems improves plants' physiological performance and the efficiency of nutrient use.

Molecular identification of Trichoderma sp. isolates and biochemical characterization of antagonistic interaction against rice blast.

This study aimed to identify four isolates of Trichoderma sp. (Ufra.T06, Ufra.T09, Ufra.T12, and Ufra.T52) and characterize their interaction with Magnaporthe oryzae in vitro and in vivo conditions. The four isolates of Trichoderma sp. were sequenced, investigated as an antagonist against M. oryzae in five Petri plate assays, and as an inhibitor of conidial germination appressoria formation. Finally, were quantified the lytic activity of chitinase (CHI), glucanase (GLU), and protease (PRO) during co-cultivation of Trichoderma sp. and M. oryzae. In vivo, leaf blast suppression was evaluated in two assays: simultaneous and curative application. Both in vitro and in vivo assays were scanned by electron microscopy (SEM). All isolates were identified as Trichoderma asperellum. All in vitro Petri plates assays reduced M. oryzae colony growth (paired-91.18% by Ufra.T09, volatile metabolites-all isolates equally reduced, non-volatile-68.33% by Ufra.T06, thermostability-99.77% by Ufra.T52 and co-cultivate-64.25% by Ufra.T52). The filtrates and conidia suspensions for T. asperellum isolates inhibited the conidia germination and appressoria formation significantly. In co-cultivate (mycelial or cell wall), all enzymes (GLU, CHI, and PRO) and times (24, 48, and 72 h) showed increased activity. In vivo, reduced leaf blast severity until 94.64% (Ufra.T52cs) in a simultaneous and until 85% (Ufra.T09 24 and 48 hasi) in a curative application. T. asperellum isolates showed efficient control of M. oryzae by mycoparasitism, and antibiosis mechanisms were interfered with by the M. oryzae infection process.

Açaí palm seedling growth promotion by rhizobacteria inoculation.

Lower growth rate of the açaí palm seedlings limits the crops' commercial expansion. The goal was evaluating the biometry, biomass accumulation, nutrient contents, chlorophyll-a fluorescence, and gas exchange in açaí seedlings inoculated with rhizobacteria. The treatments were individual inoculations of the seven rhizobacteria isolates and one control (without inoculation) on the roots. Biometry and biomass data were submitted to cluster analysis to separate the isolates into groups according to the similarity degree, and groups' means were compared through the SNK test. Three groups were formed; group 1 was composed of the control; group 2 of the UFRA-35, UFRA-38, UFRA-58, UFRA-61, UFRA-92, and BRM-32111 isolates; and group 3 was composed of the BRM-32113 isolate. Group 2 and 3 isolates promoted an increase in growth, biomass accumulation, higher levels of nutrients and chlorophyll, and improvements in the gas exchange and chlorophyll-a fluorescence in comparison with the control. The results evidenced that the rhizobacteria accelerate the growth, increase the photosynthetic efficiency, and induce the leaf nutrient accumulation in açaí palm seedlings. The rhizobacteria inoculation can contribute to the sustainable management of the açaí palm seedling production in nurseries.

Bioagents and silicon promoting fast early upland rice growth.

Upland rice can overcome major challenges through the insertion of silicate fertilization and the presence of plant growth-promoting microorganisms (PGPMs) during its cultivation, as these factors promote an increase in vigor and plant disease resistance. Two consecutive experiments were conducted to evaluate the beneficial effects of silicon fertilization combined with the PGPM, Pseudomonas fluorensces, Burkholderia pyrrocinia, and a pool of Trichoderma asperellum, in upland rice seedlings, cultivar BRS Primavera CL: (a) E1, selecting PGPM type and Si doses for rice growth promotion and leaf blast supression, and (b) E2, evaluating physiological characteristics correlated with mechanisms involved in the higher vegetative growth in highlighted treatments from E1. In E1, 2 Si t ha-1 combined with the application of T. asperellum pool or PGPM mixture increased 54% in root dry matter biomass and 35 and 65% in shoot and root lengths, respectively; it also suppressed 99% of rice blast severity. In E2, shoot and root dry matter biomass and length, photosynthetic rate, water use efficiency, total soluble sugar, and chloroplastidic pigments were superior in BRS Primavera CL seedlings treated with 2 Si t ha-1 and T. asperellum pool or PGPM mixture. Higher salicilic and jasmonic acid levels were found in seedlings treated with Si and T. asperellum pool, individually. These physiological characteristics may explain, in part, the higher vigor of upland rice seedlings promoted by the synergistic effect between silicate fertilization and beneficial microorganisms.

Effects of beneficial microorganisms on lowland rice development.

Microorganisms can promote plant growth by increasing phytomass production, nutrient uptake, photosynthesis rates, and grain yield, which can result in higher profits for farmers. However, there is limited information available about the physiological characteristics of lowland rice after treatment with beneficial microorganisms in the tropical region. This study aimed to determine the effects of different beneficial microorganisms and various application forms on phytomass production, gas exchange, and nutrient contents in the lowland rice cultivar 'BRS Catiana' in a tropical region. The experiment was performed under greenhouse conditions utilizing a completely randomized design and a 7 × 3 + 1 factorial scheme with four replications. The treatments consisted of seven microorganisms, including the rhizobacterial isolates BRM 32113, BRM 32111, BRM 32114, BRM 32112, BRM 32109, and BRM 32110 and Trichoderma asperellum pooled isolates UFRA-06, UFRA-09, UFRA-12, and UFRA-52, which were applied using three different methods (microbiolized seed, microbiolized seed + soil drenched with a microorganism suspension at 7 and 15 days after sowing (DAS), and microbiolized seed + plant spraying with a microorganism suspension at 7 and 15 DAS) with a control (water). The use of microorganisms can provide numerous benefits for rice in terms of crop growth and development. The microorganism types and methods of application positively and differentially affected the physiological characteristics evaluated in the experimental lowland rice plants. Notably, the plants treated with the bioagent BRM 32109 on the seeds and on seeds + soil produced plants with the highest dry matter biomass, gas exchange rate, and N, P, Fe, and Mg uptake. Therefore, our findings indicate strong potential for the use of microorganisms in lowland rice cultivation systems in tropical regions. Currently, an additional field experiment is in its second year to validate the beneficial result reported here and the novel input sustainability.

Biomass, gas exchange, and nutrient contents in upland rice plants affected by application forms of microorganism growth promoters.

Microorganisms are considered a genetic resource with great potential for achieving sustainable development of agricultural areas. The objective of this research was to determine the effect of microorganism application forms on the production of biomass, gas exchange, and nutrient content in upland rice. The experiment was conducted under greenhouse conditions in a completely randomized design in a factorial 7 × 3 + 1, with four replications. The treatments consisted of combining seven microorganisms with three application forms (microbiolized seed; microbiolized seed + soil drenched with a microorganism suspension at 7 and 15 days after sowing (DAS); and microbiolized seed + plant sprayed with a microorganism suspension at 7 and 15 DAS) and a control (water). Treatments with Serratia sp. (BRM32114), Bacillus sp. (BRM32110 and BRM32109), and Trichoderma asperellum pool provided, on average, the highest photosynthetic rate values and dry matter biomass of rice shoots. Plants treated with Burkolderia sp. (BRM32113), Serratia sp. (BRM32114), and Pseudomonas sp. (BRM32111 and BRM32112) led to the greatest nutrient uptake by rice shoots. Serratia sp. (BRM 32114) was the most effective for promoting an increase in the photosynthetic rate, and for the greatest accumulation of nutrients and dry matter at 84 DAS, in rice shoots, which differed from the control treatment. The use of microorganisms can bring numerous benefits of rice, such as improving physiological characteristics, nutrient uptake, biomass production, and grain yield.