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.
The authors have investigated the effects of different doses of mineral fertilizers combined with co-inoculation of Bacillus subtilis and Trichoderma asperellum to promote plant growth and use efficient nutrients in a plant Urochloa (Syn. Brachiaria) brizantha cv. Marandu. Individual experiments with doses of the nutrients nitrogen (N), phosphorus (P), and potassium (K) were carried out. The experiment was conducted in a completely randomized design, factorial 3 × 5. With the treatments: control noninoculation, inoculation with Bacillus subtilisUFRA-92, and coinoculation (MIX) with T. asperellum (UFRA-06, UFRA-09, UFRA-12, and UFRA-52) + B. subtilis x nutrient omissions (0%, 25%, 50%, 75%, and 100%). Each treatment had five replications. Biometric parameters, nutrient content, and nutrient use efficiency were evaluated. The results showed that the inoculants promoted growth in Marandu grass. The use of inoculants promoted growth and increased N, P, and K uptake by Marandu grass. Co-inoculation changed leaf area, shoot length, elongation rate, and leaf appearance for N and K and root dry mass for P. In addition, the co-inoculation combined with doses of 75% of N, 50% of P, and 50% of K increased the nutritional content of the leaves by 256% of N, 280% of P, and 29% of K and provided greater agronomic efficiency, with increments of 462% of N, 544% of P, and 177% of K, compared to the control treatment. We present the potential of co-inoculation of B. subtilis and T. asperellum to promote the growth of Urochloa under reduced fertilizer application. There was an improvement in plant growth and nutrient use efficiency.
The objective of this study was to evaluate changes in the chemical attributes of the soil caused by the use of limestone associated or not to with gypsum in no-tillage system. The experiment was conducted on a dystrophic Yellow Latosol in Pará state, Brazil. The experimental design was in randomized blocks in split plots with three replications. The treatments consisted of five doses of limestone (0, 1, 2, 3 and 4 t ha -1 ), with and without gypsum (0, 0.5 and 1 t ha -1 ). Soil samples were collected at depths of 0-20 and 20-40 cm. There was a significant effect on the analyzed variables at both depths. The doses of 3.64 and 2.19 t ha -1 of limestone associated with 0.5 t ha -1 of gypsum, were responsible for the largest increase in soil calcium content in the 0-20 and 20-40 cm layers, respectively. The highest increase in Ca + Mg content was found at 3.63 t ha -1 limestone combined with 0.5 t ha -1 gypsum. It was observed that 3.13 t ha -1 of limestone combined with 0.5 t of gypsum increased soil CEC. The 2.89 t ha -1 dose of limestone combined with 0.5 t of gypsum contributed to the increase in base saturation (V%). The use of limestone and gypsum Journal of Agricultural Studies 364 promotes soil chemical conditions, as reflected by increased corn yield when compared with control (no treatment) plots.
The aim of the present study was to evaluate the effects of sowing depth and inoculation with Pseudomonas fluorescens on germination, emergence, shoot and root growth of Urochloa brizantha . A completely randomized design was used, in a 6 × 2 factorial arrangement, with 12 repetitions. The following sowing depths (SD) were evaluated: 0, 1, 2, 3, 6 and 12 cm; and the seed inoculation with P . fluorescens (I): with and without. Evaluations were carried out 25 days after plant emergence. No effects of the PS × I or I interaction were observed for all variables evaluated (P> 0.05). The germination and emergence percentages decreased linearly (P <0.05) as the SD increased. No plant emergence was observed at and at 12 cm depth. The morphometric characteristics of the plants (height, number of leaves, length of root and leaf blade width) decreased linearly with the increase of SD (P <0.05). Dry matter production of the aerial part and root were not affected by SD (P> 0.05). However, an effect was observed on the shoot:root ratio, where plants sown more superficially had a greater relationship. The inoculation with Pseudomonas fluorescens in the seed, has no effect on the initial growth of Marandu grass. On the other hand, greater sowing depths affects negatively the initial growth.
The objective of this work was to evaluate the effects of application of Bacillus cereus combined with the use of substrate and reduction in conventional fertilization on the growth of green dwarf coconut seedlings in Brazil, the Santa Isabel nursery in the state of Pará, Brazil. The experiment design was completely randomized with four treatments: soil+100% fertilizati+on; soil+ 50% fertilization + B. cereus; coconut fiber+100% of fertilization; and coconut fiber+33% of fertilization plus B. cereus, with 5 replications. Biochemical tests were performed with B. cereus and in the field where the following were evaluated: biometrics, hormonal and nutritional profile compared by t Test (P <0.05). Isolate B. cereus produced siderophores, IAA and phosphate solubilizer. In the field, the treatmwxent with inoculated coconut fiber and B. cereus stood out where nursery time was reduced by two months. Increments by 190% in IAA, 31% in GA3, and 17% in GA4 were found. This combination resulted in an increase by 98% in N, 42% in P, 82% in K, 103% in Ca, 68% in Mg, 84% in B, 41% in Fe, compared to control plants in coconut fiber+100% fertilization. Therefore, the use of B. cereus to obtain coconut seedlings is a technology that provides greater development in a shorter time in nursery and reduction in application of inputs.
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