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The relationship between bacterial diversity and the bioavailability of nutrients, toxic metals and the herbicide oxyfluorfen in a tropical vegetable growing area was evaluated. The study was conducted in a vegetable growing area located in the mountainous region of Rio de Janeiro (Brazil), and samples were collected in areas of vegetable cultivation and areas of environmental reserve. Fertility analyses and determination of the pseudototal levels of toxic metals in the soil samples were performed. The profile of the soil bacterial community was determined by amplification of the 16S rRNA gene and separation by DGGE. The results showed that the levels of toxic metals and elements associated with soil fertility were higher in vegetable production areas. These differences in the physical and chemical characteristics of the soil favored the presence of a greater number of OTUs in the cultivation areas (17.3-27 OTUs) than in the areas of environmental reserve (13-22 OTUs). Therefore, this study demonstrates that the presence of toxic metals and the herbicide oxyfluorfen and the increase in fertility in soils in areas with intensive vegetable cultivation resulting from the intensive management adopted in these areas promotes a differentiation of the bacterial profiles in soils in tropical vegetable growing areas. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effect of controlled-release fertilizer N14-P14-K14 (CRF) on the morphological traits and chlorophyll indices of black pepper plantlets (cv. Bragantina). One experimentation was carried out in a greenhouse between March and July 2018 in the Rio de Janeiro state/Brazil. Were tested four doses' equivalents to 0.0, 2.5, 5.0, and 10.0 kilogram of CRF per cubic meter of the substrate, which was obtained by mixing clayey soil and crushed coconut fiber, on 1:3 volume proportion. The experimental design was completely randomized, with 17 replicates to assess the morphological characteristics and nine replicates to assess the chlorophyll contents. At 120 days after transplanting were assessed main stem height (H), the number of leaves (NL), leaf area index (LAI), total dry matter (TDM), shoot dry matter (SDM), and root dry matter (RDM). Chlorophyll a, b, a+b contents and a/b ratio were assessed too. The application of CRF fertilizer increased the NL and SDM values until 9.6 kg m-3 dose. The values of H, TDM, LAI, and RDM increase until 9.3, 8.4, 8.2, and 6.4 kg m-3 doses, respectively. The chlorophyll a and b contents increased until 7.7 kg m-3 dose. It's recommended to apply 8.4 kg of CRF 14N-14P-14K per cubic meter of the substrate to produce black pepper plantlets with adequate commercial pattern and chlorophyll levels. [ABSTRACT FROM AUTHOR]