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The physic nut is an oilseed plant that has stood out as an alternative source for biodiesel. However, using it in this way requires determining the edaphoclimatic conditions and adequate fertilization to guarantee maximum productivity. This study objectived to evaluate and establish adequate rates of Nitrogen (N), Phosphorus (P), Potassium (K) to maximize the growth and productivity of physic nut in two edaphoclimatic conditions. Two experiments were performed over two consecutive years, one under Quartzarenic Neosol in the municipality of Diamantina and the other under Red-Yellow Latosol in the municipality of Governador Valadares. The treatments comprised rates of N: 0, 25, 50, 100 kg ha−1; P: 0, 35, 70, 140 kg ha−1; and K: 0, 40, 80, 160 kg ha−1. Plant growth was evaluated every 30 days until flowering. Seed and oil productivity was also assessed, with one harvest in Diamantina and two harvests in Governador Valadares. The edaphoclimatic condition of Governador Valadares was a determining factor in providing greater growth and productivity of the physic nut when compared to that of Diamantina. The application of N rates was unnecessary for the growth and productivity of the physic nut in Diamantina. Thus, phosphate fertilization was unnecessary in Governador Valadares and potassium fertilization was unnecessary for both regions. In Diamantina, 84 kg ha−1 and 87 kg ha−1 of P is recommended for growth and maximum productivity, respectively. Whereas, in Governador Valadares, 49 kg ha−1 and 55 kg ha−1 of N is recommended for growth and maximum crop productivity, respectively. [ABSTRACT FROM AUTHOR]

Structural and physiological leaf traits and their plasticity were compared in the hemiepiphyte Vanilla phaeantha. This species grows along a phorophyte reaching different understorey positions and exhibiting diverse responses to environment changes. We analysed three height strata above the ground, establishing a light gradient, and considering seasonal water fluctuations. The upper leaves had higher area and mass and were less pigmented. The dry season induced a reduction of approximately 2 h of stomatal opening over the diel 24 h crassulacean acid metabolism (CAM) cycle in the leaves at all understorey positions. The leaves more exposed to sunlight were larger with higher titratable acidity during the rainy season, while the leaves near the ground maintained the same rates of stomatal conductance and nocturnal acidification between seasons, with lowest values of carbon isotopes in the rainy season. Our research showed that some structural leaf traits (such as specific leaf mass, biomass, and saturated water content) are sensitive to variation in understorey position. In contrast, other physiological traits (stomatal conductance, transpiration, and fluorescence parameters) are more sensitive to seasonal variations. The results are a novelty in assessing the variation of CAM along the same plant in a height gradient and under field conditions. Surviving in conditions of water fluctuation and light heterogeneity by plants requires to be plastic. We showed that the hemiepiphyte Vanilla phaeantha adjusts leaf traits and their metabolism for atmospheric CO2 capture in function of the vertical gradient of the understorey (that has different light availability and air humidity), and according to water seasonality. The morphological traits mainly varied according to the understorey position, while physiological ones were more sensitive to seasonal variations. [ABSTRACT FROM AUTHOR]

Phytoremediation is a technique with high viability due to its low cost and minimal environmental impact. However, there are a few results regarding the use of tropical grasses in the phytoremediation of manganese (Mn), and there is no clear definition of which extractor is more suitable for assessing Mn availability in soils. The objective of this study was to evaluate the growth potential and phytoremediation of five tropical grasses in Mn‐contaminated soil, as well as to assess the efficiency of four extractors in Mn extraction. The grass cultivars evaluated included Aruana and Tanzânia of Megathyrsus maximus, Xaraés and Marandu of Urochloa brizantha, and Basilisk of Urochloa decumbens grown in Typic Hapludox (Oxisol) amended with 0, 50, 150, and 450 mg of Mn per kg−1 of soil. The experiment was conducted in a greenhouse, using a completely randomized experimental design in a 5 × 4 factorial scheme, with five replications. The experimental period lasted for 90 days. The dry matter of the shoot and root of the grasses was evaluated. Mn concentration in dry matter and its availability in soil were extracted by Mehlich‐1 and DTPA pH 7.3, while the semitotal concentration was determined by USEPA 3051 and total Mn by USEPA 3052 method. Tropical grasses showed reduced growth with increasing Mn rates in the soil, with the following sequence in the reduction in growth: Aruana > Basilisk > Marandu > Xaraés and lastly the Tanzânia. The Aruana cultivar showed greater potential for phytoextraction due to its higher ability to accumulate Mn in its biomass, followed by the Basilisk cultivar. The four different evaluated extractors were efficient in measuring Mn concentrations in the soil, with higher toxicity critical levels for the USEPA 3051 method due to the semitotal extraction nature and USEPA 3052 due to total Mn extraction. The growth of tropical grasses is reduced with increasing Mn rates applied to the soil. The Aruana of M. maximus grass has greater potential for phytoextraction of Mn‐contaminated soils, followed by Basilisk of Urochloa decumbens, Xaraés and Marandu of U. brizantha, and Tanzânia of M. maximus. The Mehlich‐1, DTPA pH 7.3, USEPA 3051, and 3052 extractors were efficient in extracting and evaluating Mn availability in soil for tropical grasses. The USEPA 3051 and 3052 methods presented higher toxicity critical levels. [ABSTRACT FROM AUTHOR]

Phytoremediation has become a promising technique for cleaning Pb-contaminated soils. Grasses have a phytoextractor potential for extracting metal from soil by transporting it and accumulating it in high concentrations in their shoots, and they have the ability to immobilize and inactivate it via phytoliths. The objective of this work was to evaluate the phytoremediation potential of forage grasses through the production of phytoliths and the occlusion of Pb in the phytoliths cultivated in Pb-contaminated soils. Three greenhouse experiments were conducted in a completely randomized design, separated by soil type (Typical Hapludox, Xanthic Hapludox and Rhodic Hapludox), in a 3 × 4 factorial scheme consisting of three forage grasses (Megathyrsus maximus, Urochloa brizantha and Urochloa decumbens) and four Pb rates (0, 45, 90 and 270 mg kg−1) with four repetitions. The forage grasses were influenced by increases in the Pb concentrations in the soils. The higher Pb availability in Typic Quartzipsamment promoted Pb toxicity, as indicated by the reduced dry weights of the shoots, increased phytolith production in the shoots, increased Pb in the shoots and Pb occlusion in the phytoliths of the forage grasses. The production and Pb capture in the phytoliths in the grasses in the Pb-contaminated soils were related to the genetic and physiological differences in the forage grasses and the Pb availability in the soils. Urochloa brizantha was the most tolerant forage to the excess Pb, with a higher production of phytoliths and higher Pb occlusion in the phytoliths, making it a forage grass that can be used in the future for the phytoremediation of Pb-contaminated soils. [ABSTRACT FROM AUTHOR]