ABSTRACT Essential oils in plants are produced in very low concentrations and elicitation stands out among the techniques used to increase their productivity. This work evaluated the potential elicitor of salicylic acid (SA) or seaweed extract (SE) on the biomass yield, physiological parameters and essential oil production in Varronia curassavica Jacq. plants. The elicitors were applied through foliar spray in four serial applications (21, 34, 53 and 70 d after transplanting the seedlings to the pots - DAT), in concentrations of 1 mM (SA) and 5 mL L-1 (SE). The control plants were sprayed with water. Biometric measurements of plant height and number of branches were performed after 2, 3 and 4 elicitor applications. Plants were harvested at 91 DAT and biometric, biochemical and phytochemical parameters were evaluated. Application of SA resulted in increases in number of leaves (11.68%) and foliar concentrations of chlorophylls (57.67%), anthocyanins (73.80%), carotenoids (42.58%), total soluble sugars (19.48%) and essential oil (18%). The plants treated with SE had no changes in leaf biomass or essential oil production. The SA treatment increased by twice the amount of α-humulene and (E)-caryophyllene present in the essential oil while for SE treatment there was an average increase of 78.6%. It was concluded that the elicitation of V. curassavica plants by SA foliar pulverization is an efficient strategy for promoting the higher productivity of leaves and essential oil. Foliar pulverization of SA or SE modifies essential oil quality, inducing increases in the compounds of greatest interest for the pharmaceutical industry.

ABSTRACT Iron (Fe) is an essential micronutrient for plants, as a cofactor in multi-heme cytochromes and within iron-sulfur clusters. However, Fe can be toxic at high concentrations. Free Fe in cells can disrupt the cell redox balance toward a pro-oxidant state, generating oxidative stress. The focuses of this review were to elucidate the Fe detoxification strategies used by plants, as well as describe the Fe excess effects on the plant body and its impact on the physiological, morphological and metabolic traits. Therefore, we highlight the importance of evaluating Fe toxicity and provide a paper compilation on Fe detoxification strategies and morpho-physiological responses to excess Fe, directing further research in this segment.

ABSTRACT Sweet potato [Ipomoea batatas (L.) Lam.] has wide adaptability to different climatic conditions. However, its yield can be affected by prolonged periods of drought. Application of exogenous jasmonates can modulate several physiological and biochemical processes, improving plant tolerance to abiotic stress. This study sought to evaluate the role of exogenous application of methyl jasmonate (MeJA) in attenuating the adverse effects of drought stress by physiobiochemical analyses and their impact during the early initiation of tuberous roots. The experimental design was completely randomized and arranged in a 2 x 2 factorial, comprised of two concentrations of a MeJA plant regulator [without (0 µmol·L-1) and with (13 µmol·L-1) application] and two water regimes (optimum and drought conditions, corresponding to a field capacity of 100 and 40%, respectively). Plants treated with MeJA showed a reduction in total leaf area and leaf dry biomass but increased adventitious root dry biomass. In addition, MeJA application in sweet potato plants affected photosynthetic performance and increased and antioxidant phenolic compounds, carotenoids, anthocyanins, and proline. The evaluated response mechanisms showed that the severity of drought was more prominent than the positive effects of MeJA, since the increases on antioxidant pigments and secondary metabolites were not sufficient to mitigate stress caused by drought, which was reflected in the reduced tuberous root production.

RESUMO: O cultivo do algodoeiro no Brasil está concentrado no período chuvoso, e no momento do estabelecimento da lavoura frequentemente há períodos prolongados de baixa radiação solar. O objetivo deste trabalho foi avaliar o desenvolvimento radicular de cultivares de algodoeiro submetidos ao sombreamento na fase inicial da cultura. O experimento foi realizado em ambiente controlado, em rizotrons. O delineamento experimental foi um fatorial 2x2 em blocos ao acaso com cinco repetições. Os tratamentos foram as cultivares de algodão TMG 11WS (precoce) e TMG 81WS (tardia) e as condições de sombra: sem sombra e com sombra (50% de redução da luminosidade). Não houve interação entre os fatores “sombra” e “cultivares estudadas” para nenhum parâmetro avaliado. A sombra reduziu o crescimento radicular total e das raízes laterais a partir dos 21 dias de emergência (DAE) e da raiz principal aos 24DAE. O sombreamento reduziu o comprimento (60%), a superfície (65%), o diâmetro médio (15%), o comprimento por volume (60%), o volume radicular (69%), a massa de matéria de seca da raiz (83%) e da parte aérea (64%), o teor (36%) e o acúmulo de carboidratos na parte aérea (73%). Em conclusão, o sombreamento na fase inicial de desenvolvimento do algodoeiro reduz a produção de carboidratos da parte aérea, afetando o acúmulo de matéria seca e o crescimento radicular, sendo que essa resposta independe da cultivar.

ABSTRACT: Cotton cultivation in Brazil tends to occur mostly in the rainy season, and at the time of developing the crop there are often prolonged periods of low solar radiation. The objective of this work was to evaluate the root development of cotton cultivars subjected to shading in the initial phase. The experiment was carried out in a greenhouse, using rhizotrons. The experimental design was a 2x2 factorial in randomized blocks with five replications. The treatments were composed of cotton cultivars TMG 1WS (early) and TMG 8WS (late) and luminosity conditions: non-shaded and shaded (50% reduction of luminosity). There were no interactions between the factors “shading” and “cultivars” for any parameter evaluated. Shading reduced total and lateral root growth from the 21 days after emergence (DAE) and the main root at 24DAE. Shading caused reductions in length (60%), surface (65%), mean diameter (15%), root volume (69%), root dry matter mass (83%) and shoot (64%), as well as decreasing the content (36%) and the accumulation of carbohydrates in the shoot (73%). Shading at early cotton development reduces the shoot carbohydrates production, affecting dry matter accumulation and root growth, and this response is independent of the cultivar.

Resumo O funcho é uma planta medicinal, condimentar e ornamental, utilizada na culinária brasileira e na fabricação de cosméticos e de fitoterápicos. A aplicação exógena do ácido salicílico (AS) pode agir na ação hormonal, estimulando o crescimento e o desenvolvimento vegetal, e na indução das respostas de defesa das plantas. O objetivo deste trabalho foi determinar o efeito da aplicação foliar de AS sobre a produção de biomassa e a síntese de compostos secundários em plantas de funcho, uma espécie medicinal produzida comercialmente como matéria-prima para a indústria mundial de fitomedicamentos. O experimento foi conduzido em plantas envasadas em estufa, sem controle de umidade e temperatura. A aplicação do AS foi efetuada nas concentrações 0; 0,25; 0,50 e 1,00 mM, aos 20 dias e 90 dias após o transplante das mudas para os vasos. O efeito do AS sobre o metabolismo das plantas de funcho foi avaliado através de parâmetros biométricos de crescimento e bioquímicos. Conclui-se que a aplicação exógena de AS constitui-se em técnica de manejo vantajosa para a obtenção de aumento na biomassa das plantas de funcho: massa seca da parte aérea, na concentração de 0,50 mM, e massa seca de raízes e razão raiz/parte aérea, na concentração de 0,25 mM. O efeito elicitor foi obtido na concentração de 0,25 mM de AS, resultando em maior valor econômico da matéria-prima, devido ao aumento na produção de compostos secundários, tais como fenóis totais e flavonoides, além de um concomitante aumento na atividade antioxidante do extrato vegetal e no teor do óleo essencial nesta espécie, na concentração de 1,00 mM.

Abstract Fennel is a medicinal and aromatic plant that is commonly used in Brazilian cuisine and in the manufacture of cosmetics. The exogenous application of salicylic acid (SA) can act on the hormonal action stimulating plant growth and development and the induction of plant defense responses under stressful conditions. The objective of this study was to determine the effect of the foliar application of SA on the production of biomass and synthesis of secondary compounds in fennel plants. For this purpose, an experiment was carried out in potted plants in a greenhouse with the application of SA at concentrations of 0, 0.25, 0.50 and 1.00 mM, 20 days and 90 days after transplanting the seedlings to the pots. The effect of SA on the metabolism of the fennel plants was evaluated using growth and biochemical parameters. The exogenous application of SA increased the plant shoots dry weight at the concentration of 0.50 mM, whereas an improved dry root mass and root/shoot ratio was achieved with the concentration of 0.25 mM. The elicitor effect was observed at 0.25 mM of SA, resulting in greater economic value of the biomass due to the higher production of secondary compounds, such as phenolic compounds and flavonoids. In addition, an increase in antioxidant activity of the plant extracts and of the essential oil content of the species was obtained at the concentration of 1.00 mM.