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 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.

A produtividade agronômica e florestal sofrem restrições impostas pela deficiência hídrica, alta temperatura e alta radiação solar. Este trabalho objetivou avaliar as capacidades de atenuação do estresse e promoção de crescimento da aplicação de ácido salicílico (AS) a mudas de eucalipto (híbrido E. urophylla x E. grandis) submetidas a deficiência hídrica. Adotou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 3x4 (três regimes de irrigação: irrigação constante com 40% (IC40%) ou 100% (IC100%) de reposição diária da água evapotranspirada e suspensão temporária da irrigação com apenas 40% de reposição da água evapotranspirada (S40%); e quatro concentrações de AS: 0 mg L-1, 100 mg L-1, 200 mg L-1 e 300 mg L-1). Foram avaliados parâmetros fotossintéticos das plantas e características biométricas de crescimento. A limitação estomática foi maior nas plantas submetidas ao regime de irrigação S40%, entretanto, a aplicação de AS reverteu esse resultado, permitindo a manutenção do potencial fotossintético. Houve interação entre regimes de irrigação e doses de AS para número de folhas, relação área foliar/ número de folhas e massa seca da parte aérea e raiz. Concluiu-se que a aplicação de 200 mg L-1 de AS afetou positivamente o crescimento das mudas de eucalipto sob condição de deficiência hídrica, constituindo-se como técnica de manejo auxiliar para o seu processo de rustificação.

The agricultural and forest productivity suffer restrictions imposed by water stress, high temperature and high solar radiation. This study aimed to evaluate the capacity of stress attenuation and growth promotion of salicylic acid (SA) application in eucalyptus (E. urophylla x E. grandis hybrid) seedlings under water stress. A completely randomized design, in a 3x4 factorial scheme (three water treatments: constant irrigation with daily replacement of 40% (CI40%) or 100% (CI100%) of evapotranspirated water, and temporary irrigation suspension with replacement of only 40% of evapotranspirated water (S40%); and four SA concentrations: 0 mg L-1, 100 mg L-1, 200 mg L-1 and 300 mg L-1), was used. Plant photosynthetic parameters and biometric features were evaluated. The stomatal limitation was higher in plants under S40% irrigation, however, the SA application reverted this result, allowing the maintenance of the photosynthetic potential. There was interaction between irrigation regimes and SA doses for number of leaves, leaf area/number of leaves ratio and shoot and root dry mass. It was concluded that the application of 200 mg L -1 of SA positively affected the growth of eucalyptus seedlings under water stress, being considered an auxiliary management technique to their hardening process.

As sementes de pimenta podem apresentar baixas taxas de germinação, fato que, aliado ao desconhecimento do melhor estádio de colheita das mesmas, limita a oferta de sementes com máximo rendimento e alto vigor. Este trabalho objetivou avaliar a emergência de sementes de pimenta jalapenho extraídas de frutos colhidos aos 128 dias após o plantio, apresentando dois estádios de maturação (verde e vermelho) e submetidas ao armazenamento por 0, 7, 14, 21 e 28 dias, antes da extração das sementes. A qualidade fisiológica das sementes foi avaliada pelos testes de percentagem de emergência, primeira contagem de emergência, índice de velocidade de emergência e condutividade elétrica. Pôde-se concluir que, independentemente do estádio de maturação dos frutos, a permanência das sementes dentro deles proporcionou aumento de vigor nas sementes. A permanência das sementes por 28 dias, dentro dos frutos colhidos verdes, mostrou-se ideal para que as sementes completassem o seu desenvolvimento e adquirissem maior qualidade fisiológica.

Pepper seeds can show low germination rates and that, together with the unfamiliarity concerning their best harvest time, limits the seeds offering with maximum yield and vigor. This study aimed at evaluating the emergence of jalapeno pepper seeds obtained from fruits harvested at 128 days after sowing, with two maturation stages (green and red) and stored for 0, 7, 14, 21 and 28 days, before the seeds extraction. The seeds physiological quality was evaluated by using the tests of emergence percentage, first emergence counting, emergence rate index and electrical conductivity. It was possible to conclude that, independently of the fruit maturation stage, the post harvest rest of seeds inside the fruit increased their vigor. The post harvest rest for 28 days inside green fruits showed to be ideal for a complete seed development and higher physiological quality.

O objetivo deste trabalho foi avaliar os efeitos da deficiência hídrica e aplicação de ácido abscísico (ABA) sobre aspectos fisiológicos e teor de flavonoides em plantas de calêndula. O experimento foi instalado em condições de casa-de-vegetação com plantas envasadas. No início do florescimento de plantas de calêndula, foram aplicados quatro intervalos de suspensão da irrigação (irrigação diária; três; seis e nove dias sem irrigar), acompanhados por três doses de ABA (0, 10 e 100 μM). Avaliou-se o conteúdo relativo de água na folha (CRA) e as trocas gasosas, utilizando-se um analisador portátil por infravermelho (A: fotossíntese líquida, gs: condutância estomática, E: transpiração, Ci: concentração intercelular de CO2 e EUA: eficiência de uso da água). Aos nove dias sem irrigação ocorreram reduções significativas em todas as variáveis de trocas gasosas analisadas, independente da aplicação de ABA. Concluiu-se que o efeito principal do ABA foi o de causar diminuição na gs, a qual foi acompanhada de redução em A somente quando as plantas estavam desidratadas. As intensidades de deficiência hídrica testadas não causaram interferência no acúmulo de flavonoides nas inflorescências. Entretanto, o ABA restringiu a biossíntese de flavonoides, tanto nas plantas-controle como nas plantas submetidas à deficiência hídrica.

The goal of this study was to evaluate the effects of water deficit and abscisic acid (ABA) application on physiological parameters and flavonoid production in marigold plant. The experiment was performed under nursery conditions with potted plants. It was tested water deficit by withholding water (control - diary irrigation, 3, 6 and 9 days without irrigation) followed by 3 ABA concentrations (0, 10 e 100 μM) applied in the beginning of blooming. It was evaluated the relative water content and the leaf gas exchange using a portable infrared gas analyzer (A: net photosynthesis, gs: stomatal conductance, E: transpiration, Ci: CO2 intercellular concentration and EUA: water use efficiency). At the end of 9 days of water deficit there were significant decreases in all the characteristics evaluated, independent of ABA application. This suggests that the main effect of ABA was to cause a reduction on gs which was accompanied of a reduction in A, only when the plants were submitted to the water deficit. There was no significant difference among the levels of water deficit tested in relation to the total flavonoid content in inflorescences. However, ABA restricted the flavonoids biosynthesis both in control plant and stressed plants.