Effect of salt stress on the growth of Lippia gracilis Schauer and on the quality of its essential oil

Abstract

This study evaluated the effect of salt stress on the growth of Lippia gracilis Schauer, a species native to the caatinga (shrublands) of Brazil and rich in essential oils, as well as on the quality of its oil. We exposed individuals of L. gracilis to NaCl, in the following concentrations, for a period of 40 days: 25 mM; 50 mM; 75 mM; and 100 mM. An additional group of plants was not exposed to NaCl (controls). Data were collected on days 20 and 40. We evaluated relative growth rate; shoot and root dry weight; relative water content; proline concentration in leaves; and chemical composition of the essential oil. At all concentrations, NaCl reduced the relative growth rate in comparison with that observed for the controls. No significant difference in relative water content was observed among treatments. In all treatments, the proline concentration in leaves was highest on day 40. Salt stress did not affect the yield or the concentrations of the constituents of the essential oil of L. gracilis, carvacrol and thymol showing the highest concentrations in all treatments.

‘Doce do Havaí’ Maize Cultivar Presents Tolerance to Saline Stress in Hydroponic Cultivation

“…In that study, the water content did not differ statistically, showing that there was not a variation due to the accumulation of soluble compounds responsible for osmotic adjustment. This response possibly indicates an adaptive mechanism in which the stability of water content under saline stress reflects the soluble compound accumulation in leaves, allowing osmoregulation and hydration maintenance as verified by Ragagnin et al (2014).…”

Salt-induced changes in solutes, pigments and essential oil of two basil (Ocimum basilicum L.) genotypes under hydroponic cultivation

“…In aromatic plants the production and biosynthesis of secondary metabolites are strongly influenced by biotic and abiotic stresses (Çoban and Baydar, 2016). Under salt conditions, the essential oil content in plants may decrease (Khorasaninejad et al, 2010), increase (Bernstein et al, 2010) or not change (Ragagnin et al, 2014), depending on the species studied. It has been reported that the increase in oil content is commonly followed by restriction of biomass production (Valifard et al, 2014;Rebey et al, 2017).…”

Prolina livre e flavonoides totais de Lippia origanoides submetidos a níveis de saturação por base e estresse hídrico

“…Segundo os autores, mesmo baixo, para a espécie, este valor é uma resposta da planta submetida ao estresse hídrico e ácido salicílico, que desempenha funções fisiológicas análogas ao silício. Enquanto que a Lippia gracillis submetida às concentrações crescente de NaCl (0,25 a 100 mM), aumentou o teor de prolina de 1,03 na planta controle para 7,56 mg g -¹ de prolina de massa fresca aos 40 dias após estresse, não diferindo entre as concentrações (Ragagnin et al, 2014). O baixo teor de prolina na espécie estudada em relação às espécies aromáticas acima mencionadas pode ser devido à especificidade de metabólitos secundários em resposta fisiológica como mecanismo químico de defesa de cada espécie.…”

“…Este fato explica a razão deste teor de prolina para a planta, pois, ainda que este seja um aminoácido livre acumulado em resposta passiva ao estresse, nesta espécie é produzido em menores quantidades. Os resultados deste estudo mostraram que é possível cultivar plantas medicinais com baixa disponibilidade hídrica, uma vez que a qualidade do produto, independe da escassez de água, sendo mais sensível às variações na temperatura (Ragagnin et al, 2014;Ribeiro et al, 2016).…”