Salicylic acid in marigold seeds (Calendula officinalis L.) under different stressesMarigold (Calendula officinalis L.) is an important medicinal and decorative plant also used in cooking and in the manufacturing of cosmetic and phytotherapic products. The plants are susceptible to biotic and non biotical aggression and although they do not present defense through agile movement, they can present deep modifications in the cell metabolism as defence including protein synthesis activated by single molecules or complex mechanisms. The exogenous application or the synthesis stimulus of organic acids such as salicylic acid may act as an inductor of tolerance protein to different biotical or non biotical stresses increasing the detoxification enzyme activity, specially those involved in the degradation of reactive oxygen species. The aim of this study was to investigate the role of salicylic acid in the germination and vigour of marigold seeds (Calendula officinalis L.) in ideal or stress conditions. Seeds were put to germinate on paper moistened with SA (zero; 0.0125; 0.025; 0.05; 0.1 and 0.2mM). Germination, first germination count and germination speed index were measured. Only germination was significant, and the best doses were 0.025 and 0.05mM SA. Three other experiments were carried out, one with acid water, adjusted to the pH of the related salicylic acid solutions (6.0; 4.8; 4.2; 3.6 and 3.2), one with different water potentials, induced by mannitol (0; -0.3; -0.6; -0.9 and -1.2MPa) and one with different temperatures(20, 25, 30 e 35ºC).The salicylic acid treatment of 0,025 mM was positive for germination and the germination speed index of Calendula officinalis Marigold seeds under ideal conditions and water stress at the temperature of 35 C.
systemic acquired resistance; water deficit; germination
