Influence of temperature on the germination and root size of Acmella oleracea (L.) R. K. Jansen

Acmella oleracea is a herbaceous plant native to the Amazon region that is currently arousing industrial interest due to its potential gastronomic, cosmetic and pharmaceutical uses. Accordingly, the objective of the current study was to test the influence of temperatures on A. oleracea seed germination and seedling vigor. A completely randomized design (CRD) with five treatments and five replicates was used. Treatments consisted of temperatures: 23, 26, 29, 32 and 35 oC. The study was conducted in BODtype climate chambers with relative humidity above 90% and a 12 h photoperiod. Germination, germination speed index (GSI), average germination time, root length and number of normal and abnormal seedlings were recorded. Temperature influenced all analyzed variables, except average germination time and number of normal/abnormal seedlings. A quadratic model best described the relationship between dependent and independent variables. In general, maximum germination values, and GSI and root lengths were obtained at temperatures close to 29 °C, while the lowest observed values for these variables occurred at extreme temperatures (23 and 35 °C). The highest percentage of germinated seeds occurred on the second day. Temperatures above 29 oC induced a significant reduction in the A. oleracea seedling root lengths.