Seed longevity, viability and germination of four weed-ruderal Asteraceae species of ethnobotanic value

Abstract

Background: A high proportion of Asteraceae species are considered weeds, some of them have recognizable biological properties. To design production protocols and ex situ seed conservation programs is necessary to determine the effect of storage temperature on seed viability and longevity. It is known that cold temperatures maintain seed viability and thus prolong seed longevity. Hypotheses: The seeds of Aldama dentata, Verbesina virgata, Stevia origanoides and Roldana barba-johannis stored at low temperature (5 ºC) will have greater longevity than when stored at room temperature (16.45 ± 1.94 oC) and will decrease their viability as they age. Study site and dates: Seeds of the four Asteraceae were collected (November-December 2015) in The National Park “El Tepozteco”, Morelos, Mexico and in the “Chamilpa” campus of the Universidad Autónoma del Estado de Morelos. Methods: The monthly germination experiments (11) were implemented with seeds stored under both temperatures, germination (%) and mean germination time were registered to estimate seed longevity. The seed viability stored at room temperature was evaluated with the tetrazolium test. Results: Germination and viability decreased with seed age. Along the experiment, seed germination was similar at both storage temperatures. A. dentata and S. origanoides showed the highest germination but A. dentata alone reached the major seed viability. The oldest seeds germinated faster. Conclusions: Seed longevity of all the species exceeded one year. For propagation purposes, it is recommended to use seeds between 8 and 9 months of age, when their germination and viability are the highest.