Germination responses and resin production ofGrindelia glutinosa and G. tarapacana from the Atacama desert

Germination responses and early seedling growth were examined for Grindeliaglutinosa and G. tarapacana, two species that preliminary field and laboratory results had suggested could become a new resin crop for the hyper-arid Atacama desert in northern Chile. Initially we examined the germination responses to cold stratification and soil moisture. Stratification inhibited the germination of both species, but mostly of G. tarapacana. Best germination was obtained with about 50% soil moisture levels. Based on these results, we carried out factorial experiments with both species, two levels of nutrients and two levels of soil moisture. Although significant differences were not detected for the growth rate of the species, both benefited from nutrient and humidity additions. Germination rate of G. glutinosa was, in all cases, significantly higher than that observed for G. tarapacana. Resin yields were 17% for G. glutinosa and 26% for G. tarapacana, very high compared with the yields of other species in the genus