Propagula and shoots ofSyntrichia pagorum(Pottiaceae) exhibit different ecological strategies of desiccation tolerance

Abstract

Abstract We posed two questions regarding the desiccation tolerance (DT) of the moss Syntrichia pagorum: (1) What is the ecological strategy of DT in three available life phases (propagula, juvenile and adult shoots)? and (2) which desiccating factor, rate of drying or equilibrating relative humidity, has the greater effect on plant survival and health in these three life phases? Plants of S. pagorum were regenerated from an herbarium specimen collected from the American southwest, subcultured to remove field effects, and grown in Petri dishes on native sand for up to 6 months, producing in sequence juvenile shoots, adult shoots and propagula. Whereas juvenile shoots exhibited an ecological strategy of inducible desiccation tolerance (IDT), the propagula and adult shoots largely exhibited the strategy of constitutive desiccation tolerance (CDT). This conclusion was reached by subjecting each life phase to two rates of drying (20 min and 48 hours at subturgor) in combination with two equilibrating relative...