Geophyte ecophysiology and traits

Premise of the study: In semi-arid regions, decreasing rainfall presents a challenge to perennial seedlings that must reach sufficient size to survive the first year’s seasonal drought. Attaining a large storage organ size has been hypothesized to enhance drought resilience in geophytes, but building larger storage organs requires greater growth rates, and paradoxically, some traits conferring faster growth are highly sensitive to drought. We examine if tuber size confers greater drought resilience in seedlings of four closely related geophytic species of Pelargonium.

Methods: We imposed two drought treatments when seedlings were two months old: chronic low water and acute water restriction for ten days. Plants in the acute dry-down treatment were then rewatered at control levels. We compared morphological and ecophysiological traits at two, three and six months of age and used mixed-effects models to identify traits determining tuber biomass at dormancy.     

Key results: Despite...