Convergent relationships between flower economics and hydraulic traits across aquatic and terrestrial herbaceous plants

Maintaining open flowers is critical for successful pollination and depends on long-term water and carbon balance.Yet the relationship between how flower hydraulic traits are coordinated in different habitats is poorly understood.Here,we hypothesize that the coordination and trade-offs between floral hydraulics and economics traits are independent of environmental conditions.To test this hypothesis,we investigated a total of 27 flower economics and hydraulic traits in six aquatic and six terrestrial herbaceous species grown in a tropical botanical garden.We found that although there were a few significant differences,most flower hydraulics and economics traits did not differ significantly between aquatic and terrestrial herbaceous plants.Both flower mass per area and floral longevity were significantly positively correlated with the time required for drying full-hydrated flowers to 70%relative water content.Flower dry matter content was strongly and positively related to drought tolerance of the flowers as indicated by flower water potential at the turgor loss point.In addition,there was a trade-off between hydraulic efficiency and the construction cost of a flower across species.Our results show that flowers of aquatic and terrestrial plants follow the same economics spectrum pattern.These results suggest a convergent flower economics design across terrestrial and aquatic plants,providing new insights into the mechanisms by which floral organs adapt to aquatic and terrestrial habitats.

Cavitation resistance of peduncle,petiole and stem is correlated with bordered pit dimensions in Magnolia grandiflora

Variation in resistance of xylem to embolism among flowers,leaves,and stems strongly influences the survival and reproduction of plants.However,little is known about the vulnerability to xylem embolism under drought stress and their relationships to the anatomical traits of pits among reproductive and vegetative organs.In this study,we investigated the variation in xylem vulnerability to embolism in peduncles,petioles,and stems in a woody plant,Magnolia grandiflora.We analyzed the relationships between water potentials that induced 50%embolism(P50)in peduncles,petioles,and stems and the conduit pit traits hypothesized to influence cavitation resistance.We found that peduncles were more vulnerable to cavitation than petioles and stems,supporting the hypothesis of hydraulic vulnerability segmentation that leaves and stems are prioritized over flowers during drought stress.Moreover,P50 was significantly correlated with variation in the dimensions of inter-vessel pit apertures among peduncles,petioles and stems.These findings highlight that measuring xylem vulnerability to embolism in reproductive organs is essential for understanding the effect of drought on plant reproductive success and mortality under drought stress.