Complementary water and nutrient utilization of perianth structural units help maintain long floral lifespan inDendrobium

Abstract

Most orchids have high ornamental value with long-lived flower. However, the mechanisms by which orchids maintain floral longevity are poorly understood. Here, we hypothesized that long floral longevity in Dendrobium is maintained by high resource investment and complementary water and nutrient utilization in different structural units of the perianth. To test this hypothesis, we determined which water- and nutrient-related traits are correlated with flower longevity in twenty-three Dendrobium species or cultivars and examined the variations of the related traits during flower development of one long-lived cultivar. We found that floral longevity was correlated with dry mas per unit area of perianths and total flower biomass, which indicates that maintaining long floral longevity requires increased resource investment. During development of long-lived flowers, labella showed high capacity for water storage and nutrient reutilization, which can partly remedy high water demand and biomass investment. Sepals and petals, in contrast, had stronger desiccation avoidance and higher metabolic activity with lower biomass investment. These findings indicate that Dendrobium flowers maintain longevity by complementary water and utilization strategies in the sepals, petals and labella, with labella consuming more water and nutrients to extend flower display, while sepals and petals use a more conservative strategy.

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

“…Previous study showed that the relationship between water potential at the turgor loss point (ψ tlp ) and osmotic potential at full turgor (ψ sft ) is the same for flowers and leaves, suggesting that the methods for rapidly assessing turgor loss point in leaves from osmometer measurements ( Bartlett et al., 2012 ) can also be applied to flowers ( Roddy et al., 2019 ; Li et al., 2022 ). Therefore, we measured flower osmotic potential using the VAPOR pressure osmometer model 5600 (ELITechGroup Inc, Logan, USA).…”

Monocots and eudicots have more conservative flower water use strategies than basal angiosperms

“…A previous study found that flower structure-function relationships are related to flowering time and that the corolla buffers high evaporative demand during dry periods by increasing water content (Teixido et al 2019). The prolonged existence of long-lived flowers might significantly deplete plant water and energy resources (Nobel 1977;Southwick 1984;Li et al 2022). These findings indicate that flowers regulate the water demands of long-lived flowers by enhancing water retention within floral tissues or increasing water storage capacity.…”

“…For instance, high temperatures and drought can reduce floral longevity, while favourable environmental conditions can prolong it (Jorgensen & Arathi 2013;Teixido & Valladares 2015). Although long-lived flowers increase reproductive opportunities, they also require more carbon and water for maintenance (Ashman & Schoen 1994;Zhang et al 2017;Li et al 2022). Moreover, under reduced water supply, flower size consistently decreases Kuppler & Kotowska 2021).…”

Metabolic, physiological, and anatomical analyses reveal that storage in the scapes of Dendrobium ‘Garnet Beauty’ contributes to maintaining racemes

“…Previous studies have indicated that orchids characterized by prolonged flower longevity often possess a larger floral biomass, higher dry weight per unit area, and greater floral thickness. These findings imply that orchids incur high construction and maintenance costs to support the longevity of their flowers (Zhang et al, 2021;Li et al, 2023). Notably, it has been established that there are significant variations in the longevity of flowers produced at different positions within an individual inflorescence (Zhang and Li, 2009), and some researchers have proposed that such spatial variation serves as an adaptive mechanism that enables plants to maximize the benefits of floral display, whilst reducing the detrimental effects (Zhang and Li, 2009).…”

“…Studying the functional traits of plant organs is an important approach for gaining an understanding of plant adaptations (Wright et al, 2004). Currently, however, research on the functional traits of floral organs is relatively limited compared with that on other organs, and the research that has been conducted has tended to focus on traits such as longevity, thickness, vein density, and biomass (Zhang et al, 2017;Zhang et al, 2021;Li et al, 2023). Among these, flower longevity reflects the conditions and functions of plant growth and reproduction, and is positively correlated with traits related to resource investment in plants (Roddy et al, 2021).…”