Why flowers close at noon? A case study of an alpine species Gentianopsis paludosa (Gentianaceae)

Abstract

Repeatable floral closure with diurnal rhythms, that is, flower opening in the morning and closing in the evening, was widely reported. However, the rhythm of flower opening in the morning but closing in the midday received much less attention.Gentianopsis paludosa, Gentianaceae, has an obvious petal movement rhythm opening in the morning and closing at noon at northeast of the Qinghai-Tibetan Plateau.In this study, we examined the effects of temperature (T), relative humidity (RH), and illumination intensity (II) on G. paludosa's flower closure. Furthermore, we monitored the environmental changes inside and outside of the flowers, aiming to test the effect of floral closure on the stability of microenvironment inside the flower. Finally, we artificially interrupted temporal petal closure and investigated its effects on reproductive fitness. The results showed that high/low temperature contributed more to the flower closure than low RH, while illumination intensity had no significant effect on it. The medium temperature, relative humidity and illumination intensity (environmental conditions at 10:00) did not delay flower closure when flowers at pre-closing period or stimulate reopen when flowers full closed. Floral closure provided a stable temperature condition and a higher RH condition inside the flower. Meanwhile, compulsive opening and delayed closure of flowers decreased the seed-set ratio while no effect was found when flowers were forced to close. We conclude that endogenous rhythm regulates floral closure. The rhythm of petal movement providing a stable microenvironment for G. paludosa, increasing the seed production and saving energy from flower opening maintenance, which might be an adaptive strategy to against unfavorable environmental conditions.

Dynamic Shape Change of Liquid Crystal Polymer Based on An Order‐Order Phase Transition

“…An exemplary instance is the opening and closure motion of flowers, often regulated by an intricate interplay of factors such as internal circadian rhythms, light, temperature, and moisture. Taking inspiration from Gentianopsis Paludosa, an alpine herb known for its petal movement rhythm of opening in the morning within a stable microenvironment, and closing during the heat of noon and the chill of night, [17] we fabricate a flower‐shaped bilayer actuator by laminating Kapton tape onto the LCP film at 60 °C. This actuator emulates closure and blooming motions over a temperature range of 25 to 60 °C (Figure 4b, refer to Movie S15), capturing the essence of the natural phenomenon.…”

Urban environment decreases pollinator availability, fertility, and prolongs anthesis in the field bindweed ( Convolvulus arvensis Linnaeus, 1753)

“…Except for the effect of urbanization, the duration of the anthesis was negatively influenced by the intensity of the illumination, but not by the relative humidity. Light is tightly associated with temperature and humidity, 27 and an interaction of these environmental factors influences the circadian clock. 52 These factors need to be addressed under well-controlled laboratory conditions.…”

“…These behaviors seem to be very sensitive to urbanization; for example, summer blooming plants occurring in high human population densities are associated with extended flowering duration. 25 Flowering duration is a result of complicated interactions involving abiotic (temperature [urban heat effect, climate change, 25 relative humidity and illumination, 26 , 27 and biotic factors (pollinator availability. 26 , 28–36 Flowering is costly, 29 , 37 thus a reduction of flowering duration prevents additional physiological costs associated with flowering duration.…”

Reproductive biology and pollination ecology of Ipomoea triloba L. (Convolvulaceae): An alien invasive species of the Indo‐Burma biodiversity hotspot

“…inside the corolla tube to enhance the rate of pollen germination and pollen tube growth (Delgado-D avila et al, 2016;Zhang et al, 2021). However, single-day open flowers with a relatively short anthesis period might pause a dilemma of lower reproductive fitness by decreasing the chances of outcrossing due to the shortened representation time of floral resources to the pollinators (Hou et al, 2022).…”