Comparison of sand burial-dependent growth responses of two Tragopogon species from different habitats

Gederts Ievinsh,Kristīne K Lejniece

doi:10.35513/botlit.2021.1.2

Abstract

Wind-driven sand movement leading to sand burial is an essential environmental factor in coastal sand dunes; therefore, plants native to sand dunes need to possess specific adaptations. The present study aimed to compare responses to variable sand burial intensity of Tragopogon heterospermus, rare plant species native to coastal dunes, and Tragopogon pratensis taxonomically related grassland species. Plants in culture were established from seeds collected in natural habitats, cultivated in an automated greenhouse, and individuals of different age were buried by sand in the different depths. Both plants had basic sand burial tolerance, seen as an elongation of adult plants’ leaf bases under moderate sand burial conditions. However, only dune-adapted T. heterospermus plants exhibited efficient resource allocation from roots to shoots with increased sand accretion intensity. T. heterospermus plants had pronounced age dependence of burial tolerance, with higher sensitivity to sand burial at an earlier stage due to small shoot height and, possibly, certain physiological factors.

Highlights

Wind-driven sand movement leading to both sand accretion and sand erosion is an important environmental factor in coastal dunes, affecting both species distribution and their physiological status (Lee & Ignaciuk, 1985; Maun & Perumal, 1999; Isermann, 2011; Dech & Maun, 2005; Keijsers et al, 2015)
The age and height of T. heterospermus seedlings at the beginning of sand burial treatment had a significant effect on their burial tolerance
Lower sand burial intensities (4.5, 9 and 14% of plant height buried by sand) were used with the 36-day-old T. heterospermus plants to find a relationship between the degree of moderate burial and that of leaf elongation response

Summary

Introduction

Wind-driven sand movement leading to both sand accretion and sand erosion is an important environmental factor in coastal dunes, affecting both species distribution and their physiological status (Lee & Ignaciuk, 1985; Maun & Perumal, 1999; Isermann, 2011; Dech & Maun, 2005; Keijsers et al, 2015). The open dune species’ ability to successfully grow and reproduce under the influence of sand burial is related to specific adaptations at the morphological and physiological level (Hesp, 1991; Ievinsh, 2006). Even within the same sand-affected habitat type, the degree of particular species’ adaptivity to sand burial can differ significantly. Response to sand burial is a complex and highly dynamic biological process, which involves different structural organisation levels and various mechanisms, from the perception of the environmental signals to hormonal regulation, gene expression and resulting metabolic and morphological changes (Maun, 1998). An ecologically significant feature of plants regarding sand burial is related to changes with the individual’s ontogenetic phase in the degree of tolerance and type of responses. Seedlings and smaller young plants are less tolerant to sand accretion (Li et al, 2010); intensity, and timing of the burial episode in respect to the Ievinsh G., Lejniece K.K

Methods

Results

Conclusion