The environmental adaptation strategy of seed germination, and roles of the seed pappus on dispersal and hypocotyl hairs on seedling anchorage inTamarix ramosissima

Abstract

Seed dispersal, germination and seedling establishment are affected by various ecological factors in desert plant species. Tamarix ramosissima Ledeb. has evolved multiple strategies to facilitate its survival in harsh environments during the early stages of development. In this study, we investigated the effects of different ecological factors on seed germination and seedling growth, the function of the seed pappus in seed dispersal, as well as the function of the hypocotyl hairs in seedling establishment. We found that the seed germination of T. ramosissima was rapid and could occur under a wide range of temperatures (5–30°C), after long periods of storage (at least 12 months on dispersal), under high concentrations of salts (700–900 mmol·L -1) and PEG 6000 (500 g·L -1) and under medium concentrations of alkalis (300–500 mmol·L -1). Lower concentrations of salts and PEG promoted seedling growth. The seed pappus had no effect on seed germination, but it might function as an accessory structure that provides a buoyancy force and promotes long-distance seed dispersal. The hypocotyl hairs located on the edge of the hypocotyl end might aid the upright positioning of the seedlings during early development, especially when seed germination occurs under floating or flooding conditions. In conclusion, the germination of T. ramosissima seeds and seedling development can occur under diverse types of abiotic stress, and the seed pappus and hypocotyl hairs played an important role in seed dispersal and seedling establishment.

The Developmental Delay of Seedlings With Cotyledons Only Confers Stress Tolerance to Suaeda aralocaspica (Chenopodiaceae) by Unique Performance on Morphology, Physiology, and Gene Expression

“…Paraffin sections were prepared following Li et al ( 2021 ) to visualize the development of the apical growth point of seedlings in S. aralocaspica . For fixation, an FAA solution was used to fix the tissue of the joint part between two cotyledons and the hypocotyl.…”

Structural modifications in Bermuda grass [Cynodon dactylon (L.) Pers.] ecotypes for adaptation to environmental heterogeneity

“…For instance, plant capacity to maintain high water potential was largely explained by the anatomical modifications including cuticular composition, greater leaf thickness, and stomatal behavior that were associated with increased resistance to water flux ( Bolger et al, 2014 ), Thus structural modifications are important to assess degree of tolerance in plant species under variety of environmental stresses in addition to other physiological and biochemical processes ( Moray et al., 2015 ). In this context, structural development and modification are crucial in the survival and growth of plants under harsh climatic conditions ( Li et al.2022 ; Li et al., 2021 ). Modifications such as pubescence or salt hairs and glands ( Ahmad et al., 2016 ), aerenchyma formation ( Watson et al., 2015 ), succulence, stomatal size, density and orientation, bulliform cells ( Manokari et al., 2021 ; Iqbal et al., 2022 ) and high plasticity vessel numbers and lumina contribute to the prevailing water availability ( Beniwal et al., 2010 ).…”