# Determining the Dormancy Type of the Endangered Linum mulleri by Testing 7000 Seeds

## TL;DR

This study tested 7000 seeds of the endangered Linum mulleri to determine its dormancy type and germination conditions for better conservation strategies.

## Contribution

The study identifies type 3 non-deep physiological dormancy in Linum mulleri using a large seed sample and various germination treatments.

## Key findings

- Germination was highest at 15 and 20 °C, with less than 5% at 5 and 30 °C.
- Warm stratification, dry after-ripening, and GA3 effectively overcame dormancy and expanded germination temperature ranges.
- Cold stratification induced secondary dormancy, delaying germination.

## Abstract

Linum mulleri is an endemic taxon of southwestern Sardinia (Italy), categorised as Endangered (EN) on the IUCN Red List and included in Annexes II and IV of the Habitats Directive (92/43/EEC) as priority species for conservation. This study investigated the germination ecophysiology of L. mulleri and the possible presence of dormancy by using 7000 seeds, providing useful information for conservation strategies. The germination response of fresh seeds was evaluated under different temperatures, photoperiods, pre-treatments [cold stratification (C); warm stratification (W); W+C; C+W+C; dry after-ripening (DAR)], and different gibberellic acid (GA3) concentrations. L. mulleri germinated under controlled conditions, particularly at 15 and 20 °C, while germination percentages (GP) never exceeded 5% at 5 and 30 °C. C and C+W+C induced secondary dormancy, delaying germination, whereas W, DAR, and GA3 stimulate it. Light and dark incubation showed no significant differences in regards to GP. W, DAR, and 250 mg/L GA3 effectively overcame physiological dormancy (PD), expanding the germination temperature range to below 10 and above 25 °C. These responses suggested type 3 non-deep PD, as germination temperatures extended from a moderate range to both low and high temperatures. Analyzing 7000 seeds provided crucial information regarding dormancy and germination strategies, supporting both ex situ and in situ conservation efforts.