Influence of Temperature on Seed Germination of Five Wild-Growing Tulipa Species of Greece Associated with Their Ecological Profiles: Implications for Conservation and Cultivation

Effect of Temperature on Breaking of Morphophysiological Dormancy and Seed Germination Leading to Bulblet Production in Two Endemic Tulip Species from Greece

Due to botanical tulips' economic interest coupled with limited information regarding their seed germination, we investigated the effect of temperature on dormancy release and germination in two endangered local endemic tulip species of Greece (Tulipa hageri Heldr., T. orphanidea Heldr.). Their germination responses at five constant temperatures (5, 10, 15, 20, and 25 °C) were evaluated in growth chambers, while the type of seed dormancy and the temperature effect on its release were determined based on open-sourced, R-derived species-specific ecological profiles illustrating abiotic conditions of their wild habitats. The results indicated a range-specific temperature dependence in seed germination for both studied species with seed germination observed only in very low temperatures (5-10 °C). The seeds of both species after dispersal had an underdeveloped embryo. The existence of a complex morphophysiological seed dormancy was confirmed in both species by the significant embryo development only at 5 and 10 °C (almost doubled after 30 days) coupled with observed delay in germination only at low temperatures. Furthermore, to facilitate their cultivation and ex situ conservation, the germinated seeds were planted in pots to develop bulblets in greenhouse conditions resulting in bigger T. orphanidea bulblets compared to T. hageri.

Adaptability of Wild-Growing Tulips of Greece: Uncovering Relationships between Soil Properties, Rhizosphere Fungal Morphotypes and Nutrient Content Profiles

Wild-growing Greek tulips are protected plants but almost nothing is known about their natural nutrient status and rhizosphere fungal morphotypes in the wild, thus no insight is currently available into their growth and adaptation to their natural environment or artificial settings. To this end, several botanical expeditions were conducted with a special collection permit, and 34 tulip and soil samples were collected, representing 13 species from two phytogeographical regions of Greece (North Aegean Islands, Crete Island) and seven regions of mainland Greece. The tulips' content in essential macro- and micro-nutrients, respective physicochemical soil properties, and rhizosphere fungal morphotypes were assessed across samples, and all parameters were subjected to appropriate statistical analysis to determine their interrelationships. The results showed that soil variables played a significant role in shaping tulips' nutrient content, explaining up to 67% of the detected variability as in the case of phosphorus (P) in the above-ground plant tissue. In addition, significant correlations were observed (with an r value of up to 0.65, p < 0.001) between essential nutrients in the tulips, such as calcium (Ca) and boron (B). The principal component analysis (PCA) revealed that between the three spatial units examined, the total variability of tulips' nutrient content produced a clear distinction among sampled species, while the first two PCA axes managed to explain 44.3% of it. This was further confirmed by the analysis of variance (ANOVA) results which showed corresponding significant differences (at p < 0.05) in both the tulips' nutrient content and the studied soil properties as well (mean values of N, P, and K in the North Aegean Islands tulips' nutrient content, up to 53%, 119%, and 54% higher compared to those of the Crete Island, respectively). Our study sheds light on Greek tulips' adaptability and resilience in their original habitats, facilitating at the same time the undertaken efforts regarding their conservation and potential domestication in artificial settings.