Water content and reserve allocation patterns within the bulb of the perennial geophyte red squill (Liliaceae) in relation to the Mediterranean climate

Abstract

The patterns of water content and reserve allocation in the bulb parts of red squill (Urginea maritima (L.) Baker) and the plant's adaptive strategy to Mediterranean climate (Crete, Greece) were investigated. The different bulb parts serve varying ecological functions in terms of their resources and their importance for these functions. The basal plate is the active centre, developing one or two apical meristems and roots in autumn, as well as the flowering bud in late summer. The middle of the bulb (approximately the third bulb scale) stores the resources and the tunics (the outer covering structures) that provide mechanical defense. The water content and reserve allocation patterns synchronize the plant's phenological development with the seasonality of the Mediterranean climate. The adaptive strategies are based on the development of a deciduous semisubterranean life form primarily for the avoidance of drought, herbivores, and other environmental hazards, as well as nutrient shortage. The presence of cells containing lipids, polysaccharides, raphides, water, mucilage, bufadienolides, the presence of sclerenchyma, the tightly packed epidermis, and the presence of the tunics facilitate this.Résumé : Les auteurs ont examiné les patrons de teneur en eau et l'allocation des réserves dans les parties du bulbe du Urginea maritima (L.) Baker, ainsi que les stratégies d'adaptation de la plante au climat méditerranéen (Crête, Grèce). Les différentes parties du bulbe servent différentes fonctions écologiques, en termes de ressource et de leur importance pour ces fonctions. La plaque basale constitue le centre d'activité, développant à l'automne un ou deux méristèmes et des racines, ainsi que le bourgeon floral à la fin de l'été. Le milieu du bulbe (environ la troisième écaille du bulbe) emmagasine les ressources, et les tuniques (structures enveloppantes externes) servent à la défense. La teneur en eau et les patrons d'allocation des réserves synchronisent le développement phénologique de la plante selon le caractère saisonnier du climat méditerranéen. Les stratégies d'adaptation reposent sur le développement d'une forme vitale décidue semi-souterraine, surtout pour éviter la sécheresse, les herbivores et les autres aléas environnementaux, ainsi que l'emmagasinage des nutriments. Ceci est facilité par la présence de cellules contenant des lipides, polysaccharides, raphides, eau, mucilage, bufadienolides, la présence de sclérenchymes, l'épiderme bien serré et la présence de tuniques.

Tunicate bulb size variation in monocots explained by temperature and phenology

“…The mean value for each taxon was calculated and used in subsequent statistical and phylogenetic comparative analyses using R v. 3.5.3 (R Core Team, ) (see below). Lastly, each taxon was coded as either synanthous or hysteranthous based on available descriptive resources (Al‐Tardeh et al, ; de Andrade et al, ; Boeken & Guttermann, ; Dafni, Cohen, et al, ; Dafni, Shmida, et al, ; Daniels, Mabusela, Marnewick, & Valentine, ; Duncan, ; Hoffmann, Liberona, & Hoffmann, ; Snijman & Linder, ; Speta, ; Stedje, ) and/or herbarium vouchers. In some taxa, hysteranthy is facultative (Dafni, Cohen, et al, ; Dafni, Shmida, et al, ), resulting in herbarium vouchers with both leaves and flowers.…”

“…Therefore, the evolutionary and ecological consequences of bulb size may play a more critical role in their survival relative to other geophytic taxa. The plant bulb is a modified shoot system consisting of a compressed stem with short internodes surrounded by concentric layers of leaf bases, which are where nutrient and water storage occurs (Al‐Tardeh et al, ; De Hertogh & Nard, ; Rees, ; Ruiters, ). The vast majority of bulbous monocots are tunicate bulbs (Rees, ), which retain the outer, dried layers of leaf bases (i.e., the tunica; e.g., the dried outer layers of an onion) that are thought to improve water retention and/or provide protection from external factors, such as soil shrinkage due to drought, while dormant belowground (Al‐Tardeh et al, ).…”

“…Geophytes, plants with buds located belowground on structures such as stem tubers, bulbs, corms, and rhizomes (e.g., potato, onion, crocus, and ginger), make for an interesting study system when investigating the macroevolutionary processes promoting and constraining plant size. Many taxa can accumulate sometimes large amounts of carbohydrates and/or water in belowground organs (Al-Tardeh, Sawidis, Diannelidis, & Delivopoulos, 2008;Boeken, 1990;Ranwala & Miller, 2008;Ruiters, 1995;Veselý, Bureš, & Šmarda, 2013). Therefore, conceptually, the larger the organ, the greater resource storage capacity a taxon retains.…”

Nectary structure and nectar presentation in the Mediterranean geophyte,Urginea maritima(Hyacinthaceae)

“…Bundles of raphides usually occur in cells of U. maritima roots (Al-Tardeh et al 2006), leaves (Al-Tardeh et al 2008b), bulb parts (Al-Tardeh et al 2008a), subsidiary tissue (Figs. 6, 13, and 28), and the ovary wall (Fig.…”

Growth, Development, and Mineral Nutrient Accumulation and Distribution in Tulip from Planting through Postanthesis Shoot Senescence

“…Several studies followed the accumulation and distribution of biomass and nutrient resources to plant parts in various geophytes throughout the growing season including three cormous perennials (Ixia flexuosa [40], Gladiolus caryophyllaceus [41], and Sparaxis grandiflora subspecies fimbriata [42]), the tuberous Jerusalem artichoke (Helianthus tuberosus) [43], and the bulbous red squill (Urginea maritima) [44]. Subramanian et al [45] studied the dry matter and nutrient distribution within potato (Solanum tuberosum) tubers at harvest.…”