Ecology of seed germination and features of ontogeny of floating mat-forming hygrogelophyte Calla palustris (Araceae) under laboratory conditions

Abstract

This article examines the ecology of germination and the features of ontogenesis of the floating mat-forming hygrogelophyte Calla palustris L. in the territory of some regions in the central part of European Russia and the Republic of Belarus under laboratory conditions. It has been found that in the surveyed territory in the dense ear-like collective fruit of C. palustris, 40.7 ± 6.4 fruits, juicy berries, are formed and the number of seeds produced (actual seed productivity), averages 164.0 ± 89.3. Widely varying data on the number of berries in the collective fruit, as well as a variable number of ovules in them, shows that the seed productivity of C. palustris depends on a whole range of endogenous and exogenous factors, including the effectiveness of pollination of flowers by insects. In laboratory experiments, various storage periods (2 and 12 months) and methods of presowing seed treatment (stratification, drying, ice-freezing) were applied to simulate the ecological conditions of the growth of white alder. It is shown that freshly harvested seeds do not germinate at once, and wet cold stratification makes it possible to achieve maximum values of laboratory germination (from 84.4 to 99.0) and germination energy (from 66.6 to 88.3). Given that the features of germination are indicators of dormancy, it is demonstrated that seeds of C. palustris are in a state of shallow physiological dormancy, conditioned by the physiological mechanism of inhibition. Along with dry storage, wet cold stratification is the main way for seeds to enter a non-dormant state. Such mechanisms are consistent with the climatic features of the regions in which the species grows. It is found that C. palustris seeds, in common with many other species of hygrogelophytes, can float on the water surface for a long time (more than 30 days), spreading with water flow (hydrochoria). Seeds of C. palustris are photosensitive, germination is observed in a wide range of temperatures – from 10–14 to 30 ºС (at constant humidity), type of germination – underground (hypogeal). It is found that ontogeny of individuals of generative origin of C. palustris in the laboratory is terminated (the plants died after passing the juvenile ontogenetic state). The formation of C. palustris seedlings under laboratory conditions lasts 23–25 days and is characterized by the appearance of the main organs of the plant and the anisotropic growth of the shoot axis. At the final stage of development, the seedling is represented by a uniaxial monopodial and anisotropic growing rosette shoot with shortened internodes. The juvenile ontogenetic state in laboratory conditions lasts up to 7 months, after which the plants die off. In the framework of ontomorphogenesis, the stages of ontogenetic development under study (the seedling and the juvenile plant) correspond to the phase of the primary uniaxial rosette shoot. The plant in this period is represented by a uniaxial monopodially growing anchorage shoot. The detection of virgin plants in natural conditions indicates the possibility of their further development from the rudiments of generative origin. The main way of the species reproduction is vegetative, characteristic of most aquatic and semi-aquatic plants. In the course of ontogenesis, progressive features of development such as cotyledon greening and early death of the radicle root have been revealed.

A Calla palustris egykori magyarországi előfordulásáról

“…A sárkánygyökér vízi, vízparti növény, amely magok útján és rizómadarabok révén is kiválóan szaporodik (SCRIBAILO & TOMLINSON 1992). Hydrochoria esetén a mag akár 30 napon túl is megőrzi lebegőképességét (BELYAKOV et al 2017), így a hazai folyóinkon (zavartalan terjedés esetén) néhány napon belül be-és át is úszhatnak az ideiglenes megtelepedésre alkalmas propagulumok. A legtöbb, potenciálisan alkalmas hazai élőhelyet azonban csak zoochoria, leginkább endozoochoria révén érhetik el a terjesztő képletek.…”