• Article • Advances in Polar Science doi: 10.13679/j.advps.2015.1.00024 March 2015 Vol. 26 No. 1: 24-29 Experimental culture of non-indigenous Juncus bufonius from King George Island, South Shetland Island, Antarctica Marely Cuba-Díaz*, Eduardo Fuentes, Mauricio Rondanelli-Reyes & Ángela Machuca Departamento Ciencias y Tecnología Vegetal, Escuela Ciencias. y Tecnología, Universidad de Concepción, Campus Los Ángeles, Juan Antonio Coloma 0201, Los Ángeles, Chile Received 5 August 2014; accepted 11 March 2015 Abstract Juncus bufonius L. (Juncaceae) is recognized by the US Department of Agriculture as a weed or invasive plant. Recently, we reported on J. bufonius L. var. bufonius associated with the native vascular plants Deschampsia antarctica and Colobanthus quitensis in the environs of the Polish Arctowski Station, King George Island, in the Maritime Antarctica. In this study, we evaluated the developmental stages and morphological characteristics of J. bufonius plants cultivated in controlled conditions beginning with seeds obtained from plants of the Antarctic population. Germination occurred at 3 weeks and the germination percentage was low (22.5%). The average time between the anthesis and seed formation was 7 weeks, similar to that reported for other species in the Juncaceae. According to data reported in the literature, Antarctic individuals were significantly smaller than their relatives growing in other conditions, except for the number of inflorescences. The morphological characteristics of a species vary according to its distribution and the edaphoclimatic environment where it occur; cosmopolitan plants shuch as J. bufonius also have reduced stature in cold environments. The low percentage germination may have been due to water availability in the plant chamber in which the study was conducted. J. bufonius is intolerant of dry environments, and once it suffers hydric stress its recovery is very low; thus, a moister environment could be beneficial. J. bufonius has become established amongst native vegetation near Arctowski Station and without careful control or eradication; it may have the potential to spread far beyond the site, as has happened with the alien grass Poa annua as human disturbance and climate warming increase. Keywords Antarctica, invasive plants, Juncus bufonius (toad rush), non-native species, regional warming Citation: Cuba-Díaz M, Fuentes E, Rondanelli-Reyes M, et al. Experimental culture of non-indigenous Juncus bufonius from King George Island, South Shetland Island, Antarctica. Adv Polar Sci, 2015, 26: 24-29, doi: 10.13679/j.advps.2015.1.00024 1 Introduction Antarctic Peninsula and islands, where the temperature increase has been +0.56°C per decade from 1951 to 2000[6-7]. Antarctica is still a relatively pristine biome, but the This has caused a major and accelerated retreat of the glaciers increasing presence of Man combined with global climate and thus a greater availability of ice-free areas, which could [8-10] change, which is accelerated in this region of the Earth, is be colonized by local native plant species . With the causing substantial changes to the Antarctic ecosystem[1-5]. increase in human activity in many parts of Antarctica, the Regional warming is more pronounced in the adjacent likelihood of other non-indigenous species arriving has also increased, and these may colonize and become invasive[11-15, 5]. There have been several reports of non-native plants * Corresponding author (email: [email protected], mcubaster@ in Antarctica, such as Poa annua L., which is recognized as gmail.com) journal.polar.org.cn Antarctic Juncus bufonius experimental culture 25 the most widely distributed non-native species, and is able to 2 Materials and methods colonize sites far distant from its introduction site. Recently was recorded in a new habitat away from of their original 2.1 Plant material habitat, in the vicinity of Polish Antarctic Station Arctowski, on the deglaciated moraines of the Ecology Glacier, possibly In this study we used seeds of Juncus bufonius L. obtained [16] having been dispersed by the wind . Poa pratensis L. has in the Biotechnology and Environmental Studies Laboratory been noted for its persistence, and is restricted only to its of the University of Concepción, Los Ángeles Campus, from original site of introduction in Cierva Point (Punta Cierva), material collected from the environs of the Polish Arctowski Danco Coast, northwest Antarctic Peninsula, because of Station on the western coast of Almiralty Bay, King George the abiotic inhibition of its sexual reproduction and the low Island, South Shetland Islands[18]. The laboratory plants [17] human activity where it is located . were obtained from at least three plants from field and an Recently, another non-native vascular plant, Juncus indeterminate numbers of seed from field that germinated bufonius L. was isolated in the laboratory from plant under controlled condition in the laboratory. associations with Colobanthus quitensis and Deschampsia [18] antarctica, the two native species in this biome . 2.2 Developmental stages Nevertheless, to date it has not been possible to specify either the size of the population or how long this species In order to study the phenology of J. bufonius in controlled has been in Maritime Antarctica. In a recent visit has been conditions, 200 seeds were placed on a substrate of identified probable site where J. bufonius were collected, in earth:peat:perlite (3:2:1), in a plant growth chamber with a an area approximate of 250−270 m2 between meteorological photoperiod of 16/8 h light/dark, a temperature of 15±2°C, building and tourist shop. This area is full of human activity, a photosynthetic photon flux density (PPFD) of 75± high animal influence (mainly penguin), very close to the 20 µmol.m-2∙s-1, and a relative humidity of 80%±5%, with sea and gravel soil with abundant plants in the rockery that manual irrigation with tap water, without nutrients addition. characterizes this area. J bufonius commonly known as Parameters such as germination percentage, germination toad rush, is a monocotyledon angiosperm belonging to the time, time between anthesis and seed formation, as well as Juncaceae family, and is recognized by the US Department the development time of each of the age stages described of Agriculture as a weed or invasive plant (plants.usda.gov). according the classical work of Gatzuk et al.[27] Juncus and Luzula are the only genera in this family that have species with an annual life cycle strategy, J. bufonius 2.3 Morphological measurements is possibly the only annual Juncus[19-20]. The Juncaceae have colonized all moist environments, particularly in Morphological parameters were measured using 10 plants temperate regions, and are wind-pollinated[21]. In Western at 20 weeks of age from 50 seeds germinated under the Europe five species belonging to the same complex as J. conditions described above. With a Vernier caliper (Mitutoyo, bufonius have been recognized, with J. bufonius being the USA), total plant length, stem length, leaf length, number of only polyploid[22-24]. Various studies have shown that this leaves per plant, leaf width, root length, crown diameter and species is derived from the hybridization of diploid species number of reproductive leaves per plant were measured. belonging to the complex[24], which may have given it greater genetic and physiological variability, affording it greater 2.4 Statistical analyses adaptability to variable abiotic conditions. J. bufonius has a cosmopolitan distribution[25], including mainly sandy coastal The data from the morphological measurements are shown habitats in cool and cold climates zones or mountainous descriptively with the mean ± standard error (SE) according regions with moderately high rainfall[20]; it can also tolerate to a previously established formula[28]. saline conditions. Although usually growing in mixed- species communities, it may also develop pure stands[26]. It 3 Results is expected that because of the morphological variability and adaptability of J. bufonius to different environmental 3.1 Developmental cycle of Antarctic J. bufonius conditions and the more favorable conditions in the Antarctic ecosystem caused by regional warming, this species could growing in controlled conditions successfully established in Maritime Antarctica. Under the culture conditions used in this study, the The aim of this work was to study the developmental germination percentage was low (22.5%). The time taken stages and morphological characteristics of Juncus bufonius from sowing to the different developmental states is shown in plants cultivated in controlled conditions beginning with Figure 1. In three weeks was observed that seedlings already seeds obtained from plants of the Antarctic population in had 4−5 foliar buds or leaves (seedling state, PL) and that the order to shed light regarding its potential success in the complete development cycle took 7 months (G3 state). The current conditions in Maritime Antarctica due to regional young generative state (G1) was observed at 4 months after warming. sowing, and the time taken from anthesis to seed formation 26 Cuba-Díaz M, et al. Adv Polar Sci March(2015) Vol. 26 No. 1 was approximately seven weeks, thus, individuals considered 78% for seeds that have been hermetically preserved for to be in the middle-aged generative state (G2) were observed 12 months at 5°C in dry air conditions[30], occasionally with 6 months after sowing. up to 85%-90% germination of seeds stored in various conditions and for various durations. 3.2 Morphological characteristics of Antarctic J. The cooling system in the plant chamber used in this bufonius growing in controlled conditions study provides a dry cold air intake and manual irrigation and the programmed irrigation regime maintained the relative Table 1 shows that the J. bufonius plants had greater humidity inside the chamber never above 75%, it may have stems (6.76 cm) than roots development (3.30 cm) and produced areas and short periods where the substrate was that the leaves were long, spanning more than half of the drier.