Plant Species for the Removal of Na+ and Cl– from Greenhouse Nutrient Solution

Certain ions such as Na+ and Cl– can accumulate in recirculating greenhouse nutrient solutions and can reach levels that are damaging to crops. An option for the treatment of this problem is phytodesalinization with Na+ and Cl– hyperaccumulating plants that could be added to existing water treatment technologies such as constructed wetlands (CWs). Two microcosm experiments were conducted to evaluate eight plant species including Atriplex prostrata L. (triangle orache), Distichlis spicata (L.) Greene (salt grass), Juncus torreyi Coville. (Torrey’s rush), Phragmites australis (Cav.) Trin. ex Steud. (common reed), Spartina alterniflora Loisel. (smooth cordgrass), Schoenoplectus tabernaemontani (C.C. Gmel.) Palla (softstem bulrush), Typha angustifolia L. (narrow leaf cattail), and Typha latifolia L. (broad leaf cattail) for their Na+ and Cl– accumulation potential. An initial (indoor) experiment determined that J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia were the best candidates for phytodesalinization because they had the highest Na+ and Cl– tissue contents after exposure to Na+ and Cl–-rich nutrient solutions. A second (outdoor) experiment quantified the Na+ and Cl– ion uptake (grams of each ion accumulated per m2 of microcosm). J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia accumulated 5.8, 3.9, 8.3, and 9.2 g·m−2 of Na+ and 25.7, 18.2, 31.6, and 27.2 g·m−2 of Cl–, respectively. Of the eight species, T. latifolia and S. tabernaemontani showed the greatest potential to accumulate Na+ and Cl– in a CW environment, whereas S. alterniflora, D. spicata, and P. australis showed the least potential.

Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia)

Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia)Žitný ostrov, the largest island of the Danube River (SW Slovakia) gained its present shape in the Neoholocene period. As a result of increased flood and geomorphological Danube river activity dated to 1378-1528 AD, the Lower Dudváh River was abandoned and its alluvium became a part of the Žitný ostrov. Study of a Dudváh terrestrialized paleomeander by means of pollen and macrofossil analysis provides new information about the paleoenvironments of the Danubian Plain. The meander under study was cut-off during the Sub-Boreal period when the land was mostly covered by oak-dominated mixed forest with a notable high frequency ofFagusandAbies.In low-lying depressions,Alnus glutinosaformed typical alder carrs. The largest decline of the mixed forest occurred during the Sub-Atlantic period. Until the mid-19thcentury the region was strongly influenced by shallow groundwater and periodical floods, as reflected by pollen of aquatics and marsh species. Amongst non-arboreal taxa, pollen of Cyperaceae, Brassicaceae/Cuscuta, Poaceae and Apiaceae prevailed. Local successional changes started with i) stage of abandoned oxbow still with influx of moving water, poor in both macrophytes and molluscs, ii) shallow eutrophic oxbow lake with slowly flowing or stagnant water overgrown with aquatics (Ranunculussubgen.Batrachium, Potamogetonsp.,Ceratophyllum demersumetc.) and abundant molluscs, iii) an open marsh dominated by Cyperaceae (mainlyCarex riparia) withAtriplex prostrata, supporting diverse molluscan and Ostracod fauna. Present-day habitat is a result of landscape changes, which have been associated with draining, intensified agriculture, ruderalisation and spread of invasive species.

Germination response of dimorphic seeds of two halophyte species to environmentally controlled and natural conditions

To determine whether or not tolerance limits at the germination stage of development and annual germination patterns affect plant distribution in an inland salt marsh, we assessed germination of dimorphic seeds for Atriplex prostrata Boucher ex DC. and Salicornia europaea L. under field and laboratory conditions. Statistically significant differences were found in germination across marsh zones for both species in the field. However, germination percentages for small seeds of A. prostrata and S. europaea were above 50% and 75%, respectively, across all zones for seeds placed on the surface. For large seeds of each species placed on the surface, germination was above 90% across all zones. Small seeds for both species had primary dormancy, a light requirement for germination, and appeared to exhibit dormancy cycling. Large seeds of A. prostrata were nondormant from December through March, whereas large seeds of S. europaea were nondormant when produced. Persistent seed banks were most likely to be formed from small seeds of both species. Seeds typically germinate in the spring when salinity across the marsh is sufficiently low for seeds to germinate in all zones, indicating that the germination stage of development does not effect the spatial distribution of A. prostrata or S. europaea on the marsh.Key words: Atriplex prostrata, seed dormancy and germination, halophyte, Salicornia europaea, seed dimorphism, salt marsh zonation.