Determining Salinity-Tolerance of Giant Salvinia Using Chlorophyll Fluorescence

摘要: Salvinia molesta Mitchell, a floating invasive aquatic plant, is one of the top 10 worst weeds in world. It was discovered lower Pascagoula River 2005 and evidence suggests that this non-native species spreading along northern Gulf Mexico. These plants exhibit rapid growth nutrient uptake rates, allowing them to out compete other similar habitats. Distributional observations suggest S. able survive salinities up 7 ppt River. The response three salinity levels (0, 5, ppt) tested using chlorophyll fluorescence. health measured over period month, log scale series observation intensities (hourly, daily, weekly). Plant responses indicated an acute effect after about 4-6 hrs then gradual chronic decline. Compared initial measurements, final actual quantum yield (∆F/Fm’) dropped by 5%, 6% 29%, while potential (Fv/Fm) 6%, 27% 39% 0, treatments, respectively. Only 0 treatment showed significant new growth. Plants 5 appeared maintain themselves, but at all exhibited signs severe stress loss color, turgor, tissue viability d. Tolerance brackish has been reported past, implications for use biological control agent, weevil Cyrtobagous salviniae, can only tolerate freshwater conditions. IntroductIon Aquatic be grouped into types: emergent, floating, submerged (Pieterse Murphy 1993), with some most successful being group (e.g., Eichhornia crassipes molesta). are aggressive, competitive impact environments, local economies, human (Holm et al. 1977). these on body dramatically illustrated molesta, world (Room Julien 1995, Carley Brown 2006). become worldwide problem, invasions bodies tropical countries, introduced United States 1995 (Julien Tipping 2002, USGS 2005). doubling time d (Mitchell Tur 1975) found (MS DMR Evidence McFarland (2004) Mexico (GOM). In Alabama Mississippi, there many suitable habitats native plants; four river drainage systems 121 km (75 mile) coastline state Mississippi alone. largest River, which holds distinction longest un-dammed, natural remaining continental USA provides habitat numerous important endangered salt marsh (Schueler 2002). Much system remains relatively unimpacted development, except very reaches between towns Gautier Pascagoula, MS. during outbreak personnel Department Marine Resources (DMR) parts per thousand (ppt) River; tolerance earlier Divakaran (1980) from tests conducted 11 ppt. This agent salviniae infestation, as conditions (Thomas Room 1986, distressing two respects: (1) portion population escape control; (2) more salinity-tolerant variety could easily spread abound GOM elsewhere. Pulse amplitude modulated (PAM) fluorescence tool measure photophysiological processes vivo. While it cannot used directly mechanisms osmoregulation, successfully demonstrate physiological resulting change number plant (Ralph 1998, Kamermans 1999, 2003, Biber PAM stress, such desiccation (Adams Bates 1994, Bjork 1999), temperature or shifts Ralph even changes ambient light short durations (Beer 2000,