Abstract Detail



Ecology

Huebner, Cynthia [1], Waterland, Nicole [2].

Regional Responses to Drought on the Growth and Fitness of Microstegium vimineum (Trin.) A. Camus (Japanese Stiltgrass).

Microstegium vimineum is a C4, shade-tolerant, annual grass which has invaded disturbed and forested areas throughout the northeastern US.  There are regional patterns of genetic variation detected between populations located in the Ridge and Valley province (RV, lower annual precipitation) and the Appalachian Plateau province (AP, higher annual precipitation) of West Virginia.  This grass has demonstrated rapid evolution of phenology during invasive range expansion, suggesting sufficient genetic diversity to drive adaptively significant evolution leading to expansion into drier environments.  We evaluated the effects of drought on the growth and reproduction of M. vimineum under light conditions of typical disturbances within the RV and AP provinces.
Seed were collected from three populations in each province and grown in two greenhouse rooms in which light levels were set for conditions similar to (1) a first-year shelterwood harvest (HL) and (2) a thinned forest (LL).  Drought levels included (1) field capacity or 35% volumetric water-content (VWC) or C, (2) half field capacity at 18% VWC or M, and (3) one-fourth field capacity at 8% VWC or D.  After 30 days of growth under C-level drought, the drought treatments were applied and maintained for two weeks.  The D-level plants were allowed to wilt for 24 hours after which watering was resumed and plants recovered over three days.  Plants were kept at the same drought levels with occasional short-term wilting in the D-level drought treatment for another three weeks until the plants formed seed. 
HL plants produced more shoot and root biomass, tillers, flowers, and seed than LL plants, but the seed number did not differ significantly.  The LL and RV plants had significantly higher seed-to-empty-floret ratios than the HL and AP plants.  The D-level drought treatment had nearly twice as large seed-to-empty-floret ratios, but were only marginally significant.  There was a trend for the RV, LL, and D-level plants to have the most viable and largest seed.  Percent germination was higher for LL, D-level, and RV plants, but was not significant for province.  LL, RV, and D-level drought plants appear to produce fewer flowers that do not go to seed and more viable seed that are ready to germinate under optimal conditions than HL, AP, and C or M-level drought plants.  This strategy of using high seed production and seed germination to combat stressful environmental conditions (low light and drought) once conditions improve appears more likely to occur with RV province plants.  


1 - 1514 Westbrook Dr, Morgantown, WV, 26508, United States
2 - West Virginia Univesity, Division of Plant and Soil Sciences, Morgantown, WV, 26501, USA

Keywords:
Microstegium vimineum
drought
range expansion
Plant Reproduction Biology.

Presentation Type: Oral Paper
Number:
Abstract ID:195
Candidate for Awards:None


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