A comparative study of Miscanthus floridulus (Labill) Warb and M-transmorrisonensis Hayata: Photosynthetic gas exchange, leaf characteristics and growth in controlled environments

The relationship between temperature and the distribution of Miscanthus floridulus (Labill) Warb and M. transmorrisonensis Hayata along altitudinal gradients in central Taiwan was examined. Responses of biomass accumulation, leaf characteristics and photosynthetic gas exchange to growth temperature (from 10 to 30 degrees C) of M. floridulus from an altitude of 390 m and of M. transmorrisonensis from 2700 m were determined. There were differences between the two species in above-ground biomass, CO2 uptake characteristics and leaf chlorophyll contents in response to growth temperature. The optimal temperatures for biomass accumulation were 30/25 (day/night temperature) and 25/20 degrees C for M. floridulus and M. transmorrisonensis, respectively. Light saturated photosynthetic rates (A(max)) were largest in plants grown at the optimal temperature. Growth at 15/10 and 10/10 degrees C compared to the optima reduced accumulated biomass, leaf chlorophyll content and photosynthetic rate in both species with a greater reduction in M. floridulus than in M. transmorrisonensis. We concluded that growth of M. floridulus at high altitude is limited by an inability to grow at temperatures lower than 15 degrees C, while M. transmorrisonensis is able to grow in chilling temperatures at higher altitudes. (C) 1998 Annals of Botany Company.