Plant indicators of available soil water in Miscanthus x giganteus Greef and Deu.

Miscanthus x giganteus is a potential crop for biomass. In order to evaluate the tolerance of the species to low soil water availability which in Mediterranean environment occurs during the warm and dry summertime, a 2-year research was carried out in the field on the eastern coast of Sicily (Southern Italy), comparing the physiological responses of the crop to three levels of ETm restoration (25%, 50% and 100%). All the studied plant indicators (predawn and mid-day leaf water potential, leaf transpiration and stomatal conductance) were affected by soil water deficit according to a relationship described by an asymptotic curve. However, the pre-dawn leaf water potential was more strictly related to soil water content, among those tested, due to its relative independence from weather conditions and then may represent a valid indicator of plant water status for irrigation scheduling. Indeed the variations in leaf water potential, transpiration and stomatal conductance, measured during the warmest hours of the day, were related to the air vapour pressure deficit in the well-irrigated treatment (100% of ETm restoration).