Professor Bill Davies
Professor of Environmental Plant Biology
Research Interests
The Environmental Physiology research group is concerned with the regulation of growth and functioning of plants subjected to environmental perturbation.
In the recent past we have given much attention to relative importance of hydraulic and chemical influences on the behaviour of stomata.
Our work, along with that of of several other groups around the world, has suggested a role for chemical influences in the regulation of gas exchange.
This may particularly be the case under drought but recent work in the lab suggests that ABA in the transpiration stream will also influence stomatal behaviour of plants that are well supplied with water.
Our feeling is that the plant may use ABA delivery to the hormone binding sites on the guard cell as a way of regulating water loss as a function of the edaphic and atmospheric water balance. We have a very specialised root pressure vessel combined with a sophisticated gas exchange system to enable us to sample xylem sap on line while monitoring and manipulating gas exchange. Current, NERC-funded, work in the lab is concerned to further understand these responses.
In addition, we are developing a parsimonious model of leaf gas exchange which will describe the response of stomatal conductance to both transpiration and photosynthesis.
The BBSRC has also supported work in the lab on the chemical regulation of gas exchange. Here we have made good progress in the elucidation of a role for a pH signal and have shown that drought-induced changes in xylem pH can explain stomatal responses to soil drying, even in the absence of variation in xylem ABA concentration. We have identified a pH sensitive ABA carrier in the leaves which seems to have an important regulating effect on apoplastic ABA balance.
In this work we are collaborating with Prof Wolfram Hartung from the University of Wurzburg. We are also concerned with the effects of high CO2 in the growth and functioning of greenhouse crops HDC has funded work on the cucumber crop, where high CO2 may result in damage to leaves and consequent restrictions in yield.
