Xylem function and growth rate interact to determine recovery rates after exposure to extreme water deficit
Brodribb, TJ and Bowman, DMJS and Nichols, S and Delzon, S and Burlett, R, Xylem function and growth rate interact to determine recovery rates after exposure to extreme water deficit, New Phytologist, 188, (2) pp. 533-542. ISSN 0028-646X (2010) [Refereed Article]
• Motivated by the urgent need to understand how water stress-induced embolism
limits the survival and recovery of plants during drought, the linkage between
water-stress tolerance and xylem cavitation resistance was examined in one of the
world’s most drought resistant conifer genera, Callitris.
• Four species were subjected to drought treatments of )5, )8 and )10 MPa for
a period of 3–4 wk, after which plants were rewatered. Transpiration, basal
growth and leaf water potential were monitored during and after drought.
• Lethal water potential was correlated with the tension producing a 50% loss of
stem hydraulic conductivity. The most resilient species suffered minimal embolism
and recovered gas exchange within days of rewatering from )10 MPa, while the
most sensitive species suffered major embolism and recovered very slowly. The
rate of repair of water transport in the latter case was equal to the rate of basal
area growth, indicating xylem reiteration as the primary means of hydraulic repair.
• The survival of, and recovery from, water stress in Callitris are accurately
predicted by the physiology of the stem water-transport system. As the only
apparent means of xylem repair after embolism, basal area growth is a critical part
of this equation.