| Abstract: | Wounding of root or stem water conduction systems or coolingof roots in Abies amabilis produced rapid stomatal closure independentof evaporative demand or leaf water potential. The responsealso occurred in a branch if its xylem was only partially cut,but did not occur if the branch was completely severed. Removingpart of the root system or cooling the roots produced the sameeffect as partial severing of the stem. The speed and uniformityof stomatal closure indicated that the stimulus was physical,linked to water flux in the xylem, and not caused by releaseof a chemical stimulus at the point of xylem flow disruption.The results suggested that stomatal closure could be rapidlyinduced with a change in the flux of water through the soil-plant-atmospherecontinuum. Key words: Capacitance, Stomata, Xylem water flux, Xylem wounding |
