Short-term responses of growth and leaf physiology of the sclerophyllous Cryptocarya alba (Molina) seed sources to water restriction

Abstract

ABSTRACT There are concerns about the vulnerability of some dominant sclerophyllous species in Mediterranean zones to water restriction, especially at outplanting, and much of the efforts for active restoration are on identifying proper seed sources. This study aimed to determine the short-term responses of growth, biomass partitioning, and leaf-physiological traits of Cryptocarya alba provenances to water restriction in nursery conditions. Three seed sources from xeric sites (northern distribution) and one from a more mesic site (southern distribution) were subjected to water restriction for three months and then evaluated in increments in root collar diameter and height, biomass components (leaves, shoots, roots), gas-exchange and fluorescence parameters, and carbon (Δ13) and oxygen (δ18O) isotopic ratios. Water restriction decreased growth and leaf biomass as a short-term response, but this effect was not expressed in stem and root biomass. Similarly, water restriction decreased the photosynthetic rate (Asat), stomatal conductance (gs), and maximum efficiency of PSII. Moreover, water restriction also increased the intrinsic water use efficiency (WUEint), but it had no effect on Δ13 or δ18O. Seed sources did not differ in any traits except in stem and total biomass. The results did not confirm a better performance of seed sources from xeric than mesic origin sites to water restriction.