Abstract
ABSTRACT: Intensification of drought in Mediterranean–type climates has limited seedling establishment. The knowledge of the ecology of selected species and its intraspecific variation to water stress at the seedling stage should be considered in order to overcome limitations. We investigated variations in growth, survival, and leaf–level physiology in four provenances of the endemic Cryptocarya alba (Mol.) during water stress and after re–watering. Seedlings were cultured in the nursery during 23 months and then subjected to two watering treatments based on soil water content (well–watered and water restriction, 0.38 and 0.17 cm3 cm−3, respectively) for 45 days. At the end of the watering treatments, seedling growth, above– and belowground biomass, survival, and leaf gas exchange were measured. Right after the watering treatments, the surviving seedlings were submitted to a recovery period of 21 days, in which all seedlings were re–watered at 0.38 cm3 cm−3 of soil water content and measured for leaf gas exchange. Provenances differed in growth and biomass allocation. Unlike growth and biomass, interaction between provenance and watering treatments was found for photosynthesis, stomatal conductance, transpiration, and water use efficiency of northern provenances, exhibiting the highest performance under water restriction. However, most variations observed occurred before the re–watering period and only a few occurred after this period. The four provenances under study exhibited similar photosynthesis and stomatal conductance after re–watering. Our study demonstrated phenotypic variation of C. alba and the capability of the species to withstand and recover from water stress.
Highlights
Water stress is a major cause of failure in Mediterranean– type forest ecosystems (Mendoza et al, 2009)
Seedlings were cultured in the nursery during 23 months and subjected to two watering treatments based on soil water content for 45 days
Interaction between provenance and watering treatments was found for photosynthesis, stomatal conductance, transpiration, and water use efficiency of northern provenances, exhibiting the highest performance under water restriction
Summary
Water stress is a major cause of failure in Mediterranean– type forest ecosystems (Mendoza et al, 2009). In order to estimate the relative capacity of a species to survive and grow under drought conditions, information on variations in the responses of seedlings to water stress is needed because of the highest mortality rate observed in seedling establishment of woody Mediterranean species (Davis, 1989). The wide ecological distribution suggests that the species has high phenotypic variation and that different provenances may differ in their ability to withstand water stress. C. alba shows a lack of changes in the allocation of roots in relation to shoots as adaptive responses to water scarcity (Donoso et al, 2011; Ovalle et al, 2015). This study is aimed to assess the early response in survival, growth, biomass, and leaf–level physiological traits of four provenances of C. alba to water stress and re– watering under nursery conditions, representing various climate zones in central Chile. We tested the hypothesis that seedlings from drier provenances are better adjusted to water restricted conditions
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