Modulation of relative growth rate and its components by water stress in Mediterranean species with different growth forms |
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Authors: | Jeroni?Galmés Josep?Cifre Hipólito?Medrano Email author" target="_blank">Jaume?FlexasEmail author |
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Institution: | (1) Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Universitat de les Illes Balears, Carretera de Valldemossa Km.7.5, 07122 Palma de Mallorca, Spain |
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Abstract: | Effects of water availability on seedling growth were analysed in eight Mediterranean species naturally occurring in the Balearic
Islands. Seedlings were grown outdoors during summer under two irrigation treatments: field capacity and 35% of field capacity.
The relative growth rate (RGR) strongly depended on the growth form, from highest values in herbs to lowest in woody perennials.
The main component associated with interspecific variation in RGR was the specific leaf area (SLA), and a quantitative grouping
of the different growth forms appeared along the regression line between both parameters. The slow-growing species, i.e. woody
perennial shrubs, had the lowest SLA and the fast-growing perennial herbs, the highest, while woody semi-deciduous shrubs
appeared intermediate. Decreases in RGR due to water stress were analysed in terms of the relative contribution of the leaf
mass ratio (LMR), SLA and the net assimilation rate (NAR). Pooling all species, the decrease in RGR caused by water deficit
was mainly explained by decreases in SLA. However, this general pattern was strongly dependent of growth form. Thus, in the
woody perennial plants, the decrease in RGR was accompanied by a three-fold decrease in NAR which, however, increased in perennial
herbs. SLA increased with decreasing water supply in woody perennial plants, and decreased in woody semi-deciduous shrubs
and perennial herbs. Finally, decreases in LMR partly explained decreases in RGR in perennial herbs and woody perennial shrubs.
This different response of the different growth forms may reflect differences in seedling adaptation and surviving strategies
to drought periods. |
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Keywords: | Balearic endemics Drought Leaf area ratio Net assimilation rate Specific leaf area |
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