Plastic responses to temporal variation in moisture availability: consequences for water use efficiency and plant performance

Abstract

The ability to appropriately modify physiological and morphological traits in response to temporal variation should increase fitness. We used recombinant hybrid plants generated by crossing taxa in the Piriqueta caroliniana complex to assess the effects of individual leaf traits and trait plasticities on growth in a temporally variable environment. Recombinant hybrids were used to provide a wide range of trait expression and to allow an assessment of the independent effects of individual traits across a range of genetic backgrounds. Hybrid genotypes were replicated through vegetative propagation and planted in common gardens at Archbold Biological Station in Venus, Florida, where they were monitored for growth, leaf morphological characters, and integrated water use efficiency (WUE) (C isotope ratio; delta(13)C) for two successive seasons. Under wet conditions only leaf area had significant effects on plant growth, but as conditions became drier, growth rates were greatest in plants with narrow leaves and higher trichome densities. Plants with higher WUE exhibited increased growth during the dry season but not during the wet season. WUE during the dry season was increased for plants with smaller, narrower leaves that had higher trichome densities and increased reflectance. Examination of alternative path models revealed that during the dry season leaf traits had significant effects on plant growth only through their direct effects on WUE, as estimated from delta(13)C. Over the entire growing season, plants with a greater ability to produce smaller and narrower leaves with higher trichome densities in response to reduced water availability had the greatest growth rate. These findings suggest that plants making appropriate changes to leaf morphology as conditions became dry had increased WUE, and that the ability to adjust leaf phenotypes in response to environmental variation is a mechanism by which plants increase fitness.

Photosynthetic response of the floating-leaved macrophyteNymphoides peltatato a temporary terrestrial habitat and its implications for ecological recovery of Lakeside zones

“…The ability to modify physiological traits in response to temporary variation can increase fitness (Picotte et al, 2007). Our study demonstrated that N. peltata developed a series of photosynthetic acclimation features to help the plant cope with temporary terrestrial habitats, which included less stomatal density, a smaller stomatal aperture area, lower E and g s , and high WUE.…”

Are there morphological and life‐history traits under climate‐dependent differential selection in S TunesianDiplotaxis harra(Forssk.) Boiss. (Brassicaceae) populations?

“…Additionally, among other traits, length‐width ratio of leaves was found exhibiting considerable plasticity in Piriqueta caroliniana Urban (Turneraceae), with narrower leaves being produced under more arid conditions in successive years (Picotte, Rhode, & Cruzan, 2009) or even in successive seasons of the same year (Picotte et al. 2007). However, as we lack measurements from natural habitats and our experiment has not been carried out under natural conditions in common gardens with Mediterranean and/or semidesert climate but under glasshouse/garden conditions with optimal supplies of water, light, and nutrients, the observed trends rather demonstrate that plants with provenances from semi‐arid habitats either have broader leaves or are capable to produce broader leaves than those from more mesic conditions when confronted with optimal growth conditions and that this trait or the plasticity of this trait is selected for.…”

The relevance of seed size in modulating leaf physiology and early plant performance in two tree species

“…One interpretation of the above result is that low WUE was advantageous for plants. An efficient use of water may help plants to survive persistent droughts in arid environments but be disadvantageous in seasonally dry and competitive habitats (Ehleringer 1993;Mediavilla and Escudero 2003;Nicotra and Davidson 2010;Picotte et al 2007;Sandquist and Ehleringer 2003). Alternatively, assuming that first-year leaf 5 C resulted from the seed-toleaf mobilization of C-enriched components, the increasing probability of survival of Q. pyrenaica as leaf 5 C decreased could be mostly reflecting a positive effect of first-year photosynthetic carbon gain on subsequent survival.…”

“…Thus, maximizing net carbon assimilation relative to water loss, i.e. leaf water use efficiency (WUE), generally increases plant growth (Dudley 1996;Geber and Griffen 2003;Picotte et al 2007) and survival (Casper et al 2005;Ehleringer 1993) in these ecosystems. There are multiple ways in which seed size and dispersal microsite can affect leaf WUE.…”

“…Milla et al 2009;Picotte et al 2007). In this study, we use path analysis to explore the effects of seed size and light availability on the growth of 1-year-old seedlings of Quercus pyrenaica Willd and Quercus petraea (Matt.…”