Do water and soil nutrient scarcities differentially impact the performance of diploid and tetraploid Solidago gigantea (Giant Goldenrod, Asteraceae)?

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Department of Biological Sciences


RATIONALE: Plants require water and nutrients for survival, although the effects of their availabilities on plant fitness differs amongst species. Genome size variation, within and across species, is suspected to influence plant water and nutrient requirements, but little is known about how variations in these resources concurrently affect plant fitness based on genome size. We examined how genome size variation between autopolyploid cytotypes influences plant morphological and physiological traits, and whether cytotype-specific trait responses differ based on water and/or nutrient availability. METHODS: Diploid and autotetraploid Solidago gigantea (Giant Goldenrod) were grown in a greenhouse under four soil water:nitrogen+phosphorus treatments (L:L, L:H, H:L, H:H), and stomata characteristics (size, density), growth (above- and belowground biomass, root/shoot ratio), and physiological (net photosynthetic capacity, transpiration rates, water use efficiency) responses were measured. KEY RESULTS: Resource availabilities and cytotype identity influenced some plant responses but their effects were independent of each other. Plants grown in high-water and nutrient treatments were larger, plants grown in low-water or high-nutrient treatments had higher water use efficiency but lower transpiration rates, and photosynthesis and transpiration rates decreased as plants aged. Autotetraploids also had larger and fewer stomata, greater biomass, and greater photosynthetic capacity than diploids. CONCLUSIONS: Nutrient and water availability could influence intra- and interspecific competitive outcomes. Although S. gigantea cytotypes were not differentially affected by resource treatments, genome size may influence cytogeographic range patterning and population establishment likelihood. For instance, the greater size of autotetraploid S. gigantea might render them more competitive for resources and niche space than diploids.

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Plant biology (Stuttgart, Germany)