Bowsher, Alan , Donovan, Lisa .
Seedling root characteristics in relation to age, life history, and nutrient supply in Helianthus.
Recent field studies of plant roots suggest the existence of a fundamental trade-off governing root form and function. Fast-growing species are thought to exhibit higher specific root length (SRL), lower tissue density, and shorter lifespan than slower-growing species; a trade-off thought to reflect contrasting resource strategies. However, our understanding of root trait variation and its relationship with plant growth strategies is still limited due to the small number of cross-species comparisons to date. Additionally, in order to better understand interspecific variation, it is important to know how factors such as ontogeny and resource supply can affect intraspecific variation in root traits. In this study, two annual and two perennial Helianthus (sunflower) species were grown in either high or low nutrient supply in the greenhouse, and fine root characteristics were measured either three or five weeks after sowing. In all species, SRL tended to decrease over time due to increases in tissue density and/or mean diameter over time. Low nutrient supply tended to result in high tissue density, but had inconsistent effects on SRL and mean diameter. Tissue density and relative growth rate were negatively correlated, with perennials tending towards lower tissue density than annuals. Contrary to expectations, H. annuus, the fastest-growing of the four species, had among the lowest values for SRL due to high mean diameter. These results provide further support for the importance of tissue density in differentiating plant growth strategies, but the significance of SRL and mean diameter is still unclear. Additionally, this study clearly points out the need to consider both ontogeny and soil resources when comparing field-collected roots, as both factors had a strong effect on commonly measured fine root traits.
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1 - University of Georgia, Department of Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602, USA
plant growth strategies
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM