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Luis Valenzuela

Root and leaf responses to different levels of reproduction in Vaccinium corymbosum

PhD in Horticulture, 2008

Present position:  Postdoctoral fellow, USDA-ARS

Collaborators: Kathy Demchak, Elsa Sanchez

Luis has been supported by Consejo Nacional de Ciencia y Tecnologia (CONCYT) fellowship and the National Science Foundation.

Optimizing carbon (C) allocation is key to maximizing fruit production without diminishing long-term plant vigor. Fruit production constitutes a large C sink, which competes with the production, maintenance, and storage pools of shoots and roots. The level that a crop affects root and shoot processes depends on the photosynthetic capacity of the plant. Thus, a whole-plant C budgeting approach is necessary to fully understand the effects of crop load on plant vigor. Fine root carbon costs are the least understood, but can have high construction and maintenance costs. Roots that turnover more quickly have higher production costs. Similarly, leaf costs are governed by the number of leaves produced, how frequently they need to be replaced to maintain a given canopy size, and the costs (dark respiration) required for their maintenance. In addition, leaf C assimilation may increase somewhat with increases in crop. Therefore, I will determine how blueberry root and leaf production, turnover and maintenance as well as whole-canopy C assimilation, are affected by different levels of reproduction. Blueberry plants may be particularly unique in this regard. Blueberries and other members of the Ericales are very distinct from other plant orders because of the unique root architecture. Blueberry roots are extremely fine, extensively branched, lack root hairs and are colonized by ericoid mycorrhizal fungi. This may cause the carbon costs of blueberry roots to differ markedly from other plants.

Publications:

  • Valenzuela-Estrada, Luis R. 2008. PhD in Horticulture. Above and belowground physiology in Vaccinium corymbosum L. (Northern highbush blueberry) in response to water stress and reproductive effort.
  • Valenzuela-Estrada, Luis R, V. Vera-Caraballo, L.E. Ruth, and D.M. Eissenstat. 2008. Root anatomy, morphology and longevity among root orders in Vaccinium corymbosum (Ericaceae). American Journal of Botany 95: 1506-1514.
  • Valenzuela-Estrada, L.R, Richards, J.H., Diaz, A., and Eissenstat, D.M. 2009. Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions. Journal of Experimental Botany 60: 1241-1247.
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