Document: LAU-3-31-11

Influences of canopy size, soil moisture and root characteristics on root demography in Concord grape vines.

ANDERSON, L.J.*, L.H.COMAS, H.A.YOUNG and D.M.EISSENSTAT

Pennsylvania State University, University Park, PA 16802 USA ¹

Abstract:
The production and maintenance of fine roots represent a significant carbon sink for plants. Changes in canopy leaf area (e.g., pruning or herbivory) may alter carbon availability for roots, as well as water and nutrient demands by the shoot. How do roots respond to reduced leaf area, particularly when soil resources are limiting? Information on root responses is critical to understanding root-shoot interactions under varying stress levels and assessing whole-plant effects of pruning in crops. We examined root demography in Vitis labrusca (Concord grape) vines receiving different levels of canopy pruning and irrigation (2 x 2 factorial design) using minirhizotron techniques. Our goal was to determine how changes in carbon and water resources interacted to influence root demography. Roots growing against minirhizotron tubes were videotaped every two weeks from April to November in 1997, 1998 and 1999. Production was assessed as numbers of roots appearing in minirhizotron windows. Survival data for 1998 cohorts were analyzed using Cox proportional hazards regression methods, with pruning, irrigation, root diameter, number of neighbor roots, and soil depth as covariates potentially affecting survival. Preliminary analyses suggested irrigation had a strong influence on total root production. In 1998, a dry year, irrigated treatments produced 69% more roots in the top 30 cm of soil than non-irrigated treatments. The opposite pattern occurred in 1997, a wet year. For May and July 1998 cohorts, pruning and irrigation did not have significant effects on root survival, but small diameter roots (< 0.4 mm) were less likely to survive than coarser roots (P < 0.01). The presence of other roots also significantly increased the chances of root mortality (P < 0.05). Our data suggest that root production and survival in grape are more influenced by soil moisture and root characteristics than moderate canopy manipulation.

Keywords: root ecology, plant carbon balance, soil moisture, minirhizotron, root lifespan

This abstract is being presented at: 3:30 PM in session:
ROOT PROCESSES