The belowground ecophysiological responses of grapevines to competition by cover crops

Open Access
Author:
Klodd, Anne Elise
Graduate Program:
Plant Biology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
February 25, 2015
Committee Members:
  • David Eissenstat, Thesis Advisor
  • Michela Centinari, Thesis Advisor
Keywords:
  • Grapevine
  • cover crops
  • competition
  • roots
  • ecophysiology
  • plasticity
  • carbon partitioning
Abstract:
Excessive grapevine vigor can decrease viable fruit yield, fruit quality, and overall profit in commercial vineyards. Growers have become increasingly interested in using cover crops as a means to control excessive vigor, through competition with the grapevines for growth-limiting soil resources. Studies have found substantial variation in the magnitude of cover crop effects on grapevine canopy size. This variation could potentially be influenced by a number of factors including soil environment, climate, competitor plant strategy, grapevine age, or grapevine root responses to competition. However, little is known about the magnitude of competition caused by cover crops in humid climate vineyards, or how grapevine root systems respond to competition on a physiological level. Our study examined the ecophysiological responses of grapevine roots to grass competition, by measuring changes in absorptive root distribution, morphology, and resource uptake between vines grown with and without Festuca rubra L. (red fescue). We also evaluated the whole-plant cost of belowground competition by comparing above- to belowground biomass partitioning of grapevines between groundcover treatments. The results revealed that grapevine canopy biomass did not decrease in response to cover cropping, despite marked shifts in root distribution, reduced overall root proliferation, and evidence of reduced root access to nutrients. While we found no evidence that cover cropping impacted grapevine water and nitrogen uptake, phosphorus competition did occur. These results indicate a plastic root response of grapevines to grass competition that may allow them to maintain growth and resource acquisition despite limited access to belowground resources.