title: Limited linkages of aboveground and belowground phenology: A study in grape.
abstract: OBJECTIVE
  Plant phenology influences resource utilization, carbon fluxes, and interspecific interactions. Although controls on aboveground phenology have been studied to some degree, controls on root phenology are exceptionally poorly understood.
  
  
  METHODS
  We used minirhizotrons to examine the timing of grape root production over 5 yr in Fredonia, New York, USA, in a humid continental climate; and over 3 yr in Oakville, California, USA, in a Mediterranean climate. We used data from previous experiments to examine the relationship of root phenology with aboveground phenology. We compared interannual variability in root and shoot growth and determined the influence of abiotic factors on the timing of root initiation, peak root standing crop, peak root growth rate, and cessation of root growth.
  
  
  RESULTS
  Root phenology was not tightly coupled with aboveground phenological periods. Both sites typically had one yearly root flush and high interannual variability in root growth. Root phenology was more variable in California than in New York. In this and other published studies, interannual variation in root phenology was greater than variation in aboveground phenology. The three phenological phases of root growth-root initiation, peak root growth, and root cessation-were related to different suites of abiotic factors.
  
  
  CONCLUSIONS
  Root phenology is highly variable among years. Analysis of potential controlling factors over several years suggest that belowground phenological phases should be analyzed separately from each other. If aboveground grape phenology responds differently than belowground phenology to changes in air temperature, global warming may further uncouple the timing of aboveground and belowground growth.
authors.affiliation: Department of Ecosystem Science and Management and the Ecology Graduate Program, The Pennsylvania State University, State College, Pennsylvania, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Radville
authors.affiliation: Department of Ecosystem Science and Management and the Ecology Graduate Program, The Pennsylvania State University, State College, Pennsylvania, USA.|School of Integrative Plant Science, Cornell University, Ithaca, New York, USA.
authors.forename: Taryn L
authors.initials: TL
authors.lastname: Bauerle
authors.affiliation: Department of Ecosystem Science and Management and the Ecology Graduate Program, The Pennsylvania State University, State College, Pennsylvania, USA.|USDA-ARS Water Management and Systems Research Unit, Fort Collins, Colorado, USA.
authors.forename: Louise H
authors.initials: LH
authors.lastname: Comas
authors.affiliation: Department of Ecosystem Science and Management and the Ecology Graduate Program, The Pennsylvania State University, State College, Pennsylvania, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Marchetto
authors.affiliation: Horticulture Section, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Alan N
authors.initials: AN
authors.lastname: Lakso
authors.affiliation: Department of Viticulture and Enology, University of California-Davis, Davis, California, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Smart
authors.affiliation: Horticulture Section, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Dunst
authors.affiliation: Department of Ecosystem Science and Management and the Ecology Graduate Program, The Pennsylvania State University, State College, Pennsylvania, USA dme9@psu.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Eissenstat
mesh_terms: D002140:California; D002980:Climate; D009518:New York; D010641:Phenotype; D018517:Plant Roots / Q000254:growth & development* / Q000502:physiology; D012621:Seasons; D013696:Temperature; D027843:Vitis / Q000254:growth & development* / Q000502:physiology
keywords: Vitis labruscana; Vitis vinifera; minirhizotrons; root growth; root phenology; ‘Concord’; ‘Merlot’