RESPONSE OF YOUNG APPLE TREES TO GRASS AND IRRIGATION

Authors: Tworkoski, Thomas; Glenn, David

Submitted to: Annual Cumberland Shenandoah Fruit Workers Conference
Publication Type: Proceedings
Publication Acceptance Date: 11/30/2007
Publication Date: 9/10/2008
Citation: Tworkoski, T., Glenn, D.M. 2008. Response of young apple trees to grass and irrigation. Annual Cumberland Shenandoah Fruit Workers Conference. November 15-1, 2007, Winchester, VA (Daniel Ward, ed) p.75.

Interpretive Summary:

Technical Abstract: Ground covers and irrigation are important components of orchard floor systems that affect fruit tree vigor and productivity. Experiments were conducted in a greenhouse to determine the relative water use of candidate ground covers (roughstalk bluegrass (RB, Poa trivialis), Chewing's fescue (CF, Festuca rubra subsp. commutata Gaudin), creeping red fescue (RF, Festuca rubra L. subsp. rubra), tall fescue (TF, Festuca arundinacea Schreber, Fawn), and perennial ryegrass (PR, Lolium perenne L., Saint)) and the response of apple trees to those ground covers and to drip irrigation applied at two soil depths. Grass ground covers with large and deep root systems (TF and PR) used more water than shallow-rooted grass (RB) and leaf water potential decreased more rapidly in apple trees grown with TF than RB when irrigation was withheld. Although apple tree shoot growth was greater with shallow- than deep-rooted grass, photosynthesis, transpiration, and root biomass distribution were not differentially affected by grass type. When grown with RB or TF, irrigation depth affected apple tree growth. During the first season in the greenhouse, deep irrigation at 37 cm depth increased apple root length density near emitters but shoot growth was less in apple with deep irrigation compared with surface irrigation (0 cm) and split irrigation at 0 and 37 cm. During the second season in the greenhouse, irrigation location did not affect apple shoot growth but deep-rooted TF suppressed it. Deep irrigation did not overcome interference effects of grass on apple trees, regardless of grass root system size or distribution. Split irrigation to surface and 37 cm depths had intermediate effects on apple tree growth and physiology than irrigation only at 0 and 37 cm. The results indicate that grasses with shallow root systems may be grown beneath apple trees and that split irrigation at two depths can provide flexibility that is necessary for water management of ground covers and apple trees.