Thesis
Timely deficit irrigation as a tool to improve fruit quality and bitter pit incidence in 'Honeycrisp' apple
Washington State University
Master of Science (MS), Washington State University
2019
Handle:
https://hdl.handle.net/2376/101177
Abstract
'Honeycrisp' is among the most rapidly planted apple cultivars in Washington State. The environmental conditions of apple growing regions in Washington State leave this cultivar predisposed to large fruit that can be susceptible to bitter pit. Prior research has linked fruit size to bitter pit incidence. Irrigation can be used as a tool to predictably control fruit size. Currently, there is little knowledge as to how 'Honeycrisp' trees and developing fruit respond to water-limited conditions. In 2017 and 2018, three-year old 'Honeycrisp' were subject to one of four different irrigation regimes. A well-watered control was maintained at 80-90% of field capacity compared to water limitations imposed early at 15-45 days after full bloom (DAFB), mid-season at 45-75 DAFB, or late season at 75-105 DAFB. Soil moisture was reduced and held at approximately 30-40% of field capacity during these time periods. Stomatal conductance, leaf gas exchange, and plant water status were measured every 15 days from 30-105 DAFB. Fruit size, quality, and bitter pit incidence were measured at harvest. Stomatal conductance was significantly reduced during irrigation deficit periods. Net gas exchange was approximately 50% lower during all water limited periods compared to the well-watered control. Stem water potential was 30-50% lower throughout the growing season depending on temperatures during the deficit period. In 2017, fruit firmness and soluble solids content from the late season water limitations were greater than the well-watered control. In the same year, bitter pit incidence decreased for the mid-season and late season treatments compared to the well-watered control. Return bloom was not affected by irrigation timing but was significantly lower in the second year for all treatments. These finding indicate that stem water potential in combination with soil moisture monitoring can be used as tools to make irrigation decisions. Along with crop thinning and calcium sprays, deficit irrigation can be used to reduce bitter pit while still maintaining good fruit quality in 'Honeycrisp' apple.
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Details
- Title
- Timely deficit irrigation as a tool to improve fruit quality and bitter pit incidence in 'Honeycrisp' apple
- Creators
- Michelle Nicole Reid
- Contributors
- Lee A. Kalcsits (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525054401842
- Language
- English
- Resource Type
- Thesis