Thesis
Leaf area and crop load management in new apple cultivar: WA38
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/101656
Abstract
Optimizing fruit quality in the orchard requires the fine tuning of several horticultural factors and practices. These include aspects like training systems, rootstock selections, pruning techniques, and crop load management. In 2017, Washington State University released a new apple cultivar, WA38, commercialized as Cosmic Crisp. An estimated five million trees are projected to be planted in Washington State by 2018. Research is needed to guide the industry towards optimal WA38 production and management in order to understand the productive characteristics of this cultivar to optimize fruit quality. This research focuses on non-destructive leaf area estimation in an orchard and how factors like training systems, rootstocks, and pruning impact leaf area index (LAI), light interception, and yield in WA38. Further, WA38 crop load influence was investigated in relation to vegetative parameters, fruit quality, and return bloom. Hemispherical photography was utilized to predict LAI in WA38 and an optimized methodology was developed. Based on the results of this research obtained in our environmental conditions, a promising combination of a training system, rootstock, and pruning technique for WA38 appears to be a Spindle system, with a low-moderate vigor rootstock, combined with "click" pruning; a shortening cut of one-year old shoots at the end of branches. Also, mechanical pruning was shown to be a viable option, given its minimal impact on fruit quality, lack of loss on yield, and significant savings in time. In respect to consistent bearing, reduced cull percentages, and high fruit quality, a crop load threshold of five to six fruits/cm2 of trunk cross-sectional area (TCSA) is preferable for WA38. Future research should be focused on evaluating the impact of higher crop load thresholds on return bloom and vegetative parameters.
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Details
- Title
- Leaf area and crop load management in new apple cultivar: WA38
- Creators
- Brendon Michael Anthony
- Contributors
- Stefano Musacchi (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
- 99900525397901842
- Language
- English
- Resource Type
- Thesis