Interested Members of the University Community are invited to attend the Final Oral Examination for the Degree of Master of Science of Plant Agriculture Yu Jia Li of the Department of Plant Agriculture

DATE: Monday, May 16, 2022
TIME: 12:30 PM
METHOD: Via Zoom: https://zoom.us/j/94233932383?pwd=QzdzcEtxTWJMcXJsWTI2OExzeG1GUT09
MEETING ID: 942 3393 2383
PASSCODE: 623820

Thesis Title: “Crop Load and Thinning Timing Effects on Flower Bud Initiation in “Gala” and “Honeycrisp” Apple Trees and Observations of Flower Bud Initiation in “Gala”, “Empire”, “Fuji” and “Honeycrisp” Apple Trees”

Advisory Committee
Dr. John Cline, Advisor
Dr. Istvan Rajcan
Dr. Jaideep Mathur
Dr. Max Jones

Examination Committee
Dr. John Sulik, Chair
Dr. John Cline
Dr. Max Jones
Dr. Darren Robinson

ABSTRACT

Biennial bearing (BB) is a physiological problem in apples which occurs when there are alternate annual cycles of production. Flower bud initiation (FBI) is the primary cause of BB and is closely related to crop load management. Experiments were conducted to investigate cultivar differences and the degree and timing of flower and fruit thinning on FBI. In 2018, the onset of FBI was earlier for “Empire” and “Honeycrisp” than “Fuji” and “Gala”, while in 2019, FBI was earlier for “Honeycrisp” than “Empire”. The onset of FBI was earlier when thinning was conducted at 10-12 mm fruitlet diameter compared to petal fall and after June drop for both “Gala” and “Honeycrisp”. “Honeycrisp” trees with higher crop loads had earlier onset of FBI. “Gala” and “Honeycrisp” trees that were thinned had enhanced return bloom compared to un-thinned trees, irrespective of crop load or timing. This research will inform producers of appropriate thinning strategies for BB cultivars.