Date of Award:

12-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Committee Chair(s)

Grant Cardon

Committee

Grant Cardon

Committee

Matt Yost

Committee

Teryl Roper

Abstract

Fruit production in Utah can be challenging due to local climate and soil conditions. Tart cherries and apples are major fruit crops in Utah, and improvements to these cropping systems would be beneficial for farmers and local consumers. Two experiments were conducted to evaluate desired improvements for these crops. The first study looked for salt tolerance in ten new apple rootstocks. Salty soils can be found throughout the state limiting the land suitable for apple production. When grown in salty soils apple trees often have reduced growth and production potential. A specialized drip irrigation system was constructed in a greenhouse to deliver a range of salt treatments and sodium chloride was used as the salt for this experiment. Rootstocks were grown under treatment for 30 days. A commonly used rootstock (M.9) was tested alongside the new rootstocks for reference. Linear regression was used to compare rootstock growth response to increasing salt levels. Three rootstocks (84R5P2-062, 85SA11-41, and 85SA22-5R) grew less than M.9 indicating sensitivity to salt. The 84RSA22-84R, 85SA22-13R, 85SA22-33, 85SA22-34R, 85SA22-6R, and 92(786346-67(179)-1 rootstocks may be salt tolerant, but further testing is needed to determine long-term growth response and potential limitations. The second study aimed to improve nitrogen fertilizer recommendations for tart cherry production. Improved recommendations could decrease costs for farmers and reduce the loss of fertilizer to the local environment. This was evaluated by establishing 12 fertilizer treatments using different combinations of rate, timing, and source of fertilizer used. These factors in addition to placement are often referred to as the 4Rs (right rate, right source, right timing, and right placement) and are used to determine best practices for fertilizer applications. Treatments were applied in an established tart cherry orchard. Yield data was collected to look for treatment effects. No significant differences between treatments were seen in the first three years as yields are influenced by the growing conditions and management of previous years. Yield data from year four indicated that changing the timing of application alone resulted in a lower yield than changing the source, rate, and timing together.

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