Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Plant and Environmental Science

Committee Chair/Advisor

Dr. Juan Carlos Melgar

Committee Member

Dr. Sruthi Narayanan

Committee Member

Dr. Geoff Zehnder

Abstract

Deciduous fruit tree production worldwide may need to alter management strategies due to an increase of variable climate conditions. These include warmer than average temperatures during the year along with too much or little water during the growing season. Predicting best practices for orchard management will require a thorough understanding of how temperatures and soil moisture alter carbon acquisition and nutrient movement in trees, especially during the end of the growing season when tree reserves are accumulated for the following spring. Over two consecutive years, the effect of warmer fall temperatures, which delayed natural leaf senescence, and variable soil moisture conditions were evaluated on two-year old ‘Autumnprince’ and ‘Scarletprince’ peach trees at Clemson University, South Carolina, USA. The delay of leaf senescence did not change leaf CO2 assimilation rates during the fall, but increased the rate by which nutrients were returned to perennial tissues. Dryer soil moisture conditions reduced overall carbon assimilation the first fall season, and increased nutrient concentrations in perennial tissues. Cultivar also affected overall carbon assimilation during the second fall season, and nutrient resorption of phosphorus, potassium, calcium and magnesium. Changes in these natural cycles of nutrients and carbon assimilation affect dormancy and spring growth, thus, predicting differences resulting from variable fall events could be used for optimizing orchard practices such as the use of dormancy-breaking chemicals or tree fertilization.

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