Date of Award


Document Type


Degree Name

Master of Science (MS)


Plant and Environmental Science

Committee Chair/Advisor

Juan Carlos Melgar

Committee Member

Sruthi Narayanan

Committee Member

Dario Chavez


Young peach trees are often rainfed in the southeastern U.S. and periods of dry weather can cause tree water deficit that can be detrimental to orchard productivity. There is a lack of understanding of the influence of water regimes and rootstocks on the nutritional status and gas exchange of the peach tree. Most peach growers in Southeastern United States do not irrigate their young peach trees because they do not produce fruit until the third leaf. In this region, peach growers use Guardian as a rootstock, although MP-29 is also interesting for growers with orchards that have Armillaria root rot problems. Nevertheless, growers should understand how both rootstocks uptake nutrients under different water regimes (well-watered conditions or periods of drought stress) to improve tree performance. The experiment was carried out under a screen house at the Musser Fruit Research Farm, located in Seneca, South Carolina, USA. The experiment had a factorial design with two factors: irrigation (well water and drought stress) and rootstock (Guardian and MP-29. All the trees were grown in pots. The first experiment tested the influence of water stress and rootstock on nutritional status of young peach trees and found that nutrient uptake was affected by the main effects of irrigation, rootstock and by their interaction. Over two consecutive years, measuring stem water potential was required to evaluate tree water status throughout the experiment. The interaction between water regime and rootstock showed that drought stress increased the leaf N and K concentrations in trees on MP29 more than in trees on Guardian, whereas well-watered trees increased leaf Ca and Mg concentration in both MP-29 and Guardian. The second experiment assessed the effect of water regime and rootstock on gas exchange. Water regime had a significant influence on gas exchange in the two seasons of the study; specifically , drought stress reduced the photosynthesis, leaf transpiration, stomatal conductance, and increased water use efficiency. However, rootstocks or the interaction between water regime and rootstock did not influence gas exchange.



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