Physiological Performance and Nutrient Uptake of a Low-Chill Peach Tree Grafted on Different Rootstocks Under a Subtropical Climate

Peach scions with low chilling requirements allow fruit production in subtropical regions with reduced chilling periods. Differences between scions and rootstocks may affect mechanisms regulating plant responses in grafted plants. This study aimed to investigate how various rootstocks affect physiological performance and nutrient uptake capacity of a low-chill peach scion in a subtropical climate. Plant material consisted of low-chill peach “UFSun” grafted on low- (“Okinawa” and “Flordaguard”), medium- (“Barton” and “P-22”), and high (“MP-29”) chill requirement rootstocks. Photosynthetic parameters, SPAD Index, chlorophyll fluorescence, stem water potential, and nutrient concentrations were assessed in spring, summer, and fall of 2021 and 2022. Most parameters varied throughout the growing season. Rootstocks showed no effect on photosynthetic rate, stomatal conductance, or intercellular CO2 concentration. Transpiration rates of trees grafted on “MP-29” were at least 11% higher than those grafted on “Okinawa” and “Flordaguard.” Stem water potential of trees grafted on “P-22” and “MP-29” were at least 9% higher compared to those grafted on “Okinawa,” “Flordaguard,” and “Barton.” Nitrogen concentration was up to 8% higher in trees grafted on “MP-29” compared to other trees, while P concentration in trees grafted on “Barton” was 7% and 12% higher, respectively, compared to those grafted on “Flordaguard” and ‘P-22. No significant K differences related to rootstock were reported. Our results suggested that rootstocks can vary in water and nutrient uptake capacity thereby influencing their levels in low-chill scions. Assessing water uptake capacity of grafted plants could help to assess the adaptive potential of scion-rootstock combinations to subtropical environments.