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Prunus rootstocks influence stem water potential, C/N ratio and shoot ash content in peach

Mayer, N. A., Reighard, G., Bridges, W., Glenn, D. M.
Acta horticulturae 2014 no.1058 pp. 365-373
Prunus americana, ash content, carbon, cultivars, dormancy, genotype, nitrogen, nitrogen content, peaches, planting, rootstocks, scions, shoots, trees, vigor, water potential, South Carolina
Many peach rootstocks have been released in recent years with limited information about their physiological effects on scion vigor and productivity. In this study, two trials were established with ‘Redhaven’ on 9 (planted 2006) and 18 (planted 2009) rootstock cultivars at the Musser Fruit Research Center, Seneca, South Carolina. A stem water potential (SWp) curve was developed with a Scholander pressure bomb on a single day ~ 6 weeks after harvest (August, 2011) with hourly evaluations between 5 am and 8 pm on a ‘Redhaven’/Lovell tree. For each trial, SWp readings were done before dawn and in the afternoon (~4 pm). The maximum negative SWp occurred at ~4 pm. Carbon (C), nitrogen (N) and ash content analyses were done on 1-year-old shoots at the beginning of dormancy in November, 2011. Rootstocks influenced all variables studied in both trials. Trees that were more stressed (high negative SWp) before dawn were also more stressed in the afternoon (i.e., rootstocks Prunus munsoniana and Empyrean®). A similar pattern was observed for those trees/rootstocks with less negative SWp (i.e., Prunus Americana, Fortuna and KV010127) in the predawn hours as they also remained less negative in the afternoon. There was no correlation between SWp and C, N, C/N ratio or shoot ash content. There were negative correlations between C/N ratio and ash content and the N and C/N ratio. There was a positive correlation between N and ash content. These data suggested that SWp was not a reliable method to predict C, N or ash content accumulation in 1-year-old peach shoots from trees grown on many different rootstock genotypes.