The influence of rootstocks on chilling injury symptoms of 'Big Top' nectarine fruits

The influence of nine different Prunus rootstocks budded with the 'Big Top' nectarine cultivar was evaluated in a rootstock trial established at the Experimental Station of Aula Dei (Zaragoza, Spain). Chilling injury (CI) symptoms as browning, mealiness, leatheriness and bleeding were determined after 28 days of cold storage at 5 degrees C plus 2 days of shelf-life. Agronomical basic fruit quality traits as firmness, soluble solids content (SSC) and titratable acidity (TA) were determined at harvest, after 28 days of fruit storage at 5 degrees C and after 28 days plus 2 days of shelf-life. In addition, biochemical compounds as main individual sugars and organic acids, relative antioxidant capacity (RAC), total phenolics content (TPC), total flavonoids content (TFC), vitamin C (AsA) and anthocyanins content (AC) were also quantified. Moreover, enzymatic activity of key enzymes related with the tolerance against CI such as phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POX) were determined. Significant effect of Prunus rootstocks was found on leatheriness and bleeding symptoms, firmness, TA, sugars and organic acids, AC and enzymatic activities. Sugars, organic acids, TPC, AC and the enzymatic activities of the phenylpropanoid pathway and ROS metabolism enzymes seemed to be important parameters to consider in the prevention of CI susceptibility. These results may be helpful in the choice of rootstocks inducing lower chilling injury susceptibility.