|ROBINSON, TERENCE - Cornell University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/25/2022
Publication Date: N/A
Technical Abstract: An experiment aimed at understanding the genotypic potential of certain widely planted scion cultivars to transport nutrients in their vascular systems (stems) was set up by generating apple trees that featured interstems of different scion cultivars. Four rootstock replicates of the vigorous rootstock B.118 were bench grafted with scion varieties ‘Empire’, ‘Golden Delicious’, ‘Honeycrisp’, ‘Ida Red’, ‘Jonagold’, ‘Liberty’, ‘Mutsu’ and ‘Red Delicious’ in March of 2016 and planted in a nursery. Grafts were trained to a single shoot which was chip budded with B.118 buds 15 cm above the graft union in August 2016 to generate consistent interstems of the various cultivars 15 cm long. The healed dormant buds were forced by topping the trees 2 cm above the chip bud in May 2017 and the B.118 shoot was trained to a single stem. Fully expanded leaves from the top 1/3 of the tree were harvested in September 2017 and processed for nutrient analysis which yielded concentration values of N, P, K Ca, Mg, S and other micronutrients. Trees were planted in an orchard in Geneva, NY in June 2018. In November 2019 an XRF instrument was used to monitor relative concentration of P, K, Ca, S and some micronutrients like Fe, Mn, and Cu in one and two-year-old stems. While the variances for some nutrient genotypic means where too large for mean separation at less than 0.05 significance level – probably because more replications were needed – we were able to notice some general trends for each of the nutrients when comparing the genotypic mean to the overall mean. From the leaf analysis data we found that leaf calcium concentration means ranged from 0.8% to 1.1% with values for Red Delicious, Liberty, Honeycrisp and Empire interstems were below the overall mean (0.99%) while the values for the rest of the cultivars were above the mean. For leaf potassium, Honeycrisp displayed the highest values (1.8%) whereas Empire and Liberty had the lowest values (1.3%). Leaf sulfur and leaf nitrogen were highly correlated variables and among cultivars Honeycrisp had the highest means (1.88% N and 0.13% S) and Liberty had the lowest means (1.61% N and 0.11% S). These results show that the vascular system of each scion cultivar displays differential capacity to transport some nutrients. This work has implications for the practice of top-working older orchards with new scion varieties. It also has implications with regards to using interstems. This work is part of a larger project aimed at understanding the connection between rootstocks and fruit quality being studied in the USDA NIFA Specialty Crop Project “AppleRoot2Fruit”.