Reig, G; Lordan, J; Fazio, G; Grusak, MA; Hoying, S; Cheng, L; Francescatto, P; Robinson, T
A study was carried out to determine the horticultural performance and leaf and fruit elemental nutrient concentrations of 48 apple rootstocks grafted on 'Fuji' apple cultivar, and grown on a commercial farm in the Hudson Valley (Milton) New York State, USA from 2005 to 2015. Tree circumference was measured at the end of each year, and fruit yield data were collected from the third year (2007) to the eleventh year (2015). Leaf and fruit macro- and microelements were evaluated at the tenth year of the study. Most of the rootstocks evaluated survived well in the Hudson Valley conditions, with the exception of the Geneva. (G or CG) rootstocks CG.4002 and CG.5030. The smallest trees were on CG.2034, M.27 and JM.4 and had the lowest cumulative yield and the lowest cumulative number of fruits, and medium to low fruit size, but the highest cumulative yield efficiency (kg cm(-2)). Other rootstocks, such as the dwarfing CG.2002, CG.2426, CG.4008, CG.5757, M.9 and the semi dwarfing rootstock CG.6006, also had higher yield efficiencies. On the other hand, the medium vigor CG rootstocks such as CG.6001, CG.6253, CG.6976, and CG.8189 had high cumulative yield and high cumulative fruit number, and medium to high yield efficiency. Rootstocks had a significant influence on most of the fruit and leaf mineral concentration (dry weight basis). G.935, G.222 and CG.5257 conferred some of the highest values of fruit boron whereas M.9, M.27 and PiAu51.11 had the lowest. Fruit phosphorous values were closely associated with leaf boron, leaf potassium, and leaf sodium. Fruit calcium was highest in G.214, CG.2406, G.969, JM.4 and CG.5757, while the lowest values were with JM.1, PiAu51.11, and JTE-C. Fruit nitrogen values were lowest in M.7, PiAu51.4, B.54-118, and CG.8534 and the highest values were in the dwarfing rootstock CG.2034 and semi dwarfing rootstock CG.4011. Weak but significant positive correlations were found between fruit size and leaf and fruit Mg, and leaf C. Significant correlations were found between nutrients: leaf B, P and K were highly positively correlated, and leaf Zn with leaf Mn and leaf Na. A strong positive correlation was found between fruit P and fruit K, fruit P and fruit B, and moderate positive correlation between fruit S and fruit K suggesting similar mechanisms of rootstock induction for these nutrients. These nutrient data are being utilized to customize scion nutrient requirements to rootstock-induced nutrient profiles.
