Yield, Biennial Bearing, and Fruit Quality of Ten Commonly Available Strain/Rootstock Combinations of 'Fuji' Apples at a Single Harvest Date over Seven Years

Abstract

'Fuji' apple (Malus× domesticaBorkh) has gained popularity and the objective of this study was to investigate effects of ten most commonly available 'Fuji' strain/rootstock combinations on tree trunk cross sectional area (TCA; in 2010), yield and biennial bearing index (in 7 years; 2004-2010), and harvest-time fruit quality attributes (in 6 years) under climate conditions of southwest Idaho, USA. The strains and rootstocks were: 'Autumn Rose Fuji', 'Desert Rose Fuji', 'Myra Fuji', 'September Fuji', and 'Top Export Fuji', each on RN 29 rootstock, and 'Beni Shogun Fuji', 'Naga Fu 12 Fuji', 'Sun Fuji', 'T.A.C. 114 Fuji', and 'Torres Fuji', each on M.9 T337 root-stock. Tree TCA was relatively the largest in T.A.C. 114/ M.9 T337 but smallest in Naga Fu 12/M.9 T337. Myra/ RN 29 trees appeared to be more precocious and had more yield per tree in 2004 than Beni Shogun/M.9 T337, Naga Fu 12/M.9 T337, T.A.C. 114/ M.9 T337, and Torres/M.9 T337. Myra/RN 29 trees also had relatively higher cumulative yield efficiency and a lower biennial bearing index than many other strain/rootstock combinations. The 6-year average fruit weights of Desert Rose/RN 29 and Sun/M.9 T337 were lower than those of Beni Shogun/ RN 29, Naga Fu 12/M.9 T337, September Wonder/RN 29, and T.A.C. 114/ M.9 337. Desert Rose/RN 29, Beni Shogun/M.9 T337, and September Wonder/RN 29 had evenly distributed red blush and Myra/RN 29 had a uniform pink and attractive color. Myra/RN 29 had significantly higher 6-year average soluble solids concentration than Autumn Rose/RN 29, Sun/M.9 T337, and T.A.C. 114/M.9 T337. Beni Shogun/RN 29, September Wonder/ RN 29, and Myra/RN 29 had higher but Top Export/RN 29 had lower starch degradation pattern (SDP) than other strain/rootstock combinations. Among all treatments, fruit of Beni Shogun/M.9 T337 and September Wonder/RN 29 matured earlier than other strain/rootstock combinations as indicated by their higher SDP and lower firmness. Considering all yield and quality attributes at harvest, Beni Shogun/M.9 T337 and September Wonder/RN 29 were the most suitable choices for early 'Fuji' and Desert Rose/RN 29 and Myra/RN 29 were the best choices for late-maturing strain/rootstock combinations. Myra/RN 29 was particularly desirable for its relatively high yield efficiency, low biennial bearing, and attractive pink fruit color that resembled bagged 'Fuji' without the expensive cost of labor associated with bagging.