|Gmitter, Jr., Frederick|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2011
Publication Date: 6/1/2011
Citation: Castle, W.S., Bowman, K.D., Baldwin, J.C., Grosser, J.W., Gmitter, Jr., F.G. 2011. Rootstocks affect tree growth, yield, and juice quality of 'Marsh' grapefruit. HortScience. 46(6):841-848. Interpretive Summary: Results are presented from two rootstock trials with grapefruit in the east coast area of Florida. A total of 44 rootstocks, including several standard rootstocks, were evaluated in the replicated plantings and compared for tree growth, tree survival, fruit yield, and fruit quality over the first four harvest seasons. Four mandarin x trifoliate orange hybrids and one sweet orange x trifoliate orange hybrid were identified as the most promising rootstocks for commercial use under the conditions of these trials.
Technical Abstract: Two adjacent rootstock trials were conducted in the east coast Indian River region of Florida with ‘Marsh’ grapefruit (Citrus paradisi Macf.) scion. The objective was to find rootstocks to replace sour orange (C. aurantium L.) because of losses to citrus tristeza virus, and to replace Swingle citrumelo ½C. paradisi • Poncirus trifoliata (L.) Raf._ because of its limited usefulness in certain poorly drained coastal sites. The trials were conducted in randomized complete blocks with 12 single-tree replicates spaced 4.6 • 6.9m. The soils were of the Wabasso and Riviera series. The first trial consisted largely of trees on citrange ½C. sinensis (L.) Osb. • P. trifoliata_ and citrumelo rootstocks, ‘Cipo’ sweet orange (C. sinensis), and various hybrid rootstocks. The second trial involvedmandarin rootstocks (C. reticulata Blanco) and sour orange and related rootstocks. Trees were grown for 7 years and yield and juice quality data were collected for the last 4 years of that period. Those rootstocks identified as the most promising, based on combinations of smaller tree size and high productivity and juice quality, were two Sunki mandarin • Swingle trifoliate orange (TF) hybrids (C-54, C-146), a Sunki mandarin • Flying Dragon TF hybrid, C-35 citrange, and a Cleopatramandarin • Rubidoux TF hybrid (•639). The trees on these five rootstocks cropped well leading to soluble solids (SS) values of 3000 to 4000 kg/ha when they were 7-years old. The trees on C-54 and C-146 were relatively large, somewhat taller than trees on sour orange, whereas those on C-35 and the Sunki • Flying Dragon hybrid were smaller and similar to sour orange in tree height. Fruit quality among the trees on C-35 and the Sunki • Flying Dragon hybrid had relatively high SS concentration (better than sour orange), and the other three rootstocks had relatively lower solids concentration (poorer than sour orange). The trees on C-35 and the Sunki • Flying Dragon hybrid would be good candidates for higher density orchards.