Rootstocks affect tree growth, yield, and juice quality of 'Marsh' grapefruit

Abstract

Two adjacent rootstock trials were conducted in the east coast Indian Riverregion of Florida with 'Marsh' grapefruit (Citrus paradisi Macf.) scion. cx Poncirus trifoliata (L.) Raf.]because of its limited usefulness in certain poorly drained coastal sites. The trials wereconducted in randomized complete blocks with 12 single-tree replicates spaced 4.6 × 6.9m.The soils were of theWabasso and Riviera series. The first trial consisted largely of trees oncitrange 1/2C. sinensis (L.) Osb. × P. trifoliate] 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 yearsand yield and juice quality data were collected for the last 4 years of that period. Thoserootstocks identified as the most promising, based on combinations of smaller tree size andhigh productivity and juice quality, were two Sunki mandarin × Swingle trifoliate orange(TF) hybrids (C-54, C-146), a Sunki mandarin x Flying Dragon TF hybrid, C-35 citrange,and a Cleopatramandarin × Rubidoux TF hybrid (×639). The trees on these five root stock scropped well leading to soluble solids (SS) values of 3000 to 4000 kg/ha when they were7-years old. The trees on C-54 and C-146 were relatively large, somewhat taller than tree son 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 theSunki × Flying Dragon hybrid had relatively high SS concentration (better than sourorange), and the other three rootstocks had relatively lower solids concentration (poorerthan sour orange). The trees on C-35 and the Sunki × Flying Dragon hybrid would be goodcandidates for higher density orchards.