Abstract
‘Parson Brown’ sweet orange [Citrus sinensis (L.) Osb.] is a well-known early-maturing seedy variety whose importance has slowly declined over time. Its usefulness as a commercial variety has been based on its better juice color and soluble solids content compared to the most common early-season orange, ‘Hamlin’. The juice traits of ‘Parson Brown’ have fit into the production and marketing profile of various companies; thus, an unreplicated rootstock planting was initiated in 1988. The planting was located near Basinger, FL, on the property of a grower-cooperator. Bud sources of PB-S-F-56-2-XE infected with citrus tristeza virus were used to propagate trees on 19 rootstocks. A single double-row bed (≈100 trees) was planted with trees of one rootstock in a site of Valkaria fine sand soil. The trees were spaced 10 × 25 ft. In some instances, a second bed or only a row or partial row of a rootstock was planted. Yield was measured annually along with juice quality for 9 years between the 1992–93 and 2000–01 seasons. Yield and juice quality were also measured among trees on five additional rootstocks in adjacent blocks. Tree survival was >80% except for those trees on Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] (73%) and Changsha mandarin (C. reticulata Blanco) (72%). Tree height after 13 years ranged from 6.3 ft (Hybrid 1573-26 Poncirus trifoliata × ‘Ridge Pineapple’ sweet orange) to 14.9 ft (Vangasay lemon; C. jambhiri Lush.). Cumulative yield ranged from 9.6 (hybrid 1573-26) to 29.0 boxes/tree (Changsha mandarin). Tree height was significantly correlated with cumulative yield (r = 0.72) and cumulative pounds-solids/acre (r = 0.69). Cumulative pounds-solids/acre (PS/acre) was highly correlated with cumulative yield (r = 0.96). Thus, the high-yielding, tall trees on Changsha mandarin rootstock produced the largest cumulative PS/acre (26,073); however, high-yielding smaller trees on other rootstocks with high quality juice such as Rusk citrange (22,493 PS/acre) and the Rangpur × Troyer hybrid (20,155) were also among the most productive trees.