DWARFING ROOTSTOCKS FOR 'VALENCIA' SWEET ORANGE

The Brazilian and other citrus industries will likely require, among other technologies, the use of rootstocks that are suitable for higher planting densities with high production efficiency of high quality fruits and tolerant to abiotic and biotic stresses. Considering this approach, hybrid rootstocks have been obtained by the Citrus Breeding Program of Embrapa Cassava & Fruits, in Cruz das Almas, Bahia State, Brazil. One experiment evaluating the first three commercial crops of ‘Valencia’ sweet orange budded on several rootstocks in Colômbia, São Paulo State, Brazil, indicated that the hybrids ‘TSKC (‘Sunki’ mandarin) × [LCR (‘Rangpur’ lime) × TR (trifoliate orange)]-059’, ‘TSKC × CTSW (‘Swingle’ citrumelo)-033’, ‘TSKC × CTSW-041’, ‘LCR × TR-001’, ‘HTR (trifoliate hybrid)-051’, ‘HTR-053’ and ‘HTR-069’ allowed planting densities higher than those attained with the use of the traditional rootstocks ‘Rangpur’ lime and ‘Sunki’ mandarin. They also induced higher production efficiency of fruits with higher or equivalent quality in comparison to fruits on ‘Rangpur’ lime, which is the usual rootstock in Brazil. Additionally, ‘TSKC × (LCR × TR)-059’ and ‘LCR × TR-001’ induced high tolerance to drought, with results similar to ‘Rangpur’ lime, and the first hybrid also induced early fruit bearing of the scion variety. In spite of not being dwarfing rootstocks, the hybrids ‘TSKC × CTTR (‘Troyer’ citrange)-002’ and ‘TSKC × CTSW-028’, as well as ‘Rangpur’ lime selection ‘CNPMF-003’, ‘Sunki Tropical’ mandarin and ‘Indio’ and ‘San Diego’ citrandarins performed well.