Citrus Breeding History Breeding Goals Rootstock Rootstock Hybrids
History • Early agriculturalists selected natural Citrus Breeding hybrids and mutants for seed propagation • 1800’s- grafting and cuttings became popular to propagate best varieties Kevin M. Crosby • 1900’s- artificial cross-pollination practiced Breeding Goals Rootstock • Rootstock- tree size, stress tolerance • Dwarfing- Poncirus, some mandarins • Scion- fruit color, size, shape, flavor, yield • Compatability- citrus better than Poncirus • Disease resistance- CTV, Phytophthora, • Seedling vigor and scion yield CVC, Alternaria, Scab, Greening, etc. • Fruit quality- size, shape, flavor, juice Rootstock Hybrids Carrizo Citrange • ‘Carrizo,’ ‘Troyer’ Citrange- navel orange x Poncirus, very popular in FL, CA • ‘Swingle’ Citrumelo- grapefruit x Poncirus, very popular in Florida, salt intolerant • ‘Sunki’ x ‘Swingle’ tf- semi-dwarfing, salt- tolerant, possible replacement for SO in TX 1 Swingle Citrumelo Rootstock Fruit Scion Scion Hybrids • Vigor, yield potential, cold tolerance • ‘Orlando,’ ‘Minneola’ tangelos- ‘Duncan’ grapefruit x ‘Dancy’ tangerine • Fruit type- mandarin grapefruit, orange • ‘Page’ mandarin- ‘Minneola’ x ‘Clementine’ • Fruit quality- flavor, size, seediness, appearance, shelf-life • ‘Oro Blanco’ grapefruit triploid- tetraploid pummelo x grapefruit Disease Resistance Breeding Techniques • Viruses- CTV, Psorosis, Exocortis • Cross-pollination- combine genes from different parents in hybrid progeny • Bacteria- Citrus Variegated Chlorosis, Greening, Canker • Self-pollination- fix genes of interest in one line to stabilize
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