ISHS Acta Horticulturae 183: IV International Rubus and Ribes Symposium
CHARACTERIZATION OF RUBUS PROGENIES FROM EMBRYO CULTURE AND FROM SEED GERMINATION |
| Authors: | G.J. Galletta, A.D. Draper, R.L. Puryear |
| Abstract:
Our Rubus improvement emphases continue to be development of hardy thornless clones which bear consistent crops of high quality fruit. Large seeds of thornless blackberries germinate poorly (1–10%) following acid scarification and stratification of 12 to 15 weeks. Embryo culture methods yield up to 50% transplantable seedlings. Selfing and intercrosses among thornless blackberries often produce progenies with reduced vigor (inbreeding depression). Segregating progenies of certain tetraploid heterozygous thorny blackberries contain fertile thorny and sterile (often dwarfed) thornless plants. Intercrosses of diploid blackberries have yielded small progenies having many partially sterile or small-fruited individuals with desirable plant characters. Heteroploid raspberry-blackberry and blackberry crosses have also given small progenies and partial sterility. Thornless blackberry-raspberry hybrids are being backcrossed to both thornless and hardy thorny types. Some F2 and F3 purple thornless raspberry hybrids have superior fruit, but are still only partially cold hardy. Newer hardy raspberries and blackberries are being hybridized with thornless blackberries. Our newest thornless blackberry, 'Chester Thornless' is more hardy and cane blight resistant than previous releases, and it has the same high solids and low acidity of its sister seedling, 'Hull Thornless'. | |
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