|Authors: ||J.R. Ballington, G.E. Fernandez|
|Keywords: ||Rubus idaeus, Rubus parvifolius, raspberry genetics, interspecific hybridization, heat tolerance|
Cultivated raspberry varieties are typically poorly adapted to warm temperatures and high humidity during summer as well as fluctuating temperatures during winter.
The current and previous raspberry breeding programs at North Carolina State University have utilized raspberry species from eastern Asia to attempt to overcome these problems through interspecific hybridization with cultivated raspberry genotypes. Rubus parvifolius has proven to be the most promising parent from the standpoint of heat and humidity tolerance as well as fertility of the F1, BC1, and BC2 generation derivatives.
F1 hybrids involving R. parvifolius x red raspberry have not been fully resistant to fluctuating winter temperatures.
However, BC1s and BC2s to red raspberry segregate for this trait. Rubus innominatus has shown the best overall adaptation to the climate of North Carolina as a species.
However, the fruit does not mature until the heat of summer and is of poor quality, and F1 and BC1 hybrids involving red raspberry have generally been only partially fertile as a rule.
Eastern black raspberry (R. occidentalis L.) genotypes native to eastern North Carolina also appear promising as a source of genes for resistance to fluctuating winter temperatures, and at least moderate tolerance to warm humid summers.
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