Other Blackberry Breeding 



Another complex blackberry hybrid which seems to offer some possibilities 

 is one obtained by pollinating New York 32 blackberry with pollen from 

 a triploid hybrid made by crossing Hailsham tetraploid raspberry with 

 Korean Tree Berry, Ruhiis morijolius. Some of the plants from this complex 

 hybrid involving three species are hardy with fruits which look like black- 

 berries. 



Early Harvest Blackberry Crosses 



Early Harvest, a diploid cultivated blackberry, when crossed with selected 

 nearly thorniest wild blackberries presumed to be Ruhus canadensis, has 

 given a fairly hardy self-fertile F2 progeny. Among this progeny may be 

 a worthwhile early variety. Succeeding generations will also be grown. Early 

 Harvest blackberry has been crossed also with both the red raspberry and 

 the black raspberry, Ruhus occidentalis. Both of these interspecific F] 

 generations were almost completely male sterile. Some seeds were produced 

 by open pollination in the field, and a small Fo generation of Early Harvest 

 X black raspberry has been grown. Some of the plants in this second genera- 

 tion appear to be promising breeding material. The plants are partially 

 self-fertile. Early Harvest blackberry has been pollinated also in the green- 

 house with pollen from a Ruhus ideaus x Ruhus arcticus plant No. 49-201-1 

 which came from Finland by way of Canada. The F^ generation from this 

 cross involving three species is a variable progeny raiiging from plants only 

 a few inches high to some four feet high. All these seedlings are male sterile 

 or nearly so, and they give no self-pollinated fruits. Some viable open-pollin- 

 ated seed has been procured from them. In the greenhouse, seed has been 

 produced by pollinating the hybrid plants involving the three species with 

 pollen from red raspberry and New Hampshire 4^1 blackberry, Ruhus 

 canadensis, and a partially fertile hybrid of Ruhus odoratus x Durham 

 raspberry. The seeds have been stratified. Such wide interspecific crosses 

 are exploratory, yet may eventually give worthwhile new varieties. A cross 

 was also secured between Early Harvest and R. pubescens. Although the F^ 

 was male sterile, an open-pollinated F2 has been grown and seeds have been 

 saved for F3. 



Blackberry x Rubiis Odoratus 



A cross between Ruhus odoratus 2n flowering raspberry and Snyder black- 

 berry 4n gave a sterile 3n hybrid. When the chromosome number in these 

 plants was doubled by the use of colchicine, a fertile plant was produced. 

 It was not horticulturally valuable. Seedlings from this have resulted in 

 fertile plants resembling the F^ cross. One such selection is 4n, another is 

 6n.* The fruit is purple; the plants are nearly thornless. Since the fruit 

 adheres tightly to the plant, their only value is as breeding material. 



* Chromosome counts were made by Richard Schreiber, a graduate student in 

 Horticulture, University of New Hampshire. 



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