full Ph.D. thesis "ASSESSMENT OF GENETIC VARIABILITY AND DEVELOPMENT OF HYBRIDS IN ROSA SPECIES"

Title: “ASSESSMENT OF GENETIC VARIABILITY AND DEVELOPMENT OF HYBRIDS IN ROSA SPECIES”

205 page thesis.

http://prr.hec.gov.pk/jspui/bitstream/123456789/14343/1/Muhammad%20Faisal%20Khan%20Horticulture%202020%20arid%20rwp%20prr.pdf

I recently got around to organizing some articles that I collected 10 to 15 years ago about genetic polymorphism. This is a broad subject, with several interesting facets.

One aspect in particular is that populations that are subject to varying environments retain more variations of various genes than populations that are maintained in more uniform conditions. The various alleles usually are not associated with obviously distinct traits. Their differences are typically in how their functions are influenced by environmental conditions.

A given gene may exist in five or six alleles. There is no “best” allele. Each may have its own set of conditions of optimum function. The various heterozygous combinations of alleles are usually better than homozygotes. And the best combinations this year are unlikely to be the best next year, or the one after.

In short, genetic diversity is useful in the present, and insurance against an uncertain future.

http://bulbnrose.x10.mx/KKing/Polymorphism.html

Tom Carruth noted that ‘Julia Child’ presented itself alike in more climates than not, which seemed to imply part of its success. While its not a rose I like, I can see how this is favorable in certain roses. Especially floribundas where uniformity in plant habit over many environments is especially sought to mirror the roundness of clusters.

I remember this because it was such an unusual thing to point out.

‘Radiance’ is another example. Unlike many other varieties, it refused to degenerate despite mass propagation. I dont know its northern limit, but it reported does about as well in Florida as anywhere else. I saw it in Kentucky looking just the same as it does in California. It grows on its own roots, or grafted.

It was bred for the cut flower trade, but proved to be highly successful as a garden rose … at least in North America. I have read that it is not so excellent in Europe, but I have not details on why or how.

I think ‘Peace’ is also stable over a wide range of conditions.