It's often a good idea to keep up on what's going on in different fields. While following up on some peach work done by our rose buddies I learned some things that might be useful to rose breeders.
First, there was Dr. Lammerts. Some peach traits are recessive (showy flowers, smooth skin) and won't show up until the second generation at the earliest. To speed things along, Lammerts cultured embryos to skip maybe a year in the process. Some cultivars have a long chilling requirement, which is also seen in the seedlings. Without the proper after-ripening, some of these long-chilling types form rosettes rather than going into normal growth. He found, by experimenting, that this chilling requirement can be defeated by raising
the minimum temperature and exposing the seedlings to continuous lighting.
http://bulbnrose.x10.mx/Heredity/Lammer ... h1943.html
Percy Wright also found a neat trick for folks in very cold areas. I first learned about this from Peter Harris, who got it in a letter from Wright.
Long ago, Wright's uncle was growing peaches at close to their northern limit in Canada. One year Percy had some cuttings of Hansen's 'Opata' plum that he wanted his uncle to propagate. No suitable rootstocks were available, so they were grafted onto the peaches. They grew well and produced fruit.
"Then, as was probably inevitable sooner or later, a test winter arrived, with the result that all his peach trees, except those with the grafts of Opata, killed back severely. When this experience was reported to me, I gave it whatever publicity I could at that time, but nobody paid attention."
"But times advance, and just a few years ago, I visited, a backlot orchard of a fruit enthusiast in Edmonton. I was with Robert Simonet of Edmonton at the time. This grower was successfully growing and fruiting, Golden Delicious apples, Bartlett pears, and Bing cherries, an incredible feat to anyone familiar with the limits of hardiness of apples, pears and cherries on our various recommended lists of the three provinces. The apples had been grafted on Siberian crab, the pears on Manchurian pear, and the cherries on our native pincherry (if memory serves). In each case, the grafts were at least waist high on their understocks, and the understocks had also been allowed to grow, making lots of leaves on extended branches."
Wright believed that leaves of the short season varieties sent a chemical message to the hardy roots. It's as good an explanation as we need to try it where appropriate.
If anyone can find page 102 of this report, I'd really like to add it.
There is another report by Wright in, North American Pomona 14(2): 73 (April 1981)
A PEACH THAT SURVIVED 41° BELOW ZERO
Percy H. Wright Saskatoon, Saskatchewan, Canada
I received seed of the wild Manchurian peach about five years ago and grew several nice seedlings. They all froze to the ground during the winter of 1978-79 with the exception of two which showed no damage, even after 41° below zero. This year the trees have fruit buds and I am hopeful of seeing some fruit in August, though I don't expect the fruit to be large or flavorsome.
That's all I can find of it.
The 'Opata' plum (Prunus Besseyi
x P. triflora
) was bred by Niels Hansen of South Dakota.
http://bulbnrose.x10.mx/Heredity/Hansen ... brids.html