Henry recently started a thread on apple seed germination. Since apples belong to the Rosaceae (rose family), the results may apply to rose seeds. The genus Rubus (raspberries, blackberries, etc.) also belongs to the Rosaceae. Roses may be more closely related to Rubus than to Malus (apples). Rubus species resemble roses (prickly canes), and have the same basic number of chromosomes as roses (14 chromosomes in diploid species). The growth habit of apples is different (prickle-free trees), and the basic number of chromosomes is different (34 chromosomes in diploid species). Research on Rubus germination might apply to roses. Here is an excerpt from a page on raspberry breeding (see link below):
Seed germination has improved remarkably over the last two decades. Our 1979 crosses germinated at a rate of approximately 3-10%. This year germination was complete on some crosses; we saved only 20,000 seedlings however. Here’s how we do it.
Plants are pollinated in a greenhouse from mid-January to early April, when bee activity outside is too high. Plants are grown in pots and given over 1200 chilling hours in a 40F refrigerator. Males are brought out two weeks earlier than male/females which are brought out two weeks before females. Most of these parents are hermaphroditic, so the terms male and female are only functional, pollen is collected by harvesting flowers before anther dehiscence and females are emasculated at first petal showing in raspberry, a day or so later (balloon stage) in blackberry. Anthers are removed from the flower and dried over Drierite (Calcium chloride pellets) overnight at room temperature. They are stored for short periods closed in their Falcon 1006 petri dishes over Drierite (in Ball Jars) in the refrigerator for short periods or in the freezer for long periods (they are viable for over 2 years). Anthers are crushed with a flat surface to release pollen. Females are pollinated immediately after emasculation, a day later and two days later. Flowers are not covered. Field pollination would be different, but it is impossible in Maryland, not so in cooler areas. Fruit are harvested at ripeness, stored in a refrigerator until all like crosses are collected and blended in a Wareing blender at full speed to release the seed (ca. 5 seconds). The water is decanted, new wash water is then redecanted and seeds are collected on a seive. Seeds are dried on paper towels overnight, collected in 1 oz glass tablet bottles (French Squares) and stored at 40F until use. I like to have them just a touch moist (sometimes a little fungus develops in the bottle), but full dry is good for long term storage. They need to be dry to survive the scarification treatment. Seed is scarified by placing it in its glass bottles on an ice bath. Concentrated 96%+ sulfuric acid (chilled) is poured to cover the seeds plus another half cm. Seeds are always kept on the ice bath. After 30 minutes for raspberry and an hour for heavier seeds, the acid and seeds are poured into water through a seive which catches the seeds. (NEVER THE POUR THE OTHER WAY-DON’T LET WATER GET INTO THE JARS OF ACID-CONC ACID IS DANGEROUS, HAVE SODIUM BICARBONATE AVAILABLE TO NEUTRALIZE ANY BURNS). Wash the seeds in running water for a minute and add 1% sodium bicarbonate to neutralize the acid. Leave this for 10 minutes and catch the seeds on the sieve and wash them in water. Scrape the seeds back into the jar and add the second scarifing solution, 3 g/liter of calcium hypochlorite (70% available chlorine) in excess calcium hydroxide (you add the hypochorite to water, stir for 40 min and then add the hydroxide). Work in a ventilated room as the HYPOCHLORITE CREATES TOXIC CHLORINE FUMES. Place the filled jars with the seeds and solution in the refrigerator for 6 days. After the seed coats have been softened again, take them out of the refrigerator and wash them in water (decant the solution off and add new water, shake a bit and decant again). Invert the clean seed in water on your palm and let the solution and seeds “woosh” onto the seedling pot by quickly sliding the jar off your hand (while it is above the pot). Do not let the seeds dry or cover them. Our seedling pots are filled with vermiculite to an inch below their rim and covered with screened peat moss or BX soilless mix and moistened to run off. The seeds in their seedling pot are misted overnight. This is an important step as it starts the fungal activity (we used to call this warm stratification). The pots are placed in plastic bags (en masse in trays) and placed in a refrigerator. After 10 weeks, the seeds should be covered with a fungal mat: this is good, excellent in fact. Seedling pots are placed in a mist under continuous light for germination. (It’s usually October when I do this). Germinated seedlings are harvested and placed in 50 cell trays for further development. But wait, we’re not finished. Black raspberries, hybrid berries and blackberries (and some northern raspberries) do not germinate yet. I give them another 6 weeks in the refrigerator and bring them out for another germination session (this time its usually January and I only need the mist for a week or two). I plant the seedlings as growing plants in plastic mulch with trickle tube using water wheels, or we have used tobacco transplanters to plant in no-till fields. GOOD LUCK and be careful----all the dangerous methods above have been published in the scientific literature, so don’t try and sue me for trying to help raspberry breeders.