See:
Horticulturae 2023, 9(8), 914; Horticulturae | Free Full-Text | Seed Germination within Genus Rosa: The Complexity of the Process and Influencing Factors
Received: 7 July 2023 / Revised: 28 July 2023 / Accepted: 8 August 2023 / Published: 10 August 2023
Abstract
Seed germination is a crucial stage in the life cycle of plants, and understanding the factors influencing germination is essential for successful cultivation, plant breeding, and conservation efforts. The genus Rosa, commonly known as roses, encompasses a diverse group of flowering plants renowned for their beauty and fragrance. Rosa germination is influenced by a variety of factors, including seed dormancy, environmental conditions, and seed treatments. Many Rosa species exhibit different types of seed dormancy, such as physical dormancy caused by hard seed coats and physiological dormancy due to internal mechanisms. Overcoming seed dormancy often requires specific treatments, including cold stratification, scarification, or chemical treatments, to promote germination. Environmental factors, including temperature, moisture, light, and substrate, play vital roles in Rosa germination. Temperatures ranging from 15 to 25 °C, moisture, and exposure to light or darkness, depending on the species, constitute suitable conditions for seed germination. Many studies have been conducted to investigate the germination requirements of different Rosa species, thereby expanding our understanding of their propagation and conservation. Additionally, advancements in techniques such as in vitro germination and molecular approaches have further enhanced our understanding of Rosa germination biology.
An always topical subject:
A brand new paper about seed germination of Rosa species. Maybe one or the other of you will find something worth knowing.
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It is not safe for me to click on that link. If you knew all of the dumb germination experiments I’ve done. Not clicking on it. Definitely not going to click on it. Might be kind of interesting, but not gonna click. I do have some 93% sulfuric acid on hand that I’m not using, but unfortunately I’m not going to click on that link so I’ll never know if it might make my rose seeds germinate much better. Hmm.
Well, I can understand you much. I am and have always been skeptical and reserved of the various chemical (explosive) treatments for germination aid, so I follow only the harmless microorganism treatments and experiment primarily with the fine-tuning of the germination substrates and an optimized coordinating stratification regime. The article is informative in that way it highlights again the entire complexity of the achenes germination process and demonstrates different approaches. In some points I see my observations confirmed and on the right path.
Hi Roseus,
I finally had time to read the whole paper, thank you for sharing this!
Unfortunately this review seems to confirm my fears for this year’s harvest. I may have messed up some of my seeds.
This year I started making some of my crosses earlier than last year, so harvested those about a month or two ahead of when I’d like them to go in the fridge.
To delay things a little, and potentially to enhance germination (?) I started to give them two months of warm stratification before the cold. These early seeds range from HTs to chinas to rugosa and hulthemia hybrids.
The temperatures here are still around 32-34°c. I doubt they will come down to consistently below 30°c before mid September. I do have a/c but only use it intermittently, so I cannot provide constantly lower “room temperature”.
The paper you shared cites two different studies that concluded that “warm” stratification temperature should be much cooler than that. They say anything above 20°-25 °c during “warm” stratification induced secondary dormancy. So it seems I have ruined those seeds. I didn’t realize there was such a thing as too hot for warm stratification. I am moving those seeds to the fridge right now and hoping I didn’t do too much damage.
I am really bummed , but thankfully, I did not do this with all of them and divided the batches, half of them went straight into the fridge.
Thank you for sharing this paper, at least now I will know that in my climate, warm stratification at this time of the year is a really bad idea!
Hi SeasideRooftop! Many thanks for feed-back! First of all, I am very happy if the publication was able to provide important informations for you.
In any case, you haven’t ruined your seeds. However, the worst case could mean, that they need another cold stratification period and wouldn’t germinate until the year after next. I am aware that this is only a small consolation for you. Maybe it works after all in a normal germination cycle. Of course I keep my fingers crossed for you.
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