We have all come across the ‘usual’ bits of advice floating around the ether about the dos and donts of how to collect pollen, remove anthers and pollinate the stigmas, in order to get seeds from our planned crosses.
Any ideas outside the usual square would be very welcome here, if you are convinced such nuances result in more seeds at harvest time!
Use good mothers:
Title: Investigation of the factors affecting cross-fertilization rate in rose.
Authors: Joung, Y.-H.; Choi, J.-C.; Kim, W.-H.; Gi, G.-Y.; Han, T.-H.
Authors affiliation: Department of Plant Biotechnology, Chonnam National University, Gwangju, S. Korea.
Published in: Acta Horticulturae (2009), 836(Proceedings of the XXIIIrd International Eucarpia Symposium Section Ornamentals: Colourful Breeding and Genetics, 2009), Pages 227-232.
Abstract: “Rose has the longest history of artificial improvement by man-kind in ornamental plants. Owing to their complex genetic constitution, rose is heavily self-incompatible and gives low cross-fertilization rates by crossing genetically distant pairs. Consequently, low cross-fertilization rates results in a neg. effect on the breeding process. In this study, we investigated the factors that would influence the cross-fertilization rate of roses. Correlation anal. was performed between cross-fertilization rate and genetic distances of the parents. Anal. of variance was also performed to study the paternal and maternal effects for the cross-fertilization rate. Reliable data for cross-fertilization rate were obtained from Jeollanamdo Agricultural Research and Extension Services, Korea in 2006. 32 Cross combinations provided cross-fertilization rates. Their genetic distances were obtained by using RAPD marker anal. In RAPD anal., we used 16 primers and obtained clear 101 RAPD markers. Genetic distances were obtained by using Nei’s coeffs. Relationship between cross-fertilization rate and genetic distance of parents was conducted by using correlation anal. The correlation coeff. as low as 0.058, was not significant. Consequently, we detd. that overall genetic distances do not influence the cross-fertilization rate by any means. The paternal and maternal effects for the cross-fertilization rate were detd. The results of anal. of variance showed that the cross-fertilization rate is only influenced by the maternal side. This shows that rose breeders must have desirable materials that can be mother plants. Moreover, we expect that more complicated factors will influence the cross-fertilization rate. Further research should be carried out to elucidate this matter.”
Assuming that we have a good mother, I wonder if there are any other tricks people have discovered can help increase the seed/hip set?
For me, the early pollinations take best and have the most seeds.
Jim Sproul
I once read that one trick that may help set more hips/seeds is to leave a few petals on after emasculation, if this is possible (not always easy to achieve this!)…Is this mythology?
George:
I think it was Paul Barden that said he leaves some petals after pollenation. I can’t remember whether it was on the RHA Forum, his web site or blog.
Jeff
I have heard Ping Lim say in a Youtube interview that 35,000 pollinations can yield 300,000 seeds for him…
Should we also realisitcally be aiming for such ratios as a benchmark for good efficiencies in our crossings?
i.e… about 8+ seeds per number of crosses made as an overall average…
Is this exceptional, or is it a good ratio to aim for in small operations.
I depends what you are using George. "Scabrosa’ gave me one hip last season with 92 seeds in it. ‘Mutabilis’ gave me hips with one big seed/hip. Rugosa are good seed mares.
Hi Simon!.. WOW!! 92 seeds (wish I had the emoticon to post here showing my jaw drop to the floor…)…I have no experience with the rugosas.
Hi Jeff - I just read you comments also - in that case the petal-retention thing must be a good idea!
Must run now…having fun doing some Iceberg x OP embryo extractions… have 19 seeds to play with!
George
Pollinate more than once:
http://home.roadrunner.com/~kuska/how_many_days_should_one_pollina.htm
Keep the local environment warm:
http://home.roadrunner.com/~kuska/hipsleftandright.htm
Spray with hormone:
For me, the single biggest factor in the number of seeds per pollination is the selection of parents. Weather is another factor. Although I can begin pollinating in March, hip set and seeds/hip aren’t very good for crosses I do in March or April, probably due to weather. Early crosses do better in the greenhouse than outdoors. Later crosses seem to do just as well outdoors as in the greenhouse.
In 2000, I had a hip of ‘R. rugosa rubra’ X ‘Duchesse de Brabant’ that had 99 seeds. 96 of them germinated. I only kept one of the seedlings and it isn’t a great rose. Quantity doesn’t necessarily mean quality. I think that there are better reasons to choose parents than the number of seeds they produce.
I think weather and timing play greater roles than we will ever understand.
Previous years on KO I averaged about 9 seed on about as many hips. This year I was disappointed to only see maybe 5 decent hips and 2 questionables. Most of these have ripened and been harvested. I was amazed to find the largest hip had 11 viable seed and another had 5. All in all I ended up with like 21 seed- more than double of years past.
I am assuming that the mum and dad are good selections…I would like as many seeds as possible out of this hypothetical cross, to maximixe the chance of getting that 1 in a million rose!! The numbers are imporatnt even with good mums and dads, no?
Also…In the last 3 days I have done a few pollinations on first generation plants. As they are in pots, I decided to move these plants indoors for the first 4 days, away from critters, rain etc…
Is the reduced light these plants are experiencing over these first 4 days going to influence ultimate hip and/or seed set?
Perhaps it is how healthy the bush is that the hips are on.
I found that hips that are on a bush that has a little blackspot or PM the hips will not grow big to hold alot of seed and more likely will abort hips early.
If you use too much pollen to gain more seed set you will end up with seeds growing outside of the hip, learned that one this season 
.
I don’t believe light really has an effect, I have hips that are buried deep inside the bush and they formed wonderfully and I do keep my hips covered most of the time to keep them from getting wet from rain and morning dew.
George be careful with spider mites having your roses inside, they can do damage to your bush and your hips.
Thanks for the tips Jeanie!
After 24 hrs of the pollination does strong wind make a difference?
Does a high potash fertiliser promote hip set?
If you use too much pollen to gain more seed set you will end up with seeds growing outside of the hip
True enough, sometimes.
The maximum number of seeds that a blossom can produce is determined by the number of pistils that it has, which you can determine by counting stigmata.
The position that a seed will occupy in or on a hip is predetermined by the morphology of the flower. At the time of fertilization the ovule, which is the part of the pistal that will become the seed when it is fertilized, is already in the position, relative to other ovules, that it will hold when the seed develops.
Ovules contained within a hip can become exogenous seeds if the seeds lower down in the ovary push them up as they mature and the ovary doesn’t expand quickly enough to accomodate them.
Some seeds are exogenous from the start, however. You may have noticed loosely attached masses of white tissue surrounding the stamens as you emasculate a blossom of particular roses. These masses of tissue often contain pistals that have formed outside of the ovary (which becomes the hip). When fertilized, the ovules that they contain become exogenous seeds (provided you don’t scratch them off the flower when you emasculate it).
I have found that keeping rain off of newly pollenated flowers for a day (in warmer weather) or even two (in cooler weather) improves seed set greatly. This prevents the pollen from being washed off before it has a chance to germinate and grow down into the stigmata.