See link below.
Link: www.eurekalert.org/pub_releases/2010-09/oup-wwc092310.php
I remember Paul saying once, I don’t recall in what context, that leaving the petals on actually improved the success rate with some of his crosses. I was thinking the physical action of removing the petals might be having some kind of domino effect on the receptivity of the stigma… almost like it was registering as a wound instead so the plant then channelled resources away from the flower to where it might be better used… so I started leaving petals on or at least one row of petals or just trimming the petals short… I haven’t done enough pollinations to have noticed any significant effect. Neither have I bothered keeping records of such data.
It has been said on here that a lot of polys were pretty self sterile so I left the petals and the anthers on and just pollinated them with foreign pollen and had a good amount of success. Seedlings came up that were clearly hybrids and the seeds germinated easily.
I also remember Jim saying that fertility of some of the persica hybrids was improved when the petals and anthers were left on when using the persica hybrid as the seed parent.
So it would be interesting to look into this effect more I think.
I remember that Wilhelm Kordes in his book ‘Das Rosenbuch’ described to leave the outer 5 petals on the bud until the pollination is finnished, but he forgot to say why ???
cheers
Bernhard
Simon I think I remember them saying the same thing. I myself tend to leave as many petals on for a few reasons. First off I do not find bees are too interested in flowers that have no pollen. Plus I usually get to them first if they are interested. Secondly I think ripping of the petals could cause more damage to the female parts. Lastly and more importantly in my dry climate if I take off all the petals I find the stigmas dry pretty fast so I tend to do my crosses and fold over the petals the best I can to help keep the stigmas moist. Wither this helps in seed set I really can not say. Right know most of my plants are not that old so any experiment I do would be skewed. But it is nice to see evidence that maybe what I am doing is not in vain Henry.
I do find I have to take the petals off of certain roses that release their pollen early. Because the petals are not fully developed by the time the flowers begin releasing pollen. I plain on this coming year selfing these species to see which ones have some self incompatibility. it would be nice to know this so that on these I could leave them develop further until a more proper time. Among these species or species hybrids are Scabrosa, Darts Dash, Darts Defender, Ann Endt, 3 forms of R. woodsii, Tausendschon, one other form of R. multiflora, R. foliosa, and R. rubignosa. I do know some rugosas and multifloras do so self incompatibility but that not to say these do and how knows on the other ones. I already know the R. glauca I have will set seed with its own pollen and some of these will grow but to a lesser extent than some of the crosses I did with it.
All my wichurana hybrids also self really early if I don’t open them up to emasculate them before they open. ‘Temple Bells’ is a shocker for this.
I have definitely been advocating leaving the outer 5 petals after pollination. My “take rate” is absolutely better when some petals are left to age normally on the flower than when all petals are removed at the time of pollination.
Note: if you watch Bees on your plants, you will soon notice that they won’t bother with flowers that have had the anthers removed; they move on to a bloom that still has its anthers intact. IE: the risk of unwanted pollination on emasculated blooms is very low, IMO.
Thats interesting, Paul, cause the very reason I never left the 5 petals on was the worry of attracting any further attention to the hip.