Wednesday, June 08, 2011

Breeding and seeding

I took advantage of this weekend’s fine weather to spend a bit of time in the glasshouse, pricking out some of this season’s iris seedlings.  Each year I troll through my Pacific Coast Iris plants and try to work out which ones present opportunities to further the way I want my irises to look, and then cross pollinate these flowers.
With irises this is not too difficult a task as the flower’s sexual reproduction organs are easily found and crossing them is not too tricky.  All the breeder has to do is gather the pollen from the ‘father’  flower while it is nice and fresh and the bees and bumble bees have  not found it, then transfer it to the stigmatic lip of the selected mother flower.  Again, it is important to do this before the bees find the intended mother and pollinate her with rogue pollen, so we usually take the falls off the flower, removing the bee’s landing pad.  If all goes to plan we should have the selected pollen reaching the selected stigma, resulting in a new hybrid.
Trouble is, my mouth is bigger than my stomach when it comes to breeding Pacific Coast Irises, and I have far many more seedlings than I could ever hope to plant out.  I have germinated seedlings in nearly fifty pots, each one a different cross, and up to a hundred plants in some pots.  Absolute madness!
It is this sort of passion on the part of breeders that has lead to the many changes obvious in many garden flowers.  Even highly bred plants, like roses and bearded irises, are still being improved, by very controlled breeding and a thorough understanding of the genes that influence their eventual display.  In order to be a successful breeder with these plants it is almost a necessity to be raising and selling plants fulltime, very difficult in a country like New Zealand.  The best rose breeders, for example, raise tens of thousands of seedlings each year, expecting to introduce perhaps five of them to the market. 
Under these conditions most seedlings do not survive their first flowering – they are ruthlessly culled and only the very best make it through for a second flowering season.
Most florists’ flowers are now produced by professional breeders, usually based in the United States, Japan or Europe.  Carnations are a good example, as the only people working with these plants are now cut flower breeders, and they are not producing varieties that are well suited for the garden.  As a result, gardeners find it harder and harder to find varieties that suit them, and the plants gradually go out of favour.
Some plants are still largely produced by keen amateurs but they tend to be those that do not have a large cut flower demand.  Across the paddocks from the back of my house (all built on now unfortunately) live a couple of the world’s most successful dahlia breeders, their varieties being voted as among the most popular in the United States.  I was once treated to a look around their garden at the height of the flowering season, and was intrigued to see they did not practise the sort of hand pollinating techniques I am more familiar with.  Instead, they grew the two varieties they were keen to cross alongside each other and left the bees to do the job.
Partly that is because the technical issues around desexing compound flowers like dahlias – it is a very tricky and time consuming method, and in reality, results are generally disappointing with successful pollination rates being low.
I have found similar troubles when trying to breed hebes – it is just too finicky to try and desex all the various flowers on the raceme – and they do not all open at the same time of course – so it is once again best left to the bees.

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