admmad said:Arisumi, a geneticist, did a large experiment trying dip/tet crosses.
He tried with 82 different diploids and 75 different tetraploid parents. There were 400 different diploid - tetraploid combinations.
The total number of pollinations was 1,607.
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Of the 400 combinations of crosses only 24 produced any viable seedlings. Fifteen of those were tet x dip and nine were dip x tet.
Only four of the 24 combinations produced more than one seedling (three produced two seedlings and one produced three seedlings); they were from tet x dip crosses.
Maurice,
Did Arisumi record any information regarding the ploidy of the seedlings from these crosses? I remember hearing that technically, they're supposed to be triploids.
There was a tendency for the ability to successfully cross (tet x dip) to be inherited, as a large number of successful crosses involved certain cultivars in the ancestry of the parents.
I've seen a little of this myself with Ed Murray, but the problem with my experience is that prior to my acquisition of Ed Murray, a supposed tet conversion of it was in fairly wide circulation, and there seemed to be a lot of uncertainty as to whether or not any random piece of Ed Murray had been treated. I obtained mine from John Benz, and he said that he had one clump which came to him as "tet. Ed Murray" and an other which was supposed to be "diploid" Ed Murray, but that for him, they both behaved similarly when bred to tetraploids.
The clone I have exhibits no outward signs of conversion, but when I looked at the pollen under a microscope, I saw diploid-size grains, a lot of chaff, some tetraploid-size grains, and a smattering of extra-large grains, maybe 5%. Every few years, I pollinate most of the blooms on Ed Murray with tetraploid pollen, and usually I'll end up with one or two seeds, which, so far, have grown out to be plants which are easily fertile with known tetraploids. I don't see much pollen from my clone (many deformed/shriveled pollen sacs), but when it's available, it's reasonably fertile with tetraploids.
Registration data isn't infallible, however the entry for
Thornbird in the NGA database shows 6 tetraploid offspring—some from a tet parent and some from a dip parent. Of these, I only have experience with
Norman Lee Hennel, which is quite fertile both ways with tetraploids.
