26 April 2014

Purple snows and snaps - autumn 2014 growout

Progress on the purple snows has been slow, but steady. Locking in 3 dominant genes from one parent (all the purple colouration ones), and two recessives(the snow pod genes)  from the other is an exercise in playing the numbers - the more you plant the greater the chances of all five turning up in one or more individuals.
I did three crosses in spring 2011 - Purple Podded X  Purple Flowered Mammoth (Yakumo), Purple Podded X Delta Louisa, and Purple Podded X Chamber of Death.

These have produced three projects - Tall Purple Mammoth and Tall Mauve Mammoth  a large podded tall purple (or mauve) snow without resistance, Delta Purple a short purple snow with some resistance and double flowers, and Resistant Purple Chamber of Death, a highly resistant purple snow.

The TPM project is now at F5, with 15 seeds each of 2 promising lines in the ground. It has been hard to fix both purple pods and flavour - sweet parents have given chalky offspring, but hopefully the F5s will have settled down a bit. Both of these lines show promise of being homozygous purple, a hard ask with three different dominant genes to fix. Well, two actually since both parents carried the A gene for anthocyanin production.I could have just taken a chance on this - growing out lots and waiting for them to stabilise, but a smarter approach is to plant a number of seeds from each purple plant from the previous generation. By growing 6 plants of the subsequent generation, if each of these show a particular dominant trait, it's about 80% certain that the parent was homozygous for that trait. This is good to know, particularly if you wish to perform additional crosses. I will probably do this - once I have a purple snow that is homozygous purple and snow, if it doesn't taste great - and this has been hard to lock in -I can cross it to a good tasting snow parent,  knowing that the snow characteristics are stabilised, and only needing to reestablish the purple.

The Delta Purple lines are at F4 seed stage, and I haven't planted any this autumn - no room.

From the spring growout of Purple Podded X Sugar Snap F2 lines, 2 plants showed full purple, sweetness, thick pods, and no fibre - an absolute blinder of a result in the F2. So half the F3 seed from each of these plants has been sown. Since thick pods and no fibre arer recessive genes, if I can lock in the purple, I'll be well on the way to a purple snap pea.

One problem with growing multiple lines from different parents is the problems of record keeping - It's a nightmare. More on that in a future post.

No comments:

Post a Comment