25 November 2012

A new onion project

Onions (Allium cepa)come in all sorts. Bulbs, big and small, long lasting and eat now, raw and cooking. For the purposes of growing onions, bulbing onions are divided into groups depending on the trigger they need to start forming bulbs - short day, medium day and long day are the usual designations. Growers in the tropics have problems growing the long keeping varieties, most of which need long days to trigger bulbs. (Actually onions respond to the period of darkness, rather than light, but let's ignore that for the moment.) This is all very messy.

I've never had much luck with onions. Timing is everything. Here in Bendigo I can choose to grow any variety I like, summer night and day periods are sufficiently different to allow me to grow short, medium and long day varieties. But I never get the sowing time right, the seedlings sit and sulk through early spring, they get swamped by weeds when young, and last year, my alliums (garlic and leeks) were struck with a failure to thrive disease, that I'm yet to diagnose.

But there is another candidate on the patch - topset or multiplying onions. These hardy individuals grow in bunches, and instead of forming flower heads, they develop little bunches of new onion bulbs at the tips of the stalks. There is some confusion about the exact phylogeny of topsets, some suggesting they are a distinct variety of A.cepa, or perhaps a hybrid between A.cepa and Allium fistulosum, the bunching or welsh onion.

There are as many names as there are cultivars - walking onions, topset onions, multiplying onions, Egyptian onions. (Potato onions are probably in the same group, but don't seem to top set bulbils). Some of these set small basal  bulbs and die down, some set small bulbs and keep growing. They come in red and white and brown. They are not really sold in Australia, and I've only ever seen them once in a nursery. Mine don't set bulbs at all really, just a minor thickening of the base. Every generation is the same, because they are vegetatively propagated.

But the big advantage of these is they grow throughout the year for me. They were totally unaffected by the disease I got, they take no trouble, they're always there in the garden, and they are so easy to propagate. Last year I noticed that some of the topset formations had a few flowers scattered through the bulbils. I did nothing. But in the last 12 months I've been reading up on alliums. Garlic also doesn't set seed. But some researchers have been inducing flowering in topset garlic (which produces little bulbils on top of the stem, just like topset onions) by removing the bulbils as soon as they form. This fools the plant into thinking it needs to reproduce, and since the bulbils aren't working, maybe they should indeed produce some fertile flowers. I wondered if this would work with my topset onions. I've spent several hours over the last week picking bulbils out of my topsets. And the flowers look like they are fertile. Good news.

A further problem with some plants that are reluctant to produce flowers can be the inability to produce viable pollen, or self incompatibility issues - where the pollen from the same plant can't pollinate its own flowers. Since all my topsets, despite being in lots of distinct clumps are all the same plant genetically, there might be incompatibility issues. By chance, I'm also growing some Japanese bunching onions, A. fistulosum, which is flowering profusely. Bees are all over the big round flower heads, and with luck, I might get a bit cross pollination, if the topsets are self incompatible (which I don't know) Seems like a bit of lucky insurance.
So what might I get out of these if they set seed?

Who knows! Maybe I'll get bigger more robust plants. Apparently lots of vegetatively propagated plants build up a virus load, which is transmitted from mother to daughter. By going to seed, its possible to shed this viral load, leading to increased vigour in the offspring. Or maybe some genetic recombination wil occur and some ancient ancestral traits will emerge. Who knows how long these things have gone without reproducing? I've been inspired by the work of Kelly Winterton, who has been quietly developing extraordinary potato onions in his backyard in Utah.

I'm not sure where mine came from. My mum had them in her garden, and passed them on to me, but I think they died out, and I replaced them with some material I bought in Albury when I lived there 15 or so years ago.

02 November 2012

Purple podded pea - first F2 line

November 2011 - crossed the first snows and purple poddeds.
Seeds in December 2012. Some sown green on 3rd December - straight out of the mature pod - for a summer shade growout.
One line PP(LSC)XPFM produced about 20 F2 seeds from three greenseed plants harvested on 4 March. These were then sown  - can't remeber if it was green or if I dried them first, but they were planted as seedlings on 25 March.

The original F1 seeds from the first crossed were sown on the 16 February. and planted out on 28 February.

These February sowings were producing fertilised pods in late April, but the early March sowings didn't produce pods until late winter. What a difference a couple of weeks makes.

The later sowings were badly affected by powdery mildew, and by the time they were flowering, many of the plants were so infected that they only produced a few viable pods, some of which were then stripped of their seed by rats or mice.

But I did get one snow pea with colour - a half purple snow. A quick chew on one end of a pod showed it to be sweet and tasty - a bonus. However at seed harvest I only managed to get around 10 seeds. I took the risk, and sowed 3 of them straight away, and have got three F3 plants growing out as tiny seedlings in a tray.
These should be stable for snow pea characteristics - those traits are recessive - but the purpleness is another matter. There is a 2/3 chance the original plant shown above was heterozygous for purple, and 1/3 chance it will be homozygous and stable.

If it was homozygous, I would expect all 3 of the new seedlings to be purple snows - if it is heterozygous, then there is a 3/4 chance that any one of these will be purple.
Oh, the anticipation!

Coloured snow pea progress

An update on the progress in the F2 grow outs.
I did my initial crosses in November 2011, crossing all sorts of peas with others.

The main focus was a search for a purple snow pea - crossing 3 different lines of purple podded peas with 5 different lines of snows and snaps including dwarf varieties and those with supposed powdery mildew resistance.

I also crossed a yellow podded variety with a purple podded, looking for a red podded pea to use as a progenitor for a red snow line. Although the  yellow is supposed to be a snow pea, it has few redeeming features apart from its pale pods, and so seemed unlikely to be able to produce a tasty yellow full snow pea. To get something worthwhile, I figured I would have to cross any red podded back to a decent snow pea.

I grew out some of the F1 seeds last summer, planting into pots, and growing them on the shady side of the house. Only one line produced any seed. I'll report on that in another post.

Most of the F1 seed was sown in February 2012, for an autumn growout. Most lines succeeded, showing real hybrid vigour. Unfortunately some set seed while I was away on holiday, and proceeded to germinate in the pod following some rainy weather in July. I returned to harvest the seed only to find that much of it was spoiled. I threw the germinated seed - even tho it was shriveled up - into some seed trays, and was rewarded with a few dozen F2 plants that I then planted in a tight little bed on the boundary fence between my backyard and the playground next door.This was the yellowX purple podded cross, not my main focus. But this line has just started to produce pods, and I've got a nice half red plant, and this morning I noticed a fully red pod on one plant. As a bonus, one of the plants has produced what appears to be a nice big yellow snow - not at all what I was expecting from this line.

The second line that pod-germinated was the yellowXsnow cross. Again, I chucked the seed into a tray, not expecting much, and planted the resulting F2s into another fence bed beside the hothouse. This seems to have produced at least one attractive looking big yellow snow.

Looking forward to the next few weeks as the rest of the plants come on stream.

And I've also got huge amounts of seed from multiple lines to explore next autumn, if I can find room.