Selecting bigger alder seeds by their falling speed in air

I may have misunderstood your proposed design, but surely you just need to blow air horizontally across a thin stream of falling seeds? No laminar flow issues, and not really any need for calculating - all seeds will fall through the same breeze. Adjust the wind speed or any baffles until light ones get blown to the side and heavy ones fall into your collector. If the proportion of small ones that get through is too highl, put the collection back in the top and do it again.

This is basically how winnowing works, isn't it?

Chas

In article , Chas writes

Exactly what I suggested a day or two ago, but Michael didn't seem to like the idea. Seems a bloody sight simpler than all the other stuff being talked about.

David

We were at cross purposes. Your idea is one that could work, but I have gone for a vertical design, where air is sucked upwards by a fan at the top, seed is put in half way up the duct, and only the heaviest falls down, the rest is blown out of the top through the fan.

Michael Bell

OK, this is basically the Millikan oil drop experiment to determine the charge of an electron, which I have done. In that case the electron has a predictable charge, the weight and air resistance of the oil drops are essentially constant and the force is provided by electrostatic plates - easy to get parallel (equivalent to laminar flow of your wind) and easy to adjust minutely. I think you will struggle with your design and I doubt very much if you can calculate the speeds required in advance, given all the variables that apply to wind resistance of real objects, but good luck.

Charles

Okay, just spoke to him.

He says the effect of the pollen on seed size is "very little" - sometimes if the pollen is bad then it will make small seeds, but otherwise it has almost no effect on immediate seed size (though obviously it can affect the size of the seed in the next generation).

One of the reasons for this is that the mother plant largely shuts down the genes from the pollen so they don't get expressed until the plant starts growing. Another is that the food supply to the developing seed is controlled by the mother plant.

If the tree is "having a good time" it will produce bigger seeds, and this is the most influential factor in seed size. It's also why some seeds in a catkin are larger than others - they have a better food supply.

He reckons that 20 generations of selection might see a significant increase in seed size in A. glutinosa, but he wouldn't be drawn on an estimate of how much.

"He", btw, is professor emeritus of botany at Oxford, and keeper of the botanic gardens and arboretum there. He was also a bigwig at Kew for a while, don't know exactly what kind. He's one of, if not the, top authorities on this in the UK - I won't post his name here, but you can ask offlist.

Yep, confirmed.

You should still choose bigger seeds, but going for the very biggest is not likely to be useful in terms of their paternity.

-- Peter Fairbrother

I will have to bear this in mind for follow-on breeding work, but not for first screening for bigger seeds: the tree whose seeds I am sampling now had a chain of ancestors going back...

It is MOST UNLIKELY that I would find THE TREE in which a mutation occurred. If a mutation has occurred, that mutation will probably appear in several trees which are not too far apart, the two will fertilise each other (though most of the pollen will come from unrelated trees) so a very small number of mutated seeds will be found in both trees. This is the kind of reason why it is so important to be able to screen through a very large number of seeds. And of course, some of the seeds which I think have promise will turn out badly. You must accept that with bulk screening.

I'll do that when I've got the immediate rush over.

Michael Bell

No no no - even if you get a seed with big-seed mutations in both the pollen and the mother, it *won't* be any larger than a seed whose mother has a big-seed mutation and whose father doesn't.

That's what I've been trying to tell you. Do you understand it? Please??

I have more useful stuff to say, but you have to understand that first.

It's important to screen a very large number of trees, not seeds. That's what the forestry commission do.

What you want to do is look for mothers who produce big seeds, not for the biggest seeds.

(there most likely won't actually be one mutation, and a double mutation isn't necessarily going to give big seeds - or any seeds at all - but so-to-speak)

-- Peter Fairbrother

Being unable to join in the genetics debate I'd like to ask a simple question. Why? In my experience Alder grow fast and die early. They also have little structural value, rot quickly and burn so fast as to be useless in an open fire or log-burner. About all I can see left is as Biomass fuel and my reading suggests that Willow and Hazel are better in most respects.

puzzled and hoping for enlightenment....

It is true that some see alder as a competitor to willow, I hadn't heard of hazel, but it is also a fast-growing "weed tree". Alder burns well, so that is a GOOD, not a bad point, and kept under water, it doesn't rot and I think much of Amsterdam is built on pilings made of it.

But I am interested in taking alder in a DIFFERENT direction. All organisms can be changed by selection, evolution is natural selection, and that is what makes alder (and all wild plants and animals) what they are today. Domesticated plants and animals have been changed by breeders and that is what I am trying to do. The odds are against my project, but I may find a Koh-i-Noor seed which changes everything.

Michael Bell

In article , Michael Bell writes

I do understand you here, Michael. I was watching the RI Christmas lecture a few weeks ago, and was struck by the extent to which the early progenitors of today's cereal crops had been changed out of all recognition by selective breeding. Many, many generations of selective breeding, to be sure, but maybe with greater knowledge you can accelerate that. I certainly wish you well with it, anyway.

Particularly struck by your comments on the wet rot resistance of alder. Now if you can breed it to produce good-sized strong timber of similar durability, that would be something.

David

It is already used as the body of electric guitars. You can't get cooler than that!

Michael Bell

Even the neighbour's cat tasted like chicken, I told the wife we should expect Veal or rabbit