The climate in the UK is bonkers at the moment. Within the last fortnight we had a frost which had me scrabbling to protect all my tender plants. Now we have a record-breaking heatwave, with temperatures well over 30° … extreme and abnormal for May. Aside from being an alarming sign of how the climate emergency is accelerating, for my pink-flowered pea project it couldn't have come at a worse time.
Peas are a cool season crop. They can't deal with intense heat from the sun. If temperatures are too high, they struggle to flower and set pods. If they're exposed to full-on hot sun, their delicately watery leaves just dry up and shrivel. Normally the British spring weather is ideal for them, but this year they have been hit by conditions they can't deal with, right at the time they started flowering!
Above is the very first flower from this batch, which opened the day before the heatwave hit.
24 hours later, many of the plants looked like this:
Yes, that is a flowering top full of newly formed buds, dried out and burned to a crisp.
Damage like this is woeful for any gardener trying to get a crop of peas, but when it's a breeding project where the seeds are irreplaceable, it's potentially calamitous. I sowed almost all of the seeds I had available, so if this crop doesn't produce seed then I'm stuffed.
I do still have a couple of spare metres of Thermacrop fabric, so I chucked that over the top of the pea frame to screen a little of the sunlight off the plants. And it seems to be working. Thermacrop is designed to do the opposite of this, keeping plants warm. But in this instance it seems to work for keeping them cool, giving them dappled sunlight rather than an intense blast, and allowing air flow through so the heat doesn't build up underneath. Many plants are already damaged but this is at least stopping it from getting any worse.
The damaged plants are gamely still opening their blossoms where they can, and those which are more severely affected should be able to produce new shoots and have another go. So fingers crossed this is a setback rather than a disaster.
Let's have a recap on this project. It started way back in 2007 when I made a cross between Alderman, my favourite tall white-flowered garden pea with outstanding flavour, and a strange little pink-flowered umbellatum-type pea which came from the Heritage Seed Library under the generic name Salmon Flowered, but which resembles a Swedish heirloom called Rosakrone. Umbellatum or crown peas, once thought to be a different species because they look so different, are the result of a combination of recessive genes which cause fasciation, or stem-thickening, leading to all the flowers and pods being produced together in a clump at the top. Now very rare, they used to be popular in the 17th century before modern pea types superseded them. The aim of this project is to create something with all the garden and culinary qualities of Alderman, but with those beautiful pink blossoms.
For various reasons it took until 2019 for me to grow out the F2 seeds from this project (see this post for the write-up) but it was broadly successful and from 16 plants I got 4 plants with the recessive pink flower trait – a perfect Mendelian ratio, no less. One of them was lost to a weather-related accident, but the other three produced seeds for the F3 generation. And those were what I sowed this year.
Here they are, newly sprouted back in March.
Ignore for now the two rows on the right hand side. These are growing alongside the others but are from a separate project, a cross between Sugar Snap and Salmon Flowered which are still at the F2 stage and will be covered in a separate post. The four rows on the left are what we're talking about here.
The first two rows are seeds from a plant numbered ASF 06, which was the best of the F2 plants in 2019. This plant produced seeds with a lot of diversity, including some which were wrinkled and some which were smoother with dimples. I've sowed one row of each, marked with W for wrinkled and D for dimpled. I thought it would be interesting to sow these separately, since wrinkled seeds are associated with higher sugar content and sweeter flavour. 16 seeds altogether from this parent plant, of which 15 germinated. Next we have 8 seeds from plant ASF 03, and 8 from ASF 15. These all germinated, so that gives me a total of 31 plants for my F3 generation. I'm pretty chuffed that most of them did germinate, given that the seeds had been left in a box for seven years.
Fast forward two months, and all of the above plants are starting to flower. There are some which are earlier than others, but there's only really a few days between them, so the flowering times are showing more uniformity than they did at the F2 stage.
Now, this project potentially has two recessive traits which I would like to get rid of. One is the umbellatum trait which has all the flowers clustering in a single bunch. I really don't want this, because it reduces yield and makes the plants top heavy and liable to fall over. The other is the gene which causes white flowers. As regular readers will know, there isn't a gene for white flowers as such, there's simply a gene which switches off all pigment production in the plant, of which white flowers are the consequence. This too I need to eliminate, because the whole point is to have pink flowers. If I'd been really lucky, I might have found one or more of these breeding lines not carrying either of the unwanted recessives. Sadly, both traits are indeed showing up in the F3 crop. Arse.
The umbellatum clump-top trait is complicated, and to the best of my knowledge involves three recessive genes. I don't know much about how they work, or whether all three of them are needed in order for the umbellatum trait to be expressed. Maybe they will only have two and will express partially, or maybe all three genes are lurking in the genome and will randomly appear in subsequent generations on the occasions when all three align. That scenario would make the umbellatum types relatively rare, but make it hard to eliminate them altogether. In this F3 crop only one plant is expressing it, and that's one of the offspring from ASF 03.
It is very pretty, and the flowers are pink, but this one unfortunately won't be contributing further to the Pink Flower project, because we don't want any more of these recessive genes thank you very much.
The white flower gene is much more straightforward. One recessive gene, with one simple function. Easy to spot and easy to weed out. Except that in the F3 plants so far, it's not inheriting in quite the way I expected.
It's still early days and not everything is in flower yet, but the presence or absence of a pink splodge in the leaf axils is a reliable indication of flower colour, so I'm able to predict what the colours will be. All three of the F3 breeding lines are producing some white flowers, so obviously all three of them have this unwanted recessive. Given the simplicity of the gene and past experience of working with it, I would expect an average of one in four of these plants to have white flowers. But the ratios are looking like this.
ASF 06 – 7 pinks and 8 whites
ASF 03 – 6 pinks and 2 whites
ASF 15 – 4 pinks and 4 whites
Hmm. We have a normal Mendelian ratio on ASF 03, but the others are looking more 50/50 pinks and whites.
A couple of caveats. One is that they aren't all in flower yet, and it's always possible that I've misidentified the colours until I actually see them bloom. The other is that this is a very small sample size and they won't necessarily make the expected ratios in such a small quantity of plants. This is probably the most likely explanation, i.e. it's nothing more than luck of the draw that I've ended up with fewer pinks than anticipated.
It's a minor frustration inherent in plant breeding. But on the plus side, I get to eat the white ones. Nom nom.
As I said, it's early days with this crop, and I now have the fun (but hard work) bit to look forward to: making notes and observations on every individual plant as they develop. I am pleased to say that nearly all the plants are showing good vigour and have grown to 5 or 6ft tall. This might be hybrid vigour from the cross of two very diverse original parents, or it might just be that they've all inherited the gene for tallness, which is dominant.
The plant which is looking to be the most interesting so far is ASF 06 / 01. Very vigorous and strong, it has lovely big pink splodges in the leaf axils and is also producing very developed sideshoots. It's too early to say whether the sideshoots will develop fully and actually produce flowers and pods, which is a relatively rare thing in peas, but they do look as though they might. This plant is also at the moment showing a very intriguing flower colour. Instead of the two-tone pink which others have, this one has a more uniform apricot pink which I've never seen before. I was quite excited when it first appeared, but knowing how environmental factors can impact the pigments in pea flowers, it may well just be a byproduct of the heat damage. As you can see in the photos below, this plant did suffer a bit while the buds were forming and so this colour may not be representative!
On the other hand, if the flowers do stay this colour I will be well chuffed! I've never seen this apricot shade in peas before, and it's lovely.
Luna Trick F4 plants all tagged up and ready to plant out
Well both my F4 Luna Trick batches are now planted out in the garden - the standard version and the sugarsnap version. They were sown a couple of weeks apart, in the hopes that their development will be staggered somewhat and I will be less overwhelmed by the workload. Growing peas is not in itself much of a workload … they are independent little dears. But breeding projects have a habit of being very time-consuming, especially this one, because I'm being very careful about collecting individual data on each plant. It takes a lot of effort to label and track every single plant in the project and write down detailed notes for all of them. But it will save me time in the long run because I will be able to select more precisely for the traits I want - and it will teach me a lot about the genetics involved, and pea genetics generally. By labelling every plant with its own number, which includes a code for its specific pedigree, I can identify which lines are true-breeding for dominant traits such as tallness. I'll be able to see which pedigree lines are entirely made up of tall plants and save seed only from those, which should eliminate unwanted recessives very quickly. If I pooled the F4 seed and selected from the whole group, I wouldn't know which of the tall ones were hiding unwanted recessives. So although it would save me a lot of note-taking for this year, I'd be weeding out unwanted dwarf types for years to come.
Luna Trick F4 plant, photographed today. This one is the offspring of LT10, which so far looks to be the only line which is true-breeding for tallness.
As these plants are so important to me, I take extra care with them. They have been raised in rootrainers, which in my experience are far more reliable than any other method for producing strong seedlings and healthy plants. The expense of rootrainers doesn't necessarily make them a good option for pea cultivation generally, but for me they are a worthy investment. The next important thing is soil preparation. I don't bother with fertilisers because peas don't really need them … they have a unique mechanism for producing their own. But what they do benefit from is a digging in of organic matter of some kind. Compost is good. Horse manure is excellent, but in the light of the disgraceful aminopyralid poisoning of Britain's grasslands, I'm not using manure in my garden at the moment. Removal of perennial weeds such as couch grass root is also important, because it's difficult to weed around peas once they get established.
The other special care I provide them with is protection from the weather. Peas are hardy, and I'm not at all worried about the April frosts. The cold nights we're getting at the moment are bringing out some lovely red colour in the leaves of peas capable of producing red colour (which Luna Trick isn't) but it's not harming them in any way. What peas do suffer with though is the cold blustery winds that are so common at this time of year. Having said that, this year has been astonishingly warm and settled, so it hasn't been an issue. They are only really vulnerable to this when they're young and first planted out … the cold winds wither and damage the young growing tips. Once they've got established after a couple of weeks, they are a lot more robust. So what I do for precious peas when first planted out is set up a netted fabric screen round them. Horticultural fleece is the conventional choice, but the lovely old lady who lived in my house before me has saved me ever having to buy any. The house was festooned with about 30 miles of net curtains, which do an admirable job in taking the edge off the winds without losing too much sunlight. I'm growing Luna Trick in a frame made of bamboo canes, so it's the work of a moment to attach the net curtains round it with clothes pegs. I do have to be careful to lay a few unwelcoming heavy twigs around the outside as well, because my cat finds it amusing to charge into the net curtains at high speed.
Doesn't that look grand? Well all right, it looks bloody awful, but old net curtains are very effective at filtering the English spring breezes while the seedlings get established. I make no apology for the state of my garden ... the breeding and heritage conservation work is so time consuming I don't have time to make it look pretty as well.
I keep each of my breeding projects in their own personal filing containers, made from ultra high-tech re-used cat food boxes. When I picked up an empty box the other day for a new project I'm starting, it turned out not to be empty. Rattling around inside were about a dozen lovingly sorted and labelled bags of Luna Trick seed from the best of my F3 lines, and three unmarked whole pods left loose in the box. I'm afraid I do have this bad habit of failing to label things and then forgetting what the hell they were. These seeds were all harvested earlier in the season, when I was selecting the best plants and harvesting the pods as they matured. I remember harvesting them but don't remember shelling them and boxing them up, which serves me right for smoking too much weed in my youth. There were about twelve pedigree lines in labelled bags, including a load of extra seed from my best plant LT10 … so I've sown another fifteen of those. You can never have enough LT10 as far as I'm concerned. And by starting off another batch of them now, in addition to the ones sown about a month ago, I'm greatly increasing my window of opportunity to make crosses with them.
The loose pods were something of a mystery, but there had to be a good reason I kept them separate instead of bagging them up like I did the others. According to my pollination records, which can also be a bit sporadic when I'm busy, I did some crosses between the best Luna Trick F3 plants and one of the trial varieties I grew in 2009, Buerre Cosse Rouge. This latter is quite a special little variety because it has red-sploshed pods … not quite the deep consistent crimson I got in my red-podder project, but reasonably close to it. And it's a sugarsnap type. It does have some frustrating weaknesses though. The plants (in my trial at least) were tiny and not very strong, and the yields absolutely miniscule. It produced miniscule pods that have about three peas in them, and more often than not they withered and fell off before they reached maturity. I didn't even get to taste Buerre Cosse Rouge, because I was struggling to scrape together enough seed just to regrow it this season. In doing these crosses, I had in my head the idea that I might get some red-pod gorgeousness into the voluptuous sweet abundance of Luna Trick. There is a chance - only a chance mind - that these loose pods had been kept separate because they were hybridised ones.
Fortunately for me and my slack incompetence, I should be able to find out fairly quickly. My old friend gene A will help me out. It's the gene which switches on the colour pigment in peas. Luna Trick doesn't have it - it's true-breeding for the recessive a a genotype which cannot produce anthocyanin pigment. Buerre Cosse Rouge presumably has the dominant A A type, because it has lots of anthocyanin colour. Crossing the two will give me the a A genotype, in which the recessive colourless gene gets elbowed out. In other words, if the seedlings show any trace of red colouring, I will know they are from a cross. If they turn out to be the normal unpigmented Luna Trick type, then I'll know they weren't from a cross. Thus nature sometimes forgives us for poor labelling.
(The seedlings have now emerged and so far are not showing any obvious traces of anthocyanin. Arse!)
This post comes with a little explanatory video (12 minutes running time) as an introduction to my Luna Trick pea project. It's the first time I've made one of these, so do let me know if it's useful.
Luna Trick is a new pea variety I'm working on. It's an exquisitely tasty edible-podded pea with pale golden yellow moon-shaped pods - named for my music partner Daniel Staniforth who has a music project called Luna Trick.
The project originally started as an attempt to breed a yellow sugarsnap pea. In 2007 I crossed Golden Sweet, a unique heritage golden-podded mangetout pea, with a modern sugarsnap pea, Sugar Ann. The result was a spectacular range of unexpected colour and flavour diversity - but sadly no yellow sugarsnaps. My chance of getting a yellow sugarsnap in the F2 generation was one in sixteen (a double recessive combination), but none showed up in that particular batch. I had yellow mangetouts and green sugarsnaps, but that was it. However one mangetout plant did stand out from all the rest for its elegant beauty, high yields, juicy golden yellow pods and truly exquisite flavour. This plant, which was numbered YSS 25, became the prototype for Luna Trick.
In 2009 I grew out 35 seeds from this one plant. I was hoping to get more plants of a similar type. And so I did - and a lot more besides!
The first Luna Trick yield. Golden yellow moon pods, exquisitely sweet and completely fibreless.
Hybrid vigour in peas is something I've often wondered about. I've often heard it said that hybrid vigour exists only in outbreeding plants, if indeed it exists at all, which is still a subject of debate. Peas are inbreeding plants - very inbreeding - and so you might expect them not to gain much vigour from being hybridised. However my experience is that peas do have a bit of a wahey in their size and growth when you hybridise them. It varies, but it's usually apparent in one way or another. And it may be the reason why Luna Trick turned out a lot taller than expected.
The parent varieties were 5ft tall and 1ft tall respectively. Under normal circumstances, I would expect most of the offspring to be around 5ft tall, as that's the dominant form - with about one in four defaulting to the recessive 1ft size, and maybe the odd intermediate. As it turned out, the dwarf types were nearer 2ft, and voluptuously chunky. Whereas the tall types - well frankly they didn't want to stop.
Daniel, in whose honour the peas are named, is a big bloke. He's 6' 4". I never thought the plants would get as tall as him, but they did.
The F3 crop reaches the same height as Daniel. I wasn't able to measure it after this point because my arms aren't long enough.
Most of the plants weren't going to stop there either. They just kept going, way beyond the 5ft tall frame I'd optimistically provided for them. I had to ram some extremely tall and sturdy poles into the ground all around the frame and wrap masses of garden twine around them to hold everything together. And still the plants kept growing. I couldn't even reach the tops. They were probably a good 8ft by the time they started slowing down.
But apart from this, they behaved very well and did everything I hoped they would do. I'm very optimistic indeed that they will turn out to be a wonderful variety. Not only that, they are TWO wonderful varieties. The original YSS 25 protoype plant was a mangetout type - but growing its offspring revealed the presence of a hidden recessive sugarsnap gene, and a large number of the F3 plants turned out to be sugarsnaps. Beautiful, crescent-podded, golden yellow sugarsnaps! So I got exactly what I had wanted when I made the original cross - in addition to developing Luna Trick as a mangetout type. A wonderful, beautiful and very much appreciated gift.
The key trait in Luna Trick is flavour. I'm aiming for it to have the same flavour as YSS 25, which stood out from every other plant in the F2 batch and was among the most refined mangetout flavours I've ever tasted. Very sweet and juicy, but there's a lot more to it than that - it had a rich and refined complexity to its flavour and no trace of bitterness. YSS 25 was good enough that you would want to eat its full size pods straight off the plant. A salad mangetout, effectively, because it tastes so good raw you really would have no incentive to cook it. I think a yellow mangetout which tastes good enough to include in a salad, even at full size, would be a very nice thing to have.
At the moment I'm getting a mixture of single pods and double pods - some plants produced one or the other but in many cases there was a mixture of both on the same plant. I'm not quite sure how this trait works - it is clearly partly genetic but I'm not sure whether there are environmental factors involved too, or a complex interaction of genes, because it doesn't follow normal patterns and ratios. Consequently I'm just not worrying about it for the moment. Two pods per node is often deemed more desirable but I tend to find that the two pods have fewer peas in them compared to the single ones, so I'm not convinced it actually matters that much either way.
A single flower bud. This is an unusual colour combination in peas - a white flower with a creamy blond calyx (the pixie hat bit).
To summarise the F3 characteristics ...
Luna Trick is stable (true-breeding) for:
Yellow pods - a very simple recessive gene is responsible for this, called gp. In order to express yellow pods, the Luna Trick prototype must have had the stable gp gp genotype. Which is fine by me. It holds only gp genes, so all its offspring will be gp gp too.
There is, however, some variability in how persistent the yellow colour is. One of the weaknesses of the parent variety Golden Sweet is that its pods tend to green up as they reach maturity, so only the young pods are truly yellow. Some of the Luna Trick F3 plants shared this tendency, but others were notable in their ability to stay yellow right up to the time they were harvested for seed. Presumably this is a genetic variable - though I don't yet know how it works - and I will select for it at the F4 stage.
Edible pods - a slightly more complicated trait, as there are two genes involved in the reduction of fibre in the pod, p and v, both recessive. They work in slightly different ways, and you need both of them to get a really good fibreless pod. I have my suspicions that Golden Sweet only has one of them, as it tends to go a bit gristly at maturity. However, Sugar Ann has them both - and now Luna Trick has them both too. There was no trace of fibre in any of the pods in the Luna Trick F3. Hurrah!
White flowers - peas need a dominant gene called A in order to "switch on" anthocyanin production. Without it, they cannot produce any purple pigment in the leaves, stems, flowers, seeds or anywhere else. Luna Trick has inherited the recessive a a genotype from Sugar Ann, and therefore cannot produce colour pigments. White flowers it is then.
Cream calyx - the flowers all have a cream calyx (sometimes with green mottling) rather than the more conventional green. This is a true-breeding trait because it's directly related to the yellow pods. It looks absolutely gorgeous with the white flowers and really gives this variety an extra beauty factor in the garden, adding to its luna blondness.
Luna Trick is still segregating for:
Height - I'm selecting for tallness, which is the work of a dominant gene called Le (internode length). The cross with Sugar Ann will have introduced the recessive type le into the mix. Although the Luna Trick prototype was tall, it had the recessive shortie gene lurking in its genome … and by a simple Mendelian ratio I ended up with dwarf types in about a quarter of the F3 plants. With a bit of luck the F4 generation should take care of this. By growing out several plants from each of several lines, I'm hoping to be able to identify the lines which produce only tall plants, and which are therefore likely to have the desired Le Le genotype.
Pod type - the prototype Luna Trick had large mangetout type pods, which represent the dominant form. However, squirrelled away in its genome was the recessive gene n, inherited from Sugar Ann, which gives sugarsnap type pods. Consequently about a quarter (or just over actually) of the F3 plants were sugarsnaps. I was overjoyed by this, as yellow sugarsnaps were the original intent when I made the cross. The way this gene works is to thicken up the pod wall, giving it its chunky and succulent 'snap' characteristic. To compensate for this thickening, sugarsnap pods tend to be slimmer. Although this genetic difference is simple and made by a single gene, it effectively creates a separate new variety.
The recessive nature of gene n means that any sugarsnap lines I follow up will be true breeding for sugarsnap pods, as they will be genotype n n. The mangetout Luna Trick, on the other hand, will continue to throw up the odd sugarsnap from recessive genes hidden away, and I'll have to eradicate those through repeated selection.
Even within the mangetout type, differences in pod size and shape are apparent. The ideal I'm looking for is a fairly wide crescent shaped pod, but some are narrower and some are extra wide, and some are not quite so crescent-shaped.
Flavour - this is the most important factor, and I would have liked it if all the offspring had tasted as good as the prototype - but only some of them did. I know very little about the genes involved in pea flavour. The combinations are very varied, and so I assume a number of genes have a bearing on it. Sugar content obviously is a major factor, but it's not the be-all and end-all. Some peas taste very sweet but are still quite bland, others have a rich and interesting flavour but aren't particularly sweet. There is also a kind of 'soapy' taste which peas are prone to which seems quite independent of the other flavour variables. The flavour variability in the Luna Trick F3 was quite considerable. They ranged from something akin to nectar of the gods to something bordering on bitterness. Some were just bland. Overall though, the vast majority tasted substantially better than Golden Sweet - and the best ones were truly exceptional. So I'm confident of creating a flavour benchmark with Luna Trick - it's just going to take a bit of careful selection.
Seed colour - the Luna Trick prototype was heterozygous for seed colour, producing both the dominant cream seeds and the recessive green ones. Some of the resulting F3 plants were homozygous for green seeds, but the lines I'm most interesting in following up happen to be heterozygous ones, so the variability will continue in this coming generation. I'm not too bothered about this. I might select one colour or the other if it becomes easy to do so, but I don't see any harm in having the variability. It would be unacceptable in a commercial variety to have mixed cream and green seed, but I don't see why not. One of the compensations of public domain plant breeding is that you're not bound by rules and conventions.
Sugarsnap version of Luna Trick. I will develop this type separately and make a new variety with a different name.
Luna Trick does have a potential weak spot which may be genetic or environmental or a combination of the two. The peas have a tendency to split their skins when ripe - much as ripe tomatoes do when they're over-watered. This isn't a problem when you want to eat them, but verily 'tis a bugger when you are saving them for seed. In the F3 crop, some plants suffered badly from it and some had no problem with it at all. So I am selecting the ones that didn't have the problem - kind of by default, because the ones that have split will not make good seed for replanting. If it's a genetic issue, selecting against it should soon eradicate it. If it's environmental (affected, for example, by how much water the plants get at a particular time) then no amount of selecting will make any difference. So far this seems to be the only flaw though in an otherwise wondrous variety.
Rain on Luna Trick blossom.
So what now? The F4 crop in 2010 I've already sown 100 seeds for this year's selection work - 50 mangetouts and 50 sugarsnaps - and these are the ones shown in the video above. Germination was 100%.
I'm working on the mangetout and sugarsnap versions as completely separate varieties, and at some point the sugarsnap one will get its own name. Some sugarsnap types will continue to show up among the mangetouts in this generation. I'm also seeing height variability, which is apparent even at the seedling stage.
I've chosen F4 seed from the best six plants of the mangetouts and the best six plants of the sugarsnaps. In the F3 there was one plant, called LT10, which stood out from all the others - it was the tallest, highest yielding, most beautiful and had the holy grail flavour I was looking for. So I'm growing more of those than any other, hoping that I can stabilise it pretty much as it is. But by growing out a few other good lines alongside it, I'm hedging my bets in case LT10 turns out to have any unexpected flaws - and also learning more about the genetics involved, by observing the ratios for different traits in different lines.
With the sugarsnaps, there was no obvious standout plant in the F3. Some were better for flavour, some for pod shape or colour, some for stringlessness ... so I've just selected the six that looked most promising and will see what I get.
All in all though, I'm very excited and optimistic about Luna Trick.
The unexpected discovery of the 'formula' for red-podded peas was the most exciting thing to happen in the garden in 2008. Without even meaning to, I'd created something unique and special and was very excited about what it might evolve into. Following all this excitement and expectation, its progress in 2009 was frustrating to say the least.
To recap briefly: I was working with two crosses, both involving a purple shelling pea with a golden yellow mangetout, with the aim of breeding a new purple mangetout variety for The Real Seed Catalogue. One of these crosses was Golden Sweet x Carruthers' Purple Podded, and among the F2 plants (the generation where all the genetic recombination happens) I found one single plant with deepest, richest blood red pods.
Beauty is not enough though, as spectacular as it is. Commercial seed catalogues are already rife with things which look good but don't taste particularly special. So much so, you could be forgiven for assuming there is a tradeoff between beauty and flavour (which there isn't) and that pretty vegetables will inevitably taste rubbish. I don't want that to happen with my red-podder. I want it to taste as good as it looks, otherwise there really is little point in it.
The original red-podded F2 plant was, unfortunately, a normal shelling pea with a fibrous membrane inside the pod. What I need is an edible podded version - which means a pod which doesn't produce a gristly inner membrane. The absence of fibre is actually achieved by the combination of two unrelated genes, both recessive. Golden Sweet, the 'mother' of red-podder, is a mangetout and has at least one of these genes, if not both. So even though red-podder itself had fibrous pods, there was a pretty good chance that it would be heterozygous at that locus - carrying a hidden recessive gene for edible pods. In fact, by the rule of Mendelian segregation it had a two in three chance of producing some edible pods, and only a one in three chance of being all gristly and inedible. Until I grew the next generation, I had no way of knowing whether it was heterozygous for that trait (carrying some variability) or homozygous (true breeding).
So in 2009 I grew the F3 plants. As the red-podded phenotype was only really asserted in one plant in my F2 crop, my F3 crop was based solely on the offspring from that one plant. The plants were absolutely stunningly gorgeous. Most of them had deep red pods, though some were coming out as plain yellows, and they all had wonderful rich colouring on the stems and tendrils, and attractive calyx markings. When the sun shines through the red pods they are out of this world.
Alas, growing the F3 revealed that red-podder is homozygous for gristly pods. In other words, it cannot produce edible pods. Homozygosity is a blessing for stabilising the traits you want. But when a trait you don't want is homozygous, you're stuffed. I could grow the offspring of my red pea for the next 100 years and probably never see an edible pod among them. The genes for edible pods are not there. It has only the genes which breed true for solid, yukky, gristly fibre.
There are five things I can do about this:
1. Stand in the middle of the garden and shout "BOLLOCKS!" in a really loud voice.
2. Go back to the F2 generation and grow out the rest of the seeds (I have about 20 left) in the hope of finding another red-podded phenotype but with edible pods.
3. Go back to an earlier generation still, the F1 seeds, and grow out some more of those. These plants will all look the same, all boring, with no red pods. But they will produce a fresh abundance of F2 seed, which I will be able to sow next year and that will give me a much better chance of an edible red-podded phenotype in the event that option 2 above doesn't yield anything.
4. I can switch to another line of F3 seed, even though none of them are proper red-podders. For example, I do have an F3 which is edible podded and produces yellow pods with a red blush. It's possible that if I grow out enough of its offspring I might get something with a stronger red. It should at least breed true for edible pods, which is half the battle. Even if it doesn't produce a decent red, it might make a nice variety in its own right - kind of peachy auburn!
5. I can grow my remaining seed from the red-podded F2 and cross it with something else. To retain the red pods I would need to cross it only with yellow podded peas - and mangetout ones at that. The most obvious thing would be a backcross to Golden Sweet, but I can go one better than that. My Luna Trick line, although not yet stabilised, is bred from Golden Sweet but is a huge improvement on it. A cross with that would give me an excellent chance of improving red podder's flavour as well as its pod structure. The other obvious cross to make is with option 4 above, which already has most of the right genes.
Apart from option 1, they will all take some time - at least a year and probably more - to get the results I want. But no matter, I have got all of them underway now. We'll see what 2010 brings.
