Thursday, 26 March 2009

Crap Crops of the Incas: my on-off-on affair with Andean root crops 4) Pachyrhizus - ahipa useless junk?

"Four legs legs good, two legs better!"  That was the bleat of the  sheep in George Orwell's 1945  allegorical tale  Animal Farm.  Their masters, the ruthless and conniving pigs, had just started strutting about on two legs and were all set to take over where the banished humans had left off. 

So, you may well ask, what the hell is the relevance of this to root crops? George Orwell's interest in roots and tubers seems to have been limited to an oblique reference to potatoes in The Road to Wigan Pier and mangelwurzels, which get a mention in Animal Farm.  No, I'm not suffering from a mashua overdose;  hopefully we all know by now that root crops are good nutritious fare and we could certainly grow a greater diversity of them.  But nitrogen fixing root crops, ones that gather nitrogen from the air and deposit it at their roots, must be even better: fill your stomach and feed your soil at the same time.  These are the Holy Grail of the rootcroppin-nostoppin-tubertastin-timewastin-globescourin-cataloguedevourin-seedbuyin-diversifyin permie (who may or may not drink any of a number of noxious carbonated beverages). 

There are a few  possible  contenders for our cool temperate climate, such as Lathyrus tuberosusPsoralea esculenta  and Apios americana - I'll attempt to cover these in later posts - and a whole load more if you move into warmer zones. Seeing as we enjoy a cool moist climate here in Britain and complain like hell about it, I think I'll limit my researches to the moan zone with which I am most familiar. 

Pachyrhizus is a genus of tuber forming beans, sometimes known as yam beans. There are several species.  The most familiar, perhaps, is jicama, Pachyrhizus erosus from Mexico and Guatemala , the roots of which are  sometimes sold in exotic markets, or you may see the seeds offered by specialist seed companies.  The 
other main species is Pachyrhizus tuberosus, probably a native of Amazonian Peru.
As you might easily deduce from their places of origin, these two Pachyrhizus species like much warmer summers than we have here, as do a considerable proportion of the populace, who apparently now live in Spain.  In fact, I daresay jicama would grow quite well there. There is, however, a higher altitude species, ahipa, Pachyrhizus ahipa, found in  Bolivia at around the same sort of elevations as yacon grows.  Not only is it better adapted to cooler climates than the other species, it is also day neutral, which jicama, for example, is not. Hallelujah, so far, so good.  It's also, usually, a bushy, free standing plant without the exuberant twining growth of its fellow species.   Brilliant.   But before we open a bottle and celebrate the advent of a new crop, one the good old boys down the allotment will roll their eyes skyward over,  how cool is cooler?  Oh yeah and what does it taste like?                                                                   
I grew my first plants back in the early 90s from seeds that were supplied by the Yam Bean Project in Denmark, led by Marten Sorensen.  Unfortunately it doesn't seem to exist any more - correct me if I'm wrong Marten.   There were initial problems with some of the ahipa seeds which had been grown in Tonga and were DOA.    Still, the hardened root crop obsessive knows that there are many twists and turns on the steep and rugged pathway to the sunlit uplands where fields of comingling  tubers flourish in delicious, delightful abundance.   The next lot of seed I received produced a few plants which were planted out in a polytunnel.   They had, unsurprisingly, bean like foliage and looked reasonably happy.  

They bore attractive purple flowers and produced large pods.  Then the cold weather came and I decided to move them somewhere warmer.  The roots were small affairs, (the vernacular"piddling" springs to mind), but I shrugged my shoulders and thought about those sunlit fields again. 

It turns out that the flowers are usually removed as a traditional husbandry technique to increase the root size. This makes perfect sense if you think about it - the developing seeds are bound to draw resources away from the bit we're after: the tubers.  So reproductive pruning is necessary, although it does present a few difficulties from a breeding point of view, especially  as ahipa is usually grown from seed every year.  

Time passes. Listen. Time passes.   Ahipa fades out of my life and then, inveigles its way back in, all over the space of a decade or so. May 2005: I find myself once again planting a few young ahipa seedlings into the ground, hoping that neither frost nor slugs will stop me from getting to try the sweet and juicy flesh of the Andean yam bean.

The plants grow well and seem to enjoy the warm summer.  I decide that rather than sacrificing the plants, I really ought to build up my seed stocks, so I forgo the delights of reproductive pruning and let the pods develop.  

The intimate study of drying paint seems almost unbearably exciting when compared to waiting for ahipa pods to ripen.  It all starts quite nicely with the purple flowers which seem to set easily and produce little bean pods - so far, so good. They swell quite rapidly and appear full of promise.  The pods get longer and fatter, with buxom bulges around each seed.   This is looking good.  Then the long wait begins.  Maybe it's just our wan late summer sun that fails to get them going, I don't know.   Those pods just sit there in a state of suspended animation like killjoy Walt Disneys.  Then, as the season deteriorates, the slugs seem to realise that rotenone, the insecticidal compound contained in the seeds, presents no threat to them;  to prove the point they tunnel their way through with their customary bare faced cheek.  Yes, slugs do have faces.  I just wish they'd keep their rasping tongues off my plants. 

Disgusted by the rank ingratitude the plants showed, a red mist descended and I decided to abandon them.  I sent the seeds of my two varieties to Frank van Keirsbilck, worthy contender to the as-yet-uncreated title of Mr More Agrobiodiversity per Square  Metre than Anyone Else (Europe).   As I suspected, he is a better grower than me - he has even been offering seeds through Seed Savers Exchange this year.   Another source, if you're still interested, is AndeanCrop Seeds on eBay.  

I recanted, of course and grew ahipa last year in a desultory way: two stunted plants in pots.   Here's proof, if any were needed, of why I should not be let loose on unsuspecting Andean root crops:

Never was the phrase "small, but perfectly formed" more apposite.  I took the offending plant, peeled the tuber and ate it.  It was sweet, certainly, but with a slightly starchy taste and texture like that of a raw potato, not that I eat raw potatoes that often, only as part of a calorie-controlled diet.  Still, it wasn't bad and would probably have been a lot better in a bigger pot where the tuber could have developed properly. 

Ahipa can grow grow quite well in the British climate, but I would say a good summer is needed.  2007 and 2008 were not vintage years for ahipa in the UK. 

To guarantee success they'll  need to be started off in a greenhouse and if you want ripe seeds, a greenhouse, polytunnel or cloche will ensure they get the extra heat needed to ripen those seeds.   Eduardo Leidi Montes, an ahipa researcher in Spain told me that he thinks the crop has real possibilities in a Mediterranean climate. Such summers tend to be the exception rather than the rule here. All those ex-pat Brits, downing Newcastle Brown and chewing  Marmite sandwiches - they
may be missing out on the ahipa plants growing in the fields opposite El Pub.  

So the school report might read something along these lines : "Ahipa shows promise, with the potential to make a useful and original  contribution. However, Ahipa  must concentrate on completing tasks in a satisfactory manner within agreed time frames and show adaptability in dealing with changing circumstances".  Overall score C-. 

Thursday, 19 March 2009

Sock it to 'em oca!

Those of you who glaze over at the sight of charts, figures and arcane jargon may prefer to look away now. Please don't - I won't detain you long.

Ben Gabel of Real Seeds mentioned to me that the crops planted in a bed which had contained oca the previous year seemed to grow less well than expected. My curiosity piqued, I decided to boldly head off at warp factor 10 to the planet Allelopathy.

Allelopathy is one of those concepts in plant science and horticulture that seems to engender a lot of heat, but surprisingly little light. It is, as interesting ideas often are, contentious. Reputations have risen and fallen; promising careers have ended in derision and ignominy. Hans Molisch, who published the first definition of allelopathy in his book Der Einfluss einer Pflanze auf die Anderd-Allelopathie (The Influence of one Plant on Another-Allelopathy) in 1937 - died the same year - suspicious or what?

So what is allelopathy and what's it got to do with oca? Allelopathy is the inhibition of one plant by the chemicals released by another. It's chemical warfare. That's one definition, or maybe two and they'll do for the purposes of this discussion.

Well, knowing a little bit about oca's biochemistry, I wondered whether some of the weird and wonderful compounds it contains might be responsible for these effects. Ones like ocatin, harmine, harmaline and those good old standbys - fluorescent β-carbolines.

So I did a quick bioassay, the so-called "Sandwich Method" using dried oca leaves, some agar and lettuce seeds. The dried leaf material was embedded in the agar and the lettuce seeds sown on the agar surface. Then the whole lot, including a control (no leaf material) were incubated for a few days at 20 C.

Here are the results, recorded as percentage elongation of lettuce roots (radicles) compared to the control:The results seem to indicate that oca leaf material exerts a powerfully inhbitory effect on lettuce root elongation. I'll say one thing though. I'd rather spend my time measuring lettuce radicles than trying to import Excel charts into this blogument. They say practice makes perfect, but strangely, not in my case..........

So perhaps what Ben noticed could be the result of allelochemicals leaching from the leaves or being exuded from the roots. Maybe these chemicals have an inhibitory effect on competitors or following crops. Maybe this is allelopathy. I don't know, but it is interesting and is worth serious investigation. I am available and my rates are very reasonable.

Monday, 9 March 2009

Amphicarpaea - The Talented Mr Talet

A while back I made clear my suspicion regarding plants with animal prefixes like pig, horse, dog and so on.  The implication is clear:  they're food  fit for dogs, hogs and horses, not humans.  Horses, dogs and hogs are all thoroughly worthy animals, but, generally speaking, although they may want our food, we tend not to want theirs. 

I am now about to break my own rule, but like a proper merchant banker I shall retain a clear conscience, if not a six figure bonus.   Amphicarpaea bracteata is the hog peanut, a widespread North American legume with a fascinating reproductive system. Of more immediate interest is its production of tasty underground beans, 
which can be harvested in the autumn.

In order to circumvent my own rules, I have therefore unilaterally elected to rename Amphicarpaea bracteata  "talet" rather than "hog peanut".  First of all, it's not a peanut, Arachis, although it does form underground pods. It's recognisably a bean. Secondly the beans  are definitely worth fighting over with the hogs. A pod isn't a root, as avid botanists amongst you will have already spotted;  this is assuredly an egregious deviation from my mission statement, but just as the first potatoes in Europe were thought to be truffles, I consider hog peanuts to be an honorary root crop. They do grow underground  in a rootlike way and are sometimes even erroneously referred to as tubers.   

So why talet you may ask?  Talet is the name given to the hog peanut in the milpas (traditional cornfield polycultures) of the Sierra Norte de Puebla, Mexico, where it is semi-domesticated, or, perhaps more correctly, an encouraged weed.   Seeds are sown with the corn and then harvested and toasted on a skillet when the fields are ploughed at the end of the season.   

Surprisingly, perhaps, they seem to grow quite well here.   The plants have trifoliate leaves and look a bit like mini French beans. They're actually rather pretty in an understated sort of way.   This photo, courtesy of Frank van Keirsbilck , provides an impressionistic sweep of talet foliage.  

The shoots will climb up any stems in their vicinity and after a while, long horizontal side branches power out from the leaf axils.  These produce thin stalks, like long antennae, that burrow into the ground. At their tips are tiny flowers  and each one has the potential to form a bean. These flowers are cleistogamous, that is they never open and are self-pollinated.  At the same time, all unbeknownst and invisible, similar shoots are developing underground straight from the parent seed. 

Later in the season the aerial flowers appear, first in the form of single cleistogamous flowers, which may go unoticed and somewhat later still  as small clusters of open- pollinated (chasmogamous)  flowers, with pale lilac petals.  So that gives the plant a range of seed types:  soft fleshy ones underground from the cotyledonary shoots, similar ones from the long aerial side shoots, both of which are self-pollinated.  Then there are the small hard seeds from the aerial flowers, some of which are self-pollinated and some of which  are open-pollinated.   In a good season the big seeds will survive until the following spring and produce big plants.  If things get a bit tricky, the small hard seeds will probably make it through until conditions improve again, perhaps several years later.   They may get carried some distance from the original plants during this time.   Their genetic variability will show up in the seedlings, some of which may be better suited to the prevailing conditions.  If they like what nature dishes up, they'll produce lots of the big seeds once more.  The technical term for this botanical bet hedging  is amphicarpy.   If you understood any of that, well done.  I think I'll go and lie down for a bit. 

Another advantage of Amphicarpaea is its abilty to fix nitrogen.  The correct strains of Rhizobium bacteria for effective nodulation  belong to the "cowpea miscellany" (weren't they a progressive rock band circa 1976?).  These tend to be absent from British soils, so I just plucked some nodules from my Apios plants, crushed them in water and poured them over the Amphicarpaea plants. It seemed to do the trick with lots of nodules developing afterwards.  

There's a closely related species in Asia, Amphicarpaea edgeworthii.  The Japanese, who leave no stone unturned when it comes to testing things for edibility, have even investigated it as a potential crop plant.  The Japanese name, "yabumame", means, apparently,  "bush soy", which is suggestive of innate potential.    I had to laugh when I saw a plant growing, oh-so-nonchalantly, right outside the dormitory building in Tsukuba,  Japan where I stayed for a couple of weeks  in 2007.  It was even funnier to step into the greenhouses and see, wholly unexpectedly,  oca, ulluco and mashua plants, but that's another story.  
I can see talet being grown as a living mulch around root crops, like, oh, I don't know, oca for example, or in a modification of its Mexican cornfield  habitat, as a ground cover in a sweet corn patch.   At the moment it expends a lot of energy producing long runners that deposit seeds far and wide.  Maybe with selection, varieties with shorter runners and bigger yields could be obtained.   The abstracts of Japanese papers I've read on the subject seem to suggest this. 

Although the plants themselves are frost tender, I have frequently noticed seedlings popping up from unharvested seeds the following May.  A tasty underground legume that can actually survive here and emerge in spring - that's no peanut.

Talet apparently needs short days to initiate flowering.  As  A. bracteata occurs right up into Canada, it's possible that varieties better suited to our long day summers might be found there.  Anyone who can provide me with seeds from such northerly locations will earn my undying gratitude and an honourable mention on the blog. 

OK, the yields are unimpressive, but this a wild plant.  Compare your average King Edward with a wild potato progenitor, say, or a wild carrot with a nice juicy Chantenay Red Core.  It's unlikely they'd be mainstays of the British diet had they not undergone rigorous selection for size and taste.   No, in my opinion, talet has definite potential. Accentuate the positive: tasty bean, grows well; eliminate the negative: low yield, daylength sensitivity and do mass selection in between.

Another interesting observation, which could be advantageous, is that, in my experience, talet doesn't want to bake in the sunniest spot in the garden.  Plants in full sun seem altogether dejected and yellow.  Give them a bit of shade and they're big and vigorous.  A shade tolerant, nitrogen-fixing bean crop that grows in Britain - Gimme! Gimme! Gimme!  Apologies to ABBA, but who'd want a man after midnight when they could spend the preceding few hours munching on handfuls of delicious talet beans from their own polyculture plot? 

Double the yield, reduce the excessive vigour and we might just have a really useful new temperate legume crop.  What are we waiting for?

Sunday, 1 March 2009

Crap Crops of the Incas: My on-off-on affair with high altitude Andean root crops 3) Mashua

I suppose an appropriate subtitle might be "mashua, the tuber with the taste that torments". Chances are, that having read such a title, you would be quickly dissuaded from reading further. That would be a shame, because mashua is an attractive and intriguing plant. It was, if my memory serves me correctly, the first of the unholy trinity of crap crops that I ever cultivated.

When Woody Allen described himself as nauseous and tingly all over, I don't think he was referring to the physical effects of mashua consumption. In his case he was either in love or had smallpox. However, when I eat mashua, I get a similar reaction - at least I feel a bit nauseous. I don't think I get any tingles. And it's certainly not love at first bite. This plant is euphemistically referred to as having an "acquired taste". I'm struggling, manfully, to acquire it. The Incas, in their wisdom, knew better. Mashua was a woman's food, which men avoided due to its anaphrodisiac effects. Mashua was, however, one of the Inca military's secret weapons. It was fed to the troops to keep their minds on the job - killing people, instead of fathering them.

Problem is, most of the females I know feel exactly the same about mashua as a food: nice plant, shame about the taste. Others, like Frank van Keirsbilck seem to think the flavour is OK, at least on occasion. I wonder if individuals experience differences in palatability because of their varying genetic ability to detect the bitter compounds mashua contains - something akin to the so-called super taster phenomenon.

Mashua (Tropaeolum tuberosum) is a tuberous version of the garden nasturtium. A range of tuber types can be seen on this post. These are visually attractive, often with purple flecks and given a mild autumn, the yields can be quite good. The word nasturtium is derived from the wrinkled nose displeasure induced by tasting watercress, the one and only truly original Nasturtium - think of it as nasal torsion, if not torture. The genus Tropaeolum acquired the common name 'nasturtium' for the similar flavour of its leaves to Nasturtium i.e. watercress. Here's a secret that anyone who hasn't eaten mashua might like to consider: if you turn your nose up at watercress, just wait till you try mashua. In fact mashua contains some of the self same compounds as the brassicas, isothiocyanates, which give it a radish-like flavour when raw. It also has a strange perfumed quality about it, which is unique, distinctive and not like any cabbage I've ever tasted. This is particularly noticeable when the tubers are boiled.

Flavour notwithstanding, mashua is actually quite nutritious, with a high protein content, good amounts of viamin C and a whole bunch of antioxidants with long names like delphinidin 3-glucoside-acetylrhamnoside , cyanidin 3-glucoside and delphinidin 3-sophoroside-5-acetyl rhamnoside.
It's also very pretty, with attractive lobed leaves on long stems, which either spread over the ground or climb upwards. This makes it a worthy ornamental that ought to be seen more often in gardens. The flowers are bright orange beacons amongst the sea of foliage, with a shape that shows their obvious affinity with the good old garden nasturtium; mashua's are smaller, but still very attractive. Bees seem to enjoy them. Here's a picture Frank van Keirsbilck has kindly allowed me to use.

Everyone talks about how tough and hardy this plant is. It resists pests and diseases and also has nematocidal properties etc, etc. These effects seem to be attributed to the presence of those isothiocyanates. There does seem to be a downside, however.

No one seems to mention that cabbage white butterflies seem to enjoy it about as much as they do cabbages. I've seen my plants covered in little black caterpillars that swell alarmingly, seemingly overnight, into bloated chavs, resplendent in lurid blue and yellow shell suits with "am I bovvered?" warning colouration. They obviously know good quality isothiocyanates when they taste them and will strip mashua plants completely.

The variety 'Ken Aslet' is an ornamental one selected for its reliable summer flowering. Frank's picture above is almost certainly this variety. It also produces yellow and purple flecked tubers in reasonable quantities. The "proper" crop varieties flower and tuberise - you've guessed it - in the late autumn. In a very mild year they try and set seed, but without protection they are frosted off in their infancy. 'Ken Aslet', on the other hand is definitely capable of producing viable seed. One year I had a whole load of self-sown seedlings appear in a polytunnel. So, unlike its comrade crap crops, oca and ulluco, breeding mashua could be a relatively simple undertaking. With a bit of daylength jiggery-pokery, it should be possible to get some of the other varieties to come into flower at the same time, cross them, then select the progeny for desirable traits like early tuberisation, vigour and hell, why not, taste even. A few inverted buckets over the plants might well suffice, or why not put that redundant rhubarb forcing pot to good use for a few weeks in the summer?

This plant, in spite of caterpillar depredations, grows well, looks good and is supposed to have numerous beneficial and pest reducing properties. So, damn it, why can't it taste better? Maybe it all depends on how you cook it. As is usual with Andean crops, they are often processed in various esoteric ways. In mashua's case this includes freezing the cooked tubers or soaking them in molasses. Still, bread production is a fairly elaborate process to the uninitiated. One resolution for this year is to try preparing the coming season's harvest in a few more imaginative ways. Boiled or roasted they retain the peculiar and distinctive mashua taste, which I find hard to stomach. I wonder if this is actually due to some of the other chemical components rather than the isothiocyanates - maybe some of those antioxidants?

Some plants seem to show fasciation, growth in which stems become flattened, with leaves massed at the top like a brush. I've seen it frequently in 'Ken Aslet' plants. I'm guessing this is caused by one of those annoying little viruses and probably depresses yields too; it certainly depresses me. Still, I'm sure a bit of plant tissue culture would rid the plants of this problem.

As is usual with these things, it has all been done before by someone else. In the late 1980s I recall reading an article in the HDRA newsletter by someone called Paul Parker. He had imported mashua from South America and was growing a number of varieties in his garden in Leicester (I think). I would be very interested to learn more about his work. Are you still out there Paul?

Here's an excellent antidote to my verbosity - another picture courtesy of Frank van Keirsbilck. You get some sense that mashua is a fairly diverse crop in terms of tuber colouration.

To my mind, mashua is a bit of a Cinderella crop. Unappreciated and overshadowed by its sister crops oca and ulluco, it needs some Prince Charming to come along and do some serious research and breeding work on it. Tuberisation and flowering somewhere a bit closer to midsummer than November is a must, as is virus removal. I'm hoping the clock will strike twelve and it'll be turned into a pumpkin - at least then it might taste better.

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