Back in the spring, I potted on a whole load of different talet varieties and left them to their fate. That was never my intention, of course. I meant to update regularly on their comparative vigour in the hope of identifying which of the six varieties was best suited to the Cornish climate. As per usual, life seems to have impeded my lofty plans, so here I am catching up once again.
Talking of loftiness, the plants became so top heavy that they kept falling over. It was politely pointed out to me that they constituted a tripping hazard, blocking as they did the narrowest defile in our famously narrow back yard. Come August, I finally took the hint and moved them down to the plot instead. It was also high time that they were repotted into something roomier than their budgie smuggler fit 7cm pots. Their leafiness, while providing a gratifying splash of green against the wall, had also meant that they were quick to dry out; resuscitation was needed on several occasions, with the poor things gasping and close to their permanent wilt point. Welcome to my world, where horticulture and homicide collide.
Originally I had randomly arranged the different varieties into those handy stackable blue crates; now I sorted them back into their individual varieties in order to compare each in terms of growth and nodulation. For illustrative purposes I set out the varieties in ascending order of vigour, left to right. 'Saratoga Battlefield' (SB) was the least vigorous, followed by 'Yabumame', which had a distinctly chlorotic cast about it. The most vigorous of the six was the unimaginatively named 'Original', which I obtained (I think) from a Seed Savers Exchange member. In terms of nodulation, 'Original' seemed to be ahead of the pack, although 'FVK' (Frank van Keirsbilck) and 'GN' (Gardens North) were quite well endowed too. The latter two early varieties had already begun producing aerial chasmogamous flowers, and also sported long and leafy axillary branches close to ground level.
|Arrayed in all their glory. August 2014.|
The repotting process gave me the perfect opportunity for a mid-season peep at what was going on below the surface of the compost. Talet, as I've previously mentioned, has the nifty ability to fix nitrogen; aside from producing damn fine beans, this is one of my prime motivations for growing the plant.
GN. Shows a small subterranean bean developing and a fair few nodules. Oh, and an earthworm.
|FVK: baby bean and some nodules.|
|Original: massive nodules, subterranean shoots ramifying nicely. Not a bean in sight.|
As I searched the yabumame root mass for nodules, it was clear these were missing, or too small to be visible with the naked eye. This might explain their stunted growth and yellowish leaves - symptoms of nitrogen deficiency. Yabumame is known to associate with its own particular strains of Bradyrhizobium bacteria in Japan, which might well have not made the trip here with the aerial seeds I received - maybe in this case absence of evidence really was evidence of absence.
Finally, in November, even 'Original' senesced and after a few weeks' hiatus, I decided to tip out the pots and assess the yields.
|State of play. November 2014|
|Yabumame.The total yield from five pots. Back to the drawing board on this one, I think.|
|GN. I've seen worse. Five pots.|
|FVK. Six pots.|
|And finally, the clear winner, Original. Six pots.|
The two pots of Saratoga Battlefield failed to produce a single bean between them. Bah!
All in all, 'Original' was by far the most productive variety, with the others lagging way behind. But I'm not entirely satisfied with my experimental method. In fact, I'm intending to run the 'experiment' again this coming season; when you hear scientists say "more research needed", this is what I think they mean. Bigger pots, more water - I owe it to them to try again.
So, those are the results - but what of their interpretation?
It could be that I potted on the early varieties way too late; they may have already been too far down the seed development process to take advantage of extra root room, nutrients and improved water availability offered by their new homes. I seem to remember noticing something similar years ago when I potted on a previous bunch of sorely neglected talet seedlings. Legumes are known to be quite thirsty when flowering and it's possible that seed development was affected by water stress at a critical stage. Perhaps 'Original', as a result of its later flowering, took advantage of the increased space, water and nutrients to grow much bigger before seed formation was initiated; it might then have directed the more abundant products of photosynthesis downwards to create fat subterranean beans.
At least I've established that if you plant one fat Amphicarpaea bean, you might get nine back - if you use the right variety and treat the plants with a modicum of respect, horticulturally speaking. I've wanted to know this indispensable piece of information for years. It isn't isn't too bad a deal, bearing in mind that talet is, as far as I'm aware, an unimproved wild plant. The next challenge is to quadruple that yield - a forty fold increase between sowing and harvest would be something like an acceptable level for a crop plant.
The variety NS (Nova Scotia) grown from aerial seeds obtained from Edward MacDonnell produced a few small beans. I'll add it to this coming season's trial. I also have seeds of a variety from Ohio, which was kindly sent to me by James Cheshire. And seeing as I still have aerial seeds of SB left over, I guess I'll give it another chance. Come to think about it, I'm sure I have some other varieties knocking around, in the form of those indurate aerial seeds. May as well liberate them too.