Air Drying Roots

[Jon Nose]

I have read (can't find at the moment) that lettuce does better if you air dry the tap roots before putting the  plants in raft system ..... question is does the same rule work for bok choy?

thank you :)

[Vlad Jovanovic]

Yep...from Bok Choi to Douglas Firs...Though there is no need to (nor do you want to) entirely "dry out the tap root". just desiccating the very tip of the tap root is enough.

[Bart]

Ok this will no doubt sound like a dumb question, but how exactly should one go about doing this? Just pull the net pot out of water for a day? Break out my daugher's hair dryer? Microwave? Bic lighter? A dry merlot? Ok so I should at least get points for making a dumb question entertaining

[Vlad Jovanovic]

+1 (hehe...while entertaining...it's not really a dumb question. I like the Merlot idea...wakka, wakka)...

First off, I never, ever,NEVER (not even under duress of paper cuts and lemon juice) start seeds off in a net pot that is standing in water non-stop. Depending on your media, temps, time of year, or where you live, that would be just begging for crown/collar rot, damping off, pythium issues etc....

So...this is my seeding table...

 I normally flood it about 2-3 times a day for about 10-15 minutes at a time (depending on time of year...i.e temps/humidity). Notice the high-tech air space beneath those rafts/net pots. Air pruning those seedlings requires that I get lazy for a day or two and flood the table only once (or twice if it's a real warm/dry part of the year) when the little tap roots begin to poke out the bottoms. That's it. The protruding tips generally dry out (desiccate) which send the little plants into a fine lateral root making frenzy...Then once the tap root tips dry out, I go back to a 'normal' flooding regime of 3 times daily). This makes for a much more efficient root system by which to absorb nutrients...which makes for slightly quicker growing plants. 

In this incarnation, the water I flood the table with comes from, and goes back into, the AP system...If the two were not connected I would just put a piece of the thinnest (cheapest) copper sheet metal I had under the rafts. When the tap root reaches the copper, it has the same effect that air pruning has...Which is temporarily suspending the synthesis of cytokinin (produced in the root tip) and allows auxins (contained in the cotyldons) to kick in and promote cell elongation and lateral root development. The copper method is a more uniform method than the one pictured (since each plants tap root is hits the Cu, there is no escaping it...The way I currently do it, there are always a couple plants here and there, whose tap roots end up staying moist enough to be un-effected...but I don't care enough to do anything about those few)...

So laziness is the key to good air-pruning...Laziness or copper, but since this is AP and all...I opted for laziness...

Hope that helped.

[Bart]

That covers it in a nutshell thanks Vlad, awesome explanation as always, thanks for taking the time.

[Vlad Jovanovic]

[Bob Terrell]

and here AGAIN Vlad teaches me something new!

[Jon Nose]

Currently testing seedlings in one inch plugs (rock wool) starting under a dome. then moving under a 400 M H

Its a about week 3 ... and I have exposed tangling roots to the air and have a small fan blowing air and they have dried out with in the day. Question is ... do I need to leave the roots exposed for 3 days or if they dry out within the day can you put them in the dwc system the next day ?

Thanks for knowledge Vlad.

[Vlad Jovanovic]

The exact amount of 'dry time' probably depends on relative humidity of the surrounding air and how moist (hopefully not totally wet the rock wool cubes are blablabla...but  can't imagine it would take "3 days" for the root cap to desiccate....especially with a fan blowing and all. 

Week three is a little later than the way I do it...Not "wrong" or anything, just different. I like to hit up that very first tap root and maybe some of the primary laterals.

Also, I seed, sprout, and grow in only hydroton...so three days for me, without watering could be pretty catastrophic for the seedlings. Rock wool retains much more moisture.

Try it one way, and try it the other...take notes and observe...(again though, I doubt that you need to go 3 days...but who knows, I bet its pretty darn humid under that dome and all)...

[Jon Nose]

Actually take the dome off in week 2 or so once the 3rd leaf is formed. Theory is more or less to get a head start so that they only need to be in the troughs for 4 weeks to finish. This would allow me to harvest 6 trays a week on a steady basis.

The tray that I put them in for the roots to dry is more or less open on the bottom so the roots are tangling in the air.

The experiment continues :)

Thanks Vlad.

[Paul Letby]

Thanks for the info Vlad!  I learned something new yet again!

 

[Vlad Jovanovic]

No problem guys. And thanks for taking an interest.  

AP is a pretty expensive way to grow food, so I think it's important to take whatever little gains in production that we can. I'm trying to use every 'trick in the book' (especially ones that don't cost much...or better yet, don't cost anything) to get more out of this big-ish system. Because man-oh-man, the fish sure do add a whole bunch of expenses...more pumping of water, more pumping of air, back up power supplies, dealing with solids, limiting the ways in which one is able to deal with plant pathogens, limiting the ways one is able to deal with plant pests etc...not to mention, quality fish feed is a heck of an expensive plant fertilizer...Don't get me wrong, I absolutely Iove AP and all, but keeping things fish-safe can certainly get pricey...And part of the point of my here big-ish system is to make some money to live and eat and pay the bills (otherwise it's just a really, really expensive hobby) from just the sales of produce (and perhaps some fish) alone...

The air pruning seems to cut down harvest time by about half a week or so (this may change a bit seasonally). Not exactly a massive gain to some, but I'll take it.... Especially when looked at over the course of a year...or three years..or five...

[Jon Nose]

Read also some where that air drying the roots help with the plant not bolting ... grew a 4 foot high romaine plant last year ...not that marketable...