ABA/RDI/PRD???...(long/geeky)

Sorry for the incomprehensible thread title.
I've been reading JamieGoode's The Science of Wine, 2'nd edition. A terrific/informative read it is. In Chap 8, he talks a bit about irrigation and really scratches my wine geek curiosity.

1. ABA: This is a plant growth regulator hormone. This apparently is generated in the root system of the vine when the roots sense water stress. ABA travels up the vine and sends its signal to the vine tendrils to stop their growing, that hard times are on the way, and that for the vine's survival, it better stop its growing of tendrils/vegetation and focus now on fruit pproduction. Which is, of course, what you're wanting for wine production.
So, you cut off irrigation at some point to force the vine to quit growing and focus on the fruit. But if you stress the vine too much, the quality of the fruit will be compromised. So, it's a tricky path you have to walk to achieve the best in quality of fruit. Of course, if you don't have irrigation, you've lost a big tool in your bag of vnyd management tricks. This is why people like DaveGates are so important to have around.
Question: What kind of time scale are we talking from when the root senses water stress and the ABA hormone reaches the growing tendril?? Hours, days, weeks??? What kind of time constant to these very bright grapevines operate on??

2. RDI: This refers to "regulated deficit irrigation". This is controlling the irrigation application to force the vine to stop its vegative growth and start focusing on fruit production. Apparently it works best but shutting off the water just after berry set, and then restoring the water after verasion to keep the berry growth healthy and not force the vine to shut down and reduce berry quality. Use of RDI has apparently been very sucessful in Australia.
Question: How widespread is the use of RDI in Calif?? Any particularly great vnyds known to be using RDI?

3. PRD: This refers to "partial root drying". This requires a dual drip irrigation system where you can shut off the water on one side of the grapevine's root system, but, alternatively, supply water to the other half of the vine's root system. And then switch back & forth from one side to the other in 1-2 week intervals. So one half of the root system signals the plant to stop growth and focus on fruit production, but the other half of the root system has the resources to keep the vine alive & healthy. Apparently, use of PRD has a big benefit in reduction of water usage, by almost half...something that might be of interest in Calif I would think. This is an important issue in Australia I gather.
Question: Is there anybody practicing PRD in Calif?? I would think there is a good business opportunity here for vnyd management companies in Calif to convert conventional drip irrigated vnyds to PRD.

Of course, this is all irrelevant in France...where they've chosen to forbid irrigation and throw themselves at the mercy of ole Mother Nature. Which, of course, explains why their wines are so crappy.

Anyway....just a few ?? that Jamie's book has provoked. Doubt I'll get any answers, but thought I'd try.
Tom

I'm sure really smart people have spent a lot of time on this but with PRD I find it somewhat hard to believe that once the water enters the dirt half is irrigated and half is not. My experience playing with dirt and water is different.

I would say this is all irrelevant in France and that is why the wines are spectacular about 50% of the time. Truly great wine can only be made in marginal climates IMHO.

I'm sure really smart people have spent a lot of time on this but with PRD I find it somewhat hard to believe that once the water enters the dirt half is irrigated and half is not. My experience playing with dirt and water is different.

I would say this is all irrelevant in France and that is why the wines are spectacular about 50% of the time. Truly great wine can only be made in marginal climates IMHO.

Thanks for taking the time to read that stuff, Tom.

That's sorta what I wondered as well. I would think if you just irrigated one half the vine, that that'd be sufficient to moisten up the dirt
on the other side of the vine as well. But maybe in well-drained/poor soils??? Who knows.
Tom

Hi Tom,
The aba hormone would most likely be more useful in the early cycle of the vines growth cycle (bud development, flower development (prevent or limit flower abortion) early fruit set (prevent or limit fruit abortion). Once a viable and fruitful seed is produced more or less each cluster (or berry for that matter) is more or less on its own. So the release of the aba hormone much later in the vines growth cycle might benefit the vines “hardness” (preparing for winter dormancy). (I can’t see it doing much for a grape cluster waiting to be harvested). The plant’s incoming transport (to the cluster and berries) eventually at some point shuts down. (It produced viable seeds its job is done).

Salute

Of course, this is all irrelevant in France...where they've chosen to forbid irrigation and throw themselves at the mercy of ole Mother Nature. Which, of course, explains why their wines are so crappy.

LOL. You are sure missing out on some good stuff there Tom. You should get out more .

I asked an Aussie winemaking friend of mine to comment on these issues. Excuse his somewhat lowbrow language, but here we go:

ABA: "If you prune the vines to give a modest yield, then, irrespective of flowering conditions, they should balance out vegetative growth and fruit development naturally. Honestly, you don’t need this shit."

RDI: "The other name for RDI is “irrigation for dummies”. A vineyard owner/manager should know his vines well enough not to over water. This is lazy, big company viticulture. Naturally, RDI has been very popular in Australia. It was developed by, amongst others, my viti lecturer at Roseworthy, Peter Dry."

PRD: "See previous comments. Again, Peter Dry was involved with the development. Irrigation is a very useful tool in viticulture, but some people are always drawn to turn these techniques into dogma. Heaven forbid that we should just let nature take its course and live with the consequences, for better or for worse. Why not grow grapes in an environment with sufficient natural rainfall?"

FWIW!

Greetings from Sweden / Fredrik L

I asked an Aussie winemaking friend of mine to comment on these issues. Excuse his somewhat lowbrow language, but here we go:

ABA: "If you prune the vines to give a modest yield, then, irrespective of flowering conditions, they should balance out vegetative growth and fruit development naturally. Honestly, you don’t need this shit."

RDI: "The other name for RDI is “irrigation for dummies”. A vineyard owner/manager should know his vines well enough not to over water. This is lazy, big company viticulture. Naturally, RDI has been very popular in Australia. It was developed by, amongst others, my viti lecturer at Roseworthy, Peter Dry."

PRD: "See previous comments. Again, Peter Dry was involved with the development. Irrigation is a very useful tool in viticulture, but some people are always drawn to turn these techniques into dogma. Heaven forbid that we should just let nature take its course and live with the consequences, for better or for worse. Why not grow grapes in an environment with sufficient natural rainfall?"
FWIW!
Greetings from Sweden / Fredrik L

Thanks for soliciting those comments from your friend, Fredrik. He clearly has his opinions, be they right or wrong.
Tom

RDI: "The other name for RDI is “irrigation for dummies”. A vineyard owner/manager should know his vines well enough not to over water. This is lazy, big company viticulture. Naturally, RDI has been very popular in Australia. It was developed by, amongst others, my viti lecturer at Roseworthy, Peter Dry."

Peter Dry--what an appropriate name for an expert on irrigation.

-Paul W.

I realize we are talking about “domestic vines”, but still I wouldn’t necessarily consider the plant’s growth hormones useless. They are there for a reason to make sure the vine itself survives and it goes through its annual cycle. Tom asks some thought provocative questions. Unlike us, plants do not have glands or specialized tissue that produces hormones, given types of plant cells themselves produce given hormone precursors and given hormones. Only certain cells react to a given hormone. Plants in general have to respond to environmental changes on an hour by hour basis. (They simply can’t move to a new more “favorable” location). It wouldn’t surprise me if the hormones or precursors are always present but at times when not needed the concentration level is “low” (“diluted”), when needed the concentration level is “higher” (“more concentrated”).

Salute