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Re: Experiments with plants..how to? -Reply

Rex Harrill wrote:
> 
> Michael E. Ross wrote:
> 
> > Janet Wintermute wrote and I snipped:
> >
> 
> > That might be harder than it sounds (the vigor part, anyway).
> 
> Maybe...maybe not.
> 
> > > 7.  Take Brix readings on *all* fruit and see if it differs significantly
> > > across the two treatment regimes and the controls
> >
> > Is it useful to check the leaves prior to fruit set and ripeness?
> 
> Is it ever useful!  You can't do anything about your fertility inputs if you wait
> until harvest time to check the Brix.  For instance, if you want to finally taste
> what lettuce is supposed to taste like (12 Brix) you had best get out there and treat
> those baby 4 Brix lettuce plants a little better as they are growing.  Similarly,
> anyone growing sour 8 Brix blueberries that expects to magically convert them into
> sweet (yes---SWEET) 14 Brix blueberries on harvest day is in for a rude awakening.
> 
> > is there a standard that you can use
> > to check the accuracy of the refractometer at the extremes and median of its
> > range of measurement?).  The standard should be accurate itself to an order of
> > magnitude or better than the instrument being measured (If you are measuring brix
> > with no decimal points, the standard liquids should be accurate to the tenth of a
> > brix point, also, is there a temperature correction that needs accounting for?
> > With both the standard and the field measurements?).  Perhaps this is all covered
> > in the literature that comes with the brixometer?
> 
> I've never seen a brixometer, but the chemical industry seems comfortable that
> refractometers are simple, reliable, and inherently accurate.  Distilled water gives
> the zero point and high-point calibration liquids are available.  A temperature
> reading must be taken to assure exact accuracy with any non-ATC (Automatic
> Temperature Compensated) model.
> 
> Actually, this is much ado about nothing in regards to the consumer at
> point-of-sale.  For instance 15 Brix orange juice is so much better tasting than the
> typical 10 Brix store-bought junk that few people are going to worry about whether
> the exact numbers were, say, 14.8 Brix and 10.2 Brix.  Similarly, you'll quit
> frequenting next-door Farmer Jim and get in the car when you realize that his 'lopes
> are 3 Brix lower than Farmer Bob's on the other side of town.
> 
> However, if you are a grower, you will soon be quite interested as to whether foliar
> "A," for instance, pushed the Brix of your tomato LEAVES, say, a half Brix higher
> than foliar "B."  You'll know that applying "A" is going to pay off at harvest time.
> 
> > I know with brix we are not so picky, but it would be good to know what to expect
> > ahead of time.
> 
> If you have kids, they will help here.  They'll bluntly refuse to eat junk once they
> know some good stuff is around.
> 
> > What lack of accuracy and precision can we accept (at least so
> > anal retentive engineers won't chalenge the results ;-) )?  Perhaps a couple of
> > people could collect and prepare samples from the same plant on the same day and
> > see if there a a lot of difference?  Does it matter where on the plant the sample
> > is taken?  If the sample is too thick, can it be diluted and accuracy and
> > precision maintaned?  If the samples sit around open to the air do they change a
> > lot?  Does sunlight and temperature make a difference?  You might find out that a
> > simple error throws off the results a couple of points, then later we all think
> > fungi are not doing anything, when really the refractometer is only good to plus
> > or minus 2 brix points on a good day.  What does a proper test look like?  How
> > much material is taken?  How is it prepared?  Are there materials that work
> > poorly  (gooey or sticky, for example)?  I know Rex messes around blending up
> > leaves and such.  I never questioned him about it, but it did sound fishy to me
> > (I am not trying to blind side you RH).  Maybe it all works just fine?  Maybe you
> > need to watch out for something?
> >
> > This sounds like a lot of trouble and maybe it is unwarranted.  However, we might
> > all end up doing fruitlees (or maybe less-fruit) work because we guessed wrong
> > and trusted an imprecise and/or inaccurate tool.
> 
> Mike, I think I hear what you are saying.  See if these two pasted in stories make
> you more comfortable.  They are intended to show that anyone can train themself to
> pick up a fruit and know if it is really good or not.  Yes, GOOD is the ultimate
> cross-check on a refractometer.
> 
> ---------------------
> Several years ago, Jeff, a farmer friend in Florida, who was growing 14
> Brix strawberries called and asked how much per pound u-pick berries were
> going for up here.  He then explained that his customers were rebelling
> because a flat of his berries weighed 14 pounds ($11) while a same-size
> flat of Plant City waterberries weighed 7-8 pounds ($6).  After a few
> minutes back-and-forth it dawned on us both that, in the case of
> strawberries, Brix & weight were closely related.  He then gently
> suggested to the complainers that they perhaps should pay less and go get
> Plant City berries.  However, none did once they actually tasted his
> berries.
> 
> Story two involves a large open air fruit market in McAllen, Texas.  I
> was staying nearby and visited the market almost every day.  This was a
> particularly good market because the Mexican owner liked to cut open each
> type fruit and set out freebie samples.  One day I was in the back
> unobtrusively squeezing some juice from a sample to test when I felt a
> tap on my shoulder.  It was the owner!
> "What are you doing?"
> Well, I'm just trying to decide which of these mangos to buy.
> "What's that thing in your hand do?"  (he was looking at the
> refractometer)
> It measures the sweetness.  (not 100% true, but the statement can get you
> out of trouble)
> "Can I look at it?"
> Sure.  (he examined it closely)
> "Can I try something?"
> Sure. (After all, I had been caught skulking in his market)
> He then went to a table with 100's of pineapples and started sorting
> through them.  In a few moments he grabbed a big knife (Yipes! I jumped
> back) and whacked open a chosen pineapple.
> "Test this one."
> Wow, this tests excellent!  How did you do that?
> "Easy...it's the weight.  Here, feel the heft."
> I do.  Pick me out any more really good ones you have.
> "Sure.  How much did your gizmo cost?"
> $150
> "I'll give you $300"
> I can't sell it, but I'll bring an address tomorrow where you can buy
> one.
> "You know, it took me a lot of years, but I can now tell good fruit just
> by picking up the boxes when the trucks deliver."
> We parted as friends.
> 
> My best,
> Rex Harrill
> 
> BTW, I routinely record air temp, sky conditions, time of day, and the part of the
> plant being tested (if other than the part normally eaten).  And---I don't want to
> freak you out, but plants can sense if storms are coming and they'll divert some of
> their Brix-ness to the root temporarily.
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