Nutrient Dense Management

Question of the day.

I pulled this from the Bionutrient Food Association :

"What proof shows that higher brix means higher quality?

Centuries of wine making and work with other fruits and vegetables always show direct relations between high Brix and high quality, expressed most simply and directly as superior taste. The process is somewhat altered for the gardener or farmer in that they test the leaf of the growing plant much earlier and are therefore afforded the opportunity to correct soil deficiencies before the crop matures. The gardener or farmer also benefits in that they soon learn that any crop with 12 or better leaf Brix will not be bothered by insect pests."

It is that last sentence that I noticed. I would love to hear what everyone thinks about this one.

Walden Heights Nursery & Orchard
Zone 3 in Vermont

Great question. In trying to look at this issue, I've had trouble getting reliable readings of apple leaf brix. The problem is that in crushing the leaves, not only the sap but the cell contents are released, giving very high brix readings which do not reflect sap values. Can anyone give me good advice on how to sample leaf brix?

Hemlock Grove Farm
Zone 5 in New York

I came across a reference to a correlation between insect susceptibility and various chemical levels in cultivars. The following study did show a positive relationship between sugar levels as well as nitrogen levels, (foliar constituents) with insect damage and negatively correlated with tannins. That is the beetles enjoyed the higher brix.

This indeed may be an isolated or erred observation, but since a higher sugar level is shown to have attracted this pest species, in runs in contrast to the idea of higher brix showing better health and deterring pests. This of course does not mean that aiding the plant in attaining maximum health in some way detracts from pest resistances, merely that brix may not be (at least in this case) a good measure of resistance.



"Volatile compounds from crabapple (Malus spp.) cultivars differing in susceptibility to the Japanese beetle" in the Journal of Chemical Ecology back in 1996.

It may be interesting to find out how these researchers attained sap readings.

Walden Heights Nursery & Orchard
Zone 3 in Vermont



Edited 1 time(s). Last edit at 02/06/2015 08:19PM by Todd Parlo.

Todd Parlo Wrote:
-------------------------------------------------------
> It may be interesting to find out how these researchers attained sap readings.

I was curious enough to track down one of the principles and pose the question.

Mr Potter wrote back:

"For our study (reprint attached), we did not extract sap. Rather, volatile compounds emitted by leaves were trapped and analyzed to compare the odors emitted by foliage of resistant versus susceptible varieties. The conclusion was that there is relatively little difference in volatile bouquets emitted by intact leaves of resistant versus susceptible cultivars. Later work showed that those cultivars do differ in palatability (acceptance or rejection) once the beetles land and taste the foliage – probably related to balance of feeding deterrents and stimulants (e.g., sugars). Once the leaves are damaged by Japanese beetles, they emit complex volatile blends that attract more beetles (like “sharks to a blood trail”)."

He also was kind enough to attach a pdf of the paper and I found the following passage:

"Recently, Spicer et al. (1995) reported marked differences in susceptibility of 42 crabapple cultivars (Malus spp.) to the Japanese beetle. Defoliation ranged from nearly 100% to less than 10% for cultivars grown at the same site. Sub-sequently, a number of physical and chemical variables of crabapple leaves were examined in an attempt to determine the factors involved in Japanese beetle discrimination between different cultivars (Potter and Spicer, unpublished results). Leaves of preferred cultivars generally contained higher levels of nitro-gen and sugars and lower amounts of tannins…"

Since that seemed to be the paper that did have a sugar variable, and he was involved with it as well, I have written back asking if the methodology used then could be expounded upon. More if and when I get a reply.

If you are interested in the full text of the first paper, or are interested in the follow up which details the "sharks to a blood trail", pm me and I will email you a copy of either as Mr Potter forwarded a pdf of both.

Interesting. I'll start taking more Brix readings and begin to document my observations. In response to Brian's question on how to sample leaves for Brix: modified vice grips. Available online. I'd like to get myself a pair.

Wildcat Valley Farm
Zone 8b
Olympic Peninsula Rainshadow
Port Angeles, Washington

There are two concepts floating around as regards the nutrient dense movement. In addition to the idea of plant management , there is the produce quality issue. Perhaps all us googlers could relay some sound studies linking nutritional quality directly related to a reading from a refractometer. Recently some retail locations have been listing brix levels for produce (this idea was put forth by Kittredge I believe). Although I do support the idea of improving the quality of the plant in the ground, and the fruit on the shelf, we had better get this right in terms of accuracy. My basic assumption is that soluble solid readings will tell little about vitamin and mineral levels in foods, and that better testing apparatus will be needed.

Walden Heights Nursery & Orchard
Zone 3 in Vermont

Good point.

I had a conversation with a friend last year about this. I hoped if pricing could account for Brix readings that it would be a good way to pitch truly quality produce to consumers that care about nutrient density.

My friend pointed out that it's easy to skew results when it comes to Brix. One easy way is once (say spinach) dehydrates a bit it will naturally show a higher soluble solids ratio..

It would have to combine other data to show a more accurate profile.. We recently took a course on Chinese Medicinal Herb Farming. Peggy Schafer, the North American guru on this, talked a lot about herb quality. In TCM, they use organoleptic evaluation (thought to be objective when administered by a highly trained practitioner) as well as chromatography.

Admittedly, I don't know much about that technology but perhaps that- coupled with Brix and average crop vitamin and mineral analysis -could show a more accurate representation of overall Apple Chi?

Wildcat Valley Farm
Zone 8b
Olympic Peninsula Rainshadow
Port Angeles, Washington