May 08 2009
Harvesting times and High Brix
A reader in New Zealand writes:
Hi,
I’m a newbie to understanding Brix and the growing of high quality produce. I have not done a lot of searching back through your files to date but will.
I have a question unrelated to my own situation at the moment. In the New Zealand Kiwifruit industry they pick commercially, the fruit is harvested mature-ripe when its soluble sugars reach 6.5 brix on a refractometer.
If I am talking to a grower and tell him he can grow higher Brix levels in his, he would likely say he would then pick earlier, as the industry requires this. The thinking process, I presume, is that they would not store if picked too late. I do know that High Brix produce does store longer but not sure how to explain this point of view.
I have had this comment from apple growers as well.
Your thoughts?
Thanks
Grant
——–
Grant,
You are dealing with a couple of different meanings concerning brix here. Your growers are not recognizing brix as something equated to quality, but are using brix as a measurement to determine when it is appropriate to harvest a fruit. Kiwifruit, Apples, and Grapes are often harvested when they reach certain brix levels. Those growers use a refractometer for those purposes.
However, they do not recognize that Brix “equals” quality. The Kiwi fruit growers don’t use brix as a means of determining quality, but use brix as a means of determining when to harvest their fruit.
One of the rules of Carey A. Reams concerning agriculture is this rule:
“The higher the phosphate content of a soil, the higher the sugar content of the crop. The higher the sugar content, the higher the mineral content. The higher the mineral content, the greater the specific gravity of a given bushel, box, bale, etc. The greater the specific gravity of the product, the healthier the animal.”
Several other rules of Dr Reams are:
“Phosphate controls the sugar content of a product.”
“The greater the density of soil nutrients, the greater the yields.”
“The less time it takes to grow something, the better the quality.”
“The higher the sugar and mineral content of plants and trees, the lower the freezing point.”
“Top Quality produce will not rot, it will dehydrate.”
“Only that plant food which is soluble in water is available to the plant.”
There are several other rules. I’ve just listed some that are easier to relate to for most people. These also have a bearing on producing that end result we are measuring when we use a refractometer to measure the brix of any given plant product. These rules all work together to produce that excellent brix level we are all seeking. The picture I am trying to give you here is that excellent brix level is an end result. Phosphate, calcium, and several other compounds in the soils must be available so they can be taken up by plants in order to achieve high sugar levels, greater yields, better quality, lower freezing points, faster growing plants, and long term storage at room temperatures. A higher density of available nutrients in the soils leads to a higher density of nutrients in the plants and excellent brix levels and all those other nice things that define high plant quality.
Only the cultural practices that exemplify these rules of Dr Reams will produce excellent brix levels in plants. The reading on the refractometer is simply showing how well you have put your cultural practices together with the goal of having high plant quality as the result. The refractometer reading indicates how well you have accomplished that goal of high plant quality.
Many growers of Kiwi, Apples, Grapes, etc., are simply using a refractometer to indicate when they should harvest their crops. They are not equating refractometer readings to higher plant quality.
I know a grower that grows and harvests 19 brix apples. His apples don’t spoil in storage after harvest. They are excellent quality. They are harvested ripe and they stay that way a long time after the end consumer buys them. They have no insect or disease problems. They are always associated with a high yield. The plants are not bothered by frosts. His high quality Apples are a result of his cultural practices used to produce that quality. The refractometer is used to verify the quality of his apples.
Perhaps those rules of Dr Reams will help you put together a “picture” for your customers so they will recognize how the quality of their crop can be tied to that refractometer reading.
Best Regards,
Thomas Giannou
