May 17, 2019
Calcium and strawberries, why so erratic?

Picture of strawberries on the plant

(Sponsored) Calcium can improve firmness and quality but is poorly absorbed by maturing soft fruit. Most growers know that calcium is important for soft fruit, as it can improve cell wall strength, which has a positive effect on shelf life, firmness and ability to withstand diseases. However, when you look at the scientific evidence it becomes clear that the calcium applied to crops like strawberries does not always end up in the fruit. Calcium is poorly absorbed by maturing strawberry fruit therefore a lot of the calcium farmers apply to their crops is wasted as ripening fruit are not able to absorb it.

So why is it the case that calcium absorption is so erratic? Calcium absorption in strawberry fruit is strongly linked to the transport of auxin, a plant hormone. In strawberries auxins in the achene (the seed) are transported into the developing fruit, allowing the fruit to absorb calcium. However ripening is triggered by cessation of auxin transport into the fruit, so as the fruit starts to turn red the ability to absorb calcium rapidly declines.

Red strawberries have very little auxin, and cannot absorb any calcium that is applied to them. So, when crops are sprayed with foliar calcium, the leaves and green fruit will absorb it, but maturing fruits will not. Usually it is exactly the fruit that can’t absorb the calcium that farmers are targeting, in order to improve firmness and post-harvest shelf life. This is why results from conventional calcium fertilizers are so erratic, sometimes the fruit can’t absorb calcium into fruit and the input is wasted.

When you understand what causes problems with firmness (inability to absorb calcium) then you can develop smarter ways of supplying it. I have been developing chemistry that helps calcium absorption for many years, the more we study the better we get at improving it. My research focuses on understanding the link between polar auxin transport, and calcium absorption. By stimulating the pumps that are normally triggered by polar auxin transport, calcium can be absorbed by fruit in the absence of auxins. We use this science to make better calcium fertilizers at OMEX®.

OMEX’s new product Cell Power® Calcium Gold and Cell Power® Calcium Platinum for improving fruit firmness uses Levity’s pioneering chemistry, to stimulate calcium absorption into ripening fruit, where conventional products cannot. It can help soft fruit producers get firmness, fruit set, shelf-life to higher standards using very low inputs.

To develop fertilizers that work better we must first understand what farmers need, then look at the crop and understand what is causing the problem, finally we can then apply science to produce technology that provides solutions for farmers. When growers use OMEX’s new products Cell Power® Calcium Gold and Cell Power® Calcium Platinum they will see good improvements over conventional products.

Pioneering Fertilizer

For more information, go to or call 559-661-6138.

— By Dr. David Marks

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345
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