Not lengthy after, I took a Plant Diet class as a part of my ‘nursery administration’ coursework at Merritt. A number of college students have been satisfied that foliar feeding labored higher for plant diet than another technique. My teacher was doubtful. She defined that leaves should not designed to absorb vitamins. There are almost microscopic holes on the bottoms of leaves, referred to as ‘stomata,’ which advanced to supply gasoline alternate – these holes permit for oxygen and carbon dioxide to maneuver between the plant and air as a part of the method of photosynthesis. They’ll expel water, however truly repel water that’s attempting to return in, utilizing a waxy coating for that goal.

More moderen analysis has revealed the existence of micro-pores on the floor of leaves, and they’re lined with unfavourable costs which magnetize positively charged cations (issues like calcium, magnesium, and potassium). This analysis has proven that vitamins can enter these pores as ions in water, however sprayed leaves dry in a short time and restrict a lot absorption, and solely about 15% of the vitamins utilized this manner are absorbed.

And as my professor then informed us, even when leaves do soak up vitamins on this manner, the plant is basically not designed to maneuver vitamins aside from sugars from the leaves to the roots, or to another a part of the plant. The entire system is designed to attract vitamins from the soil resolution (a pool of obtainable water on the rhizosphere that incorporates vitamins) up by the roots and into the xylem, which is a form of fluid river that strikes water-soluble vitamins from the roots to the remainder of the plant. There’s a downward river, too – the phloem – but it surely’s carrying sugars made within the photosynthetic course of down from the leaves to the basis zone. That’s what it’s designed to do, not carry vitamins from the stomata all the way down to the roots. So even when vitamins are coming into the leaves, they’re caught within the leaves. They’re motionless as a result of that stronger optimistic cost.

Let’s take calcium for example. A gardener just lately informed my class that she sprayed her tomatoes utilizing a foliar feed of liquid calcium to stop blossom finish rot. However calcium is not going to transfer from the leaves to the fruit. It may possibly solely transfer from the roots to the fruit. Tomatoes additionally don’t soak up calcium by the pores and skin. So that is arguably not serving to the plant keep away from blossom finish rot. (And in the event you’re a long-time reader of this weblog, you already know that blossom finish rot is not likely a calcium challenge.)