Establishing Roots

We now have mums in the fields establishing their roots for this fall! The nursery is excited to see them fill out and crack color in the coming months. Speaking of establishing roots; I am in the process of spreading and further establishing mine here at JNC. I will be changing roles away from being an Account Executive in order to grow more at JNC. I am excited to take on these new challenges as it will allow me more time to cultivate, develop, and learn.

I know what you are worried about…have no fear, you will still be able to catch my ‘fun facts’ online at the JNC website, just head over to the blog section. I plan on expanding these out to start including vlogs and other goodies.

While we are on the topic of roots it’s time for my fun fact! Tropical storm Colin helped me refresh my memory on root rot last week. I found myself dealing with rot in a ‘Brown Turkey’ Fig I had purchased and was pot growing. A lot of their roots are near the surface of the soil, but with the excessive rain my pot had become waterlogged. I didn’t notice something was off until I started to see yellowing of leaves with some dropping prematurely. I brought my fig indoors and repotted it, sure enough some of the roots had rotted. I thought to myself, why does this occur when I can propagate some plants in water? Surely if it was just excessive water they, too, would also have rot. After hitting my books and having a “why did I forget this” moment I was able to identify why the differences are there.

Just as you have epiphytes (plants with aerial roots) you can also have specialized water roots, which are completely different than soil roots. Plants that can establish water roots like Lotus, Pothos, or even most grasses (You know I love grasses!) have two distinct adaptations in their roots that soil roots do not have as much of.

The first is Aerenchyma. Yes, this is a crazy fun word, but it is equally awesome to see. All plants have this, however, water roots and water plants develop this in excess. Aerenchyma is a feature that almost looks like a sponge, however, it allows for increased gas diffusion and retention. The picture below shows a lotus root which stays submerged in mud and water. Notice how the interior of the root has large pockets for diffusion to occur across.

Bog plants can also create pockets of air that the plant can use when conditions become less favorable for the roots. The air trapped in these cell pockets are the same type of pockets on the leaf that hold air which allow water lily to float!

Plants that normally generate soil roots like Pothos are able to create Aerenchyma by the release of Ethylene. (The very same hormone that induces ripening as well as being a warning to other plants that they are in stress. NOT-SO-FUN FACT: this is why store bought tomatoes are never as good as garden grown. They are picked green and placed in ethylene in order to ripen, thus removing any retention in flavor like sugars and starches that would have normally been absorbed if left alone.) I digress… As the root dies, the gas is released which triggers the creation of new water roots.

The second adaptation in water roots is suberin, which is a waxy coat covering most of the root up to the tip. Suberin helps control the uptake of water through the root while also being a barrier to pathogens. In water roots, suberin extends down the root further and is thicker than its soil root counterpart. This helps to explain why plants grown hydroponically typically have less pathogenic disease than those grown in soil. Oxygen and nutrients pass freely in the soil, however, this also opens the door to microbiota.

There are a number of fungal pathogens in soil that can cause root rot. Once it sets in, it is best to treat the roots as soon as possible. Please keep in mind this ALSO is a signal flare from our soil to let us know something is off. In the past I have written about soil chemistry and ecology. If you have fungal diseases in plants, you will also have higher acidity, low oxygen and low bacterial counts in your soil. Bacteria are beneficial for higher rates of decomposition (greens) while fungus takes the long haul (browns). Unless you have plants that love these conditions, your first plants that succumb to root rot should be your cue to create positive change in your bed space!


Guest Blogger

Joshua Clawson,

Account Executive at Johnson Nursery

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