Re: Sweetsue's Tiny Closet - Second Grow - Sweet Dark Devil & Bomb Berry Bomb - CFL -
While I haven't been able to find any evidence supporting the claim that saponins trigger SAR in plants, I did come across a very technical paper that suggested that there isn't evidence that salicylic acid is the trigger either, although it's more widely accepted that it may be. That study hinted at lipids. Too deep for me to follow.
I did, however, increase my knowledge of saponins and now understand that their chief values may be in insect control (see below) and as a wetting agent or surfactant.
Fun Fact
The saponins found in oats and spinach increase and accelerate the body's ability to absorb calcium and silicon, thus assisting in digestion.
So eat that oatmeal and spinach.
Using Wetting Agents (Nonionic Surfactants) on Soil
Source:
Department of Soil Science - North Carolina State University
Some soils, known as hydrophobic soils, are difficult to wet because they repel water. The infiltration of water into these soils can often be improved by applying a nonionic surfactant, more commonly called a wetting agent. Wetting agents are detergent-like substances that reduce the surface tension of water, allowing it to penetrate and wet the soil more easily.
To understand how wetting agents work, it is necessary to know something about the three forces that affect the movement of water into the soil. The first is gravity; it is a constant force that pulls the water downward. The second is cohesion, the attraction of water molecules for each other. It is the force that holds a droplet of water together. It creates the droplet's surface tension, which causes the droplet to behave as if a thin, flexible film covered its surface, tending to keep the water molecules apart from other substances. The third force is adhesion, the attraction of water molecules to other substances. This force causes water molecules to adhere to other objects, such as soil particles.
Tests have also been conducted to determine whether wetting agents have any toxic effects on plants. In tests on barley shoots grown hydroponically (that is, in a nutrient solution rather than in soil), a wetting agent concentration of 300 parts per million (ppm) in the solution caused a reduction of about 70 percent in the dry weight of the shoots. However, the same concentration in water applied to shoots growing in soil or in a sand-peat mixture increased shoot growth slightly. When wetting agents are applied to soil, the concentration would have to be much higher than 300 ppm before plant growth would be impaired.
Despite frequent irrigation, the soil in these spots resists wetting, resulting in patches of dead or severely wilted turf. The water applied wets the turf but does not adequately penetrate the soil surface to reach the root zone.
but the most effective solution was to use wetting agents in combination with coring–making small holes in the soil surface to allow water to pass through the hydrophobic surface layer. Also, keeping the soil moist seemed to be the best defense against the development of dry spots. Allowing the soil to dry out intensified the problem.
Several studies have shown that the infiltration rate of a hydrophobic soil, once it has been wetted, remains higher than it was before it was wetted, even if it is allowed to dry out again.
From
Novel Advances with Plant Saponins as Natural Insecticides to Control Pest Insects
Ellen De Geyter - Ellen Lambert - Danny Geelen - Guy Smagghe. (Bold is my own)
Saponins possess clear insecticidal activities: they exert a strong and rapid-working action against a broad range of pest insects that is different from neurotoxicity. The most observed effects are
increased mortality, lowered food intake, weight reduction, retardation in development and decreased reproduction. According to the main hypotheses in literature, saponins exert a repellent/deterrent activity, bear digestive problems, provoke insect moulting defects or cause cellular toxicity effects. As a consequence these interesting plant components open new strategies to protect crops in modern agriculture and horticulture with integrated pest management (IPM) programs against pest insects, either by spraying, or by selecting high-saponin varieties of commercial crops.
MECHANISMS UNDERLYING THE ACTION (OF SAPONINS) AGAINST INSECTS
Repellent or deterrent activity
Slowing down the passage of food through the gut
Blocking sterol uptake
Antagonistic or competitive activity on the ecdysteroid Membrane-permeabilising abilities
Now, let me look into Jasmonic acid.
Love your grows Sue, thanks for spreading the knowledge. You've inspired me to start a worm bin soon.
Sue has seen my rigging. I will feature my ghetto flower tent in my next grow update. Y'all will laugh, but it works..haha
Shes lovely, as ever.
Let's see if I can figure that out by this evening.
