Agriculture Reference
In-Depth Information
Keep in mind that when large amounts of charged nutrients are allowed into the cell, the
net effect of their movement will result in a flow of electrical current and a change in the
induced voltage as well. This is a very important point in that the changing of electrical
potential across the cell boundary can bring about major physiological effects. This will be
covered in detail, shortly.
Active Transport
Plants need to take in nutrients from the soil in order to grow, and since plants are a living
container of many forms of nutrients, the concentration of nutrients within their cellular
structure is naturally much higher than that of the soil. Since diffusion only works by
moving substances from an area of high concentration to a lower one, it isn't a suitable
method for shuttling nutrients from the soil into the cellular structure of the plant. To get
aroundthis, activetransport mechanismsareused.Thesemechanismsarealsousedinother
physiological operations of the plant ranging from the delivery of sucrose that's produced
by photosynthesis, to the recharging or refractory period of the cell after a whole-plant
signaling event called an action potential .
To facilitate the transfer of charged substances into and out of cells against an established
concentration or electrical gradient, a different type of protein structure called an ion pump
is used. Situated throughout the cell wall, this type of protein requires energy in the form
of ATP to move ions “upstream” against the established concentration gradient 15 .
Since ion pumps require energy in order to operate, as noted above, keep in mind that
the use of energy. This is an important fact that should be noted with respect to using
electro-horticulture methods for extended periods of time; that is, it may be best for
electrical stimulation systems to only be active during daylight hours, when a plant can
create more of the energy it needs. However, since energy is also created during the plant's
respiration cycle, which occurs at night, this may be less of an issue. More on this topic
will be covered later in Chapter 13's section on system design .
Electrical Signaling
As we now know, biological systems are inherently electrical in their cellular makeup.
Plants and other higher organisms use electrical and chemical communication signals
to control a wide variety of biological processes including hormone synthesis, gene
expression and various metabolic processes 16 . In the following two sections we will cover
the basics of electrical and chemical signaling. Knowing how cells communicate with
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