In summation, I'm led to believe that:
1. Seeds can be treated with electromagnetism in such a way as to affect their gender and growth rate upon germination.
2. Plants can use both atmospheric and directly applied electricity to supplement the light energy they use for their functions
3. Electricity can have a beneficial effect on aerobic soil microlife, and shows potential for the control of weeds, pests, and anaerobic bacteria
4. (this is the big one that I've been playing with for some time - I'm lookin at you trichrider) The polarity reversal between the surface of the earth and the earth's atmosphere that occurs during rainstorms is at least as critical a contribution of those storms to a plant's growth and health as the water itself.
Typically, the surface of the earth carries a negative charge and the bottom of the clouds has a positive charge (no surprise to anyone who has any inkling of ancient philosophies). During a rain event, this is reversed - the sky takes on a negative charge and the earth a positive one. When rain droplets hit the positively charged earth, the water releases negative ions. The storm ends when this electrical balance is restored.
Positive and negative ionic charges directly affect the alkalinity/acidity of water which, as we all know, affects its availability for plant life processes.
Another interesting side note (which I'm not yet ready to say I fully believe) is that the amount of free electricity available in the atmosphere (which is the energy we're talking about here) is greater at mid day than morning or night; this could theoretically have something to do with plants' preference for daytime (which was proven centuries ago to be independent of their response to light, just as the response of leaves of indoor plants to outdoor storms).