الفهرس 
ABSTRACTOnly 14 pages are availabe for public view
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Abstract
Plant hormones are not nutrients, but chemicals that in small amounts promote and influence the growth, development and differentiation of cells and tissues.
The use of plant growth regulators in agricultural production began in the 1930s.
Gibberellins are a large group of related chemical compounds (over one hundred have been identified) with a wide range of effects. They were first identified by Japanese scientists. Gibberellins affect many mechanisms of plant growth including stem elongation by stimulating cell division, flowering, fruit development, breaking dormancy.
GA3 is produced by growing a naturally-occurring fungus in large vats and extracting the GA-3 from it. It is not produced synthetically by any chemical process, but is extracted and purified from a plant (fungus).
Although plant growth regulators are used to promote germination, flowering, proliferation, and fertilization in a wide variety of crops, little is known about the toxic effects of high doses of GA3 in mammals and its potential hazardous effects on human health were relatively unexplored. The Pesticide Action Network North America (PANNA) database suggests that GA3’s acute toxicity, carcinogenicity, ground water contaminating characteristic, and developmental or reproductive toxicity should be reevaluated.
The aim of this study was to evaluate and compare the sub chronic and chronic toxic effects of GA3 on the liver and testes of adult male albino rats and finally to study the after effects of GA3 by stopping administration for 6 weeks.
In this study, 210 adult male albino rats were used. They were divided into 6 groups. Group 1a served as negative control group, contained 30 rats. Each rat received only regular diet and tap water for 16 week, group Ib (positive control group contained 30 rats): each rat received 1ml of 1N NaOH added to 1000 ml of tap water orally 5 days /week for 16 weeks.
The reminder of rats was equally divided into five groups each of 30 rats. In group I, II, III and IV each rat was orally injected with 75 ppm of the reagent 5 days / week for 4, 8, 12 and 16 weeks respectively.
On the other hand, group VI rats were orally injected with 75 ppm of the reagent 5 days / week for 8 weeks then animals were left without any treatment for 6 weeks (follow up period).