Table of contents | |
Introduction | |
Types of Plant Growth | |
Factors Affecting Plant Growth | |
Discovery of Plant Growth Regulators | |
Characteristics of Plant Growth Regulators |
Plant growth regulators, also known as phytohormones or plant growth hormones, are chemical compounds that oversee various aspects of plant development and growth. These organic substances can be either artificially synthesized in laboratories or naturally produced within the plants themselves. They exert significant control over and influence the physiological processes related to plant growth, development, and movement.
Plant growth regulators are broadly categorized into two major groups based on their effects:
Plant growth promoters include substances like Auxins, Gibberellins, and Cytokinins, while plant growth inhibitors encompass Abscisic acid and Ethylene. It's worth noting that Ethylene can sometimes be classified as either a promoter or an inhibitor, depending on its specific effects.
There are four primary factors that play a pivotal role in determining plant growth:
The discovery of major plant growth regulators, although initially a result of serendipity, can be traced back to the work of Charles Darwin and his son, Francis Darwin. They observed the phenomenon of phototropism, where coleoptiles of canary grass exhibited growth towards a source of light. Through a series of experiments, they deduced the existence of a substance that could influence the growth of canary grass towards light. This substance, later identified as auxin, was isolated by F.W. Went.
Subsequently, various scientists made further discoveries and isolated different plant growth regulators. E. Kurosawa reported the presence of gibberellins or gibberellic acid in uninfected rice seedlings. Another growth-promoting substance, now known as cytokinins, was discovered by F. Skoog and Miller and initially referred to as kinetin.
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