Plant growth promoting substances

Epibrassinolide has been shown to be highly desirable for application to increase crop yields. Farmers in China acknowledge the practical use of epibrassinolide, especially since it is naturally derived and is an effective plant growth-promoting substance. Until now, the practical use of epibrassinolide on wheat and com has been expand to an area of more than 2,664 ha (40,000 mu) per year. 

As plant growth-promoting substances, BRs have a broad spectrum of stimulatory and protective activities, all of which should have positive effects on the quantity and quality of crop yields. 

MOCKERIDGE F.A. 1924. Auximones I. The formation of plant growth promoting substances by micro-organisms. Annals of Botany, 38, 723-734. 

Clapp, C. E., Chen, Y., Hayes, M. H. B., and Cheng, H. H. (2001). Plant growth promoting activity of humic substances. In Understanding and Managing Organic Matter in Soils, Sediments, and Waters, Swift, R. S., and Sparks, K. M., eds., International Humic Science Society, St. Paul, MN, pp. 243-255. 

The first plant bioassay [Avena sativa L (oat) coleoptile test] was employed by F.W. Went in the 1920 s to demonstrate the existence of and to quantitatively assess the first growth-modifying substance [indole-3-acetic acid (IAA)] isolated from plants.122 Plant bioassays have been extremely useful and intimately linked to the discovery and characterization of the major classes of plant hormones. In fact, many of the bioassays used now were developed for PGRs. Bioassays have been used to screen, evaluate phytotoxicity or plant growth promotion, study mode... 

In 1963, Fletcher and Renney (.2) detected a plant growth inhibitor in knapweed and they suggested an allelopathic role for the substance(s) that could promote the spread of knapweed. Although these results are widely quoted, the inhibitor has never been identified nor has its existence been confirmed. Twenty years later, knapweed allelopathy was reexamined in our laboratory. A series of diffuse knapweed isolates were found to be inhibitory to ryegrass germination in petri dish assays... 

The discovery of ethylene as a plant growth substance followed from the observation in Germany that leakage of gas used in street lighting was associated with the defoliation of trees. Subsequent research demonstrated the active component as ethylene, which was then implicated in the endogenous acceleration of ripening, the promotion of flowering and sex determination in addition to abscission of plant parts. 

In a search for safer biodegradable plant growth substances that may have potential uses in agriculture, particularly for crop production, our laboratory has developed some new bioassay systems to screen various plants for growth-regulating activity. Our screening efforts resulted in the discovery of both growth promoters and inhibitors. 

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