Plant growth synthetic

Table 2. Authorized Synthetic Plant Growth Regulators ...

Fig. 3. Synthetic plant growth regulators authorized for use in the United States and elsewhere. See Table 2.

Fig. 5. Experimental synthetic plant growth regulators. See Table 3.

In view of the great agricultural importance today of the synthetic plant growth substances in controlling the growth of plants of economic importance, details of the history of this development of investigations on plant hormones are presented. 

Table 3. Experimental Synthetic Plant Growth Regulators 1...

Controlling Biological Behavior of Plants with Synthetic Plant Growth Regulating Chemicals... 

The work of many investigators soon showed it to be extremely widespread in plants, and it became clear that it was a fundamental plant hormone (e.g., reviews 530, 655a). Excessive production of indoleacetic acid by parasites is responsible for certain types of plant tumor (e.g., 948). The synthetic plant growth regulators, which are in general substituted phenoxyacetic acids, probably function as indoleacetic acid analogues. 

Auxins. Term for naturally occurring or synthetic plant growth substances which resemble the natural plant hormone auxin ( 3-indolylacetic acid) in their activities. In low doses A. have growth stimulating activities and at higher doses herbicidal effects. 

Four main classes of natural and synthetic plant growth substances are distinguished 1) The 3-indolylacetic acid derivatives (lAA) and other C-3 substituted indoles, previously known as auxins, induce a pronounced longitudinal growth, stimulate the formation of roots and flowers, the activity of the cambium, and influence fruit ripening and numerous other developmental processes in the plant. In the literature many compounds with different constitutions are also designated as auxins if they have activities similar to those of lAA. These include, e. g., 2-naphthyloxyacetic acid, benzoic acid, phenoxycarboxylic acid derivatives. 

Natural Products as Inducers of Insect Resistance. Plant growth regulators have been shown to increase the biosynthesis of certain secondary plant constituents that in turn decrease plant attack by insects. -Naphthaleneacetic acid, for example, elicits increased terpene biosynthesis in citrus, thus decreasing attack by fruit flies. The approach of using both natural and synthetic plant growth regulators may continue to find applications in insect control. 

A complementary approach is the use of chemical inhibitors of GA-biosynthesis. Surprisingly this method using synthetic plant growth retardants has only recently been used (20, 21, 23) to study GA-biosynthesis in the absence of the normal fungal metabolites. 

Given the wide variety of natural and synthetic materials that are beneficial to the growth of plants, a virtually unlimited number, of products could truthfully be labeled fertilizer and marketed as such. The main drawback to uncontrolled marketing of fertilizer materials is the problem of the relative effectiveness of the product, and this depends on its composition. Unless the farmer can be sure that each lot of fertilizer he buys will have the same effectiveness as the preceding lot, he cannot be sure that he is fertilizing his crops in a rational man-ner. regardless of his stock of pei nal experience or advice from experts. 

Chloroethanephosphonic acid (ETHREL, ethephon), a synthetic plant growth regulator (Cook and Randall, 1968), readily releases ethylene in neutral solution according to the following reaction ... 

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