The Role of Endogenous Growth Substances in the Fruiting of Upland Cotton

Abstract

SUMMARYTwo acidic growth substances, one promoting, the other inhibiting, straight growth of wheat segments were extracted with diethyl ether from cotton fruit of different ages. The changes in concentration of these substances with time were not related to fruit shedding. The addition of the substances to young fruit did not alter either rate, or level, of shedding and it was concluded that these substances are not controlling abscission of fruit, although they may be connected with fruit development.

Identification of Plant Hormones from Cotton Ovules

“…Various bioassays and chemical methods have been used to tentatively identify IAA in cotton extracts (1,3,9). Our results ( Fig.…”

“…Many research workers have attempted to identify and measure hormone levels in cotton plants by using various bioassays (1,6,7,9,24,25,28). Because plant hormones are present in microgram quantities, the usefulness of bioassays has been limited because of interference of excessive quantities of impurities in extracts containing the hormones (2,14).…”

“…A single extract contained abscisic acid, indoleacetic acid, and gibberellins A1, A3, A4. A7, A9, and A13 in the first fraction; ethyl indole-3-acetate and indole-3-aldehyde in the second fraction; and the cytokinins 6-(3-methyl-4-hydroxybutylamino)purine (dihydrozeatin), 6-(4-hydroxy-3-methyl-2-trans-butenylamino) purine (zeatin), 6-(3-methyl-2-butenylamino)purine (2iP), 6-(3-methyl-2-butenylamino) .9 -A -D -ribofuranosylpurine (2iPA), and 6-(4-hydroxy-3-methyl-2-trans-butenylamino) -9-/3-D-ribofuranosylpurine (zeatin riboside) in the third fraction.Many research workers have attempted to identify and measure hormone levels in cotton plants by using various bioassays (1,6,7,9,24,25,28). Because plant hormones are present in microgram quantities, the usefulness of bioassays has been limited because of interference of excessive quantities of impurities in extracts containing the hormones (2,14).…”

Changes in Abscission‐accelerating Substances With Development of Cotton Fruit

“…4) is consistent with Cams' observations. Dale and Milford (1965) indicated that they could find no correlation of boll shed with either grovi1:h inhibitors or growth promoters that they extracted from cotton fruit over a period of 28 days from anthesis. Interestingly, however, the data depicted in their Fig.…”

“…The concentration of this substance reached a maximum between 5 and 8 days after anthesis, coincident with the period of maximum fruit abscission. Dale and Milford (1965) found an acidic growth promoter and two acidic growth inhibitors in developing cotton fruit, one from the fruit contents and one from the fruit wall as determined by the wheat coleoptile straight growth assays. They indicated that they found no correlation between shedding and maximum content of these substances.…”