POSSIBLE INVOLVEMENT OF ABSCISIC-ACID, ETHYLENE AND PHENOLIC-ACIDS INPOTATO-TUBER DORMANCY

Changes in ethylene production, contents of abscisic (ABA) and phenoli c acids were determined in the course of dormancy, prolonged dormancy and sprouting in bud meristems of control tubers and tubers from 2-chl orethylphosphonic (CEPA)-treated plants. The ethylene production in co ntrol tubers and tubers from treated plants was highest during the dor mancy inception (14 times higher in tubers from CEPA-treated plants th an in control), then decreased and remained at a low level until the b eginning of sprouting. The content of ABA in buds sharply increased du ring dormancy inception, reached the maximum value approximately in th e middle of deep dormancy and then declined until the end of dormancy. The increase in ABA content in buds of CEPA-treated plants was much m ore pronounced than in the control. The period of increased ABA level coincided with CEPA-induced prolongation of dormancy. The content of f ree phenolic acids increased during the dormancy period, reached maxim um at the end of dormancy and then declined during sprouting. Maximum of free phenolic acids in buds of CEPA-treated plants coincided with p rolonged dormancy and its slow decline corresponded with the beginning of delayed sprouting. The increase in the contents of conjugated form s (esters and glycosides) of phenolic acids occurred during dormancy r elease and sprouting. The possible participation of phenolic acids in the endogenous regulation of dormancy and sprouting in potato tubers i s discussed.