Gas chromatography-mass spectrometric determinations of abscisic acid levels in the cap and the apex of maize roots

Abstract
Quantitative analyses of abscisic acid (ABA) in different parts of maize root tips (Zea mays L. cv. Kelvedon 33) were performed by mass fragmentography using the hexadeuterated analog of ABA as internal standard. It was found that the cap and the apex contained 36.1 μg and 66.5 μg ABA kg−1 fresh weight, respectively. The possibility that the growth regulator formed in the cap and inhibiting the elongation of the extending zone of the root is ABA is discussed.