Comparative Effectiveness of Gibberellins A1, A2, A3 and A4, with Special Reference to That of A4

Abstract

Comparative effectiveness of gibberellins A1, A2, A3 and A4 (GA1, GA2, GA3and GA4) in promoting the elongation of rice seedlings, in accelerating the expansionof green radish leaf disks and of etiolated bean leaf disks, and in inducing the darkgermination of tobacco seeds, was investigated. These four gibberellins were allactive in every investigated phenomenon, but different in comparative activity. Inthe leaf expansion and the tobacco seed germination, unlike in the elongation of riceseedlings, GA4 was especially active and new orders of effectiveness such as GA4_??_GA3>GA1>GA2 or GA4_??_GA1>GA3>GA2 were observed. It appears that gibberellinsshow different effectiveness with different physiological phenomena