Seed and Pod Wall Development inPisum sativum, L. in Relation to Extracted and Applied Hormones

Abstract

Developing fruits of Pisurn sativum, L., cv. 'Alaska', contain relatively large amounts of hor mones, mainly concentrated in the embryos and liquid endosperm. A close relationship can be demonstrated between changes in extractable amounts of gibberellins (mainly GA20), auxins (methyl 4-chloroindol-3yl acetate and probably 4-chloroindol-3yl acetic acid), and abscisic acid, and changes in growth rates of both the pod wall and seeds. Growth of the pod wall appears to depend largely on hormones supplied by the seeds. Marked changes in the germination capacity of the maturing seeds are closely associated with changes in extractable amounts of methyl-4-chloroindol-3yl acetate and abscisic acid. It is believed that high concentrations of these substances in the embryo, rather than any restriction imposed by the testa, may prevent precocious germination of the seeds.