Hormones and Pod Development in Oilseed Rape (Brassica napus).

The endogenous levels of several plant growth substances (indole acetic acid, IAA; abscisic acid, ABA; zeatin, Z; zeatin riboside, [9R]Z; isopentenyladenine, iP; and isopentenyladenosine, [9R]iP were measured during pod development of field grown oilseed Rape (Brassica napus L. var oleifera cv Bienvenu) with high performance liquid chromatography and immunoenzymic (enzyme-linked immunosorbent assay, ELISA) techniques. Results show that pod development is characterized by high levels of Z and [9R]Z in 3 day old fruits and of IAA on the fourth day. During pod maturation, initially a significant increase of IAA and cytokinins was observed, followed by a progressive rise of ABA levels and a concomitant decline of IAA and cytokinin (except iP) levels. The relationship between hormone levels and development, especially pod number, seed number per pod, and seed weight determination, will be discussed.