Cytokinin Content of Pea Seeds during their Growth and Development

Seed development in Pisum arvense L. cv. New Zealand Maple has been studied in relation to changes in level of total endogenous cytokinins. Growth of both the whole seed and the embryo is diauxic, having two phases of active growth separated by a lag period. The two maxima in the growth rates of the whole seed and the embryo occur about the 23rd and 31st days after anthesis. The lag period occurs between days 26 and 28. Cell division is thought to have ceased prior to day 19 and the changes in total cytokinin content in pea seeds after this time are believed to be largely independent of cell division. The three maxima in the cylokinin content per gm. fresh weight of seed and per seed were found to be coincident with the maximum volume of endosperm per seed and the two maxima in the growth rates of the whole seed and the embryo.