A Comparison of Leek (Allium porrum) and Onion (Allium cepa) Seed Development

Leek and onion seed dry weight increased exponentially for thefirst 31 days after flowering (DAF) but thereafter the increasein dry weight was slower. Before maximum seed dry weight wasreached at 45 DAF in onion and 59 to 66 DAF in leek, seed moisturecontent, seed oxygen uptake and conductivity of the seed steepwater fell from initially high levels. Although some seeds germinated31 DAF in both species, full germination in both was not reacheduntil 66–80 DAF. Tolerance of the seed to artificial dryingimmediately after harvesting occurred 45 DAF in onion and 74DAF in leek. Free nuclear division continued in the endospermuntil 17–22 DAF in onion and until 31–35 DAF inleek but it was not until 45 DAF in onion and 66 DAF in leekthat the embryo and endosperm filled the cavity formed by thepericarp. After formation of cell walls in the endosperm thepattern of change in cell number in both species was similar.The shrunken appearance of the seed coat in leek, which occurredearly in seed development, was associated with the period offree nuclear division in the endosperm and, in addition, thepericarp was thinner than in onion. There was no evidence thatthe shrunken seed coat early in development was associated withself as opposed to open-pollination. Allium porrum, Allium cepa, seed development, endosperm, embryo, cell number, germination, respiration, seed leachates