GERMINATION AND EARLY SEEDLING GROWTH IN SOME NORTHERN WILD-RICE (ZIZANIA-PALUSTRIS) POPULATIONS DIFFERING IN SEED SIZE

A field survey of eight northern Zizania palustris populations indicated that there is substantial variation in seed size. Variability is partitioned approximately equally among populations and among individuals within populations. Germination dynamics and temperature sensitivity of germination differed among four populations tested, but the differences were not apparently related to mean population seed size. Mean population seed size did appear to influence the germinability of viable seeds, such that a greater proportion of larger seeds exhibited prolonged dormancy. In a test using three populations differing in mean seed size, those with large seeds produced larger seedlings than populations characterized by small seeds. It appears that in Z. palustris seed size influences whether or not a viable seed will germinate and the size of the resulting seedling, but not the rate at which germinable seeds are recruited to form a seedling population.