Interrelationships between the mode of reproduction and the habitat of two weedy Agropyron species, A. tsukushiense and A. humidorum, Gramineae.

Abstract

The interrelationship between the mode of reproduction and the habitat was compared in the common type and the early ecotype of Agropyron tsukushiense var. transiens and A. humidorum. Compared with the common type, the seeds of the early ecotype and A. humidorum maintained their germinating ability well even under submerged storage. Most culm segments of the common type and the early ecotype sprouted soon when stored in soil in July, while those of A. humidorum did so in September. These results agreed with the observation at the natural habitat, where the two species had grown sympatrically in fallow paddy fields in winter. The early ecotype was reproduced only by means of seeds since its stump died under submerged conditions because of the weak dormancy of the axillary buds. On the contrary, A. humidorum has a more positive adaptation to paddy fields on account of its reproduction by means of stumps or perennialized culms as well as by means of seeds.