Summer dormancy in Phalaris tuberosa

Abstract

Summer dormancy of field-grown plants of five strains of Phalaris tuberosa L. was investigated at various times during the summer by transferring them to trays with moist sand kept at room temperature (20–25°C). The rate of appearance of new shoots was used to measure differences in dormancy Levels. Differences between strains were significant in most experiments. They were largest in January, and decreased subsequently. The average level of dormancy was high in January, low in February, and increased again after mid February without reaching the original level. Development of new shoots was retarded by high temperatures. It is suggested that in the early stages dormancy is mainly a continuation of inhibition of bud growth by elongated tillers, whereas in the later part of summer, soil temperature and soil moisture are the main factors which control the development of new shoots.