Field and laboratory germination responses of achenes of Polygonum lapathifolium, P. pensylvanicum, and P. persicaria

Abstract

The annual smartweeds Polygonum lapathifolium L., P. pensylvanicum L., and P. persicaria L. are weeds of cereal crops, waste places, and wet ground in Canada. Their ‘weediness’ is attributed, in part, to the production of large numbers of achenes which are capable of lying dormant in the soil for several years or until suitable conditions arise for germination.Dormancy–germination characteristics of achenes from Ontario plants were examined in the laboratory and in the field. Three types of dormancy have been identified, each of which prevents germination under a different set of unfavourable conditions. An innate dormancy prevents germination in fresh achenes immediately prior to winter. An enforced dormancy prevents germination during the winter and in achenes which are deep in the soil. An induced dormancy is caused by hot or dry periods (at least in P. persicaria). Germination occurs as a series of flushes whenever achenes are brought to the soil surface and (or) whenever rainy spells occur.

The Role of Temperature on the Dormancy Cycle of Seeds of Rumex obtusifolius L.

“…It is known that drying can change the dormancy level: in some species dormancy is induced (Stanforth & Cavers, 1979), while in other species dormancy is removed by drying (Karssen, 1980/81). It is known that drying can change the dormancy level: in some species dormancy is induced (Stanforth & Cavers, 1979), while in other species dormancy is removed by drying (Karssen, 1980/81).…”

The influence of chilling requirement on the southern distribution limit of exotic Russian olive (Elaeagnus angustifolia) in western North America

“…The North treatments received less warm incubation time to overcome dormancy because these treatments were cooler. Additionally, studies have found that cold stratification extending beyond the ideal length can induce secondary dormancy in nondormant seeds (Kebreab and Murdoch 1999, Staniforth and Cavers 1979. My North treatments received 1138-1507 S tt units, substantially more than the ideal germination range found by ~800-900 S tt units).…”

Interactions between substrate temperature and humidity in signalling cyclical dormancy in seeds of two perennial tropical species

“…Seeds submitted to humid/dry treatments demonstrated a gradual alleviation of dormancy after suspending irrigation (dry substrate) but subsequent increases in dormancy levels once the soil became humid again. A number of workers have shown that seed desiccation followed by rehydration can induce Signalling cyclical dormancy in seeds of tropical species secondary dormancy (Staniforth and Cavers, 1979;Downs and Cavers, 2000), and that periodic changes in soil humidity can affect the dormancy levels of buried seeds (Batlla and Benech-Arnold, 2010) -thus acting as an additional signalling factor for secondary dormancy (Stoller and Wax, 1993;Vleeshouwers, 1997).…”