The study of dormancy, germination and emergence biological aspects of jagged-chickweed (Lepyrodiclis holosteoides) seeds

In the recent years, false jagged-chickweed (Lepyrodiclis holosteoides) has become one of the most problematic broadleaf weeds in wheat and canola fields of temperate and cold regions of Iran. Due to the the importance of the time of emergence of seedlings in the success of weed competition in crop ecosystems and consequently, the use of effective weed management methods, a series of studies were conducted in the fields of Karaj and in the Weed Research Department of Iranian Institute of Plant Protection (Tehran) during 2013-2016 to determine the biological aspects of dormancy and germination of this invasive weed seeds. Results showed that there is polymorphism in seed dormancy of false jagged-chickweed. Dormancy of false jagged-chickweed seeds can be classified in the physiological category (which is related to the presence of chemical inhibitors inside the seed and the hormonal balance between Abscisic acid and Gibberellic acid). Also, seeds of false jagged-chickweed are very photo sensitive in the germination process. The results showed that first date of the emergence of false jagged-chickweed occurred in the second half of November and seed vigor of this weed reduced significantly by increasing of seeds longevity. Lepyrodiclis seedlings emerged in form of multiple flashes during autumn and winter, however more than 85 percent of total emerged seedlings appeared after receiving 552 GDD over the period of December 12th to January 12th.