Dormancy breaking, germination, and seedling emergence from seeds of Crataegus submollis
2007
Bujarska-Borkowska, B.,Polish Academy of Sciences, Kornik (Poland). Inst. of Dendrology
Effects of several stratification variants on seed dormancy breaking were compared in Crataegus submollis Sarg. (hairy cockspur-thorn or Quebec hawthorn). Ripe seeds were collected (in October), cleaned, and dried to a moisture content of 7-12 percent. Seed dormancy in this species was broken most effectively by warm-old stratification of nutlets, in a substrate or without any substrate, at 15-25/3 deg C or 20-30/3 deg C, i.e. with a cyclically alternating warm stage (16+8 hrs or 24+24 hrs/cycle) lasting 16-20 weeks, followed the cold stage lasting ca. 20 weeks, i.e. till the appearance of the first germinating seeds. After stratification, emergence rate is equally high (ca 50 percent) at cyclically alternating temperatures of 3-15 deg C and 3-20 deg C (16+8 hrs). Chemical scarification of nutlets in 96 percent sulphuric acid for 3 hrs, followed by warm-cold stratification at 20-30/3 deg C, with a short, 4-week warm stage, also ensures a high emergence rate (58 percent). Seed desiccation (in nutlets) slowly to a moisture content of 10-12 percent, after stratification in a substrate or without any substrate as well as after scarification, results in a reduced emergence rate, especially if seeds are dried to the lower moisture content. Seed storage (in nutlets after drying to a moisture content of 10 percent) for 10 years at -3 deg C, does not decrease the emergence rate (93 percent) after stratification at 20-30/3 deg C in a substrate, with a cyclically alternating warm stage (24+24 h) lasting 16 weeks
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