Temperature requirement for germination of Solanum nigrum seeds

Sammanfattning: Solanum nigrum has become an increasingly difficult weed in field-grown vegetables in the southern part of Sweden during the last decade. To be able to predict the timing of seedling emergence in the field, which is important for the timing of weed control measures, a study was made with the aim to investigate the timing of seed germination in the weedy species Solanum nigrum L., as affected by the level of dormancy and temperature conditions. Germination requirements of non-stratified seeds and seeds stratified at 5 and 15 °C were investigated. Germination was tested at i) constant temperatures ranging from 6 to 38 °C, ii) alternating temperatures with 15 °C constant amplitude and increasing mean temperatures from 16 to 33.5 °C, and iii) alternating temperatures with constant mean temperature of 25 °C and increasing amplitude from 0 to 20 °C. It was concluded that seed germination of S. nigrum depends on the level of dormancy and, to a large extent, on the current temperature. Seeds with lower level of dormancy germinate at constant temperatures and alternating temperatures result in a high percentage of germination in seeds with different levels of dormancy.