Influence of incubation temperature on the germination of 23 Iberian or North African-Iberian plant endemisms

摘要

We investigated the influence of temperature of incubation on germination of 16 Iberian and 7 North African-Iberian plant endemisms, 9 of them endangered. Germination tests were carried out under constant temperatures of 5, 10, 15, 20, and 25 deg C,respectively. A fluctuating temperature treatment of 20-10 deg C was also tested. Photoperiod was 12 h in all treatments, and germination-record period lasted 30 days. Brassica repanda subsp. gypsicola, Erysimum mediohispanicum, Iberis saxatilis subsp.cinerea, Sisymbrium arundanum, Armeria villosa subsp. alcaracensis. Antirrhinum subbaeticum and Senecio auricula reached high final percentages of germination (65-100 percent) in all tested conditions between 10 and 20 deg C. Diplotaxis ilorcitana and Sideritis serrata also reached their highest germination percentage (45 and 71.5, respectively) within the same temperature range. In Sisymbrium austriacum subsp, hispanicum, Centaurea citricolor, Linaria hirta, Moricandia moricandioides, and Diplotaxis harra subsp, lagascana, the optimal germination was recorded at low (10 deg C) and/or very low (5 deg C) temperatures. Brassica barrelieri, Antirrhinum barrelieri subsp, litigiosum and Nepeta tuberosa subsp. reticztlata showed their optimum germination level at low (10 deg C) and intermediate (15 deg C) temperatures. Andryala agardhii and Reseda suffiruticosa achieved high germination levels in all tests except at very low (5 deg C) temperatures. Ziziphora aragonensis and Iberis pectinata also showed veryhigh germination percentages in all tests except at very high temperature (25 deg C). In Centaurea debeauxii subsp, nevadensis and Teucrium oxylepis subsp, marianum, additional treatments of gibberellic acid or wet cool stratification were required to overcome seed dormancy.