Seed germination in diverse apricot cultivars

The seeds of six apricot cultivars of various ripening dates were stratified, in Petri dishes at -1 and +1°C for 60, 90, and 120 days, to test germinability. When stratified for 120 days at +1°C, almost 70% rotted versus 0-6% at -1°C. While the higher temperature allowed 3-40% germination throughout stratification, and exposed the seeds to rotting, the lower temperature suppressed germination, and allowed flexibility of sowing date. After 30 days in a growth room the germination of the seeds exposed at -1°C for 120 days reached 100%, while those kept at +1°C had the highest rate after 60 days of stratification, ranging from 56-96% depending on the cultivar. The seedlings from seeds stratified at +1°C showed 90%, 50% and 15% rosetting after 60, 90, and 120 days respectively, while no rosetting was found with the -1°C treatment. Germination was correlated with lipid content (r=0.94) and seed dry weight (r=0.89), but not with protein (r=0.72), starch (r=0.49), or sugar (r=-0.47) content. Seed dry weight and lipid, sugar, and protein content, but not germination, were significantly related to time of ripening. Since germination rate was found to be correlated to seed dry weight and lipid content, attention must be paid to fruit ripening date, since early ripening genotypes accumulate less dry matter, and consequently give seeds with a low germination potential. Genotypes with low seed dry weight should be avoided as maternal parents in crosses, unless special care is taken to aid germination.