Improving seed germination of native species for camel rangeland restoration: effects of cold stratification and temperature

Native plants of the Sahara are remarkably resistant to prolonged droughts and are important sources of forage, food, and medicine. Their regeneration from seeds after strong anthropogenic disturbances is a challenging step toward their conservation and to mitigate desertification. We studied the germination responses of 43 dominant native species of the Sahara desert that could be propagated from seeds for future ecological restoration projects, exploring the effects of cold stratification and temperatures on seed germination. Seeds were stratified at 4 degrees C for 3 days and then tested for germination at 5, 10, 15, 20, 25, 30, 35, and 40 degrees C. While cold stratification negatively affected four species, it improved the germination of 36 species. Five of these species required cold stratification to germinate. Temperatures during the germination trial significantly influenced seed germinability. Twenty-three species (54%) germinated to higher percentages at intermediate temperatures (20 to 30 degrees C) similar to the maximum temperatures of the rainiest months, when germination in the field is high. Thirteen species (30%) also germinated at a higher temperature (40 degrees C). Seven species (16%) germinated best at low temperatures (5 to 10 degrees C). Our results suggest that cold stratification is an efficient and easy treatment to apply prior to sowing seeds in the field for restoration.