Breaking seed dormancy of Tulipa scardica Bornm. and Tulipa kosovarica Kit Tan, Shuka & Krasniqi by pre-chilling, plant growth regulators and some chemical treatments

Tulipa scardica and T. kosovarica are rare, endemic and endangered plants in Kosovo. This research was carried out to study the dormancy breaking treatment in Tulipa scardica and T. kosovarica seeds by pre-chilling and various concentration of potassium nitrate (KNO3), gibberellic acid (GA3), kinetin, thiourea and sulfuric acid (H2SO4). The experiment was conducted with untreated seeds (without stratification) and with stratified seeds (8 weeks) and treated with different concentration of some chemicals and plant growth regulators. Results showed that the final germination percentage (FGP) of seeds without stratification at both Tulipa plant species was zero, while germination was enhanced by pre-chilling (stratification) especially after treatment of these seeds by above mentioned treatments. Both Tulipa species showed an increase in mean germination time (MGT), an indication of slower germination, as different chemicals or plant growth regulators increased. Depending on treatments, germination was ranging from 80 % to 90 %, the maximum germination was detected in seeds treated with KNO3, GA3, and their combination, while the minimum germination in seeds without treatments and treated with thiourea. The conservation of these plants in botanic gardens by cultivation or propagation for commercial use as ornamental plants could give an effective contribution to the conservation of these plants.Abbreviations: KNO3 – potassium  nitrate; GA3 - gibberellic acid; H2SO4 – sulfuric acid; FGP – final germination percentage; MGT – mean germination time