The dormancy characteristics and optimum conditions for seed germination of Alstroemeria ligtu had not been explained. In vitro and in vivo alstroemeria (A. ligtu hybrid) seed germination tests were conducted in a Randomized Completely Design at two different treatments (gibberellic acid (GA3) 0, 100, 200 and 400 mg/l with and without stratification in 5±1°C) in four replications. Seeds were planted in the soil mixture (peat/sand/perlite 1:1:1) or 1/2 MS media (1% sucrose, 0.7% agar and pH to 5.8). After 3-weeks keeping in the stratification conditions, transferred to the growth chamber (21°C and 16h photoperiod). Shoot and root length, number of root and leaf, root and shoot fresh and dry weight, seed germination percentage, germination rate and mean germination time were recorded during experiment. Stratification had a significant effect on seed germination (p<0.05). Soaking for 24 h in 100 mg/l GA3 supplemented with stratification under in vitro and in vivo conditions increased germination up to 76.67% and 70.00%, respectively. Mean germination time (MGT) decreased with duration of stratification and concentration of GA3. Seeds treated with 100 mg.l-1 GA3 plus 21 days of stratification produced the seedlings with the higher number of leaf, length of shoot, shoot and root dry weight in both In vivo and in vitro conditions. Non-stratified seeds without GA3 application fail to germinate, whereas seeds chilled for 21 days had 36.6%, 40.0% germination under in vivo and in vitro, respectively. Stratification was successful in breaking seed dormancy; stratification at 5±1°C for 21 days or 100 mg/l GA3+21 days of stratification overcame seed dormancy and increased the germination percentage of A.ligtu hybrid seeds. Thus, seeds of A.ligtu hybrid species probably exhibit a combination of physiological dormancy. In general, In vivo germination rates were lower than in vitro rates.
