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| ŠUMARSKI LIST 9-10/2020 str. 36 <-- 36 --> PDF |
time and subjected to eight weeks of stratification period after soaking in water for 48 hour without GA3 treatment (81 %). DISCUSSIONS RASPRAVA The germination percentage of Acer trautvetteri seeds stratified for eight weeks was higher than seeds unstratified in both the growing chamber and the greenhouse conditions. This fact confirms that seeds of Acer trautvetteri exhibit physiological dormancy and require stratification period to remove seed dormancy. Similarly, Yılmaz (2007) and Varbeva and Iliev (2015) reported that Acer trautvetteri seeds exhibit physiological dormancy. Several researches have already investigated that some maples had seed dormancy and mature Acer seeds require at least eight weeks of cold moist stratification to overcome dormancy (Urgenc 1998; Piotto and Noi 2003; Nasari et al. 2018; Erdogan Genc and Ucler 2020 ). Also, Kumar et al.(2017) obtained highest percentage of germination in Acer acuminatum after cold moist stratification for a period of 60 day. Whereas, Yılmaz (2007) reported that the dormancy of Acer trautvetteri seeds was completely removed by three months of chilling but all seed germinated during the chilling period. In the present study, cold-moist stratification period was determined as eight weeks for Acer trautvetteri seeds in the preliminary trials. When the stratification period was prolonged, most of the seeds germinated during stratification period. This situation was also detected in Acer cappadocicum seeds (Erdogan Genc and Ucler 2020).Yahyaoglu et al. (2006) reported that seed germination during stratification period was an important factor in obtaining low germination in sowing. Because of this reason, stratification process should be continued to species requiring stratification period before germination process until the first germinant appear in stratification medium. Because, the germination of the seeds in stratification medium negatively affected seed germination percentage. Urgenc (1998) also reported that stratification period could extend from one week to 3-4 weeks or even longer depending on the species. If startification period extend, the seeds could begin to germinate during stratification medium. This situation was also detected in some Maple species (Urgenc 1998; Piotto and Noi 2003; Varbeva and Iliev 2015). Therefore, in the present study, stratification period was suggested as eight weeks because of this sitution can be cause failure in sown. However, it is also stated that stratification period should be longer in order to break dormancy in seeds of Acer saccharum (Evans and Blazich 1999), five different Acer species (Yang and Lin 1999), Acer ceasium (Phartyal et al. 2003). Also, Farhadi et al. (2013) pointed out that the highest germination value of Acer velutinum seeds was obtained after 16 weeks of cold-moist stratification. In this study, it was determined that soaking unstratified seeds in water for 48 hours before germination trial was no statistically significant effect on germination in growth chamber conditions (Table 2). When treatments evaluated on the basis of indivudual, the highest germination percentage in the greenhouse was obtained from seeds collected at third seed collection time and subjected to eight weeks of stratification period after soaking in water for 48 hours without GA3 treatment (81 %) (Figure 2). Smilarly, Bourgoin and Simpson (2004) reported that the highest germination value of Acer pensylvanicum seeds was obtained from seeds subjected to the moist chilling for 16 weeks after soaking 48 hours (92 %). Furthermore, it was observed that soaking different Acer seeeds in water for 48 hr before germination trials increased germination rate |