The article presents the results of study the effect of the light day duration on the embryological features of apomixis in Poa pratensis L. (Poaceae). The plants were grown under different day length (15 (control), 10 and 24 hours). The some embryological characteristics (frequency of ovules with a few embryo sacs, frequency of the parthenogenetic proembryo and a frequency and range of the gametophyte anomalies) were analyzed.