Vitality and germination of lemon balm (Melissa officinalis L.) seeds

In 2012-2014, the germination ability of lemon balm seeds were tested. The investigated seeds were obtained from the lemon balm breeding project conducted at the Institute of natural Fibres & Medicinal Plants of Poznań, Poland. The germination rate was done by using ISTA seed germination rules and the high fluctuation of germination rate was observed. Low rate of germination usually disqualificates the seed material. Thus, the anatomy of the investigated lemon balm seeds was analyzed by scanning electron microscopy (SEM) and tetrazolium test was done. SEM analysis showed accurate morphological structure of all seed parts. The embryos, endosperm and testa were well and correctly developed. Seed coat was typical for all species of Lamiaceae. Abnormal seed part were not found. Tetrazolium test revealed the high rate of vitality of the investigated strain seeds. Thus, other useful tests should be recommended before seed disqualification will be done in case of low germination rate.