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

Between 2012-2014, the germination abilities of lemon balm seeds were tested. The investigated seeds were obtained from lemon balm breeding project conducted in Institute of Natural Fibres & Medicinal Plants (INF&M), of Poznan, Poland. The germination rates were calculated by using International Rules for Seed Testing (ISTA) seed germination rules and a high fluctuation of germination rates was observed. A low rate of germination usually devalues the seeds. Therefore, the anatomy of the investigated lemon balm seeds was analyzed by scanning electron microscopy (SEM) and a tetrazolium test was done. SEM analysis showed correct morphological structures for all seed parts. In particular, the embryos, endosperm and testa were well and correctly developed and abnormal seeds parts were not found. The tetrazolium test revealed a high rate of vitality for the investigated strain seeds. Thus, before seed are disqualified because of low germination rate, we recommended that other useful tests should be done.