Effect of seed age and fertilisation on the growth and decorative quality of selected ornamental grasses

Ornamental grasses have become a popular group of plants for use in landscaping. The aim of the present experiment was to assess the influence of seed age on the germination of ornamental grasses. In the glasshouse experiment, seeds of three grass genera, Melica, Pennisetum and Stipa, were tested. The seeds came from the Plant Breeding and Acclimatisation Institute in Bydgoszcz. They were harvested in 2005, 2006 and 2007 (so they were three years old, two years old, and one year old, respectively). In all the genera, the youngest seeds showed the highest germination, which varied between 61% (Melica transsilvanica) and 74% (Melica ciliata ssp. taurica). The germination process of the oldest seeds (three years old) proceeded at various rates, depending on the species, but the highest ability to germinate was observed in Pennisetum flaccidum (39%) and Stipa tenuissima (42%). After germination, Melica sp. and Stipa sp. plants were repotted and treated with Hydrocote (a slow-release fertiliser). The results obtained indicated that the fertilisation of the grasses significantly increased the height of the plants. Plants of Melica altissima ‘Atropurpurea’ also formed three times more inflorescences than the control plants. The application of the fertiliser had a positive effect on leaf colour (a more intense green) in all of the tested genera.