The impact of fertilisers and fungicides on seed germination and the initial phase of seedling growth in black alder Alnus glutinosa (Gaertn.)

Abstract To test the influence of selected fertilisers and fungicides on the germination of black alder seeds and the initial phase of seedling growth, we conducted a laboratory experiment outlined in this paper. Six treatments were applied on petri dishes each containing 30 seeds. The substrate for germination was sterile filter paper wetted with an aqueous solution of either one of two fungicides, two organic fertilisers, a mineral fertiliser or distilled water (control). Fungicides and fertilisers were applied according to the manufacturers' recommendations. In order to keep genetic variability to a minimum, seeds originated from a single tree in a seed stand located in the Chotyłów Forest District, eastern Poland. Germination and growth took place at a temperature of 23°C ± 2°C with a 14 h/10 h day/night cycle. Seeds began to germinate as early as the second day after sowing, except for the mineral fertiliser treatment, in which the first sprouting was observed on day 3. Seedling length was measured daily from the day of germination of a given seed through to day 15. Germination was found to proceed most rapidly in the control, while the largest increments in length and dry mass occurred in the control and fertiliser treatment with the so-called N1 fertiliser (solely comprising growth stimulators in the form of humic acids, chitosan and silicon). The most limited growth was observed under the influence of the F1 fungicide (active compound Thiram) as well as the organic fertiliser N2 (a mixture of mineral components and organic growth stimulators). Roots were found to develop most rapidly in the control and in the treatment with N1 (no mineral components). These are also the only two treatments in which the roots were longer than the stems after 15 days. Fertiliser N2 was found to have the most unfavourable influence on both, germination and the first phase of seedling development. The fact that selected fertilizers and fungicides affected black alder seeds and seedlings under laboratory conditions does not mean that they will have an impact under field conditions or on other forest tree species. Therefore, this type of research will need to be conducted individually for each forest tree species.