There were statistically significant differences between the clones in both orchards as regards amount of flowers, size of the seed crop and seed quality. The annual variation in flowering and the size of the seed crop were also large. In general, the seeds from cones collected in October matured well and their germination percentage was high. The effects of fertilization on flowering, the size of the seed crop and seed quality were small. It would appear that the size of the crop can be affected to a much greater extent by favouring clones with a high seed-producing capacity than through fertilization.
Fertilization is unnecessary if the nutrient status of the soil is satisfactory.
Pinus sylvestris , seed orchards, fertilization, flowers, cones, seed crops, seed weight, germination. Saarsalmi , The Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland. Back to Vol. Growth and nutrition of willow clones. Growth and nutrition of 20 clones representing different species and interspecific hybrids of willows growing on an abandoned field were studied.