Impact of pre-sowing treatment and sowing season on Douglas fir emergence rate in a specific seed lot

Abstract

Not only in the Czech Republic there is a problem with low yield of Douglas fir seedlings in forest tree nurseries. It can be caused mainly by two factors: the type of pre-sowing treatment and the temperature at the time of sowing. The aim of this study is to find out their influence on the emergence rate of Douglas fir. We have tested one specific seed lot originated from the Czech Republic subject to the following variants of pre-sowing treatment: soaking for 48 hours, stratification without a medium for 21 days and for 30 days after 48 hours of soaking and stratification for 30 days with a medium. The treated seeds were sown in a phytotron at temperatures of 13/8 °C – 10/14 hours (day/night) (simulation of early sowing season in February or March) and at temperatures of 17/13 °C – 14/10 hours (simulation of late sowing season in May). In case of the early sowing season, approximately half of the germinable seeds emerged in all treatment variants including the control variant (seeds without stratification). The late sowing season resulted in different emergence rate of the seeds that were subject to different variants of pre-sowing treatment (24–51 %). Then, 21day and 30day stratification were not sufficient for the tested conditions of the early and late sowing season. None of the combinations of pre-sowing treatment and sowing time resulted in full use of the seed potential of the tested seed lot.