Temperaturens betydelse för groning och uppkomst av ... - SLU

Summary
The Swedish oilseed rape association is running a project called 20/20. The goal is to reduce
cost with 20 % and increase the oilseed production with 20 % until 2010. The big project is
split into smaller projects and one of them is Establishment – degree-days. In this study,
degree-days have been used as a tool in experiments concerning germination and
establishment of oilseed rape.
The main part of the study was carried out under laboratory conditions. The studies aimed at
finding a base temperatur for germination and plant emergence, and to study how different
temperatures, seeding depths and seedweights affect germination and emergence. Six
different varieties were sown at 5, 10, 15 and 20ºC at seeding depths of 1, 3 and 5 cm. The
number of emerged plants was counted two or three times per day.
The results from the laboratory study were then compared with results from field
experiments. Plant emergence and soil temperature data from field experiments were
collected from OS7-190 which included different varieties and seeding dates, R2-4135 which
included different seeding dates and preceding crops and R2-5079 which was an
establishment trial with spring oilseed rape. The location for the two OS7-190 trials used was
in Östergötland, while R2-4135 and R2-5079 were located just outside of Uppsala.
The base temperature for spring and winter oilseed rape was around 2,9°C. Oilseed rape
needed 70 – 80 degree-days for emergence from 3 cm depth during controlled conditions
(base temperature 2,9°C). Even at low temperatures and great seeding depths (5 cm) the
number of emerged plants was more than 70 %. Number of emerged plants or emergence rate
were not affected by seed weight. The results from the laboratory experiment correlated well
with the results of the field experiments.
The study shows that degree-days are useful for predicting plant emergence under field
conditions. Increased number of degree-days for emergence indicates limiting factors in the
germination and emergence process.
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