Epsilon Archive for Student Projects

Abstract

Soybeans are one the most traded crops in the world with main production areas in north and south
America. Europe only produces 5 % of its domestic need for soybean. In the Nemoral zone of
northern Europe no commercial cultivation of soybeans exists today. However, between 1940 -1960
there existed a breeding programme for soybeans in Sweden, but it never reached a commercial
scale. Soybeans are interesting to introduce to Swedish organic farming for replacing imported
soymeal in animal diets as well as for direct human consumption. To expand the soybean production
further north more knowledge about soybeans maturity timing and temperature requirements during
the major phenological stages needs to be acquired. An important trait for cultivation of soybeans
in the Nemoral zone is capacity to germinate under the low temperatures which in this zone are
common in spring. This thesis aims to study three germination dynamics parameters of soybeans;
the base temperature for germination (Tb), growing degree days to 50 % germination (GDD50) and
the maximum germination rate (b). Secondly, this study aims to investigate if there is an increased
tolerance of germination under low temperatures for modern cultivars compared to historic Swedish
cultivars. Thirdly, germination dynamic parameters of the most common weed species were studied
with the aim to gather more information about weed-crop competition dynamics and possible
implications on non-chemical weed management practices. In total 12 soybean cultivars and 10
weed species were studied. Germination experiments were carried out in climate chambers with 12
constant temperatures between 0 – 40 °C. Log logistic functions were used for estimation of the
mentioned germination dynamic parameters. The results showed that there were significant
differences regarding Tb, GDD50 and b between the studied soybean cultivars. There were also
significant differences between modern cultivars and the historic cultivar ‘Fiskeby V’. Germination
dynamic parameters of the studied weed species varied greatly. Based on the study results it can be
concluded that a selection of soybean cultivars with contrasting germination dynamic parameters
compared to the main weed species can help to optimise the timing of non-chemical weed
management measures. Further it can be concluded that the studied parameters could be included in
the future soybean breeding programs aiming for the adaptation of this crop to northern climates.