Department of Physics, Chemistry and Biology (IFM)

Method

Rhizomes of E. arvense were dug up from four regions in Sweden; Skåne, Östergötland, Uppland and Västerbotten during summer and autumn. At each region, rhizomes were taken from three sites, with the criterion that the sites should be at least three km apart from each other in each direction. The plants were cloned and grown in pots outdoors during summer. 

In the begining of autumn the first plants of E. arvense were harvested. Three pots from each population, 36 in total, were randomly chosen and dug up. It was decided that if the aboveground biomass on a plant did not reach the criterion of at least 0.5 cm living biomass the plant was discarded and replaced with another randomly chosen plant from the same population. Each pot was "immediately after collection" placed in a plastic bag, so that none of the above- and belowground biomass was lost. The aboveground biomass was cut of and placed in small aluminum containers and dried for ca 48 hours at 105 °C in a drying cabinet.

The belowground biomasses was cleaned from substrate and rinsed with water. The rinsing was done by hand and as careful as possible, talking care to keep tubers connected to their origin location on the rhizome or on another tuber. This was followed by detection of each tuber on each plant. The tubers on each plant were first categorized and counted with regard to location on plant. Three categories were used: attached to the rhizome, attached to another tuber but not to rhizome or fallen of from the plant. The tubers were then also categorized and counted into three different color groups: light yellow/green, light brown or dark brown/black. The tubers were then additionally categorized into three size groups: <3.5 mm, 3.5-5.0 mm and > 5 mm. The rhizomes and tubers from each plant were placed seperately in small aluminium containers and were dried at 105 °C for at least 20 hours in a drying cabinet. The above- and belowground biomass (rhizomes and tubers seperately) were weighted with an accuracy of 10 mg with a balance scale.

The above procedure was repeated on five occasions: every second week until late autumn.