Effekt av sönderdelningsgrad och planteringsdjup på uppkomsten från rhizom av Tussilago farfara

Abstract: Tussilago farfara, coltsfoot, is a troublesome perennial weed with deep lying rhizome, which can vegetatively generate new plants. The mechanical control of coltsfoot that is used today, "starvation", which consists of several cultivations of the soil, which fragmentises the rhizome. This results in production of new shoots, which leads to depletion of nutrient resources; as long the new plant is not allowed to establish. However, very little research has been done to investigate how the starving technique affects the regenerative ability of coltsfoot. The purpose of this experiment with coltsfoot was to investigate how fragmentation and burial depths affect the time of emergence, number of emerged shoots per rhizome fragment, number of shoots per node, and if the germination ability within nodes changes during the experiment. The rhizome fragments were divided into five different lengths (5, 10, 15, 20 and 25 cm) and planted on seven different soil depths in pots with four repetitions. The planting depths were 1, 5, 10, 15, 20, 25 and 30 cm. The experiment took place in a greenhouse with day/night-condition 16/8 hours. The temperature was: daily mean maximum 15.6 °C and daily mean minimum 9.3°C. The results showed that the time of first emergence was delayed with increasing burial depth. The difference in final shoot emergence (number of shoots in relation to rhizome length and planting depth) was not statistically significant dependent on rhizome length, planting depth or the interaction between rhizome length and burial depth. However, the factor planting depth was close to statistical significance (p=0.051) and no shoot emerged from the shortest rhizome length buried on the greatest depth; while at least one shoot emerged from the other combinations of rhizome length and burial depth. Conclusions of this experiment is that fragmentation of a coltsfoot rhizome system to 10 cm long fragments and then burial, by ploughing, to a depth of 20 cm can have a good effect to control the weed. In that case the time of emergence is delayed for 28 days, at the tested environmental circumstances, which is enough for an annual crop to produce closed stand before any shoots of coltsfoot can emerge.