Sprouting Ability and Seasonal Changes of Sugar Concentrations in Rhizomes of Calystegia sepium and Roots of Convolvulus arvensis

Abstract

Factors influencing the sprouting ability of rhizome pieces of Calystegia sepium and root pieces of Convolvulus arvensis were analyzed in four experiments. In the first experiment, sprouting was investigated as a function of bud number. About half of the rhizome and root pieces with one bud could sprout. Almost all pieces with 6 or more buds sprouted. Mostly several buds sprouted in longer rhizome and root pieces. In the second experiment, sprouting of rhizomes and roots was measured in dependence of burial depth in the soil. With increasing depth, the sprouting ability of about 10 cm long rhizome and root pieces decreased. From deeper than 35 cm for C. sepium and 30 cm for C. arvensis no new shoots emerged. This shows that common shallow tillage practices are mostly not sufficient to suppress vegetative regeneration of these two weed species. In the third experiment, rhizome and root pieces were collected in the field and their sprouting ability was examined in the greenhouse over the season. Rhizomes of C. sepium and the roots of C. arvensis were dormant in the winter and sprouting was highest in April and May. In the fourth trial, seasonal changes of sugar concentrations were studied in the rhizomes and roots. It was found that concentrations of fructose, glucose and saccharose were highest and starch rates were lowest in mid-June for both species. We assume that this time corresponds to the optimum time for herbicide translocation in the roots/rhizomes.