Seasonal pattern of biomass and rubber and inulin of wild Russian dandelion (Taraxacum koksaghyz L. Rodin) under experimental field conditions
The roots of Taraxacum koksaghyz (Tks) are a promising alternative source for local rubber and inulin production in the temperate zone. Recent data on the agronomic performance of Tks are rare, older data partly not reliable. Thus, this study aimed at filling this gap by providing a comprehensive data set on Tks yield performance (root and leaf biomass, rubber, and inulin) and by highlighting the challenges being associated with its cultivation. The yield performance of wild Tks was investigated over a period of 17 months in two studies conducted at one site in Germany. The biennial life cycle of Tks was documented and the seasonal pattern of biomass, expected rubber and inulin yield were investigated over two successive seasons after harvesting Tks at six different dates and growth stages. Due to varying planting densities in the two trials (60,000 plants ha−1 (trial 1), 500,000 plants ha−1 (trial 2)), all yield parameters differed significantly between the trials at seasonal level e.g. fresh root yield ranged from 1.3 to 1.9 t ha−1 in trial 1 to 2.2-3.7 t ha−1 in trial 2. All measured parameters, i.e. biomass yield, rubber/inulin concentration and content, expected rubber/inulin yield, and inulin quality showed a significant seasonal dependency. At maximum, 32 (trial 1) and 62 kg of dry rubber could be expected from dry Tks roots harvested from one hectare at the end of flowering during the second season, 14 months post field emergence. At the same time the maximum of expected inulin yield (128 kg ha−1 (trial 1), 209 kg ha−1 (trial 2)) was observed. These findings support the thesis of a synchronal harvest of Tks roots for rubber and inulin production with high yield. In addition, the degree of polymerization (DP) of inulin from Tks with >15 indicated it was comparable to chicory inulin. In contrast, low yields of biomass, rubber and inulin of wild Tks make breeding and optimization of agronomic measures in Tks a necessity to turn it into a profitable crop.