Fertilizer and planting strategies to increase biomass and improve root morphology in the natural rubber producer Taraxacum brevicorniculatum

Taraxacum brevicorniculatum produces high-quality natural rubber in its roots and could be developed as an alternative commercial source of this valuable raw material. However, current wild type accessions have a low biomass and branched roots that make them difficult to harvest. We set out to determine the optimum fertilizer and spacing requirements for T. brevicorniculatum plants in greenhouse and field trials, aiming to increase root biomass and reduce branching thus maximizing rubber yield and reducing losses during harvesting. Our preliminary data from greenhouse trials show that fertilizers containing calcium and magnesium in addition to NPK (nitrogen, phosphorus and potassium) increase root biomass by 25% compared to standard NPK fertilizer plus boron, and by 15% compared to NPK plus calcium. Fertilizers with a low N:P ratio increased the root biomass in greenhouse and field trials. Dense sowing (5-10 cm between plants) inhibits root branching and leads to the formation of single taproots that can be harvested easily. We therefore provisionally recommend the application of low N:P ratio NPK fertilizer supplemented with calcium and magnesium to closely-spaced plants in order to achieve the greatest increase in plant biomass per hectare. (C) 2011 Elsevier B.V. All rights reserved.