The influence of root-cutting radius on tuber yield and fuel characteristics of Helianthus tuberosus L. in a semi-arid area

The Jerusalem artichoke (Helianthus tuberosus L.) is an important source of biomass for bio-ethanol production. The tuber yield, calorific value, and ash content of Jerusalem artichokes were investigated using different root-cutting treatments in 2012 and 2013 in Inner Mongolia, China, to evaluate the potential of Jerusalem artichokes for bio-ethanol feedstock, and to describe the effect of root-cutting on its biomass, calorific value, and ash content. The tuber yield was improved significantly using the cutting treatments compared to the control (no root-cutting). The highest value of tuber yield, underground biomass, aboveground biomass, and total biomass was obtained under the 60 cm root-cutting treatment. The calorific value of different organs improved using the root-cutting treatments compared to the no root-cutting (control) treatment. The calorific values of the stem and tuber were higher than the other organs, including root, leaf and flower (P < 0.05), and the leaf had the lowest calorific value. The leaf ash content was the highest, and the stem and tuber ash content were lower than the other organs. The ash content was improved by root-cutting, and the calorific value and ash content were inversely related. Our results suggest that cutting the root with a radius of 60 cm is a feasible method for improving Jerusalem artichoke tuber yield and quality, and the highest yield value in 2012 was 480.06 g/plant with a cutting radius of 60 cm, which was a 90.4% increase compared to the no root-cutting (control) treatments. The highest yield value in 2013 was 469.06 g/plant at a root-cutting radius of 60 cm, which was a 125.3% increase compared to the no root-cutting (control) treatment.