Impact of Harvesting the Aerial Part of Jerusalem Artichoke (Helianthus tuberosus L.) as Forage on Tuber Yield

This study aimed to determine the effect of cutting the aerial part of Jerusalem artichoke at different growth stages, as forage, on tuber yield. Tubers were planted in a randomized complete block design in ۱۶ plots with dimensions of ۳ m × ۴ m (۴ plots in ۴ blocks). Treatments with different dates of the harvest of the aerial part were: ۱) first cut at stem elongation stage, BBCH-۳۹ and second cut at inflorescence emergence stage, BBCH-۵۹ (۶۶ and ۱۳۸ days after planting, respectively), ۲) first and second cuts at stem elongation stage, BBCH-۳۹ (۱۰۰ and ۱۷۳ days after planting, respectively), ۳) one cut at inflorescence emergence stage, BBCH-۵۹ (۱۳۲ days after planting) with no regrowth of the aerial part, and ۴) no aerial part cut. Tubers were harvested in treatments ۱, ۲, and ۳ with approaching the cold season and ensuring that the aerial part stopped growing. Treatment ۱ and ۲ resulted in lower total fresh and dry matter yield than treatment ۳. The amount of water-soluble carbohydrates and crude protein in second cuts were numerically more and fiber fractions lower elevated than the first cuts. The highest fresh and dry tuber yield in treatment ۴ was ۶۳.۳ and ۱۴.۸ t/ha, respectively, which was significantly higher than fresh (۲۵.۴-۲۹.۵ t/ha) and dry (۴.۶-۶.۱ t/ha) tuber yield in the other treatments. An increase in tuber organic matter was observed in treatment ۴ with a significant increase in soluble carbohydrate contents. The results showed that an extra cut of the aerial part of Jerusalem artichoke during the vegetative stage did not increase the aboveground biomass yield compared to the treatment in which the only harvest was made just before the flowering stage. Tuber yield was negatively affected by the cutting and regrowth of the aerial part.