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

Abstract

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 16 plots with dimensions of 3 m × 4 m (4 plots in 4 blocks). Treatments with different dates of the harvest of the aerial part were: 1) first cut at stem elongation stage, BBCH-39 and second cut at inflorescence emergence stage, BBCH-59 (66 and 138 days after planting, respectively), 2) first and second cuts at stem elongation stage, BBCH-39 (100 and 173 days after planting, respectively), 3) one cut at inflorescence emergence stage, BBCH-59 (132 days after planting) with no regrowth of the aerial part, and 4) no aerial part cut. Tubers were harvested with approaching the cold season when the aerial part stopped growing. Treatment 1 and 2 resulted in lower total fresh and dry matter yield than treatment 3. The amount of water-soluble carbohydrates and crude protein in second cuts were numerically higher and fiber fractions lower than the first cuts. The highest fresh and dry tuber yield in treatment 4 was 63.3 and 14.8 t/ha, respectively, which was significantly higher than the mean of fresh (25.4-29.5 t/ha) and dry (4.6-6.1 t/ha) tuber yield in the other treatments. An increase in tuber organic matter was observed in treatment 4 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. Yield of tubers was also negatively affected by regrowth of the aerial part.

Keywords

• chemical composition
• forage
• regrowth
• tuber