Developing row spacing and planting density recommendations for yacon (Smallanthus sonchifolius) in tropical highland conditions

Abstract

Yacon (Smallanthus sonchifolius [Poepp.] H. Rob., Asteraceae) is an Andean plant being explored as a functional food, due to high concentrations of fructooligosaccharides (FOS), a natural sweetener capable of reducing blood lipids and glucose levels, supporting prevention of chronic diseases, such as diabetes. Yacon commercial production is still being established, thus cropping practices and their impact on profitability are yet poorly explained. Improved planting recommendations are demanded, as it affects crop yield. In this background, a field trial was conducted to determine row spacing and plant populations for yacon production in tropical highland areas. The experimental design was a randomized complete block, in a split-plot scheme, where blocks were three row spacings (0.8, 1.0 and 1.2 m) and subplots covered three spacings between plants (0.4, 0.5 and 0.6 m), with four replicates. At harvest time, evaluations on accumulation of dry mass in the plant and tuber root production data (number, weight, total productivity, and per class) were made. Profitability indicators were estimated (gross income, operational profit, and benefit-cost ratio). Data suggest productive and economic variations among tested planting configurations, as an example higher productivity (31.5 t ha-1) and positive benefit-cost ratio (2.51) when using 1.0 m between rows and 0.4 m between plants for the conditions tested. These results point out the prospect to select better crop management practices for yacon, cutting costs, and increasing yield. Another key find was yacon’s capacity to overcome intense drought and temperature stress, not previously documented for this crop. Therefore, yacon is a new crop with potential to boost farming income through crop diversification.