Effect of propagule weight on production of yacon (Smallanthus sonchifolius)

Abstract

The effect of the propagule weight of yacon (Smallanthus sonchifolius) on plant yield was investigated. Tuberous root yields increased as the propagule weight was increased from 25 to 500 g with the most rapid gain in yield being up to 180–200 g and then a more gradual increase up to 500 g. Planting crown pieces of 50 g gave an average tuberous root yield of 2 kg/plant, 200 g pieces gave 5 kg/plant, and 500 g pieces gave 6 kg/plant. This increase in yield was owing to an increase in the number of tuberous roots/plant, from 17 to 57/plant over the propagule weight range, with no change in the average weight of the roots except from the heaviest propagules. There was a strong positive correlation (r = 0.83, P 0.001)) between root numbers and tuberous root weights. It is recommended that a crown piece propagule of 180–200 g is used to establish yacon crops for tuberous root production. Using this planting weight, the crowns increased in weight 10-fold. Planting smaller crown pieces gave a larger multiplication of crown planting material but this was at the expense of crop yield. The number of stems/plant increased as the propagule weight was increased and was positively related to the root number and weight of foliage, but was not sufficiently precise to be used as an estimate of yield. Extrapolated yields of tuberous roots from the plant population of 13 300 pl/ha were 26.6 t/ha from the 50 g pieces, 66.5 t/ha from the 200 g pieces, and 79.8 t/ha from the 500 g pieces, showing that propagule weight has a large effect on yacon root yield. © 2005 Taylor & Francis Group, LLC.