RESEARCH ON KONJAC (AMORPHOPHALLUS KONJAC) PRODUCTION IN NEW ZEALAND

Authors: J.A. Douglas, J.M. Follett, J.E. Waller
Keywords: shading, potash, nitrogen, lime, glucomannan

Abstract:
Konjac (Amorphophallus konjac) is being investigated as a new crop in New Zealand. Konjac corms were imported from Japan in 1996 and, following a quarantine period, plant material was multiplied and a research programme was begun. An investigation growing konjac corms under 30 and 50% shade cloth compared to no shade found the konjac yielded 66% more corms under 50% shade than without shade. After two season’s growth, corms planted at an average weight of 105 g gave 2397 g total corm weight under 50% shade cloth with the largest individual corms approaching 2 kg. Without shade the total corm yield was 1442 g. Where konjac offsets were planted instead of corms there was no response to the shade treatments. Offsets planted at an average weight of 13 g gave total corm production of 368 g after two years with some individual corms reaching over 200 g. A fertiliser trial comparing three rates of nitrogen and three rates of potassium with and without lime found that lime and potassium increased yields but increasing rates of urea reduced yields after two season’s growth. The results show konjac is a promising new crop for northern New Zealand. Research is continuing to investigate its potential.