New Zealand Journal of Crop and Horticultural Science abstracts

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Effects of soilless media, nutrition, and pH on tuber russeting in Sandersonia aurantiaca

G. E. Clark

New Zealand Institute for Crop & Food
 Research Limited
Pukekohe Research Centre
Cronin Road, RD 1
Pukekohe, New Zealand
email: clarkg@crop.cri.nz

G. K. Burge

New Zealand Institute for Crop & Food
 Research Limited
Food Industry Science Centre
Private Bag 11 600
Palmerston North, New Zealand

C. M. Triggs

Department of Statistics
University of Auckland
Private Bag 92 019
Auckland, New Zealand

Abstract  The effects of two soilless media (peat/pumice and bark), three nitrogen (N) rates (25, 100, and 500 g N/m²), three potassium (K) rates (12.5, 50, and 200 g K/m²), and media pH (4.4, 4.8, 5.5, and 5.9) on tuber russeting in Sandersonia aurantiaca were assessed in two experiments. Russeting scores were less in the bark medium and increased with N rate and with increasing pH. Tuber weight and secondary tuber numbers were less in the bark medium than in the peat/pumice medium and increased with increasing N rate and pH, but declined at the highest rates. Tuber numbers were greater in the peat/pumice medium and with increasing N rate. Tuber N concentrations increased markedly with increasing N rate. There was no effect of K rate on tuber quality. To maximise production of export quality tubers with low secondary tuber numbers and an acceptable level of russeting, N rates of up to 33 g N/m² in a peat/pumice medium are recommended at pH levels of less than 5.0. Using a bark medium will reduce tuber russeting, secondary tuber numbers, and weight.

Keywords  Sandersonia aurantiaca; sandersonia; tuber; soilless medium; nitrogen; potassium; pH; russeting; tuber quality

H03026; Online publication date 17 March 2004; Received 11 March 2003; accepted 1 September 2003
New Zealand Journal of Crop and Horticultural Science, 2004, Vol. 32: 131-138
0014-0671/04/3201-0131 © The Royal Society of New Zealand 2004

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