Screening of five elite sweet potato cultivars against reniform nematode (Rotylenchulus reniformis) under humid and semi-arid conditions of Papua New Guinea.

Abstract

Five elite sweet potato cultivars were tested against reniform nematode to determine the resistance/ tolerance status and the yield losses under wet coastal lowlands and dry lowland conditions of PNG. The cultivars showed varying degrees of above and underground symptoms of nematode infection. The overall nematode population per kilogram of soil was much higher at the Wawin farm than at the Unitech farm irrespective of cultivars. The cultivars B11 and RAB 36 had the highest and lowest nematodes populations but yield/plot in the reverse order respectively, irrespective of the location. Yield losses as non-marketable tuber for B11 ranged from 36.2- 40.1%, but in case of RAB 36 it was only 4.6 - 8.22%. B11 had the highest tuber cracking of 10 - 22.3% and L676 had between 6.5-11.9%. The other three cultivars did not show any cracking symptoms.