Reaction of potato cultivars to Potato Cyst Nematodes (Globodera rostochiensis and G. pallida) under greenhouse conditions in Kenya

Abstract

Several measures have been recommended in the control of potato cyst nematodes (PCN) with resistant potato cultivars being considered as the most practical and affordable for smallholder potato farmers in Kenya. However, the level of resistance in locally grown potato varieties is yet to be established. The aim of this study was to screen Kenyan potato cultivars against PCN under greenhouse conditions. Eleven potato cultivars namely Shangi, Dutch Robijn, Sherekea, Nyota, Roseline tana, Tigoni, Unica, Asante, Chulu, Kenya Mpya and Arka were screened with Desiree (susceptible variety), Manitou (resistant cultivar) as controls. For each potato cultivar, there were two sets of plants with the first set being inoculated with 50 cysts, while the second batch was nematode-free. The treatments were arranged in a completely randomized design with three replications. A scale of 1-9, with 9 indicating the highest level of resistance was used in the assessment of disease severity. Nematode infestation caused a reduction in root mass across the 11 cultivars from 20 to 100% compared to uninoculated controls. Reproductive index of PCN viable eggs across the 11 cultivars was <1 compared to control (Desiree). Potato cultivars Shangi, Tigoni, Dutch, Chulu, Asante, Unica, Arka, Kenya Mpya, and Roseline Tana had a severity score of 1-3 (>95%), hence were considered to be susceptible to PCN. The cultivars Sherekea and Nyota had a severity score of 4-6 (<25%) and hence were considered partially resistant to PCN. The findings of this study provides a basis of integrating partially resistant potato cultivars into PCN management in smallholder farms. Keywords: Cyst viable eggs, reproductive index, resistance, susceptible, smallholder farmers, severity score.