Abstract:
The root knot nematode, Meloidogyne is one of the most economically damaging plant parasitic nematode
groups, and are widely distributed in Kenyan agro-ecosystems. The aim of this study was to
determine the diversity of Meloidogyne species in Kenyan sweet potato fields and identify sweet potato
varieties that exhibit resistance to M. incognita. Meloidogyne species were collected from Nyanza,
Western, Eastern and Central Provinces of Kenya. Mitochondrial DNA was used to differentiate Meloidogyne
species. The most common species in all sampled regions was M. incognita. Meloidogyne hapla
was recorded for the first time in Kenyan sweet potato growing areas (Mosocho, Matayos, Teso South,
Manyatta, and Nzaui sub-counties), while M. enterolobii was observed in Kiharu, Matayos and Mosocho
sub-counties and a novel Meloidogyne sp. was identified in Kiharu sub-county. Seventy-two sweet potato
varieties collected from both agricultural fields and research stations in Kenya were evaluated for
resistance to M. incognita under greenhouse conditions in two separate trials. Known susceptible
(Beauregard) and resistant (Tanzania) sweet potato varieties were included as controls. Responses of
sweet potato varieties to M. incognita infection was assessed by the number of eggs present and level of
galling on a scale of 1e5, where 0 ¼ 0 galls and 5 100 galls. The reproduction index (RI) was used to
classify the varieties as resistant or susceptible. There was a significant difference (P < 0.001) in the
number of eggs, GI and RI among the varieties tested. Forty nine sweet potato varieties were considered
very resistant and may be used in breeding programs to incorporate resistance against M. incognita into
commercial cultivars of sweet potato or to use them in crop rotation programmes for management of
RKN. The results on Meloidogyne species diversity in Kenyan sweet potato fields will also be useful in
nematode management programs.
Description:
This work was supported by the Department for International
Development under the Climate Impact Research Capacity and
Leadership Enhancement (CIRCLE) programme and AfricanWomen
in Agricultural Research and Development (AWARD). The James
Hutton Institute received financial support from the Scottish Government,
Rural and Environment Science and Analytical Services
Division. We thank Jackson Kimani from icipe’s Geo-Information
Unit for help in creating the map.
