Abstract:
Plant-parasitic nematodes (PPN) are harmful pests that have
become a severe threat to crop production worldwide. Diversity of
PPN at horizontal and spatial scales influence the effectiveness of
control strategies. This study evaluated the vertical distribution of
PPN genera at 0 cm to 30 cm and 30 cm to 60 cm in sweet potato
fields in Central, Manyatta, and Nembure regions of Embu County,
Kenya. A significant region × depth interaction was observed
for Tylenchus. For all the other nematode genera, there were no
significant variations in the abundance at 0 cm to 30 cm and 30
cm to 60 cm depths. However, Helicotylenchus, Meloidogyne, and
Scutellonema occurred in greater numbers at both depths in all
regions. Shannon and Simpson diversity indices were higher at 0 cm
to 30 cm depth while Pielou’s evenness was similar at both depths in
the three regions. Diversity partitioning of genus richness, Shannon,
and Simpson diversities across all regions at 0 cm to 30 cm,
indicated that β component contributed 61.9%, 35.6%, and 22.6%
of γ diversity, respectively. Coinertia analysis indicated a significant
covariation between nematode genera and soil properties. The
results show that management of PPN in sweet potato fields should
be targeted at soil depths that are not less than 60 cm.
