Abstract:
Current study was carried out to compare and validate the cultivar screening
parameters against tea nematodes. Different tea cultivars exposed to
Pratylenchus loosi under standard controlled conditions at “Nematology
experimental areas” in Talawakelle and Passara were used in the statistical
validation. Growth parameters and nematode infestation levels in the
different cultivars tested were monitored under nematode infestation and
healthy conditions with known resistant, moderately resistant and susceptible
cultivars. As a case study, biochemical parameters i.e. levels o f polyphenols
and amino acids were also compared with the nematode infestation. Results
indicated that there were significant differences between infestation level,
cultivar and their interaction in relation to different growth parameters.
However, there were very high CV values observed in most o f the growth
parameters tested. In Thalawakelle, only inter nodal length (IL) and weight
o f root fragments (RF) significantly differed (P<0.05) between infestation
levels and among cultivars recording low CV values whereas in Passara, IL
and girth o f the plant recorded significant differences having low CV (<
20%) values. The correlation between growth parameters and nematode
infestation was not significant (P>0.05) in both locations. Since cluster
analysis didn’t show any clear clusters, principle component analysis was
performed for various parameters. Considering results o f principle
component analysis, analysis o f variance and CV values, only inter nodal
length can be considered as the best parameter for cultivar screening in both
locations. Biochemical investigation revealed that, root polyphenol content
and amino acid content had significant effect with nematode infestation and
different cultivars tested and therefore, can be potential factors in
determining resistance/susceptible levels o f plants when screening against
tea nematodes.
