Clonal variation for growth and resistance against trunk borer in Teak (Tectona grandis l.f.).
The present study was carried out in a clonal seed orchards of Teak located at Dandeli, Karnataka, South India, to assess the clonal variation for growth and levels resistance to trunk borer among Teak clones of Karnataka. There was significant among-clone variation for diameter at breast height (dbh) and volume. The variation within-clones was negligible, suggesting a strong genetic basis for these traits. Significant variation for borer infestation, as measured by the number of holes per tree, was recorded that ranged from 0.33 to 10.8 holes per tree with a mean 2.92. Based on the relative grading of the clones it was identified that two clones viz., MyHuN1 and MyHuT1 were 'tolerant', 7 clones were 'highly susceptible' and rest of the clones were 'susceptible'. A general trend of higher volume with higher level of tolerance to trunk borer was observed in the study although the strength of the association was not significant. The results are important in developing resistant Teak clones.