MSc

A study entitled “Screening of superior genotypes of Ailanthus triphysa (Dennst.)
Alston. (Matti) for matchwood quality” was conducted in the College of Forestry, Kerala
Agricultural University, Vellanikkara, Thrissur during the period, 2016-2018. The
objectives were to assess the variation in growth and wood traits of Ailanthus triphysa
grown in the main campus of Kerala Agricultural University, Vellanikkara under a tree
improvement trial. It was also aimed at selecting the superior genotype in this population
through an assessment of the genetic worth of their parents. Among the five best
performing progenies, FCV AT 11 and FCV AT 20 were found to perform well in terms
of height and collar diameter. The progenies of FCV AT 11 also showed highest mean
stem volume of 0.006 m3. Overall mode for number of branches was found to be zero,
only one progeny (FCV AT 3) had single branching habit. Regarding bole straightness
all the progenies scored 3 “almost straight with 1 or 2 small bends” except progeny of
FCV AT 8 and 14 CPTs scored two “slightly crooked with 2 small bends or less than 2
serious bends”. At this stage of the trial, majority of the progenies had good branching
habit and bole straightness. This aspect should be utilized in breeding programme so that
it will be helpful to improve the tree form, which ultimately upgrade the quality and
economic value of the timber. Average survival percentage of the progenies were found
to be 94.98 %. The average basic density of CPTs was found to be 0.37 g cm-3, which
shows that the wood belongs to the light wood category. Wood colour and grain pattern
studies revealed that, single colour (pale yellow) and straight grain pattern was found in
all the CPTs respectively. Fibre morphology, vessel morphology, and ray morphology
exhibited significant variation among the CPTs whereas, the variation in tissue proportion
was found to be non-significant. Pest incidence was found to be one of the major
hindrances to the growth of the species. Bioassay using Bacillus thuringiensis (Bt) was
found to be effective against both the lepidopteran defoliators, Eligma narcissus (Cram.)
and Atteva fabriciella Swederus. In case of E. narcissus, median lethal dose (LD50) was
achieved with 10 % concentration of Bt whereas in A. fabriciella, 2.5% Bt concentration
was found to be effective. Neem oil showed a clear antifeedant activity against E.
narcissus, the feeding rate was reduced to 3.58 % in 2 % neem oil treated leaves as
compared to 30.91 % in control. Scoring of pest incidence was found to be non109
significant among the progenies, all the progenies affected moderately by both E.
narcissus and A. fabriciella. Ten CPTs namely FCV AT 1, 2, 3, 5, 6, 8, 9, 11, 13, 20
were found to be good combiners for both height and collar diameter. The CPTs with
positive GCA could be potentially included in a seed production programme and for
further breeding. Broad sense heritability (H2) for height was found to be 0.03 and for
collar diameter, 0.1. It could therefore be concluded that height and collar diameter were highly influenced byenvironmental factors rather than genetic factors.