BIOPHYSICAL AND BIOCHEMICAL BASIS OF RESISTANCE AGAINST THRIPS AND MITES IN GRAPES
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Date
2017-12
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University of Horticultural Sciences, Bagalkot
Abstract
An investigation on biophysical and biochemical basis of resistance against
thrips and mites in grapes was carried out at Sector No. 70, University of Horticultural
Sciences, Bagalkot during the year 2016-17 (fore pruning).
Twelve grape genotypes were studied for incidence of thrips and mites
simultaneously along with recording the biophysical and biochemical traits of vine. The
genotypes like Red Globe, Manjari Naveen, Sharad Seedless and Krishna Sharad were
found to be superior by recording significantly lesser thrips incidence (3.28, 3.52, 3.72
and 3.98 thrips/shoot respectively). Whereas, Fantasy Seedless, Kishmish Rozavis
white, Flame Seedless and Manik Chaman clearly emerged as inferior genotypes by
recording significantly the highest thrips incidence (4.76, 4.60, 4.52 and 4.36
thrips/shoot respectively). Significantly the lowest mites was recorded in Red Globe
(8.63 mites/sq. inch of leaves), whereas significantly the highest mites was recorded in
Fantasy Seedless (14.48 mites/sq. inch of leaves). Among the biochemical traits, sugar
and amino acid in leaves exhibited significant positive correlation (r= 0.837 and r=
0.927 respectively) with incidence of thrips, while phenol and tannin in leaves showed
significant negative correlation (r= -0.881 and r= -0.948 respectively). The incidence of
mites was significant and positively correlated with amino acid and sugar (r= 0.865 and
r= 0.762 respectively), while phenol and tannin in leaves showed significant negative
correlation (r= -0.793 and r= -0.788 respectively).
The leaf thickness varied significantly between the genotypes of grape.
Significantly higher leaf thickness was recorded with the genotypes, Manik Chaman
(141.40 μm) followed by Sharad Seedless (132.60 μm). Whereas the lower leaf
thickness was recorded with genotypes Crimson Seedless (110.40 μm) followed by
Flame Seedless (116.20 μm). Leaf thickness exhibited a positive correlation with the
incidence of thrips.