METHYL JASMONATE INDUCED RESISTANCE AGAINST Tetranychus urticae Koch IN GRAPES CV. THOMPSON SEEDLESS
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Date
2021-08
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bagalkot).
Abstract
An investigation on Methyl jasmonate (MeJA) induced resistance against
Tetranychus urticae in grapes cv. Thompson seedless was carried out at Horticulture
Research and Extension Centre, Vijayapura (Tidagundi) during the year 2020-21
(forward pruning). The bio-efficacy of MeJA against T.urticae in cv. Thompson
Seedless revealed that the, two sprays of abamectin 1.9 EC @ 0.3ml/l and MeJA +
Azadirachtin 10000 ppm at 1mM + 2ml/l found to be superior in suppressing the eggs
and mites population. Further, abamectin 1.9 EC @ 0.3ml/l and MeJA + Azadirachtin
10000 ppm at 1mM + 2ml/l has recorded highest yield (17.86 and 17.37 t/ha,
respectively). Whereas, highest B:C ratio was recorded in abamectin 1.9 EC @ 0.3ml/l
(4.05) followed by moderate B:C ratio in MeJA + Azadirachtin 10000 ppm at 1mM +
2ml/l (1.52). The maximum total soluble solids (TSS) was recorded in MeJA +
Azadirachtin 10000 ppm at 1mM + 2ml/l (23.23 ˚B). The results obtained from
biochemical analysis of the grape plants which received different MeJA treatments
against T.urticae revealed that the foliar application of MeJA + Azadirachtin 10000
ppm at 1mM + 2ml/l, MeJA + Azadirachtin 10000 ppm at 0.75mM + 2ml/l and MeJA +
Azadirachtin 10000 ppm at 0.5mM + 2ml/l found to enhance the resistance in grape
plants as it was indicated higher amount of phenols as against other treatments. The
correlation studies revealed that there was a positive correlation between the population
of mites and analysed biochemical parameters like total sugars and reducing sugars
whereas, phenols showed significant negative correlation with population of mites.
Treatment, MeJA + Azadirachtin 10000 ppm at 1mM + 2ml/l has recorded the longest
egg, larval, prototonymphal and deutonymphal period of development of mites. The
biochemical analysis in seedlings of grapevine after mite infestation and treated with
MeJA resulted that, the higher amount of phenols was recorded in MeJA + Azadirachtin
10000 ppm at 1mM + 2ml/l. MeJA can be used to manage the mites in grapes
effectively, however higher market price of MeJA reduces the net profit. So, further
studies were needed with this aspect.