Borah, R. K.Choudhury, Kasturi2019-05-172019-05-172017-07http://krishikosh.egranth.ac.in/handle/1/5810103602The investigations on “Molecular basis of varietal resistance of brinjal against Leucinodes orbonalis Guenee (Lepidoptera: Pyralidae) and its eco-friendly management” were carried out at College of Agriculture, Assam Agricultural University, Jorhat during 2013-14 and 2014-15. Studies on the varietal screening of brinjal varieties revealed that the minimum shoot as well as fruit infestation on number basis recorded on variety Khorua-1 with 2.96 and 9.31 per cent, respectively. The minimum fruit infestation on weight basis was recorded on variety Brinjal long green (5.54 %). The highest infestation of shoot (17.85 %) and fruit infestation on number basis (36.52 %) and weight basis (36.08 %) noted on variety JC- 1. The remaining varieties viz., Brinjal long green , Khorua-2, White brinjal, Borbengena, Sagalihingia, Tita bengena, Pusa purple cluster and Pusa purple long registered shoot infestation ranged from 3.05 to 13.69 per cent, 9.70 to 21.81 per cent fruit infestation on number basis and 5.54 to 21.84 per cent on weight basis. The highest brinjal fruit yield was recorded on JC-1 (238.69 q/ha) followed by Pusa purple long (177.83 q/ha). The minimum fruit yield was recorded on Khorua-2 (30.69 q/ha). Varieties Brinjal long green, Khorua-1, White brinjal and Khorua-2 were designated as resistant to L. orbonalis as fruit damage recorded between 1.0 to 10.00 per cent. The fairly resistant varieties to L. orbonalis comprised of Pusa purple cluster, Borbengena and Sagalihingia which registered fruit infestation ranged from 11.0 to 20.0 per cent. Two varieties viz., Khorua-3 and Pusa purple long were categorized as tolerant (21.0 to 30.0%) fruit infestation. The varieties viz., Tita bengena and JC-1 were found susceptible to shoot and fruit borer with fruit infestation between 31.0 to 40.0 per cent. The influence of morphological and biochemical factors on the infestation by L. orbonalis revealed that the correlations of shoot diameter (r= 0.646), plant height (r=0.291), leaf thickness (r=0.314), and leaf area (r=0.137) with shoot infestation by L. orbonalis were positive but did not show any significant correlation , however the effect of trichome density (r = -0.140) exhibited negative association with shoot infestation , while length of pedicel (r=0.388), length of calyx (r =0.473) and fruit length (r =0.234) were statistically significant but did not show any significant correlation with fruit infestation. Among biochemical contents in shoots, the total phenol (r= -0.584), peroxidase (r= - 0.796) and polyphenol oxidase (r = -0.734) showed significantly negative correlation with per cent shoot infestation caused by L. orbonalis. In regards to the studies of defense response gene, the relative expression level of Ascorbate Peroxidase1 (AP1) and PR3 gene were significantly higher in resistant Khorua variety than in the susceptible JC-1 variety in response to L. orbonalis regurgitant. The relative expression of AP1 and PR-3 gene in Khorua brinjal were greater than 45 and 40 fold higher than untreated control, respectively. However, the expression of this gene was significantly lower in susceptible brinjal, JC1. Six different modules were tested against L.orbonalis in order to develop an ecofriendly management tactics against this pest. Among the different treatment modules, Module III that includes seedling root dip treatment by Imidacloprid 17.8 SL @ 0.5 ml/lit for 3 hrs + Clean cultivation at 15 days interval +Clipping of infested shoots and destruction of infested fruits +Intercrop with Coriander +Spraying with Spinosad 45 SC @ 0.1ml/lit were found to the best performer in suppressing of shoot infestation (6.04% and 6.95%) in 2013- 14 and 2014-15, respectively as well as fruit infestation on number basis (15.71%) and weight basis (17.16%) by L. orbonalis. All the treatment modules had also significantly reduced the shoot and fruit infestation as compared to untreated control. The maximum total increased in yield over untreated control was recorded in Module III (162.17 q/ha) followed by Module IV (133.91 q/ha), and Module V (95.47 q/ ha) while, minimum total increase in yield (88.18 q/ ha) over untreated control was recorded in ModuleI followed by Module II (92.92 q/ ha). The maximum net profit of Rs. 322790.00/ ha was obtained in Module III followed by Module IV (Rs. 279910.00/ ha), Module II (Rs. 218065.00/ ha) and Module I ( Rs. 205465.00 /ha) and Module V (Rs. 195125.00/ha) while, the minimum net profit of Rs. 97920.00 was obtained in control plot (Module VI). The maximum B:C ratio of 4.06 was obtained in Module III followed by Module IV (3.50), Module II (2.72) and Module I (2.40), Module V (1.82) and Module VI (1.60).ennullThesis