Characterisation of resistance in Okra (ABELMOSCHUS ESCULENTUS L.(MOENCH)) aganist shoot and fruit borer.,Earias vitella Fab. (Lepidoptera :Noctuidae) (Record no. 291823)
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| 000 -LEADER | |
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| fixed length control field | 08058nam a22001937a 4500 |
| 082 ## - DEWEY DECIMAL CLASSIFICATION NUMBER | |
| Classification number | 632.6 |
| Item number | ANJ/CH Ph.D |
| 100 ## - MAIN ENTRY--PERSONAL NAME | |
| Personal name | Anju Viswanathan, K |
| 245 ## - TITLE STATEMENT | |
| Title | Characterisation of resistance in Okra (ABELMOSCHUS ESCULENTUS L.(MOENCH)) aganist shoot and fruit borer.,Earias vitella Fab. (Lepidoptera :Noctuidae) |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. (IMPRINT) | |
| Place of publication, distribution, etc | Vellanikkara |
| Name of publisher, distributor, etc | Department of Agricultural Entomology, College of Agriculture |
| Date of publication, distribution, etc | 2024 |
| 300 ## - PHYSICAL DESCRIPTION | |
| Extent | 144,xixp. |
| 502 ## - DISSERTATION NOTE | |
| Dissertation note | Ph.D |
| 520 3# - SUMMARY, ETC. | |
| Abstract | Okra, also known as ladies finger, is one of the most extensively cultivated vegetable crops in the world. India ranks first in the world in okra cultivation with an annual production of 6466 thousand MT across an area of 531 thousand hectares with a productivity of 12.0 MT/ha. Yet, the crop suffers yield loss to the tune of 35 to 40 per cent due to biotic stresses alone. The okra shoot and fruit borer, Earias vitella is one of the most destructive insect pests of okra, often accounting for 35 to 80 per cent yield loss. The borer is managed mostly through chemical means, which leads to issues such as residues in fruits and adverse environmental effects. In this backdrop, more benign options against E. vitella like the use of host plant resistance assume great significance, as use of resistant varieties constitute one of the safest and cost-effective methods of pest management. It was in this context that the present study “characterisation of resistance in okra (Abelmoschus esculentus L. (Moench)) against shoot and fruit borer, Earias vitella Fab. (Lepidoptera: Noctuidae)” was undertaken at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, Kerala Agricultural University, Thrissur, during 2020 to 2023. Exploitation of plant resistance calls for screening of existing germplasm for sources of resistance, understanding the mechanisms of resistance and the factors that influence expression of plant resistance. The study aimed to throw light into these dimensions of resistance in okra to E. vitella. Fifty genotypes of okra, collected from different sources, were screened for resistance to shoot and fruit borer, E. vitella under open field conditions. Significant variation was observed between the genotypes in terms of shoot and fruit damage. Shoot damage varied from 0 to 30 per cent. Susthira, the okra variety released from KAU had recorded zero shoot damage and was followed by the genotype IC 140906 with 9.79 per cent mean shoot damage. The NBPGR accessions IC 128076 and IC 43748 recorded highest mean shoot damage of 28.21 and 30.0 per cent respectively. The fruit damage ranged from 3.42 in Susthira to 85.31 per cent in IC 117123. Susthira was rated as highly resistant, while IC 282294 and Aruna, with mean fruit damage of 11.53 and 20.14 per cent respectively, were rated as moderately resistant. IC 218900, IC 140906 and IC 128885 with mean fruit damage between 21-30.99 per cent were classified as susceptible and rest of the genotypes, with more than 31 per cent fruit damage were assessed as highly susceptible. Biophysical characteristics such as trichome length, trichome density, fruit length, fruit width, fruit rind thickness, fruit colour and shoot diameter were also recorded for all the fifty genotypes along with shoot and fruit damage. It was observed that trichome density, fruit length, and fruit rind thickness had significant negative correlation with fruit damage, while trichome length and fruit width enjoyed a positive correlation. Shoots of the resistant variety Susthira possessed modified secretory parenchyma for enhanced production of mucilage and defence compounds, thicker collenchyma for mechanical strength and also a thicker cortex, when compared to susceptible accessions. Significant positive correlation was also observed between fruit damage and biochemical parameters such as moisture content, total sugar, reducing sugar and protein. However, significant negative correlation existed between fruit damage and phenol, fibre and gossypol contents. Studies on the feeding preference of third instar larvae of E. vitella to selected okra genoytypes, through multi-choice test revealed that Susthira attracted the lowest mean value of 0.08 per cent out of the 25 larvae released. The moderately resistant IC 282284 and Aruna had 9.60 and 11.20 per cent larvae feeding on them 24 h after release, while the highly susceptible genotypes, between them, attracted 78.40 per cent of the larvae released. Similarly, in a free-choice test using the seven selected genotypes of okra to assess the ovipositional preference of adult E. vitella moths, the highest mean number of 117.91 eggs were laid on plants of IC 128076, followed by IC 282266, IC 282284 and IC 117123, with 117.90, 114.00 and 109.88 eggs/ plant respectively, all of which were categorized as highly susceptible genotypes to shoot and fruit borer in the present study. Significantly lower number of eggs were laid on the highly resistant Susthira (21.13 eggs/ plant) as well as the moderately resistant IC 282294 (59.26 eggs/ plant), and Aruna (65.89 eggs/ plant). Considerable variation was observed in the embryonic and post-embryonic development of E. vitella when reared on different okra genotypes under no-choice conditions. E. vitella recorded the shortest mean incubation period of 2.60 days, the lowest mean larval duration of 5.60 days, the longest mean pupal period of 11.05 days and the shortest mean adult longevity of 7.10 days when reared on Susthira. The insect also registered the lowest larval and pupal weight of 0.0638 and 0.0471 g respectively on Susthira, suggesting an antibiotic mechanism of resistance. On the contrary, E. vitella recorded the longest egg incubation period, of 4.30 days, the longest larval duration of 13.20 days, the shortest pupal duration of 6.15 days and the longest adult longevity of 15.90 days on the highly susceptible genotype IC 117123. The GC-HRMS and HR-LCMS analyses of the resistant Susthira revealed the presence of several insect repellents, feeding and oviposition deterrents, growthregulating compounds and insecticidal compounds in the hexane and methanol fractions of Susthira. The impact of spacing and fertilizer regimes on expression of plant resistance in okra against shoot and fruit borer was studied by planting Susthira in a 3x3 factorial design. The three levels of spacing were S1 (65 cm x 50 cm); S2 (60 cm x 45 cm) and S3 (55 cm x 40 cm) while the three levels of fertilizers were N1 (138: 44: 88 kg of NPK haˉ¹), N2 (110: 35: 70 kg of NPK haˉ¹) and N3 (83: 27: 53 kg of NPK haˉ¹). There was no shoot damage to Susthira in any of the treatment combinations. The mean fruit damage varied significantly among the different treatments. The highest fruit damage of 3.02 per cent was observed in S1N1, which was followed by S2N1 (2.60%) and S2N2 (2.31%). The lowest damage of 0.57% was recorded in S3N3, which was significantly lower than that of other treatments. The study brought out the variability in the response of different okra genotypes to shoot and fruit borer infestation, indicating the potential for utilization of host plant resistance in the management of shoot and fruit borer in okra. The resistance has been shown to be based on the morphological and biochemical attributes of plant, which, however, need to be confirmed. Both antixenosis and antibiosis mechanisms could be involved in the resistance of okra genotypes to E. vitella. The highly resistant Susthira recorded zero shoot damage and very low fruit damage under different agronomic regimes, suggesting a very strong and stable resistance in this genotype. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Agricultural entemology |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | ABELMOSCHUS ESCULENTUS L. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Resistance in Okra |
| 700 ## - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Madhu Subramanian(Guide) |
| 856 ## - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | https://krishikosh.egranth.ac.in/handle/1/5810219528 |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | |
| Item type | Theses |
| Not for loan | Collection code | Permanent location | Current location | Shelving location | Date acquired | Full call number | Barcode | Date last seen | Koha item type |
|---|---|---|---|---|---|---|---|---|---|
| Not For Loan | Thesis | KAU Central Library, Thrissur | KAU Central Library, Thrissur | Theses | 2025-01-21 | 632.6 ANJ/CH Ph.D | 176243 | 2025-01-21 | Theses |