PhD Thesis
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Item Development of gynoecious genotypes with superior fruit quality in bitter gourd (Momordica Charantia L.) through marker assisted breeding(Department of Vegetable Science, College of Agriculture ,Vellanikkara, 2024-02-06) Anju M Sunny.; Pradeepkumar, TThe doctoral study entitled ‘Development of gynoecious genotypes with superior fruit quality in bitter gourd (Momordica charantia L.) through marker assisted breeding’ was undertaken with the objective of developing gynoecious bitter gourd lines with superior fruit quality through marker assisted breeding and to analyze the genetics of sex expression and fruit quality by generating F2 and back cross population. The work was carried out in the experimental field of the Department of Vegetable Science, College of Agriculture, Vellanikkara. Gynoecious line KAUMCGy- 101, identified from the Department of Vegetable Science, and three monoecious lines viz., Preethi, Priyanka, and MC 133 were used for the hybridization. Six hybrids were produced by crossing gynoecious inbred as both male and female parents. The hybrids were, Preethi × KAU-MCGy-101, Priyanka × KAUMCGy- 101, MC133 × KAU-MCGy-101, KAU-MCGy-101 × Preethi, KAU-MCGy- 101 × Priyanka and KAU-MCGy-101 × MC133. All the hybrids with gynoecious line as male or female parent exhibited high heterosis for earliness attributing traits like days to first female flower opening, node bearing first female flower, and days to first harvest. The traits such as a lower sex ratio and a greater number of fruits per plant contributed to higher yields in these hybrids. The superiority of hybrids having a gynoecious line as a maternal parent is prominent in the present study. The correlation studies revealed a positive correlation between fruit length (0.569), fruit weight (0.612), number of seeds (0.507), and number of harvests (0.619) with yield. While days to first female flower opening (-0.386), node bearing first female flower (-0.244), fruit girth (-0.018), and days to first harvest (-0.285) showed a non-significant negative correlation. Path analysis showed a positive direct effect of fruit weight (0.568), fruit girth (0.155), number of seeds (0.579), days to first harvest (0.009), number of harvests (0.755), and number of fruits per plant (0.036) on yield per plant. The sensory attributes, nutritional potentials, and shelf life of six bitter gourd hybrids and their parents were evaluated. Bitter gourd fruits with white or light green fruits were found to have a more appealing flavor and appearance than dark green fruits, resulting in a higher overall acceptability rating. The hybrid, KAU-MCGy-101 × MC 133 was found superior with 17.05 mg/100g calcium. Preethi and KAUMCGy- 101 × Priyanka exhibited maximum shelf life among the parents and hybrids, respectively. Among the hybrids, the cross KAU-MCGy-101 × Priyanka was superior with respect to yield and quality traits (fruit weight- 172.47 g, number of fruits per plant- 69.67 and yield per plant- 9.15 kg). The genetics of economically significant horticultural traits in the cross KAU-MCGy-101 x Priyanka was studied resorting generation mean analysis. The results of the A, B, C, and D scaling tests indicate that all the traits, except for days to the first female flower opening, do not adhere to an additive dominance model. The significant and positive additive effect (d) was observed for the number of tubercles and number of fruits per plant, indicating that the additive effect of the genes is predominant and that the selection of these traits should be delayed to later generations. Regarding the yield, the interaction effect of dominance x dominance (l) was highly significant, while the other interaction effects were insignificant. Therefore, recurrent selection is necessary for improving this trait. A complementary type of epistasis was observed for the number of fruits per plant, while all other traits were observed to be of the duplicate type. The χ2 analysis for goodness of fit indicated that gynoecy in the line KAUMCGy- 101 is controlled by a single recessive gene (gy-1). The inheritance pattern of fruit color indicates that green fruit color is dominant over white. The present study identified two gynoecious lines from the F2 population namely, KAU-MCGy-101-1 and KAU-MCGy-101-2 (green and light green fruited respectively). These gynoecious lines had better fruit quality and hold immense potential for future breeding programs in bitter gourd improvement. Marker-assisted selection is considered one of the important strategies for identifying different sex forms in crop plants. The present investigation resulted in identifying one SNP primer that could produce polymorphism between the monoecious and gynoecious parents. The six exonic regions with flanking introns of the gene floral homeotic protein AGAMOUS-like (McAG2) and two exonic regions with flanking introns of the gene ACO1 were sequenced by designing exons-specific primer pairs. The primer NETBG2 developed based on the exon 2 region of the gene ACO1 accounts for eight valid SNPs within the sequenced region of the gynoecious parent used in this study. The study confirmed the monogenic recessive nature of gynoecy. The improved gynoecious lines identified will help in developing cultivars with a higher proportion of female flowers. The results of the molecular work revealed the role of the 1-aminocyclopropane-1-carboxylate oxidase (ACO1) gene in the sex expression of the bitter gourd. The SNPs identified can be used for further studies on the SNP-based marker development for identifying gynoecious plants and have the potential in marker assisted breeding based on gynoecy in bitter gourd.Item Development and evaluation of high yielding, mosaic tolerant backcross progenies in bitter gourd (Momordica charantia L.) variety Preethi using morphological, biochemical and molecular markers(Department of Genetics and Plant Breeding, College of Agriculture ,Vellayani, 2024-05-23) Ankitha, M O; KAU; Bindu, M RThe present research work entitled ‘Development and evaluation of high yielding, mosaic tolerant backcross progenies in bitter gourd (Momordica charantia L.) variety Preethi using morphological, biochemical and molecular markers’ was conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani and Farming Systems Research Station (FSRS), Sadanandapuram during the year 2020-2023, with an objective to develop high yielding mosaic tolerant backcross progenies in bitter gourd using morphological, biochemical and molecular markers. Thirty three bitter gourd genotypes, including KAU released varieties (2 No’s), NBPGR accessions (13 No’s), and local collections from all over India were used for screening mosaic tolerance. Out of the 33 genotypes, 26 genotypes were Momordica charantia var. charantia and seven were Momordica charantia var. muricata. All these genotypes were artificially inoculated with the three viruses Cucumber Mosaic Virus (CMV), Tomato Leaf Curl New Delhi Virus (ToLCNDV) and Papaya Ringspot virus (PRSV) through wedge grafting. Wedge grafting was done using the infected plant shoots as scion and the collected genotypes as root stock and regrowth from the cotyledonary axis was examined for symptom expression. Out of the 33 genotypes screened, three were highly resistant, four were resistant, five were moderately resistant, six were moderately susceptible, ten were susceptible and five were highly susceptible. The genotypes Lodhi local, Udayagiri local and Therthali local recorded a lowest Vulnerability Index of zero. Molecular markers reported in Cucurbitaceae family were validated for bitter gourd mosaic resistance gene. SSR-11-1 marker for CMV resistance and CAPS marker for Potyvirus resistance gene were used, but no amplification was obtained. Double Antibody Sandwich ELISA (DAS-ELISA) was performed to confirm the resistance reaction of three highly resistant genotypes identified in seedling screening. Optical density (OD) value of the genotypes for the three viruses, CMV, ToLCNDV and PRSV were less than twice the OD value of the un-inoculated healthy plant which confirmed highly resistant disease reaction of genotypes. Molecular confirmation was done by using coat protein primer (Deng primer) specific to the Begomovirus group. Deng primer amplifies coat protein gene of ToLCNDV (520 bp), so that band will be present in only susceptible genotypes and will be absent in resistant ones. Plant defense related enzymes such as peroxidase, polyphenol oxidase and phenyl alanine ammonialyase was estimated and there was increased rate of synthesis of these enzymes in the identified resistant genotypes. So the identified resistant genotypes, Lodhi local, Udayagiri local and Therthali local were used as the donor parent for imparting mosaic resistance into the bitter gourd variety Preethi. Lodhi local is M. charantia var. charantia genotype where as both Udayagiri local and Therthali local are M. charantia var. muricata genotypes. High yielding variety released from KAU viz., ‘Preethi’ was selected as the recurrent parent in the study. Preethi was crossed with the three donor parents and F1s were produced. The F1s were morphologically evaluated with the parents for seventeen characters and it was observed that all the characters of F1 were approximately the average of two parents. All the F1s were backcrossed with Preethi to produce BC1F1 segregants. In the backcross progeny of the cross involving Preethi and Lodhi local, a total of 176 BC1F1 lines were developed. BC1F1 lines were artificially inoculated for their disease reaction. Among the 176 BC1F1 lines, 22 were found to be highly resistant to mosaic disease, 30 were resistant, 30 were moderately resistant, 26 were moderately susceptible, 35 were susceptible and 33 were highly susceptible. Confirmation of resistance was done using DAS- ELISA, Deng primers and estimation of defense enzymes. All the 17 biometrical characters were recorded and the Euclidean distance of the highly resistant BC1F1 lines from the recurrent parent Preethi was calculated using proximity dissimilarity matrix analysis. The 14 BC1F1 lines with high phenotypic similarity to Preethi was backcrossed to develop BC2F1 lines. In the backcross progeny of the cross involving Preethi and Udayagiri local, a total of 170 BC1F1 lines were produced. Among them 15 BC1F1 lines were highly resistant. Resistant reaction of identified 15 BC1F1 was confirmed by DAS-ELISA, molecular screening and biochemical analysis. Euclidean distance of the highly resistant 15 BC1F1 lines from the recurrent parent revealed that eight lines showed similarity with Preethi and they were backcrossed to get BC2F1 lines. A total 147 BC1F1 lines of the cross involving Preethi and Therthali local were screened at seedling stage. Out of the 147 lines, 16 BC1F1 lines were highly resistant. DAS-ELISA, molecular screening using aforementioned Deng primer confirmed the resistant reaction of these lines. Euclidean distance using biometric characters found that, out of 16 highly resistant BC1F1 lines eight lines had close proximity with Preethi. These lines were used to produce BC2F1 lines. The 190 BC2F1 lines of the cross involving Preethi and Lodhi local were screened at seedling stage and in 24 BC2F1 lines, there was absence of virus coat protein band which confirmed the highly resistant disease reaction of the aforementioned lines. The 12 BC2F1 lines with the shortest Euclidean distance and high phenotypic similarity with Preethi were selfed to generate BC2F2 seeds. In the 134 BC2F1 lines of the cross involving Preethi and Udayairi local, seedling screening recorded 17 highly resistant lines. After molecular confirmation of mosaic resistance four BC2F1 lines with close proximity to Preethi were selfed to get BC2F2 seeds. Out of the 143 BC2F1 lines of the cross involving Preethi and Therthali local, 20 BC2F1 lines were highly resistant. The molecular analysis of the 20 BC2F1 lines also confirmed the highly resistant reaction. Four BC2F1 lines with the shortest Euclidean distance was selected and selfed to produce BC2F2 seeds. Although there were BC2F2 seeds of three different crosses, only the BC2F2 seeds of the cross involving Preethi and Lodhi local was carried forward for further backcrossing. This is due to the low yield potential of the backcross progenies of the crosses involving M. charantia var. muricata genotypes. So 206 BC2F2 lines of the cross involving Preethi and Lodhi local were artificially screened at seedling stage for mosaic incidence. Out of the 206 BC2F2 lines, 42 plants were highly resistant to bitter gourd mosaic viruses. The 42 mosaic tolerant backcross inbred lines developed in the study can be carried forward for the development of a mosaic tolerant essentially derived variety (EDV) in the background of high yielding variety Preethi. The backcross progenies obtained in the crosses involving muricata genotypes can be further evaluated for its nutraceutical values.Item Development and evaluation of high yielding, mosaic tolerant backcross progenies in bitter gourd (Momordica charantia L.) variety Preethi using morphological, biochemical and molecular markers(Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, 2024-05-23) Ankitha, M O; KAU; Bindu, M RThe present research work entitled ‘Development and evaluation of high yielding, mosaic tolerant backcross progenies in bitter gourd (Momordica charantia L.) variety Preethi using morphological, biochemical and molecular markers’ was conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani and Farming Systems Research Station (FSRS), Sadanandapuram during the year 2020-2023, with an objective to develop high yielding mosaic tolerant backcross progenies in bitter gourd using morphological, biochemical and molecular markers. Thirty three bitter gourd genotypes, including KAU released varieties (2 No’s), NBPGR accessions (13 No’s), and local collections from all over India were used for screening mosaic tolerance. Out of the 33 genotypes, 26 genotypes were Momordica charantia var. charantia and seven were Momordica charantia var. muricata. All these genotypes were artificially inoculated with the three viruses Cucumber Mosaic Virus (CMV), Tomato Leaf Curl New Delhi Virus (ToLCNDV) and Papaya Ringspot virus (PRSV) through wedge grafting. Wedge grafting was done using the infected plant shoots as scion and the collected genotypes as root stock and regrowth from the cotyledonary axis was examined for symptom expression. Out of the 33 genotypes screened, three were highly resistant, four were resistant, five were moderately resistant, six were moderately susceptible, ten were susceptible and five were highly susceptible. The genotypes Lodhi local, Udayagiri local and Therthali local recorded a lowest Vulnerability Index of zero. Molecular markers reported in Cucurbitaceae family were validated for bitter gourd mosaic resistance gene. SSR-11-1 marker for CMV resistance and CAPS marker for Potyvirus resistance gene were used, but no amplification was obtained. Double Antibody Sandwich ELISA (DAS-ELISA) was performed to confirm the resistance reaction of three highly resistant genotypes identified in seedling screening. Optical density (OD) value of the genotypes for the three viruses, CMV, ToLCNDV and PRSV were less than twice the OD value of the un-inoculated healthy plant which confirmed highly resistant disease reaction of genotypes. Molecular confirmation was done by using coat protein primer (Deng primer) specific to the Begomovirus group. Deng primer amplifies coat protein gene of ToLCNDV (520 bp), so that band will be present in only susceptible genotypes and will be absent in resistant ones. Plant defense related enzymes such as peroxidase, polyphenol oxidase and phenyl alanine ammonialyase was estimated and there was increased rate of synthesis of these enzymes in the identified resistant genotypes. So the identified resistant genotypes, Lodhi local, Udayagiri local and Therthali local were used as the donor parent for imparting mosaic resistance into the bitter gourd variety Preethi. Lodhi local is M. charantia var. charantia genotype where as both Udayagiri local and Therthali local are M. charantia var. muricata genotypes. High yielding variety released from KAU viz., ‘Preethi’ was selected as the recurrent parent in the study. Preethi was crossed with the three donor parents and F1s were produced. The F1s were morphologically evaluated with the parents for seventeen characters and it was observed that all the characters of F1 were approximately the average of two parents. All the F1s were backcrossed with Preethi to produce BC1F1 segregants. In the backcross progeny of the cross involving Preethi and Lodhi local, a total of 176 BC1F1 lines were developed. BC1F1 lines were artificially inoculated for their disease reaction. Among the 176 BC1F1 lines, 22 were found to be highly resistant to mosaic disease, 30 were resistant, 30 were moderately resistant, 26 were moderately susceptible, 35 were susceptible and 33 were highly susceptible. Confirmation of resistance was done using DAS- ELISA, Deng primers and estimation of defense enzymes. All the 17 biometrical characters were recorded and the Euclidean distance of the highly resistant BC1F1 lines from the recurrent parent Preethi was calculated using proximity dissimilarity matrix analysis. The 14 BC1F1 lines with high phenotypic similarity to Preethi was backcrossed to develop BC2F1 lines. In the backcross progeny of the cross involving Preethi and Udayagiri local, a total of 170 BC1F1 lines were produced. Among them 15 BC1F1 lines were highly resistant. Resistant reaction of identified 15 BC1F1 was confirmed by DAS-ELISA, molecular screening and biochemical analysis. Euclidean distance of the highly resistant 15 BC1F1 lines from the recurrent parent revealed that eight lines showed similarity with Preethi and they were backcrossed to get BC2F1 lines. A total 147 BC1F1 lines of the cross involving Preethi and Therthali local were screened at seedling stage. Out of the 147 lines, 16 BC1F1 lines were highly resistant. DAS-ELISA, molecular screening using aforementioned Deng primer confirmed the resistant reaction of these lines. Euclidean distance using biometric characters found that, out of 16 highly resistant BC1F1 lines eight lines had close proximity with Preethi. These lines were used to produce BC2F1 lines. The 190 BC2F1 lines of the cross involving Preethi and Lodhi local were screened at seedling stage and in 24 BC2F1 lines, there was absence of virus coat protein band which confirmed the highly resistant disease reaction of the aforementioned lines. The 12 BC2F1 lines with the shortest Euclidean distance and high phenotypic similarity with Preethi were selfed to generate BC2F2 seeds. In the 134 BC2F1 lines of the cross involving Preethi and Udayairi local, seedling screening recorded 17 highly resistant lines. After molecular confirmation of mosaic resistance four BC2F1 lines with close proximity to Preethi were selfed to get BC2F2 seeds. Out of the 143 BC2F1 lines of the cross involving Preethi and Therthali local, 20 BC2F1 lines were highly resistant. The molecular analysis of the 20 BC2F1 lines also confirmed the highly resistant reaction. Four BC2F1 lines with the shortest Euclidean distance was selected and selfed to produce BC2F2 seeds. Although there were BC2F2 seeds of three different crosses, only the BC2F2 seeds of the cross involving Preethi and Lodhi local was carried forward for further backcrossing. This is due to the low yield potential of the backcross progenies of the crosses involving M. charantia var. muricata genotypes. So 206 BC2F2 lines of the cross involving Preethi and Lodhi local were artificially screened at seedling stage for mosaic incidence. Out of the 206 BC2F2 lines, 42 plants were highly resistant to bitter gourd mosaic viruses. The 42 mosaic tolerant backcross inbred lines developed in the study can be carried forward for the development of a mosaic tolerant essentially derived variety (EDV) in the background of high yielding variety Preethi. The backcross progenies obtained in the crosses involving muricata genotypes can be further evaluated for its nutraceutical values.Item Mapping the QTL for yield traits in bitter gourd (Momordica charantia L.)(Centre for Plant Biotechnology and Molecular Biology, College of Agriculture, Vellanikkara, 2022) Lavale Shivaji Ajinath; Deepu MathewBitter gourd (Momordica charantia), being a rich source of phytonutrients such as carbohydrates, minerals, vitamins, and other medicinal compounds, has a great importance in healthy dietary habits. Breeders always seek to breed bitter gourd varieties for the traits such as early maturity and high yield. However, limited investigations have been made to identify the genetic loci governing yield related traits. Marker assisted selection (MAS) assures the presence of favourable alleles and fast recovery of recurrent parent genome in the cultivar under improvement. The success of MAS mainly depends on the availability of a marker-dense genetic linkage map locating quantitative trait loci (QTL) for the target traits. The present study “Mapping the QTL for yield traits in bitter gourd (Momordica charantia L.)” was carried out during October, 2018 to December, 2021 with the objective to map the quantitative trait loci and to develop chromosome-wise maps for the yield traits in bitter gourd. To develop the mapping population, high yielding bitter gourd cultivar Priyanka (Momordica charantia var. charantia) and a wild bitter gourd accession IC634896 (M. charantia var. muricata), were used as parents. A set of 450 microsatellites were screened for polymorphism using genomic DNA of parents and 47 were found polymorphic. Bitter gourd genome (GenBank acc. no. GCA_013281855.1) was scanned and new hypervariable microsatellites were identified using Genome wide Microsatellite Analysing Tool (GMATo) and named as KAUBG_n where n is a serial number. From the 75 microsatellites identified, 69 were validated through successful PCR amplification and 38 among them were polymorphic between the parents. This led to the development of a set of 85 markers polymorphic between the parents. Crosses were made between the parental lines and hybrids from the cross Priyanka × IC634896 yielded more number of fruits and total fruit produce compared to the reciprocal hybrid. An F2:3 population was developed through single seed descent method from the cross Priyanka × IC634896. A panel of 200 F2:3 plants were evaluated for twenty seven traits, including fruit-, flower-, seed-, vine-, and leaf-related traits, contributing directly or indirectly to the total yield. Wide variation was observed among the F2:3 plants for the traits studied. A group of ninety plants was selected from 200 F2:3 plants such that they represent the variation of the base population. Genomic DNA of these plants were genotyped using 85 polymorphic markers. Genotypic data from the screening of 85 markers in the mapping population were used to generate a linkage map spanning 1287.99 cM distance across eleven linkage groups (LGs) corresponding to eleven chromosomes, using IciMapping software. LG 7 (28 markers) consisted of maximum number of markers followed by LG 2 and LG 9, each having 11 markers. LG 1 had 10 markers whereas LG 3, 4 and 8 had seven markers each. LG 5, 6, 10 and 11 had only one marker each. LG 7 covered maximum map distance of 384.19 cM where LG 8 covered least map distance of 68.58 cM. The genetic map and phenotypic data were used to generate the QTL maps, using Inclusive Composite Interval Mapping (ICIM) method to locate twenty seven traits on Momordica genome. Sixty QTL, including 37 major QTL with LOD values ranging from 3.1 to 15.2, explaining 1.8 to 35.9 per cent of the phenotypic variation were identified for 24 traits, on seven chromosomes. Twenty three QTL were identified for fruit-traits with LOD values ranging from 3.1 to 7.6, explaining 5.5 to 35.9 per cent of phenotypic variation. Thirteen QTL were identified for flower-related traits with LOD value ranging from 3.1 to 15.2, explaining 7.0 to 26.0 per cent of phenotypic variation. Seven QTL each were identified for seed and leaf-related traits with LOD values ranging from 3.2 to 10.8 and 3.5 to 6.5, explaining 5.6 to 26.3 and 3.2 to 15.8 per cent of phenotypic variation, respectively. Ten QTL were identified for vine-related traits with 3.2 to 8.7 LOD values and explaining 1.8 to 17.6 per cent of phenotypic variation. Single marker analysis was performed to identify markers co-segregating with the yield contributing traits. There were 129 hits for the marker-trait association with LOD values more than 3.0, explaining 11.62 to 29.34 per cent of the phenotypic variation. Using the least and best performing F2:3 plants, markers S13, KAUBG_5 and KAUBG_11 were validated for co-segregation with fruit breadth, first pistillate flower node, and number of pistillate flowers and fruits per plant, respectively. This study gives insights into the relative locations of microsatellites and major effect QTL for yield traits in Momordica genome. QTL with shorter marker interval (qFrtL-8-1, qDPF-3-1, qDSF-3-1, qDSF-7-1, qFrtShp-8-1) can be directly used in MAS for improving yield characters. Linkage observed between microsatellites identified in this study with yield traits signifies their importance in further fine mapping as well as marker assisted selection. The linkage map constructed in this study, being the first with microsatellites from Momordica genome, paves the path for comparative and consensus map generation with other marker types. Further, fine mapping using markers within the identified QTL hotspots can lead to possible identification and cloning of genes underlying the yield traits.Item Homeostatic analysis of components of genetic variance and inheritance of fruit colour, fruit shape and bitterness in bitter gourd (Momordica charantia L.)(Department of Olericulture, College of Horticulture, Vellanikkara, 1989) Abdul Vahab, M; Gopalakrishnan, P KItem Population dynamics and biorational management of melon fly, (bactrocera cucurbitae (coquillet)) in bitter gourd (momordica charantia L.)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2006) Rameash, K; Jim ThomasItem Management of pumpkin mosaic using selected medicinal plant extracts(Department of Plant Pathology, College of Horticulture,Vellanikkara, 2003) Vimi Louis; Sukumara Varma, A"Management of pumpkin mosaic using selected medicinal plant extracts" was undertaken in the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during 1998-2002. Selection of suitable medicinal plant having antiviral property to pumpkin mosaic virus (PMV), isolation of the inhibitory principle present in the medicinal plant, management of pumpkin mosaic using the plant extract and partial purification and serological studies of PMV were the objectives of the study. Symptomatology, transmission, host range and electron microscopy of PM V were also studied. The symptomatology of pumpkin mosaic was studied by observing the development of symptoms in naturally infected as well as artificially inoculated pumpkin plants. The symptoms appeared as typical mosaic mottling with light and dark green patches in the leaf lamina. This was followed by blistering and malformation of leaves into filiform or some other shapes and resulted in reduction of leaf area. The infected plants were stunted, flowered very sparingly with less number of female flowers and reduced fruit setting. The fruits were often malformed . The virus could be transmitted mainly through sap and vector, Aphis gossypii. The virus found to be weakly transmitted also through seeds. The inoculation of PMV on host plants of four families viz., cucurbitaceae, solanaceae, fabaceae and caricaceae showed systemic infection in water melon, snake gourd, bitter gourd, winter squash,' wild ash gourd (cucurbitaceae) chilli, datura (solanaceae), soybean, cow pea (fabaceae) and papaya (caricaceae). Electron microscopic studies revealed the presence of flexuous virus particles (700-800 x 11 nm) in infected leaf sample. Antiserum was raised against the virus and used for serodiagnostic work. The antiserum showed serological relationship with poty viruses infecting snake gourd, bitter gourd, wild ash gourd, cowpea, soybean, chilli and papaya. DAC- ELISA procedure was standardized and used for detection of PM V from pumpkin. The inhibitory property of extracts of five medicinal plants namely Basella alba, Glycyrrhiza glabra, Phyllanthus fraternus, Plumbago rosea 'and Thespesia populnea were studied-against PMV by pre-inoculation application on pumpkin seedlings. The medicinal plant extracts were prepared using different extraction media viz., chloroform, distilled water, ethyl acetate and petroleum ether at different dilutions. The inhibitory property varied with extraction media and dilution used. The PMV inhibitory property of different parts of Plumbago viz., tender leaf, mature leaf, tender stem, mature stem and root were studied at different temperatures and found that all parts showed inhibitory property which varied with temperature. The root extract which showed the maximum inhibitory property at 30°C (near to room temperature) was used for further studies. The effect of Plumbago on vector transmission was studied by applying the extract before acquisition feeding and inoculation feeding of Aphis gossypii, the vector of PMV. Application before inoculation feeding was found to be effective than acquisition feeding and the inhibitory effect decreased with time after application. Distilled water extract of Plumbago was separated through silica gel column to isolate the inhibitory fraction and found that individual fractions were not effective as plant extract as such against PMV. The inhibitory effect of Plumbago water extract one per cent, on artificially inoculated and healthy pumpkin seedlings was tested by weekly, fortnightly, monthly, bimonthly and single application. Weekly spray was effective to reduce disease severity of artificially inoculated and naturally infected pumpkin seedlings. Delayed incidence of the mosaic and enhanced yield of infected plants was also resulted due to weekly spray of the extract. Enzyme, protein, chlorophyll and phenolics estimation revealed that Plumbago extract spray favoured the resistance and thereby suppression of symptoms. The DAC-ELISA of field samples showed the lower concentration of the virus in Plumbago treated plants.Item Monitoring and management of the pest complex of bitter gourd (Momordica Charantia L.)(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1999) Nandakumar, C; Saradamma, KSurveys were conducted in 1995-96 among one hundred bitter gourd farmers in Thiruvananthapuram district. Information on the personal and socio- economic characteristics of the farmers was gathered. Field visits indicated that among the pests at flowering, the jassid, H.phycitis and leaf feeder, D. indica were important. At early harvest, the jassid and fruitfly B. cucurbitae were the major pests. Among the natural enemies observed, the potential ones were Cjohnsoni (parasite on Hseptima), I.scutellare, Msexmaculatus and Snubilis . (predators on A.gossypii). Mosaic was severe in 12 per cent of the plots. Sixty two per cent of the farmers used a combination of mechanical, cultural and chemical measures against pests. Most common pesticides used belonged to the organophosphate group. Farmers in general adopted injudicious methods of chemical control. Seventy per cent farmers relied on mass media and interpersonal cosmopolites for information on plant protection. The most important constraint perceived by farmers was the high cost of inputs viz., plant protection chemicals, manures and fertilizers. Monitoring of fruit fly incidence using Biosense stikatrap (lure) indicated the maximum catch at eleven weeks after sowing. Ten carbofuran smeared banana fruit traps (in yellow coloured coconut shell) were found to be more efficient than one Biosense trap in trapping the fruit fly. 2 Studies on seasonal incidence of the pests and their natural enemies from 1995 to 1996 indicated that they were more from November '95 to April '96. In studies on the assessment of potential natural enemies of pests, the biology and efficacy of Cjohnsoni against epilachna beetle was observed. Among the predators viz., Iscutellare, Msexmaculatus and S.nubilis whose biology and feeding potential was studied, Msexmaculatus was observed as the most efficient predator of aphids. In another set of experiments, the effects of botanicals and chemical pesticides on pests and their natural enemies were studied. The antifeedant effect of botanicals on third instar Hseptima grubs indicated that neem seed oil (three per cent) and nimbecidine (0.40 per cent) were effective. Estimation of the comparative effect of chemical pesticides against the fourth instar Hseptima grubs showed that carbaryl and dimethoate were more effective than quinalphos and malathion. Toxicity studies of botanicals and chemical pesticides to Msexmaculatus grubs and Cjohnsoni adults as well as parasite emergence from treated larval! pupal Hseptima hosts indicated that botanicals were safe whereas, the chemicals were toxic to the natural enemies. Based on the above experiments, the botanicals viz., neem seed oil three per cent, nimbecidine 0.40 per cent and the chemical pesticides,carbaryl 0.15 per cent and dimethoate 0.05 per cent were selected for the pest management trial in bitter gourd. The reaction of five bitter gourd varieties viz., Priya, Arka Harit, Preethi, Priyanka and local to pests was tested in a field trial. Based on pest infestation and yield, Preethi was selected for the pest management trial. 3 The pest management trial was conducted for two seasons (January to April, 1996 and 1997). The results indicated that combination of botanical with chemical pesticide was the best in pest control. Based on the results the following recommendations were suggested as part of IPM strategies in bitter gourd. 1. Use variety 'Preethi' (MC-84) for planting 2. Basal drenching of combination of nee m seed oil three per cent soap emulsion with either dimethoate (0.025 per cent) or carbaryl (0.075 per cent) prior to seeding. This is recommended in areas where pests like pumpkin beetles are endemic. 3. Need based application of above till fruit set to control pests. 4. Apply fungicide (Mancozeb) to control foliar disease (downy mildew). 5. Monitor fruit fly incidence using lure trap. Set yellow painted coconut shell trap's containing carbofuran smeared banana (palayankodan) alternated with carbofuran poisoned ocimum I jaggery (2m spacing) at flowering till final harvest. 6. After fruit set, use (need based) a combination of neem seed oil three per cent soap emulsion and dimethoate 0.025 per cent.Item Standradisation of organic and inorganic fertiliser comnbinations for maximising productivity in bitter gourd (Momordica Charantia L.)(Department of Agronomy, College of Agriculture, Vellayani, 1999) Rajasree, G; Raghavan Pillai, GItem Integrated management of viral diseases of bittergourd (momordica charantia L.)(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Radhika, N S; Umamaheswaran, K