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Item Screening of Bitter gourd (Momordica charantia L.) genotypes for resistance to powdery mildew disease(Department of Vegetable Science, College of Agriculture, Vellanikkara, 2025-05-17) Chethan, S V; Prasanth, KItem In-vitro chemotherapy for inducing tolerance towards Tomato leaf curl New Delhi virus (ToLCNDV)in bitter gourd (Momordica charanita L.)(Department of Molecular Biology and Biotechnology, College of Agriculture, Vellayani, 2023-12-12) Adarsh, M V.; Smitha BhasiThe study entitled “In-vitro chemotherapy for inducing tolerance towards Tomato Leaf Curl New Delhi virus in bitter gourd (Momordica charantia L.)” was conducted at the Department of Molecular Biology and Biotechnology, College of Agriculture, Vellayani, Thiruvananthapuram during 2022-23. The objective of the study was the evaluation of in-vitro treatment with antiviral compounds, viz., Ribavirin, Virus–Ex and extracts of Bougainvillea spectabilis for inducing tolerance towards Begomovirus- ToLCNDV in bitter gourd (Momordica charantia L.). The explants namely seed of bitter gourd variety Preethi was collected from, Instructional farm, College of agriculture, Vellayani. Seeds were subjected to hot water treatment at 55°C for 15 minutes, followed by washing in 0.2% bavistin for 15 minutes and kept in dark for inducing germination. 91.2% germination was noticed in 3 days. The germinated seeds were grown in Murashige and Skoog (MS) medium supplemented with 2ppm BA and 20ppm concentration of various antiviral compounds viz., Ribavirin (Treatment 1), Virus-Ex (Treatment 2), extract of Bougainvillea spectabilis (Treatment 3) along with control. Percentage of culture establishment was found to be maximum (65.25%) in ribavirin treated plants followed by virus ex and bougainvillea. 20 days old in-vitro grown plants were hardened in coir pith compost and the biometric observations were taken and compared. Significant increase in plant height and number of leaves over control was noticed in treatment using ribavirin and virus ex respectively. DNA was isolated from 20 day old (hardened) treated and control plants prior to whitefly transmission and were confirmed to be virus free using PCR. Whitefly mediated artificial inoculation of virus in hardened plants (25 day old) was done and the plants were maintained inside insect proof cage for symptom development. Symptoms were observed in control plants after 10 days of whitefly transmission. Further PCR was performed to confirm the presence/absence of Begomovirus. Absence of virus in treatments with ribavirin and virus ex were 59 confirmed in PCR. Treatment using extracts of bougainvillea did not show any symptoms but confirmed positive in molecular detection. The control plants which developed symptoms was found positive in PCR. Peroxidase assay (Lobenstein and Linsey method) showed maximum increase in activity (3-fold) in plants treated with ribavirin followed by extracts of bougainvillea (2-fold) three days after whitefly transmission. Biometric observations on 35th day viz., plant height, number of leaves and leaf area were found higher in all the treatments compared to control, out of which treatment using ribavirin was found to be highly significant for all the parameters. To conclude, the present study in bitter gourd could confirm the antiviral activity of ribavirin and virus ex towards Begomovirus through whitefly mediated transmission test and molecular detection using PCRItem Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2023-04-12) Gayathri, P S; Nisha, M SThe research work entitled “Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd” was carried out at Department of Entomology, College of Agriculture, Vellayani during 2020 to 2022. The objectives were to test the pathogenicity of entomopathogenic nematodes (EPNs) and to evaluate the effective EPN formulation against cucumber moth, D. indica in bitter gourd. The pathogenicity of two strains of entomopathogenic nematodes viz. Heterorhabditis indica Poinar and Steinernema carpocapsae Weiser were assessed against 3rd instar larvae of D. indica and Henosepilachna septima Dieke. Three different formulations viz. sponge, talc and alginate gel of the effective EPN strain were prepared and stored up to 11 weeks. Then, the survival percentage and virulence of infective juveniles (IJs) in each formulation was evaluated. A pot culture study was also conducted to evaluate the pathogenicity of effective EPN formulation against D. indica in bitter gourd. In the pathogenicity test, H. indica @ 100 IJs recorded highest mortality percentage of 42.50 for D. indica and 40.00 for H. septima at 24 Hours After Treatment (HAT). No mortality was observed for S. carpocapsae at all the concentration levels (10, 20, 50 and 100 IJs) for D. indica at 24 HAT. At 48 HAT, hundred per cent mortality was recorded only for H. indica at 100 IJs and it was on par with H. indica at 50 IJs. Both H. indica and S. carpocapsae at 50 and 100 IJs showed hundred per cent mortality at 60 HAT. All treatments showed hundred per cent mortality at 72 HAT. The number of IJs emerged from cadavers were slightly more for H. indica than S. carpocapsae for the same concentration of IJs. From the 1st experiment, H. indica was found to be more effective than S. carpocapsae against D. indica and H. septima. Therefore, survival percentage of IJs of H. indica were evaluated in different formulations. Highest survival percentage (100 per cent) was observed in alginate gel formulation in 1st week and it was on par with talc formulation up to 2 weeks. More than 50% survival of IJs was observed upto 8 weeks in alginate gel, 6 weeks in talc, 5 weeks in sponges and 3 weeks in water. 112 Results on virulence of IJs in different formulations revealed that IJs from alginate gel recorded mortality percentage ranging from 32.50 to 100.00 and 0.00 to 23.33 in 1st and 11th week of storage respectively against D. indica. It was statistically on par with freshly harvested juveniles at 72 HAT up to 5th week of storage. The next best formulation was found to be talc which was on par with freshly harvested juveniles at 72 HAT up to 4th week of storage. In the pot culture study, it was observed that the mortality of D. indica caused by IJs from alginate gel-based formulation of H. indica @ 4g L-1 (42.22 and 68.88) and talc- based formulation of H. indica @ 20g L-1 (40.00 and 68.88) was superior to talc-based formulation of Beauveria bassiana @ 2% (26.66 and 62.22) and neemazal 1% @ 0.2% + tween 80 (1%) (17.77 and 42.22) at 1 and 3 DAT respectively. The effect of H. indica was on par with talc-based formulation of B. bassiana @ 2% and neemazal 1% @ 0.2% + tween 80 (1%) at 5 and 7 DAT. At the same time, the highest mortality (100 per cent) was obtained for chlorantraniliprole 18.5SC@ 30g a.i. ha-1. The damage caused by D. indica ranged from 16.92 to 34.99 in alginate gel-based formulation of H. indica @ 4g L-1 and 19.97 to 41.74 in talc- based formulation of H. indica @ 20g L-1. Its effect on damage of leaves was on par with talc-based formulation of B. bassiana @ 2% of damage percentage 28.57, 40.21 and 41.00 at 3, 5, and 7 DAT respectively. Effect of H. indica formulations on the emergence of Bactrocera cucurbitae (Coquillett) from soil was studied under in vitro. Soil treated with alginate gel-based formulation of H. indica @ 4g L-1 and talc- based formulation of H. indica @ 20g L-1 recorded 16.66 per cent emergence of B. cucurbitae and its effect was on par with chlorantraniliprole 18.5SC@ 30g a.i. ha-1. Based on the present study, it can be concluded that H. indica can be stored in formulations viz. alginate gel and talc for better shelf life and it can be used as a biocontrol agent against D. indica, H. septima and B. cucurbitae in bitter gourd.Item Elucidating the morpho - physiological and molecular changes during seed priming in bitter gourd (Momordica charantia L.)(Department of Seed Science and Technology, College of Agriculture, Vellanikkara, 2024-05-24) Thabsheer, P.; Rose Mary FrancisA study to elucidate the morphological, biochemical and molecular changes leading to enhanced germination on priming in bitter gourd variety Preethi was conducted at College of Agriculture, Vellanikkara, Thrissur, during 2020-2023. Seeds of bitter gourd variety Preethi were dried to 6.84 per cent, and the quality parameters of the sourced seeds were assessed. They were divided into three equal sub-lots (5.0 kg each). Two sub-lots were packed in 700-gauge polyethylene bags and sealed airtight and one each stored for a period of six month under i). Ambient environment (Am.S), ii). Refrigerated storage (Rf.S) at ~18OC-20OC. The third sub-lot was packed in moisture-vapour proof aluminium foil bags seeds and stored for a period of six months at Medium term storage (MTS) facility at the ICAR-NBPGR (National Bureau of Plant Genetic Resources), Regional station, Vellanikkara. At the end of the storage period i.e., six months, the quality parameters of the stored seeds under the various storage environments were assessed following which they were further divided into 11 equal parts and subjected to 10 priming treatments (T1 to T10) following standard procedure, while unprimed seeds served as the control (T11). The priming treatments included T1: KNO3 0.3% for 2 h, T2: KNO3 150 ppm for 3 h, T3: KH2P04 10-2 M for 24 h, T4: PEG 6000 -1.5 MPa for 24 h, T5: GA3 100 ppm for 24 h, T6: Solid matrix priming with Perlite for 48 h, T7: Solid matrix priming with Cocopeat for 48 h, T8: Psuedomonas fluorescens 1x106 cfu.ml-1 for 24 h, T9: Hydration hot water at 50°C for 4 h and T10: Hydration cold water soaking for 24 h. Three separate studies as enumerated below were conducted to compare the effect of priming on germination of stored seeds under three different storage conditions viz. Ia) Effect of priming on seeds stored under ambient environment, Ib) Effect of priming on seeds stored in refrigerated storage (~18-20 OC) and Ic) Effect of priming on seeds stored in medium-term storage (~ 4-6 OC). Seed quality parameters viz., number of days to emergence, speed of germination, germination per cent, seedling root length (cm), seedling shoot length (cm), seedling dry weight (g), seed moisture content (%), germination capacity (GC), speed of germination, mean germination time (MGT), time taken for 50% germination (T50), energy of germination (GE), germination index (GI), coefficient velocity of germination (CVG) and seedling vigour indices were assessed after priming treatments in each experiment. In addition to the physiological observations, biochemical parameters viz., total soluble sugar (%), total protein (%), total oil content (%), H2O2 content (μmol g_1), lipid peroxidation (MDAμmol g_1), total dehydrogenase activity (OD), α–amylase activity (μmol g_1), catalase activity (μmol g_1), electrical conductivity of seed leachate (μScm-1), leakage of amino acid (μg leucine eqiv.ml -1) and leaching of sugar (μg glucose eqiv.ml -1) were recorded along with seed structural parameters viz., total seed coat thickness (μm), thickness of testa (μm), thickness of tegmen (μm), embryo length (μm), endosperm length (μm), endosperm breadth (μm), seed length (μm) and relative water absorption (RWA). Comparison of quality parameters before and after storage under the three environments pointed out that in addition to a reduction in germination, root length and shoot length the seedlings, the vigour indices I and II had also decreased in comparison to the estimates recorded prior to storage, while parameters like MGT and T50 of stored seeds were observed to have increased after six months of storage. The per cent reduction of speed of gemination, germination per cent, seedling root length, seedling shoot length, seedling dry weight, GC, GE, GI, CVG and vigour indices was however, the least in seeds stored in Am.S condition. Hence, it became evident that the per cent deterioration in seed stored at low temperatures is low, conversely, it reinforced the fact that storing bitter gourd seeds at low temperatures (MTs and Rf.S) would help maintain seed quality longer. The effect of seed priming treatments on germination (%) after six months of storage under i) S1: Ambient storage (Am.S), ii) S2: Refrigerated storage (Rf.S) and iii) S3: Medium-term storage (MTS) was anlaysed separately, each following a Completely randomized design with three replication and 11 priming treatments, in order to assess the best priming treatment under each storage environments studied. Germination of seeds stored under varying environmental conditions were found to be significantly influenced by the priming treatment they were subjected to. Germination of aged seeds from the three storage environments when subjected to Solid matrix priming with perlite (T6: Perlite for 48 h) cocopeat (T7: Cocopeat for 48 h) and hormonal priming with GA3 (T5: GA3 100 ppm for 24 h) were significantly superior over untreated seeds. Priming with PEG 6000 (T4: PEG 6000 -1.5 MPa for 24 h) was found to adversely affected germination irrespective of the storage environment the seeds were derived from. Although bio-priming seeds from Am.S with P. fluorescens (T8: P. f at 1x106 cfu.ml-1 for 24 h) and hydropriming (T9: Hydration hot water at 50°C for 4 h) was beneficial, it was not so in seeds derived from Rf.S and MTS. Similarly, hydration with hot water @ 50°C for 4 h was not found very beneficial in seeds stored under Rf.S and MTS as compared to Am.S. The impact of storage environment (S), priming treatment (T), and their interaction on physiological, biochemical and seed structural quality indices of seeds stored were analysed following a Completely randomized design with three replications and two factors viz., Factor I: Storage environments (S1, S2 and S3) and Factor II: Priming treatments (T1 to T11). Results indicated that, irrespective of the priming treatments, the quality indices of seed stored in MTS followed by Rf.S were found to be significantly superior to those stored under Am.S. It was evident that storing seeds at low temperatures (~ 18-20 0C in Rf.S, ~ 4-6 0C in MTS) was beneficial in bitter gourd. It resulted in higher germination as well as other physiological, biochemical and structural indices of the seed. Irrespective of the storage conditions, the quality indices of the aged seeds were found to be significantly influenced by the priming treatment they were subjected to. Solid matrix priming (SMP) with Perlite (T6: solid matrix priming with perlite for 48 h) invariably followed by solid matrix priming with cocopeat (T7: solid matrix priming with cocopeat for 48 h) and hormonal priming with GA3 (T5: 100 ppm for 24 h) were found to be significantly superior to other priming treatments as well as untreated seeds. Priming with PEG 6000 (T4: -1.5 MPa for 24 h) was found to be detrimental and registered the least seed indices. The interaction between seed priming treatment and storage conditions was found to significantly influence germination as well as other quality indices of the aged seeds. Results pointed out that germination and most seed indices studied were significantly superior in solid matrix primed seeds involving perlite (T6: solid matrix priming with perlite for 48 h) under both low temperature storage (MTS and Rf.S), as well as ambient storage (Am.S). Solid matrix priming with cocopeat (T7: solid matrix priming with cocopeat for 48 h) and hormonal priming with GA3 (T5: 100 ppm for 24 h), were found to be next best to SMP with perlite under low temperature storage environments viz., MTS and Rf.S. However, unlike in the low temperature storage environments, under ambient storage conditions, bio-priming with P. fluerescens (T8: P. f at 1x106 cfu.ml-1 for 24 h) was found to be next best to SMP with perlite and superior over SMP with cocopeat and hormonal priming with GA3. However, apart from untreated seeds, osmopriming seeds with PEG 6000 (T4: PEG 6000 -1.5 MPa for 24 h), hydration with cold water (T9: Hydration hot water at 50°C for 4 h) as well as with hot water (T10: Hydration cold water soaking for 24 h), were found to be detrimental under low temperature storage (MTS and Rf.S) and ambient storage as well. The results obtained thus point out that loss of germination, vigour and other quality parameters over storage is inevitable. However, the deterioration of seed indices in bitter gourd due to ageing can be slowed down to the maximum extent by storing them under Medium-Term storage (MTS). Storing seeds under refrigerated storage (Rf.S) is highly beneficial compared to storing them under ambient conditions (Am.S). Irrespective of the environment under which the seeds were stored, solid matrix priming of bitter gourd seeds with perlite (48 h) was the best priming treatment as it resulted in significantly superior germination, growth indices of seedlings, biochemical parameters and seed structural changes over untreated seeds. SMP with cocopeat (48 h) and hormonal priming with GA3 (100 ppm for 24 h) were next best to SMP with perlite in bitter gourd. Subjecting seeds of bitter gourd stored either in low temperature environment like medium term storage and refrigerated storage or under ambient environments to solid matrix priming with perlite would result in enhanced germination and seed quality indices. Solid matrix priming with cocopeat or hormonal priming of the aged seeds with GA3 (100 ppm for 24 h) were the next best priming options, if the seeds were stored at low temperature environments. However, in seed stored under ambient environments, bio-priming with P. fluorescens (1x106 cfu.ml-1 for 24 h) would be the best priming option, next to solid matrix priming with perlite.Item Molecular characterization of gynoecy in bitter gourd (Momordica charantia L.)(Department of Plant Biotechnology, College of Agriculture, Vellanikkara, 2021) Nivethitha, B; Pradeepkumar, TBitter gourd (Momordica charantia L.) is an important vegetable of tropics and sub-tropics of Asia belonging to Cucurbitaceae family. The immature fruits of bitter gourd are valued for its culinary and medicinal importance. Having highest amount of ascorbic acid and iron content, it is considered to be the most nutritive among all the cucurbitaceous vegetables. Heterosis is well exploited in bitter gourd for early maturity, increased yield and other agronomic traits through development of hybrids. However, the production of hybrids is labour-intensive involving manual bagging and hand pollination, thereby increasing the cost of seed production. The predominant sex form of bitter gourd is monoecious which bears separate male and female flowers on the same plant. However, gynoecious type bearing only female flowers were also reported in few locations of India, Japan and China. These gynoecious bitter gourd lines can be exploited as female parent to make hybrid seed production economical and easier, as it eliminates the need for emasculation and assisted pollination. It also aids in maintaining the genetic purity of hybrids and helps in harnessing the benefit of hybrid vigour including early maturity and high yield. Usually, the sex expression in cucurbits is highly influenced by environment and hormones, which makes the early phenotypic identification of gynoecy challenging. Identification of molecular markers tightly linked to gynoecy trait would ease the identification of gynoecious line in breeding programmes. In this study, 20 putative candidate genes governing sex expression were selected from different literatures and the gene sequences were retrieved from bitter gourd and cucumber genome assembly in NCBI GenBank database. Four ethylene biosynthesis genes (ACO1, ACS2, ACS3. ACS4 and ACS7), three MADS-box transcription factor encoding genes (AG6, MADS-boxTF23 and McAG2), one auxin related gene (CsARF5) and 12 WRKY transcription factor encoding genes comprise the list. A total of 20 gene-specific primer sets were designed from the selected region of each of the 20 genes. Genomic DNA was isolated from monoecious genotype, MC-136 and gynoecious, KAUMCGy-101. Efforts were made to amplify all the 20genes, however, only seven gene-specific primer sets designed from bitter gourd produced PCR amplification. The amplicons of expected product size from both the samples were sequenced. Sequence variation analysis was done by comparing the monoecious and gynoecious sequences generated to the reference sequence (monoecious) available in NCBI database for bitter gourd. Six valid variations including three SNPs and three In/Dels were found in AG6 and McAG2. All the variations except SNP1 of AG6 were present in non-coding regions. In/Del of 48 bp ([TC] 24 ) in AG6 gene caused a significant difference in the number of ‘TC’ repeats in the sequences which was used for the development of SSR marker. The marker showed clear polymorphism between monoecious and gynoecious genotypes used. It was further validated in three other monoecious lines namely, Priya, Priyanka and the wild type M. charantia var. muricata. Expected banding pattern showing polymorphism for gynoecious line was obtained for all the three monoecious lines screened. Thus, the study identified two potential candidate genes, AG6 and McAG2 for sex expression in bitter gourd. The SSR marker developed needs to be validated in large number of population and more number of varieties to confirm its use as a reliable polymorphic marker in marker-assisted selection of gynoecious lines of bitter gourd.Item Development of inbreds in bitter gourd (momordica charantia L.) through conventional and biotechnological approaches(Department of Vegetable Science, College of Horticulture, Vellanikkara, 2020) Reshmika, P K; Pradeepkumar, TItem Nutrient management in bitter gourd under partial shade(Department of Agronomy, College of Agriculture, Vellayani, 1989) Ravikrishnan, M K; Sasidhar, V KA field experiment was conducted at the College of Agriculture, Vellayani during 1988 to study the influence of three levels of each nitrogen (50, 70 and 90 kg/ha), phosphorus (15, 25 and 35 kg/ha) and potassium (25, 50 and 75 kg /ha) on growth, yield, content and uptake of major nutrients in bittergourd VK-1 (Priya) under partially shaded conditions of coconut gardens. The trial was conducted as 33 + 1 partially confounded factorial experiment in Randomised Block design with two replications. Higher levels of nitrogen had profound influence on growth characters like days for opening of first male and female flowers and their node of emergence, internodal length, length of main vine and total dry matter production. Application of phosphorus of 35 kg/ha had significant positive effect on the node of emergence of first female flower and total dry matter production. Yield attributes like sex ratio, fruits per plant and harvest index were not influenced significantly by the main and interaction effects of the major nutrients. However the control plots registered a significant reduction in values for these parameters. The fruit set was maximum at 90 kg/ha of nitrogen, 25 kg/ha of phosphorus and 25 kg/ha of potash. Application of 90 kg N/ha, 25 kg P2O5/ha and 50 kg K2O/ha recorded the maximum yield. The response of bittergourd to nitrogen levels was linear and that to phosphorus levels was quadratic. Application of potassium at 75 kg K2O/ha was found to significantly increase the fruit weight. The length and girth of the fruits were positively influenced by the application of nitrogenous fertilizer. Potassium at the rate of 75 kg K2O/ha recorded the maximum girth of fruits signifying its effect on this character. The nitrogen and phosphorus content of fruits and plants and protein content of fruits were found to be unaffected by the main effects of nitrogen, phosphorus and potash. An increase in potash level increased the potassium content of fruits and plants. Nitrogen at 90 kg/ha significantly increased the nitrogen uptake by plants and fruits and phosphorus uptake by plants as compared to other levels. Maximum potassium uptake by fruits was obtained by application of 35 kg P2O5/ha and 75 kg K2O/ha and uptake of potassium by plants was maximum at 90 kg N/ha, 35 kg P2O5/ha and 75 kg K2O/ha. The study indicated that application of 90 kg N/ha 25 kg P2O5/ha and 50 kg K2O/ha recorded the maximum yield and net returns from bittergourd cv. VK-1 (Priya) under partially shaded conditions of coconut gardens in the red loam soils of Vellayani.Item Investigations on mosaic disease of bitter gourd(Department of Plant Pathology, College of Agriculture, Vellayani, 1994) Purushothaman, S M; Rajagopalan, BBitter gourd mosaic virus disease commonly occurring in Kerala was investigated. The symptoms appeared as typical mosaic mottling with dark green and light green patches. Diseased plants were severely stunted and produced only a few flowers and fruits. Transmission studies showed that the virus could be transmitted through mechanical means, grafting and by aphid vectors. The virus was found to be transmitted by the aphids aphis gossypii Glov., Aphis malvae Koch., Myzus persicae Sclz. And aphis craccivora Koch. Among the four species of aphids, A. gossypii and A. malvae were found to be the most efficient vectors. Investigations on the physical properties of the virus revealed that the virus had a thermal inactivation point between 50 and 600C, dilution end point between 1:1000 and 1:10000, longevity in vitro between 12 and 24 h at room temperature (28 - 300C) and 48 and 72 h at 100c. The minimum acquisition feeding and inoculation feeding period of the vector A. malvae were found to be 30s and I min respectively. But the percentage of transmission was maximum when an acquisition feeding period of 30 min and inoculation feeding period of 2 h were given. Influence of starvation before acquisition and inoculation feeding period proved that pre – acquisition starvation for 2 h produced maximum infection but post- acquisition starvation decreased the per cent infection. The vector could retain the virus for I h only. A single aphid could transmit the virus to healthy test plants, but maximum percentage of transmission was obtained with 10 aphids. Host range studies showed that the virus was restricted to the members of the family Araceae, Chenopodiaceae, Cucurbitaceae, Musaceae, Polygonaceae and Solanaceae. Datura metal acted as a symptomless carrier of bitter gourd mosaic virus. Serological studies showed that bitter gourd mosaic virus is related to cucumber mosaic virus, pumpkin mosaic virus and snake gourd mosaic virus. Varietal screening showed that all the varieties and collections were susceptible to biter gourd mosaic virus infection, but the variety Arka Harit and the collections 87 green long 1 C 68234, 61 white medium 1C 45358 and 177 green medium 1C 68324 were least susceptible. Studies on estimation of loss revealed that early infection of bitter gourd plants by the virus significantly reduced the number of leaves, leaf area, intermodal length, thickness of vines, length of vines, number of branches, number of flowers, number of fruits and other fruit characters viz., length of fruits, girth of fruits, weight of fruits and total yield of fruits.Item Characterisation and management of bitter gourd distortion mosaic virus(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2006) Reeny Mary Zacharia; Sally K MathewStudies on ‘Characterisation and management of bitter gourd distortion mosaic virus (BGDMV)’ conducted at College of Horticulture, Vellanikkara and Sugarcane Research Station, Thiruvalla during 1999-2004 dealt with various aspects especially on transmission, etiology, characterisation, identification of virus and management. Transmission studies proved that BGDMV was not transmitted through sap and seed. Germination percentage of seeds from infected plants was 45 per cent whereas seeds from healthy plants showed 85 per cent germination. The seedlings raised from infected seeds were pale, lanky and non vigorous. Studies on insect transmission revealed that whitefly, Bemisia tabaci Genn. was the vector of BGDMV. Minimum acquisition and inoculation feeding period for B. tabaci for transmission of BGDMV were found to be 15 min. Under natural conditions, common symptoms observed were light green and dark green mosaic patterns, curling, crinkling and distortion of leaves, reduction in number of flowers and fruits and reduction in size of fruits. Under artificial inoculation, symptoms initiated as light green and dark green mosaic patches in inoculated leaves, which later spread to young leaves and resulted in brittleness, pointed leaf lobes and crinkling. Average incubation period of BGDMV in bitter gourd plant was 14 days and the incubation period was found to decrease with increase in acquisition feeding period, inoculation feeding period and increase in number of viruliferous insects. A single viruliferous whitefly was capable of transmission upto 33 per cent and cent per cent transmission was obtained with increase in number of whiteflies to 10. Host range studies revealed that ash gourd, bottle gourd, coccinia, cucumber, pumpkin, snake gourd and water melon were not collateral hosts for the perpetuation of the virus. Purified preparations of BGDMV gave a characteristic ultraviolet absorption spectra of nucleoprotein with a peak at 241 nm. Average A260/A280 value of purified preparation of BGDMV was 1.62 and average concentration of the virus was 0.132 mg ml-1/100 g plant tissue. Characterisation of nucleic acid and viral proteins did not show any specific band of virus particles due to low concentration of particles in the purified preparation. Hence nucleic acid and protein coat could not be characterized. However SDS-PAGE of BGDMV infected field sample gave two additional bands at 16,419 and 24,970 D which could be proteins induced in host plant by virus infection. Electron microscopic observation of purified preparation of BGDMV gave monomers of size 18 nm diameter and geminate particles of size 18-20 x 30 nm. Infected samples from the field showed flexuous rod shaped particles of 750 nm resembling poty virus, in addition to geminate particles of size 18-20 x 30 nm, indicating a mixed infection of gemini and poty viruses. Immunosorbent electron microscopic observations using Indian cassava mosaic virus antiserum did not give a positive reaction, thus ruled out the relationship between BGDMV and Indian cassava mosaic virus. Serological tests using DAC-ELISA with 10-1 dilution of BGDMV showed that the virus was closely related to squash leaf curl virus. Based on transmission, electron microscopy and serological studies it was proved that the causal agent of bitter gourd distortion mosaic disease is a virus belonging to genus Begomo virus of family Geminiviridae. In the management studies, it was found that none of the treatments was found effective in preventing BGDMV infection. Disease incidence and severity and coefficient of infection showed a progressive trend with growth of the plant. Considering the overall performance of various treatments during the two seasons, it was found that treatment of imidacloprid 0.025 per cent was very effective in reducing disease incidence, disease severity and coefficient of infection. In the present study, application of coconut vinegar one per cent was also found to be effective in reducing disease incidence and severity of BGDMV. In the present study also treatment with Apis melliphica 30 potency and Arsenicum album 30 potency showed reduction in BGDMV and also increase in yield. During the second season, all the treatments were effective in reducing whitefly population than control. Studies on weather parameters showed that influence of mean maximum temperature, mean relative humidity on disease incidence varied with two seasons. Relative humidity in the forenoon showed positive correlation with disease incidence and disease severity in both seasons, and hence found to be the most influencing weather parameter in BGDMV infection.Item Genetic analysis of F2 and F3 generations for yield attributes and resistances to distortion mosaic virus disease in bitter gourd (Momordica charantia L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2003) Sumarani, P; Arya, KThe research project "Genetic analysis of F2 and F3 generations for yield attributes and resistance to distortion mosaic virus disease in bittergourd (Momordica charantia L.)" was carried out in Department of Plant Breeding and Genetics, College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during the period 2002-2003. The major objectives of the study were to understand the genetics of yield attributes and resistance to bittergourd distortion mosaic virus (BDMV) and to identify resistant genotype with desirable yield traits. The whole investigation was grouped into two experiments in Randomised Block Design with three replication. The F2 and F3 generation of three selected crosses and parents were evaluated for yield attributes and resistance to BDMV. Significant variation was noticed for almost all characters except anthesis of male and female flowers. Highest phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for BDMV followed by fruit yield and fruit weight in both generations. High heritability coupled with high genetic gain was noted for fruit weight, fruit yield and coefficient of infection. These characters are controlled mainly by additive genes which rendered scope for direct selection . . High yield was achieved by higher sex ratio, higher fruit weight, long fruit, optimum number of female flowers and low incidence ofBDMV. Based on the results from populations derived from the crosses IC68335 x Preethi and lC 68263B x Preethi as the best genotypes with high yield and resistance to bitter gourd distortion mosaic virus (BDMV) consecutively in both generations.