1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Divergence studies in pumpkin (Cucurbita moschata Pair)(Department of Olericulture, College of Horticulture, Vellanikkara, 1989) Suresh Babu, V; Gopalakrishnan, T RThe present investigation on "Divergence studies in pumpkin (Cucurbita moschat a Poir ) was conducted at the College of Horticulture , Vellanikkara, Trissur during June 1988 - Marc h 1989. Seventy one pumpkin genotypes collected from different part of India and abroad were utilized for the study. The extent of variability and divergence among 50 selected genotypes were assessed and grouped into 5 clusters based on Mahalanobis D2 statistic . Cluster I, II, III, I V and V contained 2, 7, 9, 12 and 20 genotypes respectively y . Intercluster distance was maximum between clusters I and II and was minimum between clusters III and V . Cluster I showed maximum average intercluster distance with any other cluster. Screening 71 genotypes for resistance/ tolerance to pumpkin mosaic and yellow vein mosaic diseases revealed that all genotypes except C M 214 were susceptible. Artificial inoculation studies confirmed immunity of C M 214 (Nigerian I oca l ) to pumpkin mosaic virus and yellow vein mosaic virus .Item 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 Selection for mosaic resistance in pumkin (cucurbita moschata poir)(Department of Olericulture, College of Horticulture, Vellanikkara, 1992) Latha, P; Gopalkrishnan, T RThe investigation “Selection for mosaic resistance in pumpkin (Cucurbitamoschatapoir)” was conducted at the College of Horticulture, Vellanikkara, Thrissur during November 1990 – April 1992. The high yielding and locally adapted variety Ambili was sown at bimonthly intervals to study the seasonal influence on mosaic incidence, vector population and yield. Incidence of yellow vein mosaic, pumpkin mosaic, bottle gourd mosaic, watermelon mosaic and cucumber mosaic were observed in crops sown during different months. Incidence of yellow vein mosaic and population of whiteflies (BemisiatabaciGenn.), the vector of yellow vein mosaic, were positively correlated with temperature and negatively correlated with rainfall and relative humidity. Fruit yield and contributing characters were significantly influenced by different dates of sowing and sowing in October was found to yield maximum because of the delayed incidence of mosaic. From the study of P1, P2, F1, F2 , BC1 and BC2 generations of the cross involving mosaic susceptible Ambili and resistant CM 214 (Nigerian Local), resistance to yellow vein mosaic was found to be governed by a single dominant gene and pumpkin mosaic by a single recessive gene. Silvery leaf trait was found to be dominant and governed by two genes. The study resulted in the identification of five promising selections from the segregating populations. Attempt was also made to improve the line CM 214 through selection. Improvement could be made in fruit set, seeds per fruit, hundred seed weight and seed germination. Germination percentage of CM 214 was significantly increased by removal of seed coat before sowing. Superior progenies of CM 214 were also selected for further improvement.Item Effect of growth regulators on fruit set and yield of pumpkin (Cucurbita moschata. Poir)(Department of Olericulture, College of Horticulture, Vellanikkara, 1984) Mohan Kumar, S; Ramachandran Nair, SAn experiment was conducted at the College of Horticulture, Kerala Agriculture University, Vellanikkara during December-April 1983-‘84 to study the effect of six levels of growth regulators viz., alar (100 and 200 ppm), CCC (500 and 1000 ppm) and ethrel (100 and 200 ppm) and of the two different stages of application (four leaf and six leaf stage) on growth, sex-expression, fruit set, yield and quality of two distinct pumpkin genotypes (Cucurbita moschata Poir.) collected from Palghat district of Kerala State. The experiment was laid out in split-plot design with three replications. The effect of plant growth retardant to suppress the luxuriant growth of the crop is further confirmed by the results of the present study. All treatments caused a significant reduction in the length of the main vine and all other vegetative characters under study. There was a drastic reduction in the number of male flowers and an increase in the female flower number, altering an otherwise male dominated sex-ratio of the crop. CCC 1000 ppm was found to be effective in promoting early fruit set and harvest of both the genotypes tried. However there was no significant increase in the number of fruits per plant, average weight of the fruit, flesh thickness and the number of seeds per fruit. CCC treatments followed by alar 200 ppm was found to be the most effective in increasing the yield. Type T1 gave maximum yield with CCC 1000 ppm whereas type T2 responded well to CCC 500 ppm concentration. CCC 1000 ppm however caused a slight reduction in the yield of this genotype. There was also a slight increase in the carotene content with CCC treatments. Type T1 recorded a slight decrease in yield with both ethrel (100 and 200 ppm) treatments. No significant difference was noticed when growth regulator sprays were given at two different stages (four leaf and six leaf) of the crop. The study thus also proved that the response of pumpkin to growth regulators sprays is governed by the genotype and the concentration of the growth regulators used.Item Genetic variability and correlation studies in pumpkin (Cucurbita moschata Poir)(Department of Horticulture (Olericulture), College of Horticulture, Vellanikkara, 1979) Gopalakrishnan, T R; Gopalakrishnan, P KEighteen diverse pumpkin genotypes were grown in a randomized block design with three replications during 1978-79 at the Instructional Farm of College of Horticulture, Vellanikkara to estimate the extend of genetic variability, association among polygenic characters and its partition into direct and indirect effects. A discriminant function analysis was also carried out to find out the efficiency, if any, of selection through discriminant function over straight selection vice versa. The 18 genotypes were significantly different for the 32 polygenic characters studied. The genotype C.M. 17 and C.M.14 emerged as high yielders with other desirable qualities (16.10 kg. and 15.38 kg. fruit yield / plant respectively). Selection of plants considering yield per S E was observed to be efficient than selection of component characters. Fruit yield /plant was positively correlated with length of main vine, average fruit weight and weight of first mature fruit. Leaves /plant and intermodal length had maximum direct effects on length of main vine. Weight of first mature fruit was positively correlated flesh thickness and circumference of fruit. Number of female flowers/plant and number of fruit /plant had no correlation with fruit yield/plant. This aberrant behaviour requires further physiological studies to define the physiological sink in pumpkin. The line C.M.18 is observed to contain the maximum amount of carotene(0.527%) among the 18 genotypes studied. The carotene content was observed rather independent fruit yield /plant.Item Barcoding and biosystematic studies on Hymenopteran pollinators of cucurbitaceous vegetables(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Erra Harisha; Shanas, S PThe study entitled “Barcoding and biosystematic studies on hymenopteran pollinators of cucurbitaceous vegetables” was conducted during the year 2017- 2019 at the Department of Agricultural Entomology, College of Agriculture, Vellayani with an objective to study the diurnal activity and dynamics of hymenopteran pollinators of cucurbitaceous vegetables and to explore their morphological and molecular diversity. To determine the composition and relative abundance of different hymenopteran pollinators visiting the flowers of five selected cucurbitaceous vegetables viz., culinary melon (Cucumis melo var. acidulus), bitter gourd (Momordica charantia L.), ash gourd (Benincasa hispida Thunb. and Cogn.), pumpkin (Cucurbita moschata L.) and ridge gourd (Luffa acutangula (Roxb.) L.) collections were made throughout the blooming period in Thiruvananthapuram and four other districts of Kerala viz., Kollam, Pathanamthitta, Alappuzha and Kasaragod from 06:00 h to 18:00 h of the day with a cone type hand net. Among the above mentioned vegetables, culinary melon was selected for detailed study on diurnal activity at College of Agriculture, Vellayani. The study on composition and relative abundance of hymenopteran pollinators revealed that, A. cerana indica was the dominant pollinator in culinary melon (42.51 %), pumpkin (38.76 %) and ridge gourd (35.16 %) whereas, T. travancorica was the dominant pollinator in bitter gourd (31.86 %) and ash gourd (33 %). Observations on diurnal activity were carried out at College of Agriculture, Vellayani in culinary melon during two crop seasons for 3 weeks at weekly intervals. For foraging rate, the number of flowers visited by each bee for 1 minute and for foraging speed, time spent by each bee per flower were observed respectively. During two seasons, the foraging speed of A. cerana indica, T. travancorica and Halictus sp. was found to be highest during 10:00-11:00 h (10.61 and 10.63, 11.23 and 11.46, 10.26 and 10.40 seconds) respectively. The foraging speed of C. hieroglyphica and Lasioglossum sp. was found to be highest during 09:00-10:00 h (9.02 and 9.11, 11.06 and 11.30 seconds) respectively. The foraging rate of T. travancorica, C. hieroglyphica and Lasioglossum sp. was found to be highest during 10:00-11:00 h (9.16 and 9.23, 4.83 and 4.85 flowers/m2/5 min) respectively. The foraging rate of A. cerana indica and Halictus sp. was found to be highest during 11:00-12:00 h and 09:00-10:00 h (10.60 and 10.88, 4.03 and 4.13 flowers/m2/5 min) respectively. Samples which were unidentified through morphological characterization were given for DNA barcoding. The sequence of 2 samples viz., Tetragonula sp. nov.1 and T. travancorica were obtained. Among these, new species (Tetragonula sp. nov.1) of stingless bee, based on adult worker specimen is described. Differences in morphology and genetic analysis based on partial sequences of the mitochondrial COI gene barcode region support the recognition of the new species. The above results revealed that A. cerana indica was dominant in culinary melon, pumpkin, and ridge gourd and T. travancorica was dominant in bitter gourd and ash gourd. The foraging speed during two seasons in the descending order was T. travancorica > Lasioglossum sp. > A. cerana indica > Halictus sp. > C. hieroglyphica. The foraging rate during two seasons in the descending order was A. cerana indica > T. travancorica > C. hieroglyphica > Lasioglossum sp. > Halictus sp. Among the pollinators, five species viz., P. phalerata phalerata, C. annulata annulata from ash gourd, M. disjuncta from bitter gourd, C. simillima, and C. unimaculata javanica from culinary melon were reported for the first time pollinating cucurbitaceous vegetables. Tetragonula sp. nov.1 of stingless bee, collected from pumpkin flower, is the new species report from the study and it is morphologically characterised.Item Characterisation of pumpkin (Cucurbita moschata duch.) varieties through morphological and molecular markers(Department of Seed Science and Technology, College of Horticulture, Vellanikkara, 2019) Agina Gopan; Rose Mary FranciesPumpkin (Cucurbita moschata Duch.), a crop of Central Mexican origin belonging to the family Cucurbitaceae, is popularly cultivated and valued in Kerala as a vegetable. The tender, large and often round immature fruits of pumpkin with a thick, smooth to slightly ribbed skin, which is mostly deep yellow to orange in colour, is an integral part of the Kerala cuisine. Despite its popularity in the state, few high yielding varieties are in cultivation. To ensure increased production, availability of high quality seeds of improved varieties or hybrids has to be guaranteed. Pumpkin being a cross pollinated crop, occurrence of cross contamination during its seed programme cannot be overruled. Hence, ensuring the purity and identity of seeds of the variety before sale becomes inevitable. Considering the importance of varietal identification in maintaining the genuineness and quality of seeds in seed production programmes, the present investigation envisaged to characterise six pumpkin varieties in the seed chain using morphological and molecular markers, and to generate fingerprints or molecular ID’s of the six varieties using selected polymorphic Inter-simple sequence repeats (ISSR) and Simple sequence repeats (SSR) markers. Characterisation of pumpkin varieties based on 28 quantitative and 16 qualitative traits was done using DUS and NBPGR descriptors. Qualitative vegetative traits like tendril characteristics (presence or absence of tendril, nature of coiling and branching) and leaf shape were not useful for grouping the varieties. Similarly, among the qualitative fruit characteristics, waxiness of mature fruit skin also proved insufficient to distinguish the varieties. Fruit shape was round flat in varieties Ambili, Suvarna and CO-2, while it was elongate/oblong in Saras, club shaped in CO-1 and flattish round in Arka Chandan. Based on qualitative traits, variety Arka Chandan could be clearly distinguished from the other varieties based on poor early growth vigour, moderately incised leaf blade margin, absence of silver patches on leaf blade, flattish round fruit shape, light green immature fruits and dark orange fruit flesh colour. In addition, the seeds of the Arka Chandan had a characteristic marking on the dorso-ventral surfaces unlike other varieties. Quantitative traits proved to be more useful than the qualitative traits for effective identification and categorisation of varieties. Results revealed that among the quantitative traits studied, leaf dimensions (blade length and width) and length of petiole could not be employed for distinguishing the six varieties. Variety Ambili flowered the earliest (49.25 days) and also possessed highly pubescent leaves, while variety Arka Chandan was late flowering (68.00 days). Peduncle length, fruit length and most of the seed dimensions (seed count per fruit, 100 seed weight, width and thickness of seed) was the least in this variety. In general, the size of seeds in varieties CO-1 and CO-2 was higher than those of others. Cluster analysis grouped Arka Chandan (Cluster V) and varieties CO-1 and CO-2 (Cluster IV) the farthest with an inter-cluster distance of 212.25. Principal component (PC) analysis indicated that trait components in PC1 registered an Eigen value of 16.79 and the traits in PC1 contributed 58 per cent to the variability among the varieties, emphasising their utility in identification of varieties. Among the 33 ISSR markers, 28 exhibited polymorphism. The total number of amplicons detected by an individual primer ranged from 4 in UBC-818 to 18 in UBC-847. High polymorphic information content (PIC) value was observed in UBC-809, whereas, low PIC was recorded in UBC-818. The six varieties grouped into four clusters based on ISSR binary data. Out of 20 SSR markers used for genotyping, only five showed polymorphism. The highest Jaccard’s similarity value (1.00) was observed between Saras and Suvarna. The most dissimilar varieties were Saras and Arka Chandan, and Suvarna and Arka Chandan, with a similarity coefficient of 0.12 each. The clustering algorithm grouped the varieties into four clusters. The polymorphic SSRs could be efficiently utilised for distinguishing Arka Chandan and therefore can prove useful for testing the genetic purity of this variety. Unique bands producing ISSR markers were used to generate variety specific DNA fingerprints. No single primer per se proved useful in distinguishing all six pumpkin varieties. However, ISSR primer UBC-822 could distinguish four out of six varieties studied. It produced unique amplicons of size 473 bp, 552 bp, 1403 bp and 517 bp, respectively in Ambili, Saras, CO-1 and Arka Chandan, proving its utility in testing for genuiness and purity of seed lot. In general, it can be concluded that the correlation that existed between morphological and molecular assessments was of medium magnitude. The absence of high consensus between the assessments should not be considered a limitation of these tools to characterize and quantify variability. It only indicates that both morphological and molecular characterisation is important and play a complementary role in providing a better understanding and differentiation of the pumpkin varieties.Item Use of synthetic pyrethroides for the control of pests of bitter gourd (Momordica charantia L) and snake gourd (Trichosanthes anguina L)(Department of Entomology, College of Agriculture, Vellayani, 1982) Kosaraju Ravindra, Nath; Sasidharan Pillai, KIn a field experiment conducted at the Instructional Farm, College of Agriculture, Vellayani, during the summer season in 1982, the efficacy of four synthetic pyrethroids viz. permethrin, fenvalerate, cypermethrin and deltamethrin, on the pests of bitter gourd and snake gourd in comparision with the standard, malathion, was evaluated. Both the crops were sprayed thrice on need basis for controlling the various pests which infested the crops at different growth stages. Spotted beetle observed on bitter gourd at the time of first spraying was controlled by all the synthetic pyrethroids along with the standard for a period of 23 days after spraying. Fruit fly of the bitter gourd also was controlled by all the three sprayings and all the insecticides were effective in most occasions. Cypermethrin at higher dose was superior to the standard during the first spraying followed by fenvalerate and deltamethrin. In the second spraying deltamethrin was not so effective whereas permethrin was found more effective. Again in the third spraying deltamethrin and fenvalerate were more effective . The fruit fly damage observed for the entire crop season revealed the superiority of fenvalerate, permethrin and deltamethrin at their higher doses over the standard. Jassid on bitter gourd was controlled by all the insecticides except permethrin and cypermethrin at their lower dose for a period of 2 days after the spraying . But aphid could be controlled only with permethrin and fenvalerate at their higher dose along with the standard malathion for a period of 2 DAS. The fruit set and the flowering pattern were not affected by any of these insecticides.Item Diversity of begomoviruses infecting major vegetable crops(Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Bincy S Basheer; Umamaheswaran, KItem Molecular basis of acaricide resistance in tetranychus truncatus ehara (prostigmata: tetranychidae) infesting vegetable crops(Department of Plant Biotechnology, College of Horticulture, Vellanikkara, 2018) Anushree Bachhar; Haseena BhaskarSpider mites of the family Tetranychidae are considered as one of the most serious sucking pests of vegetable crops worldwide. Intensive use of conventional acaricides had lead to the development of resistance in many mite species around the globe. In view of this, several novel acaricides with unique chemical structure and mode of action were introduced and commercialized for mite management. In Kerala, mite management in vegetable crops solely depends on the use of novel acaricides. Of late, several farmers have raised concern over their poor efficacy against mite pests. Spider mites have the ability to develop resistance quickly on continuous exposure to a pesticide. In this context, the present study was undertaken to investigate the status, biochemical and molecular bases of acaricide resistance in Tetranychus truncatus Ehara, the predominant species of spider mite infesting vegetable crops of Kerala. Purposive surveys were conducted in the vegetable fields of Vellanikkara, Thrissur and spider mites were collected and reared in the laboratory by assigning accession numbers. Three accessions/strains viz., VkOk1 (okra), VkAm3 (amaranthus) and VkPm3 (pumpkin) which were identified as T. truncatus were used for the study. Susceptibility of the three field strains to three commonly used acaricides, viz., spiromesifen, fenazaquin and diafenthiuron was evaluated in the laboratory following leaf dip bioassay in comparison with a laboratory maintained susceptible strain (SS). Bioassay study revealed that the strain VkOk1 recorded highest LC50 value and has developed 8, 13 and 10 fold resistance to spiromesifen, fenazaquin and diafenthiuron, respectively. This was followed by VkAm3 which showed 7.0, 5.53 and 1.67 fold resistance, while VkPm3 recorded 1.35, 1.13 and 1.03 fold resistance. The activity of the detoxifying enzymes viz., cytochrome P450 and carboxylesterase, was significantly higher in VkOk1strain followed by VkAm3. The strains VkOk1, VkAm3 and VkPm3 showed 2.69, 1.24 and 1.09 fold enhanced activity of Cytochrome P450, respectively compared to SS, while carboxylesterase in VkOk1 and VkAm3 showed an increased activity by 2.59 and 1.18 fold. However, the strain VkPm3 recorded a decrease in activity of carboxyleasterase by 0.78 fold compared to the susceptible strain. DNA isolated from the two resistant strains (VkOk1 and VkAm3) and the susceptible strain (SS) was amplified with the help of gene specific primers for cytochrome P450 and carboxylesterase. The results of PCR for cytochrome P450 gene showed that there was no amplification in the case of SS, whereas there were distinct markers in the resistant strains, okra and amaranthus at 1300 bp size. However, PCR amplification showed distinct markers for carboxyl esterase in all the three strains. The strains VkOk1 and SS showed markers at 1500 bp and 1300bp size respectively, while VkAm3 strain showed both the markers. The sequence homology search by BLASTn analysis showed that the sequences of cytochrome P450 of T. truncatus has similarities with cytochrome P450 sequences from different species of spider mites with an identity match ranging from 81 to 97 per cent, while carboxylesterase sequences showed similarity with two mRNA sequences of carboxylesterase of T. urticae. Further, the translated sequences of cytochrome P450 and carboxylesterase aminoacids from T. truncatus when analysed by BLAST P showed similarity with the amino acid sequences from other spider mites. The sequences of carboxylesterase genes from the resistant and susceptible strains did not align together, showing that there are two different caboxylesterase genes controlling the resistance to acaricides in T. truncatus. The study recorded resistance in T. truncatus to three novel acaricide molecules, for the first time from India. This is the first report of cytochrome P450 and carboxylesterase genes conferring resistance to acaricides in T. truncatus. The study also developed standard markers for discriminating the resistant and susceptible population in T. truncatus.