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ThesisItem Open Access Divergence studies in pumpkin (Cucurbita moschata Pair)(Department of Olericulture, College of Horticulture, Vellanikkara, 1989) Suresh Babu, V; KAU; 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 Iocal ) to pumpkin mosaic virus and yellow vein mosaic virus .ThesisItem Open Access Evaluative perception of appropriateness of the recommended fertiliser management practices(Department of Agricultural extension, College of Horticulture, Vellanikkara, 1989) Rasheed Sulaiman, V; KAU; Muraleedhara Prasad, RA study was undertaken to investigate into the extent of knowledge, extent of adoption and evaluative perception of appropriateness of the recommended fertilizer management practices among rice farmers (n=200) and Agricultural Demonstrators (n=54) in Palghat and Cannanore Districts of Kerala State. The study revealed that farmers of Palghat and Cannanore differed significantly with respect to their knowledge and adoption of fertiliser management practices with farmers of Palaghat having higher level of knowledge and adoptionThesisItem Open Access Flower bud differentiation in clove, Eugenia caryophyllus (Sprengel) Bullock & Harrison(Faculty of Agriculture, Department of Horticulture, College of Agriculture, Vellayani, Trivandrum, 1989) Pauline Lina, Edwin; KAU; Vasanthakumar, KInvestigations on flower bud differentiation in clove were carried out at College of Agriculture, Vellayani from August, 1936 to December, 1987. Bearing clove trees (seven years old) at the Instructional Farm attached to the college were utilized for the study. The plant specimens were stored in FAA (Formalin-acetoalcohol) and then dehydrated through tertiary butyl alcohol - iso propyl alcohol series. The specimens were Infiltrated and embedded In paraffin wax (m.p. 58-60'C) and sectioned In a rotary microtone. The sections were then de-waxed, stained and examined for the anatomical features and photoalerogra- phed. The weather parameters and the nutritional factors recorded daring the period of study and those during sixteen fortnights prior to differentiation, were correlated with the data on flower bud differentiation. Significant positive correlation was obtained between the maximum temperature during the sixth to tenth fortnights before differentiation and the percentage of flower buds differentiated. Sunshine hours during ninth to twelfth fort night prior to differentiation showed a positive correlation with the percentage of flower bud differentiation.ThesisItem Open Access Formulating fermented cassava food products Subtitle: standardisation of garl(Department of Home Science, College of Agriculture, Vellayani, 1989) Sathya, lakshmi C.; Chellammal, SThesisItem Open Access Time of application of pre-emergence herbicides in dry-sown rice(Department of Agronomy, College of Horticulture, Vellanikkara, 1989) Suja, G; KAU; Abraham, C TThesisItem Open Access Standardization of growing media for dendrobiums (Qendkobium dpp.)(Department of Horticulture, Pomology & Floriculture and Landscaping, College of Horticulture, Vellanikkara, 1989) Anitha, Paul C; Rajeevan, P KThesisItem Open Access Spatial arrangement and nutrient management for maize- fodder cowpea intercropping in rice fallows(Department of Agronomy, College of Agriculture Vellayani, Trivandrum, 1989) Geetha Kumari, S; KAU; Mohamed Kunju, UAn investigation was carried out during the summer season of l987-88 in the instructional farm attached to the College of Agriculture Vellayani to determine the best crop arrangement for a grain maize fodder cowpea inter cropping in summer rice fallows under different fertility levels • The different crop arrangements. tried were pure crop of maize at normal row arrangement, maize at normal row arrangement, + one, row of cowpea in between the maize pure crop of maize at paired row arrangement two rows of cowpea in the interpair spaces maize at paired rows of cowpea.ThesisItem Open Access Control of aphis craccivora koch. with fungal pathogens and their impact on the natural enemies of the pest(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Hareendranath, V; KAU; Vasudevan Nair, K PStudies were made to collect information on the population fluctuation of pea aphid Aphis craccivora Koch. a regular pest of cowpea in relation to time of planting and stage of the crop. The population fluctuation of pea aphid in relation to the prevailing weather factors and the predators were also investigated to collect information on host predator interactions and interrelations. A survey on the occurrence of fungal pathogens associated with pea aphid was conducted in the pulse crops raised at the Instructional Farm, College of Agriculture, Vellayani and adjacent farmers fields. The suspected fungi were isolated and their pathogencity tested in the laboratory. Pathogencity could be proved only in the case of Fusarium pallidoroseum (Cooke) Sacc. Detailed studies were made on its growth, sporulation and pathogenicity using different artificial culture media. It was observed that the cowpea crop planted during November recorded maximum population of pea aphid followed by crop planted during October and December. Lowest population of pea aphid was noticed in the crop planted during March. The active reproductive stage of the crop recorded maximum population of pea aphids. Correlation studies with weather factors and predator population revealed that relative humidity and predator population was positively correlated with the population of pea aphid. Regression analysis of the data obtained indicated that 84 per cent of variation of population could be accounted by the variables under study. Partial regression coefficient of the aphid population and relative humidity was found to be positive and significant. Partial regression coefficient between pea aphid population and predator population was also positive and highly significant. Studies on the pathogenicity of F. pallidoroseum showed that pea aphid infected with the fungus turned pale and assumed a brownish black discolouration. Death occurred in 48 to 72 hours after infection and white mycelial growth appeared on the cadavers 24 to 48 hours after death. Growth, sporulation and virulence of the fungus was found to be superior in Sabouraud medium followed by potato dextrose agar. Sporulation was maximum in 6 day old culture and virulence was highest in 6 day and 7 day old cultures. For mass production of the fungus broken maize grain appeared to be the most suitable media followed by tapioca chips and jack seed as they produced maximum number of spores. Studies on the safety aspects of the pathogen showed that the fungus was not pathogenic to the crop plants tested viz. rice, bhindi, chillies and tomato and also to the predator Menochilus sexmaculata. Bioassay showed that LC50 of the fungus to pea aphid was 3.408 x 10 6 spores per ml. Field experiment to test the efficacy of the fungus in controlling aphid population revealed that the fungus at the rate of 7 to 10 6 spores per ml and 3.5 x 10 6 spores per ml was as effective as the insecticide quinalphos 0.05 per cent. The fungal treatment did not show any harmful effects on predator population in the field.ThesisItem Open Access Impact of eucalyptus and acacia plantations on soil properties in different pedogenic environments in Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Byju, G; KAU; Thomas, VargheseEucalyptus tereticornis and Acacia Auriculiformis are two important exotic tree species introduced into our environment through National Social Forestry programme. These two species are said to have many qualities which qualify them for inclusion under the social forestry programme. These fast growing tree species have the unique capability of surviving and regulating their growth to prevailing growth factors. But environmentalists in India and abroad have questioned the feasibility of bringing fertile lands under these exotic species which they claim to have deleterious impact on soil properties, hydrological parameters, biotic associations and long-term socio-economic consequences. However, these arguments do not have a sound scientific basis due to lack of sufficient research data base. So a study was undertaken to find out the impact of these monoculture plantations on soil properties in different pedogenic environments in kerala. Soil profiles were taken from four locations representing different geoclimatic regions of Kerala. The locations were Wynad (Northern forested highland), Kottoor (Southern forested highland), Nileswar (Northern coastal) and Kazhakkoottam (Southern coastal). Altogether thirteen pedons were studied from different locations representing reserve forest, cultivated land, barrenland, Eucaiyptus plantation and Acacia plantation. Pedons were described systematically and subjected to physico-chemical analyses and also for assessing the extent and nature of microflora. Biomass studies and chemical analyses of plant samples have alsobeen undertaken. From the studies, it was revealed that monoculture plantations of Eucalyptus and Acacia have got deleterious impact on soil physical, chemical and biological characteristics. These deleterious effects were more in a forest environment compared to sandy tracts. Increase in gravel content, eluviation of clay, lower silt/clay ratio, increase in bulk density, lower water holding capacity, low moisture content and low water dispersible clay in soils under Eucalyptus in forest areas show that the process of ferrallitisation and soil degradation proceed faster under Eucalyptus. Chemical composition also showed decrease in soil fertility under Eucalyptus. In the sandy tracts, Eucalyptus and Acacia increased the soil organic matter, total nitrogen and available potassium, while almost all other parameters used for the study showed deleterious effects. Active iron ratio (Fe oxalate/ Fe dithionite) was calculated to assess the extent of induration and the results indicated a relative enrichment of crystalline iron oxides in monoculture plantations of Eucalyptus and Acacia which may also lead to induration. A decrease in microbial population was also observed in these plantations except the population of Rhozobium whose number increased in plantations of Acacia which is a leguminous tree. The above results indicated that planting of Eucalyptus and Acacia as monoculture has got very deleterious impact on soil characteristics and fertility . All these throw light on the imminent necessity to have a rethinking about the introduction of monoculture plantations with these exotic species especially in the reserve forest areas.
