PhD Thesis
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Item Investigations on yellowing of black pepper (piper nigrum L.)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Maddirala Surendra; Sujatha, V SItem Performance analysis of medicinal kaempferia species(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Akoijam Ranjita Devi; Mini Raj, NItem Genetic analysis of inbreds, inbred crosses and hybrids of Cocoa (Theobroma cacao L.)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2019) Vijayakumar Narayanapur, B; Suma, BItem Characteization and evaluation of nutmeg (Myristica fragrans Houtt.) accessions(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2016) Vikram, H C; Mini Raj, NNutmeg (Myristica fragrans Houtt.) is an introduced crop to India. There exists tremendous variability in the nutmeg population in Kerala, which is the major nutmeg growing state in the country. Assessment of the existing variability is a prerequisite for taking up successful crop improvement programmes, which is very much limited in this tree spice. In this context, the present study entitled “Characterization and evaluation of nutmeg (Myristica fragrans Houtt.) accessions” was taken up exclusively with the specific objectives to characterize nutmeg accessions based on morphological, biochemical and molecular parameters so as to scale the variability in a multidimensional way. Select fifty nutmeg accessions from a core germplasm collected and maintained in a private plantation in the Chalakudy river basin, belonging to age of fifteen years, formed the material for the study. Among the select fifty accessions, forty two were females, four monoecious and four males. In the morphological characterization, 51 qualitative and 38 quantitative characters were recorded from two trees per accession. Biochemical characterization was done in the select seventeen distinct accessions. GC-MS profiling was done in kernel and mace oils. Biochemical constituents of fresh pericarp were estimated. Isozyme profiling was done for peroxidase and polyphenol oxidase enzymes. The molecular characterization was attempted with 21 RAPD and 12 ISSR primers after screening. A key for identification of an elite nutmeg tree was developed. A descriptor for nutmeg with a set of 51 qualitative and 38 quantitative parameters and descriptor states for each of these characters was developed as the first step. This is the first study of its kind to develop a minimal descriptor for nutmeg. The descriptor developed from the present study was simultaneously utilised for morphological characterization and evaluation of the accessions. Wide variability was noticed among the accessions for 47 out of 51 qualitative characters. Four characters viz., leaf margin, fruit pubescence, grooves on nut and nature of fruit dehiscence were noted as non variable characters and hence, these were not included for further analysis. Based on the qualitative characters, accessions were classified into 11 clusters at 66 per cent similarity level. Accessions differed significantly for all the quantitative characters except shelling percentage. Performance evaluation of the accessions brought out the superiority of accession 8, 9 and 22 for yield. The accessions showed high GCV, PCV, h2 and genetic gain for most of the characters. Number of fruits per tree, fruit set percentage, number of fruits per m2, fresh and dry weight of mace, mace volume as well ratio of nut to mace exhibited high genetic gain. Hence, selection programme based on these characters will be very effective in improving the base populations. Based on Mahalanobis D2 analysis, accessions were grouped into 10 clusters. Wide range of variation was observed in contents of volatile oil, oleoresin and fixed oil of kernel and mace. Based on these constituents accessions were grouped into 26 clusters, which indicated their distinct quality. Based on the results of the morphological characterization, seventeen distinct accessions were selected for further biochemical and molecular analysis. GC-MS analysis of kernel and mace oils exhibited 20 and 24 constituents respectively. Volatile oil composition exhibited wide variability for the major constituents viz., myristicin, elemicin, safrole and sabinene apart from the presence of some unique compounds. Grouping of the accessions was done based on the per cent content of these important compounds. Two accessions recorded high contents of both myristicin and elemicin whereas another two accessions were in the complimentary; belonging to low myristicin group. High sabinene combined with low myristicin was the intrinsic quality attribute of one of the accessions. Change, as well as addition/deletion of specific constituents was also noticed in the volatile oils after storage for one year. Accessions exhibited wide range of variation in the biochemical constituents of pericarp, a valuable information for the value addition of pericarp. Total phenol and tannins exhibited high variation. The accessions were ranked based on the content of biochemical constituents. Isozyme profiling using peroxidase enzyme produced four bands and that based on polyphenol oxidase exhibited three bands. Molecular markers could assess the variability among the accessions. The selected 21 RAPD primers produced a total of 164 amplicons of which 63.21 per cent were polymorphic. The 12 ISSR primers selected produced a total of 87 amplicons of which 69.44 per cent were polymorphic. Few unique bands were detected for specific characters. Inter cluster association of each of the qualitative clusters with other clustering patterns was worked out. The results indicated the differences as well as similarities of the qualitative clusters with other clustering patterns. Finally, key quantitative characters were identified based on their direct and indirect effect on yield as also economic importance. The statistical key thus developed using 13 key quantitative characters will serve as a preliminary tool for identification of an elite nutmeg tree.Item Rapid propogation and conservation of selected leguminous medicinal plants using in vitro techniques(Department of Plantation Crops and Spices,College of Agriculture, Vellayani, 2004) Deepa Nair, S; Reghunath, B RItem Evaluation of neelayamari(indigofera tinctoria L.) for yield and glysocide content under open and shade conditions(Department of Plantation Crops and Spices, College of Agriculture , Vellayani, 2004) Sarada, S; Reghunath, B RItem Physiological investigations in relation to flowering, fruit set and capsule developmentj of cardamom (elettaria cardamomum maton)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1986) Vasantha Kumar, K; Mohanakumaran, NInvestigations were carried out at the Cardamom Research Station, Pampadumpara and at the College of Horticulture, Vellanikkara during 1982 – ’84 to gather information on the physiological factors governing flowering, fruit set and capsule development of the three popular cardamom cultivars, Malabar, Mysore and Vazhukka. Emphasis had been given to unravel the causes of fruit (Capsule) shedding so as to evolve methods of control. Studies on growth and development in a broad sense depicted that an individual tiller of cardamom had a biennial growth habit. The different aspects of flowering and fruit set studied. Indicated that the variability was high in the Vazhukka cultivar and low in the Mysore cultivar. An early crop bearing habit was exhibited by Malabar, whereas Mysore possessed a late bearing habit and Vazhukka exhibited varying trends. The percentage of fruit set was high in Vazhukka, followed by Malabar and Mysore. Influence of climatic components on the physiology of flowering showed that a distinct dry spell triggered the panicle initiation process. The onset of rain coupled with high temperature was congenial for flower opening. A high soil moisture status combined with a high status of relative humidity (which resulted from a well distributed rainfall) enhanced the setting of capsules. Histological studies conducted in the genotype PV-1 (Malabar) showed that differentiation of panicle primordial was more during November to March. A prominent vascular zonation was observed in the rhizome nodes prior to the initiation of panicle promordia. Histology of the seeds revealed the development of starch grains at the greenish- yellow seed stage. Biological assays for endogenous auxins, inhibitors and cytokinins in the developing capsules indicated a spurt in auxin and cytokinin activity preparatory to fruit set. The level of inhibitory substances rose after the fruit set stage, while that of auxins fell which favoured the formation of an abscission zone causing shedding of immature capsules. Exogenous application of NAA (40 ppm) and 2, 4-D (4 ppm) increased the plant height, enhanced the production of panicles and flowers, reduced dropping of immature capsules and increased the yield. The uptake of nutrients revealed that cardamom is a heavy feeder of potash. The Vazhukka and Malabar cultivars developed less nutrients than the Mysore cultivar for producing unit yield of capsules. Radiotracer studies showed that the photosynthetic efficiency of cardamom was more under low light intensities. The rhizome was found to be the main sink in a cardamom tiller. Gas chromatographic estimation of cardamom oils indicated that the Mysore genotype (PR-107) was superior in quality aspects (because of high content of the esters, alpha terpenyl acetate, geranyl acetate and linalyl acetate) when compared with the Vazhukka genotype (PV-5) and Malabar genotype (PV-1). For consumption as a spice as well as for distillation of the essential oils, the black seed stages (‘karimkai’) was the most idel stage in cardamom.Item Somaclonal variation in black pepper (piper nigrum L)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1996) Shylaja, M R; Sreekandan Nair, GInvestigations on the exploitation of somaclonal variation for screening for resistance to Phytophthora foot rot disease in black pepper were carried out at the Plant Tissue Culture Laboratory of the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during September 1991 to January 1995. Calliclones of different black pepper cultivars viz. Kalluvally, Cheriakanyakkadan, Balankotta, Karimunda and Panniyur – 1 were produced with and without applying in vitro selection pressure using toxic metabolite(s) of Phytophthora capsici. In vitro induction of mutation using gamma irradiation and partial purification of the toxic metabolite(s) present in the culture filtrate of P. capsici were also attempted in the present study. Leaf puncture bioassay of the concentrated culture filtrate (CCF) of P. capsici showed that toxic metabolite(s) were accumulated in the culture filtrate. The symptoms produced by CCF were quite typical of natural and artificial infection by P. capsici. Concentrated culture filtrate induced quick electrolyte leakage from leaves and calluses. Concentrated culture filtrate induced necrosis on susceptible calli. The cultivars showed significant variation in callus necrosis. Prolonged duration of selection/screening with CCF totally inhibited the regeneration potential of the calli. Concentrated culture filtrate was not found to inhibit shoot proliferation and shoot growth in already regenerated cultures but inhibited the root growth. In the three direct selection/screening methods tried for calli viz. growing in CCF incorporated MS medium (Method 1) shaking in CCF incorporated liquid MS medium (Method 2) and double layer culture technique (Method 3), cultivars showed significant differences in callus necrosis and callus growth. Direct screening of calli was not found to inhibit the regeneration of shoots, shoot proliferation and recovery of rootable shoots but affected the root growth adversely. Gamma irradiation of calli using 60Co source did not give any better response to in vitro screening. The toxic metabolite(s) present in the culture filtrate could not be separated by organic solvent fractionation. However ion exchangers like Dowex 1 and Dowex 50 could be used for separation of the toxic fraction from the filtrate. The response of five different cultivars at various stages of development of cultures when compared, it was found that the cultivars differed significantly in callusing, callus growth, regeneration of shoots, recovery of rootable shoots and root growth. The clones regenerated from screened and unscreened calli were further tested for resistance/ tolerance to P. capsici using different methods of screening viz.natural screening (keeping in infected field), screening by electrolyte leakage method and screening by artificial inoculation of culture disc of P. capsici. None of the regenerated calliclones were found to be resistant to the disease in natural screening. When the tolerance level of the regenerated calliclones was looked into, the performance of the unscreened calli derived clones was found better as compared to the screened calli derived ones. The calliclones of different cultivars differed significantly inthetolerance/susceptibility reaction to the disease. The calliclones of Cheriakanyakkadan recorded greater degree of tolerance to the disease when compared to others. Among the cultivars studied, Kalluvally exhibited high rate of somaclonal variation.Item Induction of variation in vitro and field evaluation of somaclones in ginger (zingiber officinale rosc)(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2006) Resmi Paul; Shylaja, M RItem Physiological and biochemical aspects of flowering, berry set and developement in Black Pepper(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 2000) Satheesan, K N; Nybe, E V