PhD Thesis
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Item Studies on certain chemical constituents of banana leaves in relation to incidence of leaf spot diseases: A note on the fungi occurring on banana(Division of Plant Pathology ,Agricultural College and Research Institute ,Vellayani, Trivandrum, 1966) Chandrasekharan Nair, M K; Sam Raj, JItem Intraclonal variations and nutritional studies in banana cv. Palayankodan(Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara, 1985) Rajeevan, P K; Mohanakumaran, NThe investigations were carried out at the Banana Research Station, Kannara, during 1981-84 in the banana cv. 'Palayankodan'. Twenty four accessions were subjected to detailed analysis with respect to growth, yield and quality. The plants of the accessions differed significantly with regard to height and girth of pseudostem during the later stages of growth , both in the plant crop and in ratoon 1. Significant differences observed in the number of functional leaves were not consistent. Area of the third leaf at shooting varied significantly in all the three crops. The trend in variation between the crops, however, was not consistent. Interval of leaf production, total number of leaves produced and the density of stomata in the upper surface of the leaf lamina showed significant differences. The duration from planting to shooting in ratoon 1 alone varied significantly. The plant crop took more time than ratoon 1 and ratoon 2 to come to harvest. The content of nutrient elements in the index leaf did not exhibit significant variations. The reactionof the accessions to the important pest (rhizome weevil) and diseases (bunchytop and Sigatoke) varied considerably.Item Growth pattern, flowering and yield potential of tissue cultured plants of banana "Musa (AAB Group) Nendran" and standisation of fertilizer schedule(Department of Horticulture, College of Agriculture, Vellayani, 1995) Sheela, V L; Ramachandran Nair, SThe present study was under taken with the objective of comparing the growth pattern flowering and yield potential of tissue cultured plants of Nendran banana with that of plants produced from suckers and to formulate a suitable fertilizer schedule for the tissue cultured plants Two separate experiments were conducted for this purpose in the Department of Horticulture, College of Agriculture, Vellayani for two seasons from March 1991 to February 1993. The first experiment was laidout in split split plot technique and the second in confounded factorial design in RBD. Tissue cultured plants recorded an increase in yield of 25.63 per cent compared to plants from suckers. The highest yield were obtained in both seasons with the application of 300g nitrogen and 450g potash per plant NK interaction on yield was also significant . Treatments with fertilizer application exceeding six splits did not enhance yield . The optimum nitrogen and potash for the two seasons was 299. 5g and 465. 5g per plant respectively.Item Induced mutations in banana var. Nendran(Department of Agricultural Botany, College of Agriculture, Vellayani, 1990) Radha Devi, D S; Krishnan Nair, NThe present investigations was carried out in the Department of Agricultural Botany, College of Agriculture, Vellayani during 1985-88 and in the plant tissue culture Laboratory attached to the Department of Plantation Crops, College of Horticulture, Vellanikkara, Thrissur during 1986-88. The project was taken up to standardise the techniques for induced mutagenesis in-vitro and in-vitro in banana (Musa paradiciaca L.) var. nendran and aslo to analyse the direct effect of 60 Co gamma rays on growth and bunch characters in the vM1 and vM3 generations. One, two and three months old suckers of various sizes (after removal of 25 to 75 per cent of the pseudostem) were exposed to 1.0, 1.5, 2.0, 2.5 and 3.0 kR gamma rays. For in-vitro mutagenesis, isolated shoot tips were exposed to 0.50, 0.75, 1.00, 1.25 and 1.50 kR gamma rays. Ex-vitro analysis of five plants per treatment per exposure was done in the vM1 generation for various growth, bunch and fruit characters.Item Weed management in sole and intercropped coconut gardens(Department of Agronomy, College of Horticulture, Vellanikkara, 1990) Savithri, K E; Sreedharan, CField experiments were conducted during the period from 1986 to 1989 at the Agricultural Research Station, Mannuthy, Thrissur to develop weed management practices for sole and intercropped coconut gardens. There were three fields trials. In trial - I the treatments comprised of three manual methods (digging once, digging twice and sickle weeding), six chemical methods (paraquat three sprays, glyphosate 0.4 kg ha-1, glyphosate 0.8 kg ha-1 dalapan followed by paraquat, paraquat + diuron and paraquat followed by glyphosate), two combinations of manual and chemical methods (2,4-D + diuron immediately after sickle weeding and glyphosate followed by digging) were compared with weed free and unweeded control in underplanted coconut garden. In trial - II, the treatments comprised of two manual methods (spade weeding and sickle weeding ), one cultural method (growing cowpea as an intercrop) two cultural + chemical methods (cowpea followed by paraquat or glyphosate), three pre-emergence herbicides + post-emergence herbicide (diuron followed by paraquat, oxyfluorfen followed by paraquat and atrazine followed by paraquat ) were compared with weed free and unweeded control in coconut+ banana cropping system. Unweeded control in coconut banana cropping system was compared with that in sole crop of coconut . In trial III, the treatments tried in coconut+banana cropping system were eveluated in sole crop of banana and there were thirteen treatments . All these three trials were laid out in Randomised Block Design and replicated thrice.Item Bio-ecology of the cyst nematode infecting banana(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Job Sathyakumar Charles; Venkitesan, T SPathogenicity of the cyst nematode on banana cv. Nendran carried out revealed that the nematode can affect crop growth and yield at lowest initial inoculum of 100 cyst3 per plant. However, the threshold level of initial inoculum of 800 to 1,000 cysts per plant the growth, yield and quality of fruits were considerably reduced. An initial inoculum of 100 to 1,000 viable cysts per plant at planting time could reduce bunch weight by 20.5?£ to 56.6?4. The nematode Infection was observed to affect quality of fruits by increasing acidity and reducing total sugars. This nematode attacks the minute tertiary feeder roots and not observed to attack the fleshy roots and rhizome portions. The attacked feeder roots turn black in colour and detach easily. The final nematode population revealed that there was significant build up in the density of population. The increase ranged from 15*59 to 35.18 per gram root and from 1,168 to 3,188 in 100 gram soil. A significant negative correlation was found to exist with plant growth parameters, bunch characteristics and root weight with the initial inoculum levels of cyst nematode population.Item Cytotaxonomical studies on banana cultivars(Department of Pomology and Floriculture and Landscaping, College of Horticulture, Vellanikkara, 1984) Valsalakumari, P K; Sivaraman Nair, P CVariability in banana are wide and complex with different degrees of expression of the characters of the parental species, Musa acuminata and Musa balbisiana. Commercial cultivars are many, ranging in levels of productivity and quality characters. Investigations were conducted at the College of Horticulture, Kerala Agricultural University, Vellanikkara, Trichur during 1981-83 on 100 cultivars of banana to study the cytotaxonomical aspects. Studies on morphological characters, taxonomic scoring and chromosome number revealed that many of the cultivars were identical and ultimately the cultivars were confined to 64 distinct ones. The taxonomic scoring did not indicate the ploidy. Eight cultivars with the scores of triploids, were identified as diploids. The quantitative, quality and pollen characters showed a significant variation among the cultivars. The characters were influenced by the ploidy and the genomic constitution. The presence of ‘B’ genome increased plant height and girth, leaves per plant, leaf area per plant and petiole length. Musa balbisiana (BB) recorded the highest values for all the above characters. The triploids were more vigorous than the diploids and the tetraploids as indicated by their higher growth rates. The triploids were also better than the other groups for bunch and finger characters. Among them, the triploids of hybrid origin were better for bunch characters while the Musa acuminata triploid group (AAA) was superior to the other groups for finger characters. Longer pedicel was a characteristic feature of Musa balbisiana( BB). The genomic constitution of the cultivars influenced the contents of total soluble solids, sugars and acids in fruits, more than the ploidy. Musa acuminata group AAA, had the highest sugar/acid ratio. Studies on pollen viability, size and production in cultivars revealed the possibility of including a few of them as male parents in the banana hybridization programme. Forty of the cultivars studied were polleniferous. Pollen viability and production were more in pure Musa acuminata and Musa balbisiana groups than in groups of hybrid origin. Musa acuminata cultivars had larger pollen grains than cultivars belonging to the other genomic groups.Estimates of genotypic and phenotypic coefficients of variation, heritability in the broad sense, genetic advance and genetic gain for the 26 characters indicated the scope for selection among the cultivars. Petiole length, pulp/peel ratio on volume basis, weight and volume of fruit showed higher heritability values combined with high genetic gain. Estimation of genetic divergence among the cultivars showed that the cultivars ‘Mannan’ and ‘Pacha chingan’, belonging to the genomic group AAB, were the closest and a Musa acuminata cultivar, ‘Harichal’ (AAA) and Musa balbisiana (BB) were the farthest. The 62 cultivars were grouped into eight homogeneous clusters. Similar clustering pattern was obtained in the canonical analysis also. The study revealed the predominance of the cultivars of the hybrid origin, with different degrees of expression of the characters of the parental species, in the South Indian bananas. The taxonomic scoring system was not always appropriate to find out the ploidy of the cultivars. The study also indicated the scope for selection among the cultivars and the possibility of inclusion of the cultivars with viable pollen as male parents in the hybridization programme.Item Purification and serology of banana bunchy top virus(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1998) Estelitta, S; Sukumara Varma, ABanana is one of the major fruit crop in Kerala and is often affected by the bunchytop disease caused by banana bunchytop virus. The disease is easily spread through infected suckers, which are used as the planting materials. Secondary spread is also seen through banana aphid, Pentalonia nigronervosa. Though field level quarantine measures may check the spread of the disease, rapid and convenient methods for the detection and identification of the virus in the suckers as well as in micropropagated plants have not been developed. In this background a study was designed and carried out to purify the BBTV, to produce antisera for developing a serological technique for the pre-symptomatic detection of virus in the planting materials of banana. Studies were also conducted to identify the type of nucleic acid of the virus and its morphology by direct electron microscopy. The study revealed that the disease incidence was maximum during August-November. The virus was not mechanically transmitted and tissue culture plants were the most susceptible planting materials for aphid transmission. Basic studies of virus-vector relationship were also conducted and the adult aphids were found to be effective vectors. In purification studies, among the different portions of banana plants used, the midribs of younger leaves yielded high concentration of the virus. Tissue culture plants yielded more virus concentration than other planting materials. Electron microscopy of the purified BBTV preparation revealed isometric particles of 18-22 nm size. Nucleic acids extracted from both healthy and infected samples were compared. The bands obtained were sensitive to DNase 1 and SI nuclease but not to RNase A, confirming the nucleic acid BBTV as ssDNA. SDS-PAGE analysis of BBTV coat protein revealed that it contained a major protein component of Mr 21000 with Rf value between that of β lactoglobulin (Mr 18400) and α chymotrypsinogen (Mr 25700). Antiserum of BBTV was produced in the rabbit and used for detection of virus specific antigens in different parts of the plant (midrib, petiole, leafsheath and rhizome) by chloroplast agglutination, agar gel diffusion, tube precipitation and ELISA. Among these methods ELISA was found to be highly sensitive for identification of the virus.Item Standardisation of plant part as an index of potassium status in banana, musa (AAB Group) nendran(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1994) Sumam George; Padmaja, PA field experiment in Musa (AAB group) Nendran, the most popular commercial fruit crop of Kerala was undertaken from August, 1991 to May, 1992 with seven graded levels of K as treatments replicated thrice. The soil, medium in N and P and high in K status belonged to the taxonomic class ‘loamy kaolinitic isohyperthermic aeric tropic fluvaquents’. The effects of higher levels of K on all important growth characters of the crop like height of pseudostem, girth of pseudostem at different heights from the ground level, total number of leaves, number of functional leaves, total leaf area, leaf area index and total dry matter production were more pronounced from the shooting stage of the crop after the plants had received the full dose of K supply. Uptake of major nutrients N, P and K showed increasing trend with increase in K supply. Uptake of Ca showed a negative relationship with increasing K application while Mg uptake showed an inconsistent pattern. Uptake of micronutrients Fe, Mn, Cu and Zn were maximum at K3 level of application (225 g K2O plant-1). Soil content of available K increased while exchangeable Ca and Mg contents decreased at higher levels of K supply. The maximum bunch yield of 26.18 t ha 1-which was significantly higher than all other treatments was recorded at K3 level (225 g k2O plant-1) This level also resulted in maximum values for all the yield attributing characters like number of hands bunch-1, number of finger bunch-1, weight of hand, length of finger, girth of finger and weight of finger. By adopting this recommendation a net fertilizer saving of 75g K2O plant-1 Can be achieved which is equivalent to 312.5 kg of muriate of potash costing Rs. 2000 at the present market rate. Over and above this, increase in yield obtained by doing so is 4500 kg ha-1. Additional income that could be generated by the way of sale of this at the rate of Rs. 8 kg-1 works out to Rs. 36000. Thus a total saving of Rs. 38000 ha-1 can be achieved by following the suggested recommendation. Path coefficient analysis of yield attributes showed that the character number of finger bunch-1 is having the maximum direct effect on yield followed by girth of fruit and weight of fruit. Quality characters of the fruit namely total and non reducing sugars, shelf life and flesh peel ratio showed significant and positive trend towards K nutrition. Correlation coefficient were worked out between bunch yield and important crop characters. Balance sheet of nutrients in soil after harvest of the crop was worked out to assess the final soil status of nutrients in relation to the initial status. Petiole of the third leaf up to shooting stage of the crop and that of the flag leaf there after was selected as the index of K status of the plant as the K content of the same was found to hold the maximum relationship with bunch yield at all the growth stages. The critical K levels in the petiole for maximum yield as well as maximum response to fertilizer application at each stage were determined which were found to be 1.30 per cent and 1.02 per cent respectively at early vegetative stage, 1.28 per cent and 1.06 per cent respectively at late vegetative stage, 1.80 per cent and 1.36 per cent respectively at shooting stage, 2.43 per cent and 1.98 per cent respectively at post shooting stage, 2.50 per cent and 1.80 per cent respectively at bunch maturation stage and 2.47 per cent and 1.80 per cent respectively at harvest stage. The critical K content in soil for economic yield worked out to 286.5 kg K2O ha-1 at early vegetative stage, 276.5 kg K2O ha-1 at late vegetative stage, 271.o kg K2O ha-1 at shooting stage, 239.o kg K2O ha-1 at post shooting stage, 245.0 kg K2O ha-1 at bunch maturation stage and 236.0 kg K2O ha-1 at harvest stage. Graphs were plotted relating petiole K content to soil K content at important growth stages of the crop based on quadratic regression models to provide information on soil K content at a particular stage if the petiole K content at that stage is known. Linear regression models were developed relating soil K content to fertilizer dose to find out the quantity of fertilizer to be applied to bring the soil level to the critical level.Item Integrated plant nutrition system (IPNS) for maximising yield in banana, musa (Aab group) nendran(Department of Agronomy, College of Agriculture, Vellayani, 1998) Geetha, K; Ravindran Nair, RField experiments were conducted at the Regional Agricultural Research Station, Kumarakom during 1994 – 1995 and 1995 – 1996, in order to formulate an Integrated Plant Nutrition System (IPNS) for increasing yield and quality of banana cv. Nendran. The optimum combination of various nutrient resources for the crop was arrived at in this study. The treatments comprised of three types of organic inputs (Azospirillum, cowpea and vermicompost) along with a control and four levels each of fertilizer N (0,95,143 and 190 g plant-1) and 2, 4-D (0,15,30 and 45 ppm). The design of the experiment was 43 factorial confounding the highest order interaction. There were two replications. The results revealed that cowpea (green manure) and vermicompost influenced the yield response to applied N significantly. The organic inputs helped to increase the bunch yield and net returns and reduced the chemical N requirement to 85 per cent of the present recommended dose (190 g plant-1). Besides, they improved the physical and chemical properties of the soil at the end of the experiment. Application of 2, 4-D at the rate of 30 ppm was beneficial for higher yield, particularly at the lower doses of fertilizer N. The growth regulator did not give any residue in the fruit. The effect of interaction between organic inputs and fertilizer N was clearly evident in the growth attributes. The influence of organic inputs was significant on TSS, acidity and reducing and non reducing sugars. Applied N and 2, 4-D influenced all the quality parameters. An IPN package consisting of either cowpea (green manure) or vermicompost, 85 per cent of the present recommended dose of fertilizer N (190 g plant-1) and 30 ppm of 2, 4-D is suggested for achieving high economic returns from banana cultivation.