PG Thesis
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/2
Browse
5 results
Search Results
Item Micronutrients and biostimulants for crop management in marigold (Tagetes erecta L.)(Department of Floriculture and Landscaping, College of Agriculture, Vellanikkara, 2025) Aparna, M Rajeev; Resmi PaulInvestigations on “Micronutrients and biostimulants for crop management in marigold (Tagetes erecta L.)” was undertaken at the Department of Floriculture and Landscaping, College of Agriculture, Vellanikkara during 2024 to 2025. Objectives of the study were to evaluate the influence of micronutrients, biostimulants, and plant growth promoting rhizobacteria (PGPR) on the growth, yield, and quality attributes of African marigold. Studies were carried out in the hybrid Royal Orange. The experiment was laid out in a randomized block design comprising of ten treatments with three replications each, involving combined application of recommended dose of fertilizers (RDF), boron (1 kg ha⁻¹), varying concentrations of humic acid (1%, 3%, and 5%), salicylic acid (50, 100, and 150 ppm), and PGPR Mix I and II (2% and 5%). Treatments were applied through soil application, foliar spray, soil drenching, and root dipping at different growth stages of the plants. Vegetative, floral, and biochemical parameters of the plants and soil nutrient characteristics of the experimental plot were studied. Significant variations among treatments were observed for all the traits studied except for the shelf life of flowers. Among the treatments, application of 5% humic acid along with RDF and boron (T5) recorded significant improvement in plant height (46.25 cm), plant spread (29.29 cm), number of branches per plant (15.67), and leaf count (15.5 per branch). This treatment also resulted in the highest fresh (464 g and 64 g respectively) and dry (95 g and 29 g respectively) shoot and root biomass, indicating enhanced nutrient absorption and root development. The same treatment (T5) also advanced the onset of flowering, with the earliest bud emergence (31.67 days) and 50% flowering (31.83 days), while the control treatment (RDF alone) showed delayed flowering (41.08 days). Floral attributes such as number of flowers per plant (18.67), flower diameter (6.03 cm), individual flower weight (8.8 g), and flower yield per plant (159.93 g) were also maximized in T5 (RDF + boron + 5% humic acid), followed by treatments with RDF + boron + PGPR (T9 and T10) and RDF + boron + salicylic acid (150 ppm) (T8). The duration of flowering (71.08 days) and field life of flowers (7.58 days) were prolonged under T5 (RDF + boron + 5% humic acid), reflecting improved physiological activity. Biochemical analysis revealed that treatments consisting of RDF + boron + salicylic acid and RDF + boron + PGPR improved biochemical composition of leaves and flowers. The treatment with RDF + boron + 150 ppm salicylic acid (T8) exhibited highest chlorophyll a (1.313 mg g⁻¹ FW), chlorophyll b (1.295 mg g⁻¹ FW), and total chlorophyll (2.61 mg g⁻¹ FW), suggesting improved photosynthetic efficiency. PGPR Mix II (5%), along with RDF and boron (T10), significantly increased phenolic (21.78 mg GAE/g and 54.23 mg GAE/g respectively) and flavonoid (0.307 mg QE/g and 4.51 mg QE/g respectively) contents in leaves and flowers, and carotenoid content (0.051 mg/g FW) in flowers, indicating higher antioxidant potential and stress tolerance. Nutrient uptake studies indicated that plants which received RDF + boron + 5% humic acid (T5) exhibited superior uptake of nitrogen (3.04 g plant⁻¹), phosphorus (0.238 g plant⁻¹), iron (0.219 g plant⁻¹), and zinc (0.029 g plant⁻¹). Potassium uptake was not significantly correlated with yield, suggesting that other nutrients played a more decisive role in flower production. Soil analysis after harvest of flowers showed improved macronutrient and micronutrient availability in plots receiving RDF + boron + PGPR and RDF + boron + biostimulants. Correlation studies demonstrated that yield per plant had a significant positive association with key vegetative and floral traits such as plant spread, number of branches and flowers, flower diameter and weight, duration of flowering, and total chlorophyll content, while being negatively correlated with the number of days to bud emergence and 50% flowering. Similarly, flower yield showed significant positive correlations with the uptake of nitrogen, phosphorus, iron, manganese, zinc, and boron, underscoring the role of balanced nutrition in the enhancement of productivity. Combined use of micronutrients and biostimulants improved growth, yield and quality attributes of African marigold. Integrated application of RDF + boron + humic acid (5%) enhanced the overall growth, yield and floral characteristics of African marigold. The use of RDF + boron + salicylic acid proved beneficial in enhancing chlorophyll content, flower longevity, and stress resilience, whereas RDF + boron + PGPR combinations improved secondary metabolite accumulation, contributing to superior flower colour and quality. Combinations and concentrations of micronutrients and biostimulants along with RDF identified in the present study could be utilized in further investigations.Item Identification of molecular marker linked with bacterial wilt resistance in marigold (Tagetes erecta L.)(Centre for Plant Biotechnology and Molecular Biology, College of Agriculture , Vellanikkara, 2022-04-08) Sreekutty ,S S; Deepu MathewThe annual flower crop marigold has gained popularity due to its easiness of cultivation and wide adaptability. It is grown for loose flowers for garland making, wreaths and religious offerings and is ideal for garden display. It is a rich source of some value added compounds - essential oils, carotenoid pigments etc. Bacterial wilt is a major reason for low productivity, especially in Kerala, causing a yield loss up to 65 - 70 per cent under conducive climatic conditions. Moreover, the pathogen being soil borne, management of this disease is very difficult and development of resistant varieties is the most promising strategy. Bulk sergeant analysis (BSA) is a quick strategy to find molecular markers associated with a trait. In this, plants from segregating population are grouped according to their phenotypic response to the target trait and the marker pattern will be associated with the expression. Usually, F2 population has been used for BSA because it provides the best recombination and segregation in the population so that extreme phenotypes can be easily distinguished upon artificial inoculation (Michelmore et al., 1991). The study entitled “Identification of molecular marker linked with bacterial wilt resistance in marigold (Tagetes erecta L.)” was carried out at the Centre for Plant Biotechnology and Molecular Biology and Department of Floriculture and Landscape Architecture, College of Agriculture, Thrissur during 2019 to 2021. The objective of this research programme was to identify inter simple sequence repeat (ISSR) marker for resistance to bacterial wilt disease in marigold (Tagetes erecta L.). To develop the mapping population, pollen from the resistant line M1 was used to pollinate the susceptible cv. Double Yellow. F1 seeds were collected and the hybrids were found to have moderate resistance. Flowers of F1 plants were selfed by bagging and the seeds obtained were sown to raise the F2 population. Two hundred and four F2 plants, resistant and susceptible parents were artificially screened (using fresh bacterial wilt inoculum having an OD value of 0.9 at 600 nm) for bacterial wilt resistance and the most susceptible and most resistant plants in F2 were identified. Wilting in plants was checked daily and infection was confirmed by ooze test. DNA was isolated from the parents and 10 plants each from most susceptible and most resistant F2 plants and S- and R-bulks were prepared. Fifty ISSR primers were initially screened and 21 primers yielding amplification were selected for BSA. BSA was carried out using parental DNA and Sand R- DNA bulks. A total of 179 amplicons were produced from 21 primers in ISSR marker analysis. From these 11 primers, yielded 23 polymorphic bands and four molecular markers were able to produce eight polymorphic bands segregating with bacterial wilt resistance. The markers ISSR 12 (750 bp), ISSR 16 (370 bp), ISSR 30 (150 and 800 bp) and UBC 866 (400 and 350 bp) were found segregating with the expression of resistance. Of these, markers ISSR 12 and ISSR 30 were associated with the susceptibility and the rest were associated with the resistance. Six markers identified in this study through BSA can be used in marker assisted selection for bacterial wilt resistance in marigold.Item Identification of molecular marker linked with bacterial wilt resistance in marigold (Tagetes erecta L.)(Centre for Plant Biotechnology and Molecular Biology, College of Agriculture, Vellanikkara, 2022) Sreekutty, S S; Deepu MathewThe annual flower crop marigold has gained popularity due to its easiness of cultivation and wide adaptability. It is grown for loose flowers for garland making, wreaths and religious offerings and is ideal for garden display. It is a rich source of some value added compounds - essential oils, carotenoid pigments etc. Bacterial wilt is a major reason for low productivity, especially in Kerala, causing a yield loss up to 65 - 70 per cent under conducive climatic conditions. Moreover, the pathogen being soil borne, management of this disease is very difficult and development of resistant varieties is the most promising strategy. Bulk sergeant analysis (BSA) is a quick strategy to find molecular markers associated with a trait. In this, plants from segregating population are grouped according to their phenotypic response to the target trait and the marker pattern will be associated with the expression. Usually, F2 population has been used for BSA because it provides the best recombination and segregation in the population so that extreme phenotypes can be easily distinguished upon artificial inoculation (Michelmore et al., 1991). The study entitled “Identification of molecular marker linked with bacterial wilt resistance in marigold (Tagetes erecta L.)” was carried out at the Centre for Plant Biotechnology and Molecular Biology and Department of Floriculture and Landscape Architecture, College of Agriculture, Thrissur during 2019 to 2021. The objective of this research programme was to identify inter simple sequence repeat (ISSR) marker for resistance to bacterial wilt disease in marigold (Tagetes erecta L.). To develop the mapping population, pollen from the resistant line M1 was used to pollinate the susceptible cv. Double Yellow. F1 seeds were collected and the hybrids were found to have moderate resistance. Flowers of F1 plants were selfed by bagging and the seeds obtained were sown to raise the F2 population. Two hundred and four F2 plants, resistant and susceptible parents were artificially screened (using fresh bacterial wilt inoculum having an OD value of 0.9 at 600 nm) for bacterial wilt resistance and the most susceptible and most resistant plants in F2 were identified. Wilting in plants was checked daily and infection was confirmed by ooze test. DNA was isolated from the parents and 10 plants each from most susceptible and most resistant F2 plants and S- and R-bulks were prepared. Fifty ISSR primers were initially screened and 21 primers yielding amplification were selected for BSA. BSA was carried out using parental DNA and Sand R- DNA bulks. A total of 179 amplicons were produced from 21 primers in ISSR marker analysis. From these 11 primers, yielded 23 polymorphic bands and four molecular markers were able to produce eight polymorphic bands segregating with bacterial wilt resistance. The markers ISSR 12 (750 bp), ISSR 16 (370 bp), ISSR 30 (150 and 800 bp) and UBC 866 (400 and 350 bp) were found segregating with the expression of resistance. Of these, markers ISSR 12 and ISSR 30 were associated with the susceptibility and the rest were associated with the resistance. Six markers identified in this study through BSA can be used in marker assisted selection for bacterial wilt resistance in marigold.Item Standardization of growing medium and growth retardants for compact growth of potted African marigold(Department of Floriculture and Landscape Architecture, College of Agriculture, Vellanikkara, 2021) Niranjana Gopal; Mini SankarThe study entitled “ Standardization of growing medium and growth retardants for compact growth of potted African marigold” was carried out in the Department of Floriculture and Landscape Architecture, College of Agriculture, Vellanikkara during 2020-2021. The objective of the study was standardization of growing medium and growth retardants for regulating growth of potted African marigold for display purpose. The experiment consisted of five different media viz; cocopeat (60%) + vermicompost (20%) + vermiculite (10 %) + rice husk (10%) [M1], cocopeat (60%) + FYM (20%) + vermiculite (10%) + rice husk (10%) [M2], cocopeat (40%) + soil (20%) + vermicompost (20%) + vermiculite (10%) + rice husk(10%) [M3], cocopeat (40%) + soil (20%) + FYM (20%) + vermiculite (10%) + rice husk (10%) [M4] and soil: FYM: sand (1:1:1) [M5] and two growth retardants in three different levels viz; cycocel [750 ppm (GR1), 1000 ppm (GR2) and 1500 ppm (GR3)] and paclobutrazol [30 ppm (GR4), 60 ppm (GR5) and 90 ppm (GR6)] along with a control group of each media without application of growth retardants. Four week old seedling of marigold variety ‘Double Orange’ was used for the study. Observations on vegetative characters, Floral characters as well as the nutrient status of growing media were recorded. With regard to vegetative characters, growing media, growth retardants and interaction between growing media and growth retardants had significant influence. Shortest plants were observed in M1 [cocopeat (60%) + vermicompost (20%) + vermiculite (10 %) + rice husk (10%)] and among the growth retardants, paclobutrazol at 90 ppm [GR6] was found to produce short plants. The same treatment were also found superior with respect to plant spread, number of branches and number of leaves. Regarding interaction effect an improvement in all vegetative parameters was observed in M4 [cocopeat (40%) + soil (20%) +FYM (20%) + vermiculite (10%) + rice husk (10%)] x GR6 [paclobutrazol 90 ppm]. Significant effects of growing media could be observed in floral characters and M4 was found superior with respect to floral characters Viz; number of flowers per plant (10.14), flower diameter (4.61 cm)and field life of individual flowers (9.21 days). M2 was found superior in terms of other floral ABSTRACT characters viz; days taken for first flower bud emergence and days taken from flower bud initiation to flower opening. With respect to the influence of growth retardants on floral characters, a greater number of flowers per plant (9.50), flower diameter (4.22), flowering duration (96 days) and field life of individual flowers were observed by the application of paclobutrazol at 90 ppm. Growing medium and growth retardant interaction had significant influence on floral characters. Lowest days for first flower bud emergence and from flower bud initiation to flower opening were observed in M2 [cocopeat (60%) + FYM (20%) + vermiculite (10%) + rice husk (10%)] x GR1 [cycocel 750 ppm]. Number of flowers per plant was highest in M4 x GR6, M5 x GR6 and M4 x GR5 [paclobutrazol 60 ppm]. Treatment combination M4 x GR6, M5 x GR6 and M4 x GR4 [paclobutrazol 30 ppm] were superior with respect to flower diameter and field life of individual flowers. Analysis of growing media before and after the experiment for differentphysio- chemical properties revealed that M1 had the lowest bulk density (g/cm3 ) highest porosity (%) and water holding capacity (%).The chemical properties pH and EC of all the media were found in the favourable range [pH - 5.8- 6.2; EC<1.5dS/m] both before and after the experiment. Available N, P, K before and after the experiment was found highest in M4 .Plant nutrient content (NPK), Total chlorophyll content and uptake of nitrogen and potassium by plants were also found higher in M4. From the overall performance, it could be noted that the vegetative parameters viz; plant spread, number of branches and number of leaves as well as floral parameters such as number of flowers, size of flowers and field life of individual flowers were in desirable range in treatment combination M4 x GR6. Hence the medium M4 [cocopeat (40%) + soil (20%) + FYM (20%) + vermiculite (10%) + rice husk (10%)] along with application of paclobutrazol 90 ppm [GR6] 20 and 35 days after pinching can be recommended for compact growth of potted AfricanmarigoldItem Heavy metal stabilized sewage sludge compost as a growth medium for ornamentals(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2019) Rehana, M R; Biju Joseph