PG Thesis
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Item Horticultural mineral oil for the management of pests in mango at the vegetative phase(Department of Entomology, College of Agriculture, Padannakkad, 2025-03-24) Smitha, K VAn experiment was conducted on ‘Horticultural mineral oil for the management of pests in mango during the vegetative phase’ was conducted during 2023-2024 at college of agriculture, Padannakkad and Instructional Farm II, Karuvachery. The objective of the study was to evaluate of Horticultural Mineral Oil (HMO) for the management of mango pests at the vegetative phase. The laboratory experiments were carried out in the Department of Entomology, College of Agriculture, Padannakkad. In the phytotoxicity evaluation, various concentrations of HMO (T1: 3.0%, T2: 3.5%, T3: 4.0%, T4: 4.5%, T5: 5.0%, T6: 5.5%, T7: 6.0%, T8: 6.5%, T9; 7.0%, T10; 8.0%, T11; 9.0% and T12; control) were tested on one year-old mango (Neelum) grafts, revealed that there were no signs of phytotoxicity symptoms up to T8. However, higher concentrations particularly T9, T10 and T11 caused symptoms like necrosis and chlorosis. Based on these findings, four higher concentrations viz., 5.0%, 5.5%, 6.0% and 6.5% were selected for laboratory bioassay. To evaluate the repellency against feeding and oviposition of leaf cutting weevil (Deporaus marginatus), HMO at a concentration of 6.5% effectively reduced feeding, with a recorded feeding area of 3.28 cm² and 63.47% reduction in feeding area compared to the control at 24 hours after treatment (HAT), which was on par with HMO at 6.0%. In all treatments, no oviposition by leaf-cutting weevils was observed. Evaluation of HMO against adults of leaf cutting weevil under laboratory conditions showed that HMO at a concentration of 6.0% and 6.5% caused 64% and 88% mortality of leaf cutting weevil respectively, at 24 HAT in residue film test. In spraying method, HMO at 6.0% and HMO at 6.5% had showed 72% and 76% mortality of leaf cutting weevil respectively, at 24 HAT. When HMO was evaluated against leaf cutting weevil grubs, at a concentration of 6.0% and 6.5% achieved 100% mortality at 24 HAT. Since the results for 6.0% and 6.5% were statistically similar, these two concentrations were selected for field studies. Field evaluation of HMO was carried out at Instructional Farm II, Karuvachery, College of Agriculture, Padannakkad under Randomized Block Design with seven treatments and four replications. The treatments were T1: HMO 6.0%, T2: HMO 6.5%, T3: Pongamia oil soap, T4: Neem oil-garlic soap, T5: Chlorantraniliprole 18.5 % SC, T6: Acephate and T7: Control. Observations on the mean number population of leaf cutting weevil indicated that T6, T3, T5 and T2 were more effective in reducing the mean population during the first application of treatments and it was on par with each other. During the second and third application of treatments, T6, T3 and T5 effectively reduced the mean population of leaf cutting weevils, which were statistically similar with T2 and T1. There was an effective reduction in the mean number of scraped leaves caused by leaf cutting weevil with T6 (3 DAT and 5 DAT in the first application of treatments) and T3 (7 DAT and 9 DAT), which were on par with other treatments. During the second and third application of treatments, T5 and T2 were observed more effective in reducing mean damage and were on par with each other. T1 and T2 were found to be effective in reducing mean number of cut leaves during the first and second application of treatments, which was on par with T3, T5 and T6. There was an effective reduction in mean number of fallen tender leaves from plant base by T3 (9 DAT) and T2 (3 DAT, 5 DAT, 7 DAT and 9 DAT) during the first and second application of treatments, respectively, which were on par with other treatments. For ash weevil (Myllocerus discolor), T6 was found to be effective in controlling the mean number population during the first application of treatments, which is statistically similar with T3 and T2. A similar trend of the population was followed till 9 DAT during the second and third application of treatments, which were on par with T3 and T2. Observations on mean number of damages indicated that T6 was effective in reducing the mean damage during the first (3 DAT, 5 DAT, 7 DAT and 9 DAT) and second (7 DAT and 9 DAT) application of treatments and it was on par with T1, T2 and T3. During the third application of treatments, T2 was effectively reduced the mean number of damaged leaves, which was on par with other treatments. In all three applications of treatments, HMO was effective in controlling the mean number of population and mean number of damages of both leaf cutting weevil and ash weevil and was found to be statistically similar with T6.Item Pathogenic variability and management of Lasiodiplodia theobromae causing dieback in mango(Department of Plant Pathology, College of Agriculture, Vellanikkara, 2025-02-22) Hima Mariya Dixon; Deepa JamesDifferent phenomena like mutation, recombination, natural selection, geographical locations, etc would result in the accumulation of variation in plant pathogenic microorganisms. These variants in the pathogen population often lead to loss of resistance of the cultivar, leaving it highly vulnerable to the disease. Lasiodiplodia theobromae, the causal organism of mango dieback is a highly variable pathogen known to occur in different locations and affecting different mango varieties. In this context, variability studies of Lasiodiplodia theobromae were undertaken to know the variation present among Lasiodiplodia population in Kerala. Purposive sampling surveys were carried out in five districts of Kerala viz., Thrissur (AEU 5, AEU 6, AEU 10 and AEU15), Palakkad (AEU 10, AEU 22 and AEU 23), Wayanad (AEU 20 and AEU 21), Kasaragod (AEU 11) and Kottayam (AEU 4 and AEU 9), thus covering 23 locations and 11 different agroecological units. A total of 37 isolates of the pathogen have been collected from 17 different mango varieties. Per cent disease incidence (PDI) of the different isolates ranged between 25-80 per cent whereas per cent disease severity (PDS) ranged from 17.5-62.5 per cent. General symptoms of dieback under natural conditions were necrotic leaves and black discolouration on the stem and certain isolates showed vascular discolouration too. Upon artificial inoculation of different isolates, a patch of black colour was observed and the range of incubation days varied from 10-15 days while that of lesion size from 0.55 1.1 cm. Diversity in different cultural and morphological characters was also observed. Cultural characters included colony colour (white, greyish white, grey, greyish black, blackish grey, blackish white and black), colony colour on the reverse side of the Petri dish (white and black colour), days taken to cover the Petri plate (2-5), days taken for pycnidia formation (13- 40), days taken for sporulation (22-55) and growth rate (3.34-5.2 cm/day). Certain cultural characters like texture, zonation and margin didn’t show any variation. All the isolates had wooly texture, smooth margin and no zonation was observed in any of the isolates. Different morphological characters also showed wide variation. Morphological characters observed were the colour, size and shape of conidia and the colour and size of hyphae. The range of breadth of hyphae of collected isolates was 3.36-5.18 µm, the range of length of conidia was was 20.83-23.85 µm, and the breadth of conidia was 10.68-13.32 µm. All 37 isolates invariably had cinnamon brown coloured ellipsoid conidia and brown coloured hyphae. The 10 most virulent isolates of Lasiodiplodia theobromae selected for vegetative compatibility studies based on incubation days and lesion size, showed 32 compatible and 13 incompatible out of 45 combinations. The isolates PMuNe,, WMnMa and KoKBn were compatible with maximum number of isolates (eight). Five isolates were selected for pathogenic variability studies based on cluster analysis viz., TNaM (I1), PMuNe (I2), WMnMa (I3), KPB (I4), and KoKBn (I5) and upon molecular characterization confirmed as Lasiodiplodia theobromae. Pathogenic variability of the selected five isolates of Lasiodiplodia theobromae was evaluated against two traditional mango varieties viz., Muvandan and Priyur and four commercial varieties of mango viz., Neelam, Bennet Alphonso, Banganapally, and Imam Pasand. Variability was observed in pathogenicity parameters such as PDI (33.33-100%), PDS (13.33-73.33%), lesion size (0.28-0.95 cm), and incubation period (9-17.33 days). Based on Coefficient of Index (CI) value, Neelam, Bennet Alphonso and Banganapally were categorized as susceptible while the other varieties, Priyur, Muvandan, Bennet Alphonso and Imam Pasand were categorized as moderately susceptible to mango dieback disease. All the isolates produced 100 per cent incidence on Banganapally, confirming its susceptibility. Based on virulence index, three isolates viz., WMnMa (I3), KPB (I4) and KoKBn (I5) with high value of virulence index were selected for their sensitivity to different fungicides and biocontrol agents.Item Mango varietal response to Anthracnose disease and its post-harvest management(Department of Plant Pathology, College of Agriculture , Vellayanikkara, 2025-02-15) Nikiru Lamare.; Radhakrishnan, N VThe study entitled “Mango varietal response to anthracnose disease and its post-harvest management” was done to evaluate the incidence and severity of anthracnose in different mango varieties during post-harvest storage and assess the efficacy of certain post-harvest management techniques controlling anthracnose on the quality of fruits in different mango varieties. A survey was conducted in two agro-ecological units – 1 (Southern coastal plain) and 8 (Southern laterites) covering Kollam and Thiruvananthapuram districts. Mango varieties with anthracnose symptoms were collected from the surveyed locations, and pathogen isolates were obtained. The isolates were subjected to pathogenicity testing, morphological characterization, and virulence rating. The cultural and morphological studies showed that isolates displayed fluffy or sparse mycelial growth with white to grey pigmentation and had regular margins. The conidia of all isolates were oblong, dumbbell shaped, measuring 9.2 × 3.5 to 11.4 × 3.6 μm. Upon artificial inoculation on the fruits, the isolates showed the typical anthracnose symptoms, with black or brown sunken lesions. Upon virulent rating, it was revealed that isolate C10 proved to be the most virulent, with a lesion development rate of 1.30 cm/day and PDI of 46.67%. The virulent isolate was molecularly characterized with ITS primers and confirmed as Colletotrichum gloeosporioides (accession no. PQ475860) by phylogenetic analysis. Five mango varieties, Kottukonam, Neelum, Priyur, Rumani, and Totapuri, were obtained and subjected to screening by artificial inoculation of the anthracnose pathogen and assessed the varietal variation in symptom development, lesion growth and susceptibility. Symptoms were developed in 2 days for Kottukonam and Priyur, while Neelum, Rumani, and Totapuri showed symptoms after 3 days. Kottukonam showed the highest susceptibility with a PDI of 72.33%, while Totapuri had the lowest at 45.40%. In vitro evaluation of the antagonistic potential post-harvest management strategies against anthracnose pathogens was studied. Two bacterial cultures of Bacillus velezensis PCSE-10 and B. amyloliquifaciens VLY24 were obtained from the Department of Agricultural Microbiology. The dual culture assay of the biocontrol agents against the anthracnose pathogen revealed that B. amyloliquifaciens VLY24 showed 37.08% inhibition, while B. velezensis PCSE-10 had 32.87% inhibition. Poisoned food assay of carbendazim 50% WP against the pathogen revealed that 0.1% and 0.2% concentration showed 100% inhibition while 0.05% showed 76.67% inhibition. In vitro evaluation of bacterial suspension and cell free culture filtrate (CFC) of biocontrol agents against the pathogen mycelial growth at different concentrations showed that bacterial suspensions were more effective than CFC. In both the strains highest inhibition of mycelial growth was shown in the bacterial suspension of 100% concentration with 78.78% inhibition with B. amyloliquifaciens VLY24 and 76.83% inhibition with B. velezensis PCSE-10. The evaluation of various post-harvest management strategies for controlling anthracnose disease was conducted in five mango varieties in a two-factorial Completely Randomized Design (CRD). It revealed that the combination of hot water treatment (HWT) (52°C for 10 minutes) + B. amyloliquefaciens VLY24 (BA VLY24) (100% suspension) and carbendazim (CBZ) (0.1%) resulted in the lowest per cent disease index (PDI) of 17.04%, followed by the combination of HWT (52°C for 10 minutes) + B. velezensis PCSE-10 (BV PCSE-10) (100% suspension) + CBZ (0.1%), which had a PDI of 18.68%. Among the varieties, the lowest PDI was observed in Totapuri (38.26%), while the highest was recorded in Kottukonam (46.56%). Regarding total soluble solids (TSS), the combination of HWT+ BA VLY24 + CBZ recorded the lowest TSS content (12.86 °Brix). Across varieties, Priyur exhibited the highest TSS content (17.63 °Brix), followed by Neelum (14.65 °Brix). The effects of the interaction of treatments on lesion size and PDI across all varieties were not significantly different, which implies that treatments applied across all varieties have the same relative effect, whereas the impact on TSS varied significantly among varieties as TSS content varies with varieties. A combination treatment of hot water (52°C for 10 minutes) +B. amyloliquefaciens VLY24 (100% bacterial suspension) + Carbendazim 50% WP (0.1%) was applied to five mango varieties (Kottukonam, Neelum, Priyur, Rumani, and Totapuri). The response of treated fruits was compared with untreated controls. On the 7DAI, no symptoms were observed in treated fruits except for Kottukonam, whereas untreated fruits displayed symptoms as early as the 4th or 5th day. PDI was significantly higher in untreated fruits, with the highest PDI recorded in untreated Kottukonam (50.67%) and the lowest in untreated Totapuri (22%). Biochemical analysis revealed that peroxidase and polyphenol oxidase activities were higher in treated fruits than untreated ones on the 7 DAI. Treated fruits also exhibited an extended shelf life, and Totapuri recorded the longest duration (9.33 days). Physiological loss of weight was higher in untreated fruits than in treated fruits. Sensory evaluation revealed that treated fruits exhibited superior internal and external sensory quality in terms of appearance, colour, flavour, and overall acceptability. Among the varieties, Totapuri received the highest overall acceptability score of 8.08. Biochemical assessments indicated that treated fruits had higher titratable acidity whereas, total soluble solids (TSS) and reducing sugar content were lower in treated fruits across all varieties tested. This study concluded that C. gloeosporioides was the pathogen responsible for mango anthracnose. Among the varieties, when subjected to screening by artificial inoculation, it revealed that Kottukonam was the most susceptible mango variety, followed by Priyur, while Totapuri was the least susceptible, followed by Rumani and Neelum. Effective post-harvest management of mango anthracnose can be achieved using a combination of hot water treatment (52°C for 10 minutes), B. amyloliquefaciens VLY24 (100% suspension), and carbendazim 50% WP (0.1%).Item Economics of plant protection investments in commercial mango orchards in Muthalamada(Department of Agricultural Economics, College of Agriculture, Vellanikkara, 2024-12-27) Vinodhini, P; Indira Devi, PItem Determination of optimum maturity stage in mango (Mangifera indica L.) for fruit quality(Department of Post Harvest Technology, College Of Agriculture, Vellanikkara, 2021) Janmitha Shetty; Meagle Joseph, PMango (Mangifera indica L.), the national fruit of India is nutritionally rich in carbohydrates, proteins, vitamins and minerals such as calcium, iron, and phosphorus and hence known as the “King of fruits”. Mangoes are popular in markets worldwide because of unique flavour, appealing aroma, colour and taste (Arauz, 2000). In Indian subcontinent flowering of mango starts from November in Kerala and extends to February – March in Northern India. Mangoes from Kerala fetch higher price in the main markets at other parts of the country due to earliness. But commercial cultivation of mango in Kerala is limited to a few pockets in Palakkad district and the national varieties such as Alphonso, Banganapalli, Amrapali, Ratna and Mallika are occasional. The adaptation of different varieties to the climatic conditions prevailing fruiting and yielding behaviour of the varieties, production and post-harvest management practices followed by the growers, prevailing marketing system, are some of the problems of mango cultivation in Kerala. Mango fruits gain acceptance and popularity among consumers when it is served with the correct ripeness. Mangoes harvested at full maturity had a shorter shelf life, but those harvested early had a higher weight loss but improved storability (Shahjahan et al., 1994). Maturity standards in relation to the quality of important commercial varieties have not been studied when grown under humid tropical conditions of Kerala. Hence a study on the “Determination of optimum maturity stage in mango (Mangifera indica L.) for fruit quality” was carried out at the Department of Post-Harvest Technology, College of Agriculture, Vellanikkara, Thrissur, Kerala during 2019- 21 with the objective to find out the ideal harvesting stage of two important mango varieties viz. Ratna and Mallika for good organoleptic qualities and shelf life. The varieties of mango grown in the college orchard were utilized for the study. Flowers were tagged at the time of fruit set and observations on external appearance, peel, pulp colour, stone characters and biochemical changes were taken at 90, 100,110 120 and 140 days after fruit set (DAFS) as per the IPGRI descriptor. Heat unit requirements for maturity were also studied, for determining optimum days for maturity. In case of mango cv. Ratna, 90, 100 and 110 DAFS are the three stages of growth and in cv. Mallika, 90, 110,120 and 140 DAFS are four stages of growth. Physical and biochemical characters were studied at different stages of growth. In mango cv. Ratna fruits harvested 110 DAFS with accumulation of 1107.75 HU recorded good quality attributes. Fruits harvested at this stage had attractive length (10.44 cm), diameter (26.1 cm), weight (358.8 g), firmness (1.40 kg/cm2 ), specific gravity (1.03), stone length (7.49 cm), stone weight (10.68 g), TSS (21.12 ⁰brix), acidity (0.30 %), ascorbic acid (33.48 mg/100g), total sugar (19.04 %), total phenol (32.06 mg/100g), total carotenoid (14.65 mg/100g), β-carotene (0.88 mg/100g), crude fibre (2.59 %) and total chlorophyll (0.01 mg/100g) with a score of 8.00 in overall acceptability in sensory evaluation. In mango cv. Mallika fruits harvested 140 DAFS with accumulation of 1507.00 HU was found to be good in quality attributes. Fruits harvested 140 DAFS had good length (14.80 cm), diameter (28.03 cm), weight (623.95 g), firmness (0.73 kg/cm2 ), specific gravity (1.05), stone length (11.83 cm), stone diameter (12.63 cm), stone weight (66.73 g), TSS (20.18 ⁰brix), acidity (0.73%), ascorbic acid (61.21 mg/100g), total sugar (17.00 %), total phenol (47.5 mg/100g), total carotenoid (7.56 mg/100g), β-carotene (0.03 mg/100g), crude fibre (3.44 %) and total chlorophyll (0.01 mg/100g) with a score of 8.25 in overall acceptability in sensory evaluation. Study on effect of maturity on ripening was done in the variety cv. Ratna at their mature stage. Fruits harvested at the optimum maturity stage (100 DAFS) and ten days prior to maturity stage (90 DAFS) were kept for ripening after giving five different pre-treatments, viz., control (T1), ethrel spray (T2), hot water dip with ethrel spray (T3), sanitization with ethrel spray (T4) and ozonisation with ethrel spray (T5). Treated fruits packed in ventilated CFB boxes were kept under ambient condition and observations were recorded at 3 days interval. PLW increased with increase in storage period resulted in decrease in shelf life because of more loss in weight but the TSS and sugar increased however storability was less. High ethylene evolution on 3 days after storage indicates that it is tending towards maturity and it lowers after 6 days of storage resulting in complete ripened stage. Thus it can be concluded that the fruits of mango cv. Ratna harvested 10 and 20 days prior to ripe mature stage can be stored for 6 days under ambient conditions after giving pre-treatment consisting of Ozonization @ 200 ppm and ethrel spray @ 200 ppm.Item Effect of crop regulation on yield and quality of mango (Mangifera indica L.) under high density planting system(Department of Fruit Science, College of Horticulture, Vellanikkara, 2019) Amritha Manohar; Jyothi BhaskarItem Nutrient recycling of selected tree leaf litters in homesteads(Department of Agronomy, College of Agriculture, Vellayani, 2019) Reshma Das; Sheeba Rebecca IsaacItem Susceptibility of mango (Mangifera indica Linnaeus) varieties to infestation by (Idiocerinae: Jassidae: Homoptera) of hoppers(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1981) Narasimha Murthy, B; Abraham, C CIn studies on the relative susceptibility of twelve mango varieties, Alphonso, Bennet Alphonso, Bangalore, Benganapalli, Allumpur Baneshan, Kalapady, Mundappa, Neelum, Prior, Chandrakaran, Goa and Chandenam to infestation by I. Neveosparsus and I.clypealis. conducted at the Instructional Farm and Research Station, College of Horticulture, It was found that the varieties supported extremely low populations of the two species during the pre-flowering period from June to September 1980Item Shrink wrap packaging of selected tropical fruits(Department of Processing Technology, College of Horticulture, Vellanikkara, 2016) Aiswarya, T; Saji GomezThe present study titled “Shrink wrap packaging of selected tropical fruits” was carried out in the Department of Processing Technology, College of Horticulture, Vellanikkara during 2015-2016. The objective was to extend shelf life and to maintain quality of mango, banana and pineapple during storage. The technique of shrink wrap packaging was adopted in three tropical fruits viz., mango, banana and pineapple. Each experiment consisted of 7 treatments wherein shrink wrap packaged fruits along with the unwrapped (control) samples were stored under ambient conditions. Observations on shelf life and PLW (physiological loss in weight) were recorded at an interval of three days and the biochemical characteristics were analysed at weekly intervals.Mature fruits of mango variety Prior, free of damage and bruises, were washed in plain tap water followed by surface sanitization with 100ppm chlorine for 15 minutes. The chlorinated fruits were spread out on blotting paper to remove excess surface moisture. Surface dried fruits were subjected to two forms of shrink wrapping i.e, individual fruit wrap and wrapping of 4-5 fruits in areca plates with polyolefin film of three densities viz., 15, 19 and 25 μ. Individually shrink wrapped mangoes in 25 μ polyolefin film had the longest shelf life (18 days) and the shrink wrapped fruitsItem Variability of Colletotrichum isolates inciting anthracnose in mango (Mangifera indica L.)(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2016) Priyanka, B; Beena, S