PG Thesis
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Item Impact of seed exposure to simulated microgravity on growth and development in tomato (Solanum lycopersicum L.)(Department of Seed Science and Technology, College of Agriculture, Vellayani, 2025-02-12) Ram Ambiya; Beena, RThe study titled “Impact of seed exposure to simulated microgravity on growth and development in tomato (Solanum lycopersicum L)” was undertaken with the objective to evaluation of morpho-physiological, anatomical and biochemical changes in growth and development in tomato after exposure of seeds to different simulated microgravity. The experiments were conducted using seeds of the tomato variety 'Anagha,' which were exposed to simulated microgravity conditions. Microgravity is characterized by a reduction in gravitational force, which can create stress in organisms and plants, affecting their metabolism, growth, and development. Simulated microgravity was created using a Random Positioning Machine (RPM), which rotates seeds slowly at speeds of (25-40 rpm), reducing the effect of gravity to around 10-3 g. Seeds were exposed to (4hr, 8hr, 12hr, 24hr and control different durations of simulated microgravity. Two experiments were carried out in a completely randomized design (CRD). In both experiments, the seeds were sown, and the seedlings were transplanted into pots 30 days after sowing. They were maintained under standard cultural practices, including irrigation. The study was conducted across two growing seasons: Summer and Kharif. The results revealed that exposure to simulated microgravity significantly influenced tomato growth. The simulated microgravity treatment (T4) enhanced the germination rate, which reached (95%) in the summer and (97%) in the kharif season by the seventh day. Additionally, treatment (T3) exhibited the highest seedling vigor in the summer (13.75), while treatment T4 showed the highest seedling vigor in the kharif season (15.32). Moreover, treatment T4 also displayed the highest germination speed in both seasons. In the summer, the earliest flowering occurred in treatment T4 (23.5 DAT), while in the kharif season, treatment T3 exhibited early flowering (24.75 DAT). The pollen viability in treatment T4 was enhanced, exceeding (80%) during the kharif season. Furthermore, the study reported an increase in chlorophyll content under simulated microgravity conditions, with treatment T4 reaching (1.785 mg/g) in the kharif season. Various enzymatic activities, such as peroxidase, superoxide dismutase, and catalase, increased, while malondialdehyde (a marker of lipid peroxidation) also increased. These responses suggest that the plants developed better stress tolerance under microgravity conditions. The study found that simulated microgravity significantly influenced various growth and biochemical parameters in tomato plants. In the summer season, treatment T1 showed the highest ascorbic acid content (12.62 mg g-1), plant height (87.175 cm), fresh weight (378.75 g), and root growth. In the kharif season, treatment T3 exhibited the highest ascorbic acid content (20.37 mg/g-1), anthocyanin (0.448 mg/g), and total sugar content (1.305 mg/g), while treatment T4 had the highest lycopene content (3.143 µg/g), plant height (98.4 cm), and yield (842.25 g). Root length, volume, fresh, and dry weight were significantly enhanced under treatment T3 in the kharif season. Overall, seeds exposed to simulated microgravity showed increased growth, improved biochemical composition, and enhanced fruit yield, highlighting the potential of microgravity as a tool for crop improvement in both terrestrial and extraterrestrial agriculture. In conclusion, this study demonstrates that simulated microgravity has a positive impact on the growth, development, and biochemical characteristics of tomato plants. Improved germination rates, enhanced seedling vigor, increased chlorophyll content, and higher yields were observed, suggesting that microgravity could be a useful tool for crop improvement. Furthermore, increased enzymatic activity and better root growth under stress conditions indicate the potential applications of simulated microgravity in agriculture, both on land. This is the first of its kind of study performed on Anagha seeds and such studies on other species developed within KAU can lead to interesting results and important clues on enhancing crop yield and productivity. Future research should focus on long-term exposure to simulated microgravity and its effects on other crop species. This knowledge can help optimize crop production in space missions and challenging terrestrial environments, contributing to sustainable food security on earth and beyond.Item Standardisation of seed biopriming for seedling establishment, growth, yield and nutritional characters in tomato (Solanum lycopersicum L.)(Department of Seed Science and Technology, College of Agriculture, Vellayani, 0022-02-01) Diya Amreen; Beena RThe present study entitled “Standardisation of seed biopriming for seedling establishment, growth, yield and nutritional characters in tomato Solanum lycopersicum L.). was conducted in the Department of Seed Science and Technology, College of Agriculture, Vellayani, Kerala during 2020-21. The objective of this study was to standardize the biopriming methods in tomato for germination, seedling vigour, yield and nutritional characteristics using three biopriming agents Trichoderma asperellum 106 spores mL-1and 108 spores mL-1), Pseudomonas flourescens 106 CFU mL-1 and 108 CFU mL-1) and Piriformospora indica 106 spores mL-1 and 108 spores mL-1) for one and two hours. The study was divided in to two experiments. Experiment I was conducted in Completely andomized Design C D) with fourteen treatments and three replications. During experiment I germination studies were conducted using roll towel method. Best three treatments were selected from experiment 1 based on the germination parameters. Experiment II was also conducted in Completely andomized Design with five treatments and four replications. The pot culture experiment was conducted to evaluate the effect of these best three treatments on phenological, physiological, growth, quality, biomass and yield parameters. During experiment I, among various treatments employing T. asperellum, T2 T. asperellum 106 CFU mL-1 for two hours) recorded the highest germination percentage 88.67 ), shoot length 7.60 cm), root length 6.39 cm), shoot dry weight 0.92 mg), root dry weight 0.45 mg), seedling vigour index 1 1240.09), seedling vigour index II 121.30) and speed of germination 7.28). On biopriming with P. flourescens T8 P. flourescens 108 CFU mL-1 for two hours) reported the maximum germination percentage 86.67 ), shoot length 7.56 cm), root length 7.63 cm), shoot dry weight 0.91 mg), root dry weight 0.45 mg), seedling vigour index 1 1316.26), seedling vigour index II 117.54) and speed of germination 7.23). On biopriming with P. indica maximum germination percentage 91.33 ), shoot length 7.67 cm), root length 7.82 cm), shoot dry weight 0.97 mg), root dry weight 0.54 mg), seedling vigour index 1 1414.73), seedling vigour index II 137.46) and speed of germination 7.68) was obtained from seeds bioprimed with P. indica 106 CFU mL-1 for one hour. Based on the above results the best three treatments selected were T. asperellum 106 CFU mL-1 for two hours T1), P. flourescens 108 CFU mL-1 for two hours T2) and P. indica 106 CFU mL-1 for one hour T3) along with appropriate control. Then pot culture experiment was conducted to evaluate the effect of these three biopriming treatments on phenological, physiological, growth, quality, yield and biomass parameters. Among the phenological parameters days to first flowering and days to first fruiting was minimum in T3 P. indica 106 CFU mL-1 for one hour) 51.92 and 78.75 days respectively). Biopriming with P. indica 106 CFU mL-1 for one hour T3) recorded the maximum physiological and growth parameters including chlorophyll content 2.82 mg g-1 fresh weight), specific leaf area 3.96 m² g-1), crop growth rate 0.912 g m-2 day-1) and net assimilation rate 0.027 g m-2 day-1). Among the various quality parameters analyzed, there was no significant difference observed for TSS and soluble sugar content. Highest Lycopene content 2.81 mg g-1) and vitamin C 35.56 mg g-1) content was noted in T3 P. indica 106 CFU mL-1 for one hour). Highest titrable acidity 0.68 ) was recorded in T1 T. asperellum 106 CFU mL-1 for two hours). Plant height was also maximum in T3 P. indica 106 CFU mL-1 for one hour) during vegetative 80.20 cm) and flowering stages 127.37 cm). Biopriming with P. indica 106 CFU mL-1 for one hour recorded the maximum shoot dry weight 8.31g), root dry weight 0.97 g) and total dry weight 9.28 g). There was no significant difference observed in root shoot ratio. The yield parameters including number of fruits per plant 7.25 ), fruit set percentage 56.78 ), average fruit weight 36.60 g) and yield per plant 263.56 g) was maximum in T3 P. indica 106 CFU mL-1 for one hour).The intensity of fruit drop 4.96 ) was minimum in T3 P. indica 106 CFU mL-1 for one hour). Biopriming is reported to have exerted significant influence on the growth, yield and nutritional characters of tomato. Among various biopriming agents P. indica 106 CFU mL-1 for one hour outperformed T. asperellum and P. flourescens in improving phenological, physiological, growth, quality, biomass and yield parameters. Thus being an eco-friendly technique, the farmers can adopt biopriming with P. indica as a great alternative for conventional chemical seed treatments.Item Mechanisms of host plant resistance in Tomato (Solanum lycopersicum L.) genotypes to cotton whitefly (Bemisia tabaci Genn.)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025) Naveena Unnikrishnan.Tomato (Solanum lycopersicum) is one of the most widely cultivated crops worldwide, with India ranked second in global production (Ministry of Agriculture and Farmers Welfare, MOAFW, 2023). The cotton whitefly (Bemisia tabaci) is a major pest of tomato, inflicting direct damage by feeding on phloem sap and serving as a vector for the tomato leaf curl virus (ToLCV). The extensive use of synthetic insecticides has led to resistance in whitefly populations, alongside concerns about environmental and health risks. As a result, developing host plant resistance has emerged as a sustainable alternative for pest management. Building on a previous study at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, which evaluated fifty tomato genotypes for whitefly resistance under polyhouse conditions (Tejaswee, 2023), the current study, titled "Mechanisms of host plant resistance in tomato genotypes to cotton whitefly," was conducted during 2023-2024. The primary objectives were to evaluate the resistance of different tomato genotypes to cotton whitefly under field conditions and to investigate the mechanisms behind host plant resistance. Twenty tomato genotypes selected from the previous research (Tejaswee, 2023) were evaluated for their resistance to whitefly under field conditions. The genotypes exhibited significant variation in the density of all life stages of Bemisia tabaci. The number of whitefly eggs ranged from 1.33 ± 0.30 (LC Palakkad) to 11.80 ± 0.22 (EC 617060) on the top leaves, 0.90 ± 0.40 (LC Palakkad) to 11.03 ± 0.29 (EC 617060) on the middle leaves, and 0.73 ± 0.24 (LC Palakkad) to 7.63 ± 0.39 (EC 617060) on the bottom leaves. Nymph populations varied from 1.27 ± 0.21(LC Palakkad) to 11.23 ± 0.37 (EC 617060) on the top leaves, 0.93 ± 0.16 (LC Palakkad) to 8.73 ± 0.37 (EC 617060) on the middle leaves, and 0.70 ± 0.21 (LC Palakkad) to 6.47 ± 0.24 (EC 635520) on the bottom leaves. Adult whitefly populations ranged from 0.73 ± 0.30 (LC Palakkad) to 12.50 ± 0.37 (EC 617060) on the top leaves, 0.50 ± 0.35 (LC Palakkad) to 10.33 ± 0.55 (EC 638522) on the middle leaves, and 0.43 ± 0.15 (LC Palakkad) to 8.03 ± 0.27 (EC 617060) on the bottom leaves. The pooled mean counts for all life stages were highest on the top leaves, followed by the middle and bottom leaves. Three genotypes viz., LC Idukki, LC Palakkad, and EC 519806 had mean whitefly populations under 2.62 per leaf, classifying them as resistant. Six genotypes with a mean population between 2.62 and 5.31 were moderately resistant, while six others were moderately susceptible (5.31–8), and five genotypes with >8 were highly susceptible. Additionally, the screening of genotypes for the incidence of Tomato leaf curl virus (ToLCV) and the coefficient of infection (CI) revealed that LC Palakkad, LC Idukki, and EC 519806 were highly resistant to the leaf curl disease. In the free-choice assays, whitefly settling and oviposition preferences were monitored at regular intervals in the customised experimental arenas. EC 617060 had the highest whitefly count, with 9.33 ± 0.577 per leaf at 24 hours and 7 per leaf at 48 hours. No whiteflies were observed on LC Palakkad and LC Idukki after 48 hours. LC Palakkad and LC Idukki had the lowest oviposition preference, with only 0.67 eggs/cm², while the highest oviposition (7.33 eggs/cm²) was recorded on EC 635520 and EC 638522. The epicuticular wax content of the tomato genotypes varied from 0.032 ± 0.002 mg/cm² (EC 617060) to 0.197 ± 0.002 mg/cm² (LC Palakkad). A significant negative correlation was observed between wax content and both oviposition and settling preferences of B. tabaci. Additionally, settling and oviposition preferences were negatively correlated with glandular trichome density, but positively correlated with non-glandular trichome density and trichome length. In the no-choice experiment, the developmental parameters of B. tabaci were observed in clip-cages. Oviposition rates (OR) on the tomato genotypes ranged from 0.31 ± 0.10 to 4.24 ± 0.58 eggs per day. Pre-adult survival (PS) rates varied from 0.57 ± 0.07 to 0.90 ± 0.01, while adult survival (AS) rates ranged from 0.72 to 0.98 ± 0.02. The developmental period (DP) of B. tabaci ranged from 21.95 ± 0.03 to 31.97 ± 2.77 days. Oviposition, pre-adult survival, and adult survival showed negative correlations with phenol, flavonoid, and alkaloid content, but positive correlations with free amino acid content and relative water content. In contrast, the developmental period was positively correlated with phenol, flavonoid, and alkaloid content, and negatively correlated with free amino acid and relative water content. The present study identified LC Idukki, LC Palakkad, and EC 519806 as highly resistant to whitefly, B. tabaci, exhibiting low level of whitefly population and ToLCV incidence, reduced settling preference, oviposition, survival rates, and longer developmental periods. While glandular trichomes and epicuticular wax contribute to resistance through antixenosis, the study highlights the crucial role of antibiosis, especially through phenolic compounds, in disrupting the development of B. tabaci. These results emphasize antibiosis as the primary resistance mechanism against B. tabaci in the evaluated tomato genotypes. Thus, the present study offers valuable insights for further research into host plant resistance mechanisms, aiding the development of sustainable and economically viable integrated pest management strategies for tomato cultivation.Item Mechanisms of host plant resistance in Tomato (Solanum lycopersicum L.) genotypes to cotton whitefly (Bemisia tabaci Genn.)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2024) Naveena Unnikrishnan.; Ranjith, M TTomato (Solanum lycopersicum) is one of the most widely cultivated crops worldwide, with India ranked second in global production (Ministry of Agriculture and Farmers Welfare, MOAFW, 2023). The cotton whitefly (Bemisia tabaci) is a major pest of tomato, inflicting direct damage by feeding on phloem sap and serving as a vector for the tomato leaf curl virus (ToLCV). The extensive use of synthetic insecticides has led to resistance in whitefly populations, alongside concerns about environmental and health risks. As a result, developing host plant resistance has emerged as a sustainable alternative for pest management. Building on a previous study at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, which evaluated fifty tomato genotypes for whitefly resistance under polyhouse conditions (Tejaswee, 2023), the current study, titled "Mechanisms of host plant resistance in tomato genotypes to cotton whitefly," was conducted during 2023-2024. The primary objectives were to evaluate the resistance of different tomato genotypes to cotton whitefly under field conditions and to investigate the mechanisms behind host plant resistance. Twenty tomato genotypes selected from the previous research (Tejaswee, 2023) were evaluated for their resistance to whitefly under field conditions. The genotypes exhibited significant variation in the density of all life stages of Bemisia tabaci. The number of whitefly eggs ranged from 1.33 ± 0.30 (LC Palakkad) to 11.80 ± 0.22 (EC 617060) on the top leaves, 0.90 ± 0.40 (LC Palakkad) to 11.03 ± 0.29 (EC 617060) on the middle leaves, and 0.73 ± 0.24 (LC Palakkad) to 7.63 ± 0.39 (EC 617060) on the bottom leaves. Nymph populations varied from 1.27 ± 0.21(LC Palakkad) to 11.23 ± 0.37 (EC 617060) on the top leaves, 0.93 ± 0.16 (LC Palakkad) to 8.73 ± 0.37 (EC 617060) on the middle leaves, and 0.70 ± 0.21 (LC Palakkad) to 6.47 ± 0.24 (EC 635520) on the bottom leaves. Adult whitefly populations ranged from 0.73 ± 0.30 (LC Palakkad) to 12.50 ± 0.37 (EC 617060) on the top leaves, 0.50 ± 0.35 (LC Palakkad) to 10.33 ± 0.55 (EC 638522) on the middle leaves, and 0.43 ± 0.15 (LC Palakkad) to 8.03 ± 0.27 (EC 617060) on the bottom leaves. The pooled mean counts for all life stages were highest on the top leaves, followed by the middle and bottom leaves. Three genotypes viz., LC Idukki, LC Palakkad, and EC 519806 had mean whitefly populations under 2.62 per leaf, classifying them as resistant. Six genotypes with a mean population between 2.62 and 5.31 were moderately resistant, while six others were moderately susceptible (5.31–8), and five genotypes with >8 were highly susceptible. Additionally, the screening of genotypes for the incidence of Tomato leaf curl virus (ToLCV) and the coefficient of infection (CI) revealed that LC Palakkad, LC Idukki, and EC 519806 were highly resistant to the leaf curl disease. In the free-choice assays, whitefly settling and oviposition preferences were monitored at regular intervals in the customised experimental arenas. EC 617060 had the highest whitefly count, with 9.33 ± 0.577 per leaf at 24 hours and 7 per leaf at 48 hours. No whiteflies were observed on LC Palakkad and LC Idukki after 48 hours. LC Palakkad and LC Idukki had the lowest oviposition preference, with only 0.67 eggs/cm², while the highest oviposition (7.33 eggs/cm²) was recorded on EC 635520 and EC 638522. The epicuticular wax content of the tomato genotypes varied from 0.032 ± 0.002 mg/cm² (EC 617060) to 0.197 ± 0.002 mg/cm² (LC Palakkad). A significant negative correlation was observed between wax content and both oviposition and settling preferences of B. tabaci. Additionally, settling and oviposition preferences were negatively correlated with glandular trichome density, but positively correlated with non-glandular trichome density and trichome length. In the no-choice experiment, the developmental parameters of B. tabaci were observed in clip-cages. Oviposition rates (OR) on the tomato genotypes ranged from 0.31 ± 0.10 to 4.24 ± 0.58 eggs per day. Pre-adult survival (PS) rates varied from 0.57 ± 0.07 to 0.90 ± 0.01, while adult survival (AS) rates ranged from 0.72 to 0.98 ± 0.02. The developmental period (DP) of B. tabaci ranged from 21.95 ± 0.03 to 31.97 ± 2.77 days. Oviposition, pre-adult survival, and adult survival showed negative correlations with phenol, flavonoid, and alkaloid content, but positive correlations with free amino acid content and relative water content. In contrast, the developmental period was positively correlated with phenol, flavonoid, and alkaloid content, and negatively correlated with free amino acid and relative water content. The present study identified LC Idukki, LC Palakkad, and EC 519806 as highly resistant to whitefly, B. tabaci, exhibiting low level of whitefly population and ToLCV incidence, reduced settling preference, oviposition, survival rates, and longer developmental periods. While glandular trichomes and epicuticular wax contribute to resistance through antixenosis, the study highlights the crucial role of antibiosis, especially through phenolic compounds, in disrupting the development of B. tabaci. These results emphasize antibiosis as the primary resistance mechanism against B. tabaci in the evaluated tomato genotypes. Thus, the present study offers valuable insights for further research into host plant resistance mechanisms, aiding the development of sustainable and economically viable integrated pest management strategies for tomato cultivation.Item Impact of biofertilizers and nutrients on the quality and shelflife of tomato (Solanum lycopersicum L.) and on the fruit shelflife regulator (SIFSR) gene expression under elevated CO2 condition(Department of Plant Physiology, College of Agriculture , Vellayani, 2024-03-16) Haripriya, S.; Manju, R VThe study entitled “Impact of biofertilizers and nutrients on the quality and shelflife of tomato (Solanum lycopersicum L.) and the Fruit Shelflife Regulator (SlFSR) gene expression under elevated CO2 condition” was undertaken with the objective of elucidating the effects of biofertilizers and nutrients on the quality and shelf-life of tomato and the Fruit Shelf-life Regulator (SIFSR) gene expression under elevated CO2 condition. The experiment was conducted using the Open Top Chamber (OTC) system facility in the Department of Plant Physiology, College ofAgriculture, Vellayani during 2022-2023. In the experiment, quality and shelf-life of tomato under elevated CO2 environment, as influenced by nutrients and biofertilizers were evaluated. The experiment was laid out in CRD consisting 5 treatments with three replications under ambient and elevated conditions. The treatments comprised of T1: POP, KAU+AMF, T2: POP, KAU+ PGPR Mix-1,T3: POP, KAU+Azolla T4: POP, KAU+50 ppm B + 50 ppm Zn+60 ppm Ca water spray (40, 55 and 70 DAS.) and T5: POP,KAU Control. The experimental results revealed, plant height after 75 days of sowing, specific leaf area and total dry matter increased significantly under elevated CO2 condition. Foliar spray with 50 ppm B + 50 ppm Zn + 60 ppm Ca along with POP, KAU recommendation recorded the highest plant height at 75 DAS. AMF treated plants were found to improve specific leaf area at 60 DAS and 75 DAS. Root to shoot ratio was reduced under elevated CO2 condition compared to ambient condition. Among the treatments, soil incorporation of PGPR before transplantation of seedlings resulted in the highest accumulation of dry matter. Among the physiological and biochemical parameters, total chlorophyll content, total carbohydrate content and chlorophyll stability index recorded higher values under elevated CO2 compared to open condition. However, a significant reduction was noted in total soluble protein content under elevated CO2 compared to open condition. PGPR mix 1 treated plants had recorded the highest chlorophyll and total carbohydrate content but plants foliar sprayed with 50 ppm B+50 ppm Zn+60 ppm Ca recorded the best results with respect to chlorophyll stability index. Exposure to elevated CO2 was found to increase the days for first flowering. Application of biofertilizers and nutrients reduced the days to flowering significantly. Plants came to flowering 40 DAS in the cases of PGPR mix-1 treated plants under eCO2 and AMF treated plants under aCO2. Due to high temperature associated with CO2 enrichment, pollen viability was lost and there was no fruit production inside OTC. Yield parameters such as number of fruits, fruit weight, fruit setting percentage and yield per plant showed significant difference among treatments. Among the treatments, PGPR mix-1 treated plants recorded significant increase in fruit weight, number of fruits and yield. Application of biofertilizers and nutrients had significant impact on quality of fruit and the most effective treatment was incorporation of PGPR mix-1 along with POP, KAU in terms of increased accumulation of lycopene, β-carotene, vitamin C, total sugars, pectin, moisture content, shelf-life and reduced physiological loss in weight. Foliar spray had the same impact as that of PGPR mix-1 treatment in the cases of vitamin C and beta carotene contents. Though AMF was found to increase P content of the fruits significantly, Fe content in fruits was influenced by foliar sprayed and PGPR mix-1 treatment.CO2 enrichment was found to have no influence on expression levels SlFSR gene in leaf tissues but the application of biofertilizers and nutrients was found to affect expression levels in fruits. Lowest level of expression was noted in fruits collected from azolla treated plants under ambient condition. The increase in atmospheric temperature due to increasing CO2 concentration can hasten perishability in the case of farm products. Efforts towards shelf-life extension to make fruit safe for long periods, keeping its original quality is of paramount importance today. The present programme clearly indicates that the shelf-life of tomato variety Vellayani Vijay can be enhanced by 85% through the soil incorporation of PGPR mix-1 before transplanting. This is a great achievement considering the higher perishability of tomato. Application of the biofertilizer, azolla which resulted in the 22.22% increase in shelf-life lead to down regulation of the GRAS transcriptional factor, SlFSR which controls fruit shelf-life by regulating expression of cell wall modifying genes and metabolism of pectin and cellulose. The significant extension of shelf-life achieved through the application of PGPR and AMF could be mediated through the down regulation of ethylene biosynthesis and cell wall degrading enzyme activities. Combined application of calcium, boron and zinc contributes towards firmness of fruit tissues and extended shelf-life to the same degree. The findings of the present programme revealed that application of azolla, PGPR mix-1 and AMF and combined application of calcium, boron and zinc improved the quality and shelf-life of tomato significantly. The result also proves SlFSR gene as a potential biotechnological target for the control of fruit shelf-life. The outcome of the programme will help to develop agricultural practices for improving the shelf-life and quality of tomato which is of paramount importance in the scenario of increasing atmospheric temperature and climate change.Item Screening of tomato (Solanum lycopersicum L.) genotypes for high temperature tolerance(Department of Plant Breeding and Genetics, College of Agriculture , Vellanikkara, 2024-05-28) Anjali Joy, S L; Deepthy Antony, P.Tomato (Solanum lycopersicum L., 2n=24) cultivation is prevalent in both tropical and sub-tropical climates. For optimum yield and quality, the crop needs a climate that is dry and fairly cold, and are sensitive to hot and humid climate. In the current context of global warming, high temperature is considered as a major threat to agriculture with profound consequences on yield and quality. Plant morphology, physiology, biochemistry, and molecular pathways are disrupted by heat stress. The optimum temperature range for fruiting in tomato is narrow viz., 15 to 21 °C at night and 30 to 35 °C during the day. Depending on the stage of growth, a daily mean temperature between 21 and 24 °C is ideal for tomato. The current study, ‘Screening of tomato (Solanum lycopersicum L.) genotypes for high temperature tolerance’ was conducted during 2021–2023 at the Department of Plant Breeding and Genetics, College of Agriculture, Vellanikkara. Thirteen NBPGR accessions, four hybrids from IIHR, Bengaluru, eight improved lines from the World Vegetable Centre, Taiwan, and five KAU varieties made up the 30 tomato genotypes used in the study. Genotypes were subjected to laboratory screening for thermotolerant traits, and selected genotypes were taken for polyhouse screening. Field screening was done during summer for evaluating the performance of all the genotypes for thermotolerance and yield traits. All experiments were laid out in completely randomized design with three replications for laboratory and polyhouse screening, and two replications for field screening. Physiological traits (electrolyte leakage and membrane stability) and morphological traits (pollen viability, pollen germination, style length and style protrusion) were evaluated under laboratory and polyhouse screening. Plant height and yield characters (days to 50 per cent flowering, fruit set per cent, deformed fruits per cent, number of fruits per plant, average fruit weight and fruit yield per plant) were recorded under field screening along with morphological traits. Arka Samrat, EC 538153, AVTO 1314, and Manuprabha were superior genotypes for electrolyte leakage and membrane thermostability under laboratory screening. EC 528368, EC 620486, Akshaya, and Vellayani Vijay outperformed other varieties in terms of pollen viability and germination at 40 ℃. Superior genotypes based on pollen viability and style protrusion were EC 315489, EC 523851, EC 528368, EC 538153, EC 567305, EC 620486, EC 620488, EC 636872, AVTO 0922, AVTO 1725 and Vellayani Vijay. Based on style protrusion and pollen germination at 40 ℃, and their combination with other traits, 14 genotypes (AVTO 1702, AVTO 1706, AVTO 1725, AVTO 1726, EC 315489, EC 538153, EC 549819, EC 620428, EC 620486, EC 620488, EC 620494, EC 636872, Manulakshmi, and Vellayani Vijay) were selected for polyhouse evaluation. Polyhouse screening was done inside a non-ventilated structure to ensure temperature build up, and an increase of 4-5℃ was found inside the structure compared to ambient condition. All genotypes showed a decrease in pollen viability and germination under polyhouse compared to the open condition. All the genotypes, except Vellayani Vijay showed an increase in style protrusion. Superior genotypes with respect to electrolyte leakage were AVTO 1725, AVTO 1702, AVTO 1706, EC 620428, EC 538153, and Manulakshmi. EC 549819, EC 620428, and EC 636872 were considered as superior genotypes based on style protrusion and pollen germination, as they are important thermotolerant traits. Field screening was carried out to assess the yield traits along with thermotolerant traits in summer season. EC 528360 was found to be superior in pollen viability and style length. Style protrusion increased in all breeding lines and hybrids, except EC accessions. Genotypes like Akshaya, Arka Rakshak, AVTO 1314, and EC 636872 were significantly superior for fruit set percentage compared to Vellayani Vijay. Deformed fruits percentage showed no significant variation between genotypes, and was more than 80 per cent for every genotype examined. Vellayani Vijay and EC 636872 exhibited higher fruit number per plant. Arka Rakshak had a significantly higher average fruit weight than all other genotypes. Pollen viability, style protrusion, number of fruits per plant, fruit set, average fruit weight, and fruit yield per plant all demonstrated high GCV and PCV. The GAM and high heritability of the remaining characters suggested that they had additive gene effects and can be used for selection. Correlation analysis of observations recorded for field screening showed that style length and style protrusion had a significant positive correlation with fruit set per cent, average fruit weight and fruit yield per plant. Molecular markers did not reveal polymorphism in the present study and needs further investigation to identify reliable markers. AVTO 0922, EC 523851, EC 528368, EC 549819, EC 620494, EC 636872, and Vellayani Vijay were identified as heat-tolerant genotypes based on laboratory, polyhouse, and open field evaluations. Akshaya, Anagha, Arka Rakshak, AVTO 0301, AVTO 1314, AVTO 1707, Manuprabha, and Vellayani Vijay had higher yields and, with the exception of AVTO 0301, all had high fruit set percentage in the summer season. In general, thermotolerant genotypes performed moderate to poor in terms of yield traits. Hence, the study demonstrated that specific donors for thermotolerance traits and yield traits needs to be included in crop improvement programmes for heat tolerance in tomato. Vellayani Vijay had heat tolerance traits as well as superior yield traits indicating its suitability for incorporation in crop improvement programmes.Item Physiological and molecular studies in mitigating drought stress of Tomato (Solanum lycopersicum) by biochar with organic amendments(Department of Plant Biotechnology, College of Agriculture , Vellayani, 2022-11-09) Anjusha, P; Viji, M MThe study entitled “Physiological and molecular studies in mitigating drought stress of tomato (Solanum lycopersicum) by biochar with organic amendments” was conducted at College of Agriculture, Vellayani, Thiruvananthapuram, during 2021-2022. The primary objective of this study was to determine the physiological and molecular attributes of tomato grown under water stress as influenced by biochar with organic amendments. The experiment on tomato variety ‘Vellayani Vijay’ was conducted in a completely randomized design in pot culture with five replications. In order to assess the effect of biochar (BC) (0.5% w/w) and organic amendments such as vermicompost (VC) and farm yard manure (FYM) in mitigating the consequences of water stress, individual treatments viz. (Biochar (0.5% w/w), VC (50g/10kgsoil) and FYM (50g/10kg soil)) as well as combined treatments viz. ((Biochar+VC) and (Biochar+FYM)) were carried out along with T1 control (normal irrigated condition) and T7 control (water stress). The study consisted of 12 treatments, in which T1 to T6 were irrigated normally whereas treatments designated as T7 to T12 were subjected to 25% water stress. The present study was carried out using biochar derived from rice husk that was subjected to maximum pyrolysis temperature of 550°C in a cylindrical iron tank. Water stress of 25% was imposed by gravimetric method for a period of 80 days (after three weeks of sowing). The seedlings were maintained in protected condition for the first three weeks. Various morpho-physiological and yield parameters were evaluated at different critical stages of the crop, such as seedling stage, vegetative stage, flowering stage, fruiting stage and harvesting stage. Molecular studies were carried out at 50% flowering stage. Water stress had a negative impact on morphological, physiological and yield attributes of S. lycopersicum except total soluble solids, when compared to plants under normal irrigated condition. Biochar treatment was found to effectively mitigate the deleterious impacts of water stress. Plants treated with biochar outperformed the plants grown in both VC and FYM with regard to all the physiological and morphological parameters studied. However the best yield performance (yield and yield parameters) was obtained in the treatment with 124 biochar in combination with vermicompost. According to the results obtained it was clear that the combined application of biochar and vermicompost increased the relative water content, membrane stability index, chlorophyll stability index, photosynthetic rate, total protein content, stomatal conductance, transpiration rate, plant height and primary branches per plant under both water stress and normally irrigated conditions when compared to the non-treated controls. This indicates the ability of biochar to retain water and thereby increasing soil moisture content. Furthermore, under water stress, there was a significant improvement in the morphological traits such as, root weight (57.07%), shoot weight (33.33%), root: shoot ratio (17.91%), fruit number (43.54%), fruit size (69.93%), fruit weight (13.10%), total soluble solids (10.32%) and yield (62.42%). SlWRKY8 gene has an important role under drought stress conditions and is reported to have role in the regulation of ROS pathways and mitigating the detrimental effects in plants grown under water stress condition. In the present study, quantitative real time PCR amplification of SlWRKY8 gene in tomato leaves (taken at 50% flowering stage) showed an increase in the expression level of this gene in the treatments with combined application of biochar and vermicompost, both under water stress condition (T11) (3.24 fold) and normal irrigated condition (T5) (1.51 fold) compared to their respective controls (T7 and T1). This indicates that BC and VC combinations can be applied to tomato plants grown under water stress for the upregulation of SlWRKY8 genes which regulate the ABA signaling and helps in ABA-mediated stomatal closure in water stress condition. Taken together, the study demonstrate that, the combined application of vermicompost and biochar not only boost crop production, but also mitigate the destructive impacts of water stress by influencing physiological, morphological and molecular parameters of tomato.Item Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2022-01-17) Krishnendu, M R; Jayalekshmy, V GThe study entitled “Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection” was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellayani, Thiruvananthapuram during 2020-2021. The primary objective of the study was to identify donors for genes for resistance to different biotic stresses viz., Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot nematodes from tomato varieties and elite wild species through marker assisted selection using gene specific markers. The study was conducted in 30 tomato genotypes, collected from inside and outside of Kerala which included wild species as well cultivated varieties. The genotypes were screened for the presence of genes for resistance to various biotic stress inducing diseases like Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot using tightly linked gene specific SCAR and CAPS markers. The genotypes resistant to Tomato Yellow Leaf Curl Virus (TYLCV) were screened for the presence of gene Ty2 located on chromosome 11 using the SCAR marker TG0302/TY2R1 which amplified a band of size 600 bp for genotypes with Ty2/Ty2 alleles and 450 bp for susceptible genotypes. None of the 30 genotypes screened for Ty2 gene were identified to consist the Ty2/Ty2 alleles. Another gene for resistance to TYLCV, ie, Ty3 located on chromosome 6, was screened using the SCAR marker FLUW25, which amplified the genotypes carrying Ty3/Ty3 alleles with a band of size 640 bp and 480 bp for genotypes corresponding to ty3/ty3 alleles. Presence of Ty3 gene was not found in any of the genotypes screened in the study. Verticillium wilt resistance in genotypes was screened for the presence of two closely linked genes, Ve1 and Ve2 of Ve locus. Ve1 specific CAPS marker Ve1 XbaI, distinguished the genotypes of Ve1/Ve1 alleles with restriction digested fragments of size 410bp and 332bp from the susceptible genotypes of restriction digested fragments 410bp, 310bp and 22bp. Ve2 specific CAPS marker V2LeO3F/V2LeO3R generated restriction digested products, 601 bp and 428 bp for Ve2/Ve2 alleles and undigested product of 1029bp for ve2/ve2 alleles. Among the 30 genotypes screened in the study, IIHR 2374 and Kashi Vishesh were identified for the presence of Ve1 and Ve2 genes and PNR 7 for Ve2 gene alone. The genotypes resistant to Fusarium wilt were screened for the presence of the genes I3 located on chromosome 7 and I7 located on chromosome 8. The gene I3 specific SCAR marker P743DF1/R1 amplified a band of size 1270bp for genotypes with I3/I3 alleles and 1060 bp for genotypes with i3/i3 alleles. None of the genotypes screened in the study were identified for the presence of I3 gene. The CAPS marker CAPS7774 specific to I7 gene generated restriction digested fragments of size 612bp and 196bp for genotypes of I7/I7 alleles and undigested fragment of 808 bp for susceptible genotypes. The genotypes IIHR 2205, IIHR 2374 and Vellayani Vijai were identified for the presence of I7/I7 alleles from the study. The genotypes resistant to Late blight were screened for the presence of the genes Ph3 located on chromosome 9 and Ph2 located on chromosome 10. The SCAR marker Ph3-SCAR amplified the genotypes of Ph3/Ph3 alleles with a band of size 176bp and 154 bp for the genotypes of ph3/ph3 alleles. Presence of the gene Ph3 was identified in the genotypes Pusa Ruby, CA 22053, Hisar Lalit, PKM-1 and Arka Vikas from the study. The CAPS marker dtG63 differentiated the genotypes of Ph2/Ph2 alleles with a restriction digested fragment of band size 245 bp from 221 bp of susceptible genotypes. In the study, the genotypes Shakthi, Pusa Ruby, Nenmara local, CA 22053, Manulakshmi, IIHR 2204, PNR 7 and Solanum torvum were identified for the presence of Ph2/Ph2 alleles. Resistance to Root knot in genotypes were screened for the presence of gene Mi1.2 using the SCAR marker Mi23, which amplified a band of size 380 bp for Mi/Mi alleles and 430 bp for mi/mi alleles. From the study it was confirmed that, none of the genotypes screened for the presence of Mi 1.2 gene were resistant to root knot. In accordance with the findings from the study, phenotypic analysis of the genotypes identified as donors for genes for resistan ce can be carried out, in order to ensure the disease resistance in field conditions as well as the credibility of the molecular markers used in the study. The genes for resistance to the diseases studied, located in the 30 genotypes, screened from the study could indicate the donors for tomato resistance breeding programs.Item Management of elevated CO 2 induced high temperature through nutrient and biofertilizer application in tomato (Solanum lycopersicum L.)(Department of Plant Physiology, College of Agriculture , Vellayani, 2021-12-17) Arunima, A S; R V, ManjuThe study entitled “Management of elevated CO 2 induced high temperature through nutrient and biofertilizer application in tomato (Solanum lycopersicum L.)” was undertaken with the objective of improving flowering and fruit set of tomato under elevated CO 2 condition through nutrient and biofertilizer application. The experiment was conducted using the Open Top Chamber (OTC) facility at the Department of Plant Physiology, College of Agriculture, Vellyani during 2020-2021. In the experiment, flowering and fruiting in tomato under elevated CO 2 environment, as influenced by nutrients and biofertilizers were evaluated. The experiment was laid out in CRD with nine treatments and three replications. The treatments comprised of T 1 :50 ppm B + 50 ppm Zn + water spray, T 2 :75 ppm B + 75 ppm Zn, T 3 : POP 150% N:125%P:125% K, T 4 : Azolla (soil application), T 5 :Azolla biofertilizer extract (20%) (foliar application), T 6 : Azolla biofertilizer extract(20%)(seed treatment), T 7 :POP, KAU+ PGPR1, T 8 : Control (water spray) and T 9 : Absolute control. Experimental results revealed that plant height, number of branches, number of leaves and specific leaf area increased significantly under elevated CO 2 condition at 75DAS. Among the treatments, foliar spray with 50ppmB+50ppm Zn+ water spray at 40, 55and 70 DAS recorded higher plant height (57.56%) at 75DAS. Nutrient application of 150%N:125%P:125%K found to improve the number of branches (91.82%), leaves (98.56%) and specific leaf area (40.03%) at 75DAS. Among the physiological and biochemical parameters, total chlorophyll content, total carbohydrate, photosynthetic rate, water use efficiency, chlorophyll fluorescence, chlorophyll stability index and proline content recorded higher values inside OTC compared to open condition. However, a significant reduction was noted in transpiration rate and total soluble protein content inside OTC compared to open condition. The foliar spray of 50ppm B+50ppm Zn+ water spray recorded high values for chlorophyll content (1.58 mg g -1 ) and cell membrane stability index (53.83%) compared to open condition at 75DAS. The application of POP 150% N:125% P:125% K recorded significantly higher photosynthetic rate (21.03μmol CO 2 m -2 sec -1 ), total carbohydrate(50.04mgg -1 ), chlorophyll stability index(135.38%) and chlorophyll fluorescence (0.74Fv/Fm). Also foliar application of 20% Azolla biofertilizer extract was found to significantly improve the relative water content (96.15%) and water use efficiency(6.82 mmol CO 2 mol -1 H 2 O) in tomato plants under elevated CO 2 conditions. Inside OTC, flowering delayed by 2 days and the total number of flower clusters (5.96) also increased compared to control (4.12). Reduction in pollen viability (82.42%) observed at higher CO 2 compared to control. But it was found to improve under treatment T1 (50ppm B+ 50ppm Zn + water spray) which resulted in highest fruit setting percentage (53.01%) as against the control (39.92%). Fruiting was delayed by 3 days inside OTC. However, the fruit weight was found to increase with water spray (54.46%), extra NPK(55.89%) and foliar spray of 50ppm B+ 50ppm Zn+ water spray(57.51%). Foliar application of Azolla biofertilizer extract (20%)(T5), 150% N:125% P:125% K(T3) than the recommended dose, as well as foliar application 50ppm B + 50ppm Zn+ water spray (T1) improved the yield per plant by 55.79%, 63.08% and 65.22% respectively compared to control. All these treatments also improved the quality parameters like lycopene, vitamin C, beta carotene and minerals (P, Fe) in tomato fruits under elevated CO 2 condition. The present study indicated the improved performance of tomato variety Vellayani vijay upon exposure to elevated CO 2 . But flowering, fruit set and ultimately the total yield were negatively influenced by elevated CO 2 induced high temperature. The impact of application of extra N, P and K than the recommended doses as well as foliar application of B and Zn indicate the changing nutrient requirement of tomato under the current scenario of increasing atmospheric CO 2 concentration. The response of experimental plants to foliar application of Azolla extract (20%) strongly suggest the effectiveness of this biofertilizer in overcoming the impacts of elevated CO 2 induced high temperature and thereby improving the plant performance. Recommendations based on the best treatments can be developed by extending the study to field condition since the treatments were found to improve the yield and quality even under ambient conditionItem Micro irrigation and mulching for yield optimization of tomato in rain shelter(Department of Agronomy, College of Agriculture , Vellayani, 2021-12-09) Saniga, N. S; T, Sajitha Rani.The investigation entitled “Micro irrigation and mulching for yield optimization of tomato in rain shelter” was carried out during February-May 2021to evaluate the efficacy of micro irrigation and mulching on the growth, yield and economics of tomato in rain shelter. The experiment was laid out in split plot design with five types of micro irrigation as main plot treatments and two mulching materials as sub plot treatments with four replications. The main plot treatments were i 1 (surface drip irrigation), i 2 (rain hose irrigation), i 3 (sub surface drip irrigation at 10 cm), i 4 (sub surface drip irrigation at 15 cm) and i 5 (sub surface drip irrigation at 20 cm). The sub plot treatments were m 1 (no mulch) and m 2 (organic mulch). Organic mulch (dry banana leaves) @ 10 t ha -1 was applied as per the treatments. The tomato variety Vellayani Vijai was used for the study. The growth attributes of tomato were favourably influenced by the types of micro irrigation and mulching. Taller plants were observed in sub surface drip irrigation (SSDI) at 10 cm depth throughout the growth stages and it was comparable with SSDI at 15 cm depth and 20 cm depth at 90 DAT and at harvest. The number of branches per plant was higher in SSDI at 10 cm depth at 50 per cent flowering (8.01) and at harvest (13.61) and was on par with SSDI at 15 cm depth and SSDI at 20 cm depth at harvest. The different types of micro irrigation did not had any significant influence on days to 50 per cent flowering and leaf area index at 50 per cent flowering. The root shoot ratio was higher for SSDI at 10 cm depth (0.27) and was statistically on par with SSDI at 15 cm depth. The highest dry matter production was recorded for SSDI at 10 cm depth (4751 kg ha -1 ) and was significantly superior to rest of the treatments. Between mulches, organic mulch significantly increased the growth attributes of tomato except days to 50 per cent flowering. The combination of SSDI at 10 cm depth with organic mulch recorded significantly higher dry matter production (4835 kg ha -1 ) at harvest. The root parameters viz., root depth and root volume were significantly higher for SSDI at 20 cm depth (46.46 cm) and SSDI at 10 cm depth (27.06 cm 3 ), respectively.Between mulches, organic mulch recorded higher root depth (40.39 cm) and root volume (22.78 cm 3 ) compared to treatment without mulch. The types of micro irrigation and mulching had significant influence on the yield attributes of tomato. The number of fruits per plant was significantly higher for SSDI at 10 cm depth (35.69). The average fruit weight (43.60 g) was higher for SSDI at 10 cm depth was on par with SSDI at 15 cm depth. The fruit yield per plant (1.41 kg) and fruit yield m -2 (3.44 kg) were significantly higher for SSDI at 10 cm depth. Between organic mulch and no mulch, organic mulching recorded significantly higher number of fruits per plant (31.37), average fruit weight (39.69 g), fruit yield per plant (1.24 kg) and fruit yield m -2 (2.96 kg) than without mulch. The combination of SSDI at 10 cm depth along with organic mulch produced significantly higher fruit yield per plant (1.44 kg) and fruit yield m -2 (3.54 kg). Micro irrigation, mulching or their interaction did not influence the quality attributes of the tomato. The uptake of N (59.09 kg ha -1 ), P (21.43 kg ha -1 ), K (85.94 kg ha -1 ) were higher for the SSDI at 10 cm depth. Between mulches, organic mulch obtained higher uptake of N, P and K compared to no mulch. The combination of SSDI at 10 cm depth with organic mulch registered the highest uptake of N (61.26 kg ha -1 ) and P (22.73 kg ha -1 ).The available N status of soil was higher in rain hose irrigation (229.72 kg ha -1 ) and was on par with surface drip irrigation. Available K and P were not significantly influenced by the types of micro irrigation. Between mulches, the higher available N, P and K were recorded in the treatment with organic mulch. Water requirement was the same for all the irrigation treatments, where SSDI at 10 cm depth recorded significantly higher field water use efficiency (7.47 kg m -3 ) and water productivity (3.80 kg m -3 ). Between mulches, organic mulch recorded the highest field water use efficiency (6.42 kg m -3 ) and water productivity (3.15 kg m -3 ). The combination of SSDI at 10 cm depth with organic mulch obtained significantly higher field water use efficiency (7.67 kg m -3 ). SSDI at 10 cm depth along with organic mulch recorded significantly higher net returns (₹ 5.43 lakhs ha -1 ) and benefit cost ratio (2.04).The present investigation revealed that SSDI can be successfully adopted for tomato cultivation. Combination of SSDI 10 cm depth with organic mulch (dry banana leaves) @ 10t ha -1 can be recommended for getting higher yield, water use efficiency and economics in tomato.