PhD Thesis
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Item Evaluation of phylloplane microorganisms for the management of early blight of Tomato (Solanum lycopersicum L.)(Department of Plant Pathology, College of Agriculture, Vellanikkara, 2024-08-14) Wongamthing, R.; Sainamole Kurian, PTomato (Solanum lycopersicum L.) is a widely grown vegetable and the most remunerative solanaceous crop in both tropics and sub tropics of the world. It is vulnerable to various biotic diseases among which, early blight caused by Alternaria solani is a destructive one. Management of diseases using biocontrol agents is a safe alternative in the integrated disease management system. However, success of a bioagent is dependent on its comparative survivability in the new niche. Therefore, the present investigation was undertaken to identify strains of beneficial microorganisms adept on the phylloplane of tomato for use against early blight as it is a disease affecting mainly the foliage. As part of the investigation, purposive sampling survey was conducted in Thrissur and Palakkad districts of Kerala. It was found that early blight is prevalent in all the areas surveyed and the disease severity on foliage varied from 23 to 78 per cent at various locations. Though several fungi were found to be associated with the disease, only six isolates collected from Pudukkad, Valapad, Mundathikode, Vadakarapathy, Nenmara and Parrisakal were identified as Alternaria sp.(PDK), A. alternata (VAL), Fusarium oxysporum (MUN), A. solani (VAD and NEM) and Corynespora cassiicola (PAR) which could be proved as pathogens on tomato. Phylloplane microorganisms were isolated from both the healthy and diseased leaves collected from plants at various locations and a total of 132 isolates were then subjected to preliminary in vitro screening for their ability to suppress A. solani and 59 were selected as they could antagonize the pathogen in various degrees. The antagonists thus selected were further screened by dual culture technique and 36 showed more than 60 per cent inhibition. The antagonism exerted by phylloplane isolates was clearly discerned by limited growth, or the complete absence of fungal mycelium in the inhibition zone between the pathogen and the test isolate. Out of the 36, five were selected as promising potential antagonists as they could give more than 80 per cent inhibition of the pathogen. The selected five are identified as Trichoderma spp. (PF2 and PRF1), Bacillus subtilis (MNB2), Bacillus mojavensis ii (TB1) and Ochrobactrum sp. (EB1) which showed per cent inhibition of 91.2, 90, 89.4, 88 and 85 respectively. Furthermore, when these isolates were tested for growth promotion on tomato, the vigour index of tomato seedlings varied from 2110 (Trichoderma sp., PF2) to 1676 (Bacillus mojavensis, TB1). As next step, selected antagonists were tested for induction of systemic resistance (ISR) on tomato by conducting a pot culture experiment. Increased accumulation of peroxidase (PO), polyphenol oxidase (PPO) and, phenylalanine ammonia-lyase (PAL) was observed in plants treated with phylloplane antagonists. Higher activity of PO and PPO was induced by Trichoderma sp. (PF2) and B. subtilis (MNB2) at fifth day after inoculation (DAI) of pathogen. The phylloplane antagonists Trichoderma sp. (PF2) and B. subtilis (MNB2) recorded 169.54 min-1 g -1 and 152.56 min-1 g -1 respectively for PO and 199.19 min-1 g -1 and 172.24 min-1 g -1 respectively for PPO. Higher activity of PAL at fifth DAI was obtained by Pseudomonas fluorescens (KAU) followed by Trichoderma sp. (PF2) and B. subtilis (MNB2) recording 209.86 min-1 g -1 , 198.59 min-1 g -1 and 180.85 min-1 g -1 respectively. However, the highest per cent reduction of early blight after the first spray (68.58) was effected by Trichoderma sp. (PF2) followed by (64.92 and 60.22) B. subtilis (MNB2) and Ochrobactrum sp. (EB1), respectively. The disease reduction at early stage was reflected on yield of tomato and the same treatments; Trichoderma sp. (PF2), B. subtilis (MNB2) and Ochrobactrum sp. (EB1) gave 410 g, 389.33 g and 340 g fresh tomatoes per plot respectively. Hence these three phylloplane antagonists were selected for further evaluation. An experiment was carried out under rain shelter to evaluate the efficacy of the selected antagonists, conventional biocontrol agents such as Trichoderma sp. (KAU) and P. fluorescens (KAU) and a chemical check, propineb (0.2 %). The results showed that the phylloplane antagonists Trichoderma sp. (PF2) and B. subtilis (MNB2) offered significant effect against the disease recording 40.74 and 37.04 reduction in per cent disease severity (PDS) which in turn resulted in per cent yield increase of 32.63 and 28.10 respectively. Enumeration of phyllopane microflora proved that, there is drastic reduction in microbial population on leaf surface after iii spraying with propineb whereas the population increased after application of bioagents. Further, it was found that Trichoderma sp. (PF2) and B. subtilis (MNB2) are compatible with P. fluorescens (KAU) but B. subtilis (MNB2) is not compatible with Trichoderma sp. (KAU). Trichoderma sp. (PF2) is weakly inhibited by propineb (0.2 %), but azoxystrobin (0.1 %) could reduce its growth by 58 per cent. However, B. subtilis (MNB2) could not be affected by any of the two fungicides used against leaf blight. Hence, based on the results of various experiments in this study, phylloplane antagonists, especially, B. subtilis (MNB2) seems to be suitable for inclusion in IDM for early blight of tomato. Enumeration of culturable microflora on tomato leaves revealed that, bacteria are more on healthy leaves while fungi are more on the infected leaves. However, metagenomic analysis of the phylloplane revealed great difference in density and diversity of microbial taxa between healthy and infected leaves. This indicates that, specific functions of the phylloplane microbes and their antagonistic potential are also important in determining their efficacy as biocontrol agents. The study also revealed the presence of plant pathogenic fungal genera like Cladosporium, Corynespora, Pseudocercospora, Conidiosporomyces and Ustilago on tomato leaves. Both healthy and diseased tomato leaves harbour great microbial diversity and the phylloplane dwellers include well-known antagonists like species of Bacillus, Pseudomonas, Trichoderma and Penicillium. Presence of members of genera like Klebsiella and Enterobacter which are human pathogens was also revealed by metagenomic analysis. However, they are beneficial to plants as N fixers, P and K solubilizers and siderophore and IAA producers. Phylloplane dwellers also include species of Methylobacterium, Sphingomonas and Massilia and they are reported to produce different pigments and antibiotics besides being plant growth promoters, and antagonists to plant pathogens. Furthermore, species of Staphylococcus, Cladosporium, Coprinellus and Moesziomyces are also detected from tomato phylloplane and are reported to have antifungal properties with goo plant growth attributes, while species of Meira are reported as potential biological control agents against phytophagous mitesItem Influence of rootstocks on yield, quality and bacterial wilt resistance in F1 hybrids of Tomato(Department of Vegetable Science, College of Agriculture,Vellanikkara, 2024-05-21) Remzeena, A.; Anitha, PTomato production in the tropics and subtropics is often hampered by the incidence of various pests and diseases. Among these, bacterial wilt caused by the soil-borne bacteria Ralstonia solanacearum poses a significant problem for tomato growers in Kerala. The warm, humid, tropical climate and acidic soil conditions prevailing in the state provide a favorable environment for wide spread occurrence of bacterial wilt in the state. Growing resistant varieties have been identified as one of the most effective management strategy. However, the development of bacterial wilt-resistant varieties or hybrids is challenging due to the quantitative nature of the trait, its linkage to small fruit size, and the diversity of pathogen strains. Therefore, an effective alternative is grafting tomato cultivars having high production potential onto bacterial wilt resistant rootstocks. In addition to providing complete resistance to bacterial wilt, grafting also helps in harnessing improved yield. In this context, the present study was undertaken with the objectives of identifying bacterial wilt-resistant rootstocks for tomatoes, evaluating the performance of the grafts for yield, quality, and bacterial wilt resistance, and determining their suitability for growing in the rainshelter. In experiment 1, ten F1 hybrids of tomato were collected and evaluated in sterilized medium for their yield and quality. Hybrids exhibited significant variation for yield and quality traits. Among the hybrids significantly high plant height was exhibited by Arka Apeksha. Days to flowering and harvest was minimum in Lakshmi. Arka Rakshak exhibited highest root length and spread followed by Arka Apeksha. Average fruit weight was significantly high in Arka Abhed (97.56g) followed by Arka Samrat (89.68g). Lakshmi recorded significantly highest fruit yield per plant (3.28 kg) which was on par with Arka Samrat (2.86 kg) and Arka Abhed (2.78 kg) followed by Arka Rakshak (2.65 kg), Sampurna (2.62 kg) and Arka Apeksha (2.59 kg). Fruit quality traits such as lycopene, vitamin C, TSS was the highest in Arka Apeksha. Sampurna recorded the highest acidity and total phenol was the highest in COTH3. NSC 620B recorded the highest Orthodihydroxy (OD) phenol and the lowest solasodine content was recorded in Arka Apeksha. Among the hybrids the highest bacterial incidence was recorded in Shivam (72.50 %) and the hybrid Arka Abhed recorded zero per cent incidence. Tomato Leaf Curl Virus (ToLCV) incidence was highest in COTH3 whereas, six hybrids Lakshmi, Sampurna, Arka Rakshak, Arka Abhed, Arka Samrat and Arka Apeksha was completely free from ToLCV incidence. In the experiment 2, six high yielding tomato hybrids from the experiment 1 (Lakshmi, Arka Samrat, Arka Abhed, Arka Rakshak, Sampurna and Arka Apeksha) were grafted on four brinjal rootstocks viz., Surya, Haritha, SM 3, SM 116 and two Solanum torvum rootstocks (KAU-1and TNAU-1). These grafts were evaluated for their yield, quality and bacterial wilt resistance in bacterial wilt sick field. Plant height, girth of graft (60 DAP), root length and spread, average fruit weight were significantly improved in the grafted plants compared to their non-grafted controls. The highest plant height was recorded in the grafts on SM 116 and Haritha and the lowest plant height was recorded on SM 3 irrespective of the scion. Girth of graft was significantly high when grafted on Haritha in all the hybrids which was followed by the grafts on Surya. Root length and spread were also significantly high in grafts on Haritha followed by the grafts on Solanum torvum rootstocks. Grafts on Haritha recorded the highest overall average fruit weight which was on par with the grafts on Surya. Days to flowering and days to harvest were delayed in the grafted plants compared to the non-grafted controls. However, significant improvement was recorded in the crop duration of grafted plants compared to non-grafts. Fruit yield was significantly improved compared to non-graft control on Haritha, Surya and SM 116 in all the hybrids. Arka Rakshak (4.17 kg) , Lakshmi (3.98 kg), Arka Samrat (3.85 kg), Arka Abhed (3.83 kg) and Arka Apeksha (3.76 kg) exhibited highest fruit yield per plant on Haritha, whereas, Sampurna showed the highest fruit yield per plant on Surya (3.75 kg). Among the 36 graft combinations, Arka Rakshak, Lakshmi, Arka Samrat, Arka Abhed, Arka Apeksha grafted on Haritha and Arka Rakshak, Sampurna, Lakshmi on Surya recorded the highest yield per plant and performed on par with each other. Total Soluble Solids (TSS) of the fruits of grafted plants were on par with that of non-grafted control in all hybrids. Acidity increased in the fruits of grafts compared to the non-grafts. Lycopene content of the grafts were on par with non-grafted control except in the grafts of Sampurna on Haritha and Solanum torvum rootstocks. Fruits of grafted plants also recorded a decrease in vitamin C compared to non-grafted control. However, vitamin C content of fruits of grafts on Haritha and Surya were on par with that of the non-grafted control in all the hybrids except Lakshmi. Total Phenol, OD Phenol and Solasodine content increased significantly in grafted plants compared to non-grafted control. Sensory evaluation of fruits of grafted and non-grafted plants indicated only non-significant difference between grafts and non-grafted control. Overall acceptability was similar or higher in grafts compared to non-grafts except in the grafts of Lakshmi and Sampurna on Solanum torvum rootstocks. Grafts on the brinjal rootstocks Surya, Haritha, SM3 and SM 116 recorded zero percent incidence of bacterial wilt. Whereas grafts on Solanum torvum rootstocks (TNAU- 1 and KAU- 1) recorded 6.67-13.33 per cent incidence. Rootstocks did not influenced the ToLCV incidence of the scion as ToLCV incidence was recorded in both grafts and nongrafted controls. Anatomical studies of graft union revealed the formation of thick callus and establishment of vascular connection between stock and scion in the form of vascular bridges at 20 DAP planting. At 40 DAP, differentiation of vascular tissues were initiated in all the grafts and 60 DAP well established vascular connections were observed. Callus thickness and cell wall thickness generally reduced whereas dimensions of xylem vessel and phloem tissue increased from 20 DAP to 60 DAP in all the grafts. In the experiment 3, eight high yielding hybrids identified from experiment 2 were evaluated in rainshelter during rainy season for yield and quality. Compared to open field, plant height, average fruit weight, crop duration and yield of the grafts generally increased inside the rainshelter. However, the days to flowering, days to first harvest, TSS and acidity of grafts reduced compared to open field. There was significant variation among the grafts for yield and quality when grown inside rainshelter. Arka Apeksha on Haritha recorded the highest plant height among the grafts. Arka Abhed on Haritha recorded the highest average fruit weight, fruit yield and crop duration (120.47g, 4.49kg, 167.20 days) which was on par with Arka Samrat on Haritha (117.78g, 4.33kg, 167.80 days). The highest TSS was recorded in the graft of Arka Apeksha on Haritha and acidity was highest in Sampurna on Surya. None of the grafts recorded bacterial wilt incidence when grown inside rainshelter. ToLCV incidence was highest in Arka Samrat on Haritha and Arka Rakshak on Surya whereas, Sampurna on Surya and Arka Abhed and Lakshmi on Haritha recorded zero per cent incidence. Economic analysis was performed for growing the grafts inside rainshelter and the graft of Arka Abhed on Haritha recorded the highest B:C ratio of 2.03. All the grafts realized a B:C ratio greater than 1.50 indicating the economic viability of growing grafts inside rainshelter. From the study, it can be concluded that grafting is an economic, effective and quick method for the management of bacterial wilt and the brinjal rootstocks used in the study can be successfully utilized for grafting tomatoes when grown in bacterial wilt affected areas. Apart from imparting resistance they also enhanced the yield of the tomato hybrids without impairing the fruit quality.Item Genetic improvement of horticultural traits of bacterial wilt resistant/tolerant tomato (Solanum lycopersicum L.) varieties(Department of Vegetable Science ,College of Agriculture, Vellanikkara, 2023-02-14) Athulya, M P; Anitha, PVegetable production in the warm humid tropics is hampered by the recurrence of pests and diseases. Bacterial wilt disease caused Ralstonia solanacearum is the single most impediment, putting bottle neck in the commercial cultivation of tomato in Kerala. The disease is particularly rigorous in Kerala, where variety of factors such as virulent pathogen, favorable climate, and edaphic factors are available. As the pathogen is able to survive in soil, plant debris, weeds and able to move along with irrigation water; management practices are not quite effective in curbing the disease spread. Hence, exploitation of host plant resistance is the best feasible way to manage bacterial wilt disease. Bacterial wilt resistant varieties of tomato developed from the Kerala Agricultural University are nationally renowned. However, due to small fruit size, these varieties are low in demand in the market.In this context, the present investigation entitled “Genetic improvement of horticultural traits of bacterial wilt resistant/tolerant tomato (Solanum lycopersicum L.) varieties” by following line x tester analysis was undertaken to improve yield, fruit size and quality of bacterial wilt resistant/tolerant tomato varieties.Item Breeding hotset indeterminate tomato (Solanumlycopersicum L.) resistant to bacterial wilt suitable for protected cultivation(Department of Vegetable Science, College of Agriculture, Vellanikkara, 2021) Archana, K A; Pradeep Kumar, TThe present investigation was undertaken to develop an indeterminate hotset tomato with bacterial wilt resistance through line × tester analysis. The experiment was conducted at the Department of Vegetable Science, College of Agriculture, Vellanikkara, Kerala Agricultural University, during the year 2018- 2020. The first experiment was the performance evaluation of 35 tomato genotypes for two seasons in the year 2018, summer evaluation from January 2018 and rainy season evaluation from July 2018, in two protected structures viz., polyhouse and rainshelter. Genotypes exhibited significant variation for vegetative, flowering, fruit, yield and biochemical traits under both growing structures across season. Under polyhouse during summer the genotypes EC- 164263, EC-620387, EC-620401, EC-620406, EC-620410, and EC-620417 performed better for hotset traits (flowers with exerted stigma, pollen viability and fruit set per cent) and yield traits (average fruit weight, number of fruits per plant and yield). In rainshelter, the genotypes EC-165395, EC-165690, EC- 538153, EC-620401, EC-620406, EC-620410 were superior. During rainy season, EC-164263, EC-538153, EC-620401, EC-620406, EC-620410, EC-631369 were superior under polyhouse, and EC-620395, EC-620401, EC-620406, EC-620410, EC-631369 and EC-631379 inside rainshelter, for hotset traits and yield traits. The pooled data of flowers with exerted stigma, pollen viability, fruit set per cent, number of fruits per cluster, days to first fruit set, average fruit weight, pericarp thickness, number of fruits per plant and yield per plant were subjected to multivariate analysis for discrimination of genotypes into clusters. Under polyhouse seven clusters and inside rainshelter five clusters were observed. The selection index was also applied for ranking of genotypes based on the hotset distinctions and yield attributes. The hotset genotypes with high yield potential, identified suitable for protected cultivation were EC-164263, EC-538153, EC- 620387, EC-620389, EC-620401, EC-620406, EC-620410, EC-620417 and EC-631369. The genotypes EC-620401 (1), EC-620406 (2) and EC-620410 (3) were selected as hotset line for the line × tester analysis. In the second experiment the genotypes were tested for bacterial wilt resistance. The 35 tomato genotypes were sown in 98 well pro-trays holding sterilised soil medium. Another set of pro-trays holding the same medium were drenched with bacterial suspension with OD adjusted 0.8 to 1.3 at 600 nm and kept as the sick pro-trays. The twenty-one days old seedlings were used for inoculation through root dip method. With the help of sterilized scissors the tertiary roots of the seedlings were sectioned. The root clipped seedlings were dipped in bacterial suspension for thirty minutes. The inoculated seedlings were transplanted in the sick pro-trays. The entire experiment was conducted inside rainshelter with three replications. Each replication had five plants per genotype. Periodical observation on bacterial wilt symptom expression was taken from third day onwards. The disease index has revealed EC-620382 (0.20) and Arka Abha (0.20) as highly resistant. Nine genotypes viz: EC-165395 (0.24), EC-165700 (0.25), EC-521067 B (0.25), EC-620376 (0.30), EC-620378 (0.28), EC-620427 (0.21), EC-620429 (0.23), Akshay (0.21), Anagha (0.28) were resistant. From these EC-620382 (4), EC-620427 (5), EC-620429 (6) and Arka Abha (7) were selected as testers. In the third experiment, the identified lines and testers were crossed and seeds were collected for twelve cross combinations. The fourth experiment was the evaluation of F 1 hybrids from third experiment during summer in two protected structures viz., polyhouse and rainshelter. The cross combinations were laid along with the parents and two checks viz., one check hybrid (Abhilash) and one check variety (Akshaya). The mean performance, relative heterosis (RH), heterobeltosis (HB), standard heterosis (SH) and combining ability studies were conducted. For vegetative traits, the cross combination 3 × 7 exhibited superiority in the mean performance with significant positive sca effects in both the structures. For flowering traits, the cross 2 × 5 exhibited significant positive sca effects for pollen viability and significant negative sca effects for flowers withexerted stigma with significant RH, HB and SH in both the structures. In the case of fruit and yield traits, the cross combination 2 × 5 exhibited negative significant sca effects for days to first fruit set and positive significant sca effects for pericarp thickness, average fruit weight and yield per plant with significant RH, HB and SH. Inside rainshelter, 3 × 5 and 3 × 7 noted significant sca effects and positive significant heterosis for fruit and yield traits. For biochemical traits, the cross combination 2 × 5 exhibited positive significant sca effects and positive significant RH, HB and SH for TSS, ascorbic acid and acidity under polyhouse. In the seedling stage, all cross combinations exhibited resistance reaction to bacterial wilt in the challenge inoculation. Depending on the mean performance, heterosis and sca effects, the cross combination 2 × 5 was recommended for polyhouse and the crosses 3 × 5 and 3 × 7 were recommended for rainshelter. None of the parents revealed significant and desirable gca effect for all traits studied. The comprehensive assessment of the parents by considering gca estimates revealed that among lines EC-620406 is a good general combiner for vegetative, fruit and yield characters under polyhouse, and EC-620406 and EC- 620410 could be regarded as good general combiners for vegetative, reproductive, fruit and yield, quality characters and shelf life inside rainshelter. In the case of testers EC-620427 and Arka Abha were good combiners for vegetative, reproductive, fruit characters and shelf life in both the growing structures. Dominant gene action was observed predominantly for characters studied under both the structures. Plant height at harvest, days to 50% flowering, days to first fruit set, days to first fruit harvest, number of fruits per plant, average fruit weight, yield per plant, yield per plot, lycopene, ascorbic acid, shelf life, flowers with exerted stigma, pollen viability, number of flowers per cluster, number of fruits per cluster and fruit set per cent exhibited dominant gene action under both the structures. Pericarp thickness exhibited complete dominance inside rainshelter.In the fifth experiment, available SSR markers were validated for bacterial wilt resistance. Two SSR markers, SLM6124 and SLM6-110, produced polymorphism between resistant and susceptible genotypes, two distinct bands for resistant genotypes and four bands (two distinct and two fainted) for susceptible genotypes. In conclusion, the work indicates the change in the behaviour of genotypes under different protected structures in different seasons. Hence the selection of genotype and structure depending on the season is important. The heterosis breeding is effective in improving hotset traits in tomato. The hybridisation involving one resistant parent can generate bacterial wilt resistant off-springs. The application of molecular markers can effectively reduce the time and labour intensive field evaluation.Item Management of early blight disease of tomato (Solanum lycopersicum L.) under protected cultivation(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2020) Sumbula, V; Sainamole Kurian, PItem Development of F1 hybrids of indeterminate tomato (Solanum lycopersicum L.) for protected cultivation(Department of Olericulture, College of Agriculture, Vellayani, 2015) Lekshmi, S L; Celine, V AThe present investigation entitled “Development of F1 hybrids of indeterminate tomato (Solanum lycopersicum L.) for protected cultivation” was conducted at the Department of Olericulture, College of Agriculture, Vellayani, from 2013 to 2015 with the objectives of identifying superior varieties and developing F1 hybrids of indeterminate tomato suited for protected cultivation. The study consisted of two experiments conducted in the naturally ventilated polyhouse of size 50 m x 20 m located at the Instructional Farm, Vellayani. In the first part of the first experiment, 40 tomato genotypes were evaluated for two consecutive years in an RBD with three replications. As the second part, 12 commercial hybrids were evaluated. The second experiment consisted of a 9 x 9 half diallel analysis laid out in an RBD with three replications. Analysis of variance showed significant differences between the genotypes for all the characters for two crops. Pooled analysis revealed that, LE 1 recorded the highest yield (2443.43 g) and fruit weight (108.13 g) followed by LE 7. LE 53 had maximum number of fruits per plant (65.00). In the present study, genotypes had wide variation for quality parameters. Fruits of LE 14 recorded highest TSS with a mean of 5.74 ºBrix. LE 7 had maximum ascorbic acid (30.13 mg/100g) and lycopene content (13.09 mg/100g). Beta carotene value was maximum in LE 16 (184.15 mg/100g). There was minimum incidence of pests, diseases and physiological disorders under protected conditions. Among the 12 hybrids evaluated, INDAM 9802 was the highest yielder (1444.40 g) followed by F1 T 30 (1412.22 g). F1 T 30 recorded maximum fruits per plant (35.66) which was on par with F1 Queen (35.55). Genetic parameters like phenotypic and genotypic coefficients of variation, heritability and genetic advance were studied to assess the genetic variability among the genotypes. High heritability coupled with high genetic advance were observed for characters like truss per plant, fruits per truss, fruit weight, fruits per plant, yield per plant and yield per plot. Path analysis revealed highest positive direct effect for fruit weight (0.3956), truss per plant (0.3558) and fruits per plant (0.3381). Based on D2 analysis the 40 genotypes were grouped into eight clusters. Cluster I was the largest with twenty four genotypes followed by cluster II with ten genotypes. Diallel analysis was carried out using nine parents selected based on genetic divergence and per se performance. The parents were crossed in a diallel fashion excluding reciprocals to obtain 36 F1 hybrids. The study revealed that P5 x P9 had the highest yield (3114.03 g) which was on par with P6 x P8 (3074.37 g) and P1 x P5 (3077.58 g). P1 x P5 had the maximum fruits per plant (103.93). The magnitude of relative heterosis, heterobeltiosis and standard heterosis varied considerably. For yield, relative heterosis ranged from -32.40 to 92.72, heterobeltiosis from -47.14 to 89.54 and standard heterosis from 2.91 to 160.95. The σ2gca and σ2sca ratio indicated that non-additive gene action was predominant for all traits. Among the nine parents, P9 (LE 1), P5 (LE 20) P1 (LE 2), and P2 (LE 7) were superior for yield and yield attributes. The estimates of sca effects indicated that P5 x P9 (LE 20 x LE 1), P6 x P8 (LE 39 x LE 38) and P1 x P5 (LE 2 x LE 20) were the most promising hybrids for protected cultivation. The present study revealed that the genotypes LE 1 and LE 7 and the hybrids INDAM 9802 and F1 T 30 were superior for yield and yield attributes under protection. Based on the mean performance, standard heterosis and sca effects the three potential crosses viz., P5 x P9, P6 x P8 and P1 x P5 could be adjudged as suitable indeterminate tomato hybrids for protected cultivation.Item Synergistic interaction of biocides and insecticides on tomato fruit borer helicoverpa armigera (Hubner)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2004) Lily Levin; Ranjith, A MThe tomato fruit borer Helicoverpa armigera (Hubner) is a serious pest of several cultivated crops and has attained global importance. H. armigera displays formidable biological profiles based on multihost feeding, strong flying ability and genetic versatility, and consequently it resists any synthetic insecticide used to control it world wide. This pest is out of control precisely because of overuse of synthetic insecticides, which has led to development of resistance and destruction of natural enemy complex. Hence the present study was carried out to investigate the efficacy and interaction of different plant extracts, microbial pesticides and synthetic chemicals, alone and in combination against H. armigera to reduce the cost, to avoid the after effects of commonly used insecticides and to consider its fitness in different management options. The population of H. armigera was found to be more during October to March period. There was no incidence of pest from July to September period. Among the four ecosystems, tomato recorded the highest number of larvae followed by bhendi, bittergourd and cowpea. The species of natural enemies recorded on H. armigera during the survey period were Carcelia illota, Apanteles taragamae, Chrysoperla carnea, Nosema sp. and Nomuraea rileyi. All these natural enemies are being reported for the first time on H. armigera in Kerala. The plant aqueous extracts (Acorus calamus Linn. , Andrographis paniculata Wall. and Vitex negundo Linn. ) on their own, are not very highly effective, as they cause only about 30 to 40 per cent mortality at five per cent concentration. All the essential oils (Citronella winterianus Jowitt., Cymbopogon flexuosus Steud., Kaempferia galanga Linn. and Cymbopogon martinii Roxb.) are causing more than 50 per cent mortality except citronella oil (C.winterianus). Palmarosa oil (C. martinii) at five per cent concentration recorded the highest percentage of mortality. In the compatibility study, all the three-entomopathogenic fungi (Nomuraea rileyi, Metarhizium anisopliae and Beauveria bassiana) were found to be incompatible with essential oils and compatible with plant extracts and insecticides. But all the commercial formulations of Bacillus thuringiensis were compatible with plant extracts, essential oils and insecticides. The bioassay of entomopathogens with botanicals and insecticides under laboratory conditions produced the following results In the entomopathogenic fungi and plant extracts combinations, N. rileyi + V. negundo (76.6 per cent) M. anisopliae + V. negundo (63.3 per cent) and B. bassiana + V. negundo (56.6 per cent) recorded the maximum mortality. The treatments N. rileyi+ spinosad (96.6 per cent), B. bassiana+ spinosad and M. anisopliae + spinosad (93.3 per cent) recorded the highest mortality in entomopathogen + insecticide combinations. A drastic reduction in LT50 value was noticed in combination treatments. Among the bacterial formulations + plant extract combination, Delfin + V. negundo (83.3 per cent) recorded the highest mortality percentage among the entire three (Halt, Delfin and Dipel) combination products. The time mortality response was reduced from six to seven days to three to four days in combinations. In the case of bacterial formulations + essential oil, the maximum mortality was recorded in B. thuringiensis (Halt, Delfin and Dipel)+ C. martinii followed by B. thuringiensis + K. galanga. The treatment combinations Halt + spinosad, Delfin + spinosad and Dipel + spinosad recorded the maximum mortality percentage. The mean lethal time could be decreased drastically in combinations when compared to individual treatments. The combination NPV + V. negundo recorded the highest mortality percentage in NPV + plant extract combinations. Among the NPV + essential oil combinations, NPV + K. galanga recorded the highest mortality percentage followed by NPV + C. martinii, NPV + C. flexuosus and NPV + C. winterianus. NPV + spinosad combination recorded the highest mortality percentage in NPV + insecticide combinations. The combined treatment of NPV and B. thuringiensis with plant extracts significantly reduced the digestive enzyme (protease, α - amylase, β - amylase and lipase) activity in the midgut of H. armigera. The results of the field experiment indicate that the percentage mortality was more in biocide (B. thuringiensis, NPV and N. rileyi) and insecticides combinations when compared to the individual treatments. The study has identified eight such combinations, which are immediately field worthy. This technology is considered as eco- friendly and economically viable in nature. The present findings will be of immense help to the ordinary farmer and take him out of debt traps and offer him a better future.Item Gene action and heterosis for yield, quality and fruit borer resistance in tomato (lycopersicon esculentum mill)(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2002) Ebenezer Babu Rajan, R; Chandramony, DItem Incorporation of resistance to fruit cracking in a bacterial wilt resistant genetic background in tomato(Department of Olericulture, College of Horticulture, Vellanikkara, 1995) Sadhan Kumar, P G; Rajan, SAn investigation on “Incorporation of resistance to fruit cracking in a bacterial wilt resistant genetic background in tomato” was undertaken in the Department of Olericulture, College of Horticulture, Vellanikkara during the period from January, 1991 to March, 1994. The findings are succinctly mentioned below. Evaluation for bacterial wilt resistance revealed that Sakthi and LE 79 – 5 are consistently resistant to bacterial wilt. Four addition sources of bacterial wilt resistance were identified viz., LE 214, CAV – 5, LE 415 and LE 382 – 1. Resistances to bacterial wilt in these lines was governed by recessive genes. Screening for resistances to fruit cracking resulted in the identification of fifteen tomato genotypes which were found to be resistant to both radial and concentric cracking. Resistances to concentric fruit cracking in these lines were found to be dominant. All the bacterial wilt resistant genotypes had a higher content of total phenols, O.D. phenol and ascorbic acid than the susceptible line pusa Ruby. The crack resistant varieties had a higher content of insoluble solids and pectin, lower content of acidity, total sugar and reducing sugar in fruits, thick fruit skin and pericarb as compared to susceptible variety. The elasticity of skin was also higher in crack resistant genotypes. Crack resistant varieties had a compact arrangement of parenchymatous cells when compared with crack susceptible variety. The resistant lines had a thicker cuticle also. The F1 S developed by line x tester crossing were susceptible to bacterial wilt. All the same, they were resistant to both radial and concentric fruit cracking indicating dominant gene action for crack resistance. The F2 segregants with combined resistance to both bacterial wilt and fruit cracking were selected for further improvement.Item Disease management and growth improvement in chilli and tomato using Trichoderma Spp. and flurascent pseudomonads(Department of Plant Pathology, College of Agriculture, Vellayani, 2005) Rini, C R; Sulochana, K K
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