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Item Bioefficacy of entomopathogenic fungi against cassava mealybug, phenacoccus manihotti matile-ferrero (Hemiptera: Pseudococcidae)(Department of Agricultural Entomology, College of Agriculture,Vellanikkara, 2024-02-21) Fasna, Sherin, K.; Smitha Ravi; Gowri PriyaCassava mealybug (CMB), Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae) is a major insect pest of cassava. It causes severe damage by stunting the growth points of cassava plants, sometimes totally defoliating the plants. Level of infestation and yield loss by cassava mealybug varied from 30 to100 and 30 to 90 per cent respectively. In India, the occurrence of this pest was first noticed on cassava in Thrissur, Kerala during April 2020. Control of mealybugs commonly relies on the use of insecticides. But, it is difficult to control mealybugs using insecticides, due to their cryptic life cycle, presence of waxy coating, and formation of dense colonies. Management of insect pests using entomopathogens has received considerable importance in recent times. As part of AICRP programme of 2020-22, AICRP on BCCP, Thrissur centre conducted survey in cassava growing fields of Thrissur and Palakkad district to assess the species composition of mealybugs, damage intensity and associated natural enemies. During the survey, mycosed cadavers were collected and seven isolates of entomopathogenic fungi were obtained. Out of seven, five entomopathogenic fungal isolates were selected, characterized and evaluated under the present study entitled “Bioefficacy of entomopathogenic fungi against cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae)”. The identity of five isolates was confirmed through morphological, cultural and molecular characterization. The fungal isolates were identified as two isolates of Simplicillium aogashimaense (EPF 2 and EPF 4), two isolates of Purpureocillium lilacinum (EPF 3 and EPF 7) and one isolate of Lecanicillium psallioate (EPF 5). Pathogenicity of these fungal isolates was tested against second instar nymphs of cassava mealybug, P. manihoti in the laboratory. A preliminary screening bioassay was carried out initially, and the superior isolates were subjected to dose-response and exposure-time response bioassay. In the preliminary screening bioassay, P. lilacinum isolates (EPF 7 and EPF 3) recorded more than 90.0 per cent mortality. S. aogashimaense (EPF 4) and L. psalliotae (EPF 5) registered mean mortality of 82.5 and 75.0 per cent respectively. S. aogashimaense (EPF 2) recorded the lowest mortality of 70.0 per cent, which was significantly lower than all other isolates. The best four isolates in the pre-screening were subjected to dose-response and exposure time- response bioassay. Spore suspensions of five different concentrations ranging from109 to 105 spores ml-1 were tested against mealybug. Ten days after treatment, two isolates of P. lilacinum (EPF 7 and EPF 3) recorded more than 80.0 per cent reduction in population of mealybug at the concentration of 109 spores ml-1 . The same isolates showed low LC50 and LT50 values. Efficacy of these two superior isolates of P. lilacinum (EPF 7 and EPF 3) at concentration of 1×108 spores ml-1 was evaluated in a pot culture experiment. The isolates were compared with a standard biocontrol check, NBAIR isolate of Lecanicillium lecanii @ 1×108 spores ml-1 , a botanical insecticide (neem oil emulsion @ 2%) and a chemical insecticide, dimethoate 30 EC @ 1.5 ml L-1 . Maximum reduction in the mealybug population was observed in dimethoate treated plants (99.86%). Even though, the neem oil emulsion (2%) showed significant effect on mealybugs, certain signs of phytotoxicity were observed in treated plants. Among three fungal isolates, significantly higher reduction in population was observed in P. lilacinum, EPF 7 (78.55%) followed by P. lilacinum, EPF 3 (74.92%), and both being on par with each other. In conclusion, the present study revealed that biological control of cassava mealybug, P. manihoti using two promising isolates of P. lilacinum could be a viable component in the integrated pest management. Two rounds of foliar application of any of the two isolates of P. lilacinum (EPF 3 and EPF 7), at 15 days interval at the dosage of 1×108 spores ml-1 was found effective against cassava mealybug, P. manihoti.Item Process optimization of fruit blended boba tea pearls from cassava (Manihot esculenta)(Department of community science, college of agriculture,Vellayani, 2023-11-09) Gayathri, D.; Anitha, ChandranItem Technology adoption behaviour cassava growers in Kollam district(Department of Agricultural Extension, College of Agriculture, Vellayani, 2020) Kavya, V S; Bindu, PodikunjuItem Role of mixed infection of cassava mosaic viruses in cassava mosaic disease development(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2020) Akhila, J; Makeshkumar, TA study on “Role of mixed infection of Cassava mosaic viruses in cassava mosaic disease development” was conducted at ICAR-Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, during 2019- 2020. The important findings of the above studies are summarised in this chapter. Fifty samples randomly collected from the five varieties of cassava (Kochangamuttan, Kariyilappothiyan, Karutha gandharipadappan, H226, Manja noorumuttan), showed high score (>4) symptoms scale of very severe mosaic having distorted and misshapen leaves with stunted growth of plants. Multiplex PCR could differentially detect the presence of ICMV and SLCMV from the infected leaves. Among the five varieties of cassava, leaf samples collected from only one variety (Kariyilappothiyan) had ICMV infection as confirmed by PCR. Whereas, the samples from the variety Manja noorumuttan, did not show any PCR amplification. The mosaic symptoms appeared in the leaves of the variety may be due to physiological disorders such as nutritional deficiency. But the rest of the varieties showed amplification and had SLCMV infection. Out of five varieties, Manja noorumuttan variety is free from both ICMV and SLCMV. Out of rest four cassava varieties, Kariyilappothiyan was found infected with ICMV and other three varieties were infected with SLCMV. None of the varieties showed mixed infection of ICMV and SLCMV. Using chip bud grafting, both the SLCMV and ICMV infected plants were used as stock and scion for mixed infection. The grafted cassava plants showed yellow mosaic patterns on newly appeared leaves after two weeks. No substantial changes in the symptoms were observed in the plants grafted with buds from ICMV on SLCMV infected plants. But severe symptoms were observed in ICMV infected plants grafted with buds from SLCMV infected plants. This reveals that SLCMV is more severe than ICMV. Agroinoculation of Nicotiana tabacum was done with a partial dimer of DNA A and DNA B of both SLCMV and ICMV, in order to study the symptom appearance during the mixed infection. The plants inoculated with DNA A components of SLCMV and ICMV individually, showed curling of young leaves and mild mosaic symptoms respectively. The plants infiltrated with both components of SLCMV, showed severe stunting, thickening of mild veins, curling of leaves. However, the plants inoculated with both components of ICMV showed mild mosaic and mild curling of leaves and reduction in size. In the case of mixed infection of DNA A and DNA B components of both SLCMV and ICMV in Nicotiana plants showed symptoms including curling on the newly emerged leaves, yellow mosaic pattern on older leaves and severe stunting, resembling a mild SLCMV infection. Similarly, Agrobacterium strains with infectious clones were injected in the axillary buds of cassava plants to analyse the symptomatology during the mixed infection of SLCMV and ICMV. But the cassava plants did not show any mosaic symptoms in leaves with the infectious clones until 60 days after inoculation. The study reveals that agro- inoculation method is more effective in N. tabacum than cassava.Item Screening of cassava genotype for cassava mosaic disease resistance(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2020) Preeja, P S; Makeshkumar, TThe study on “Screening of cassava genotype for cassava mosaic disease resistance” was conducted at the ICAR- Central Tuber Crop Research Institute, Sreekariyam, Thiruvananthapuram during 2019-2020. The objective of the study was to screen the cassava breeding lines for resistance to cassava mosaic disease. The screening was carried out in fifteen selected cassava breeding lines from the breeding programme to analyze their resistance to cassava mosaic disease (CMD). For the analysis of resistance, virus inoculum was introduced into the fifteen breeding lines by grafting. Chip bud grafting method was carried out to analyze the resistance of breeding lines. The Sri Lankan cassava mosaic virus (SLCMV) infected plants, confirmed through multiplex PCR were selected as the inoculum source (scion) for grafting. Periodic observations were carried out in grafted plants by morphological (symptom appearance) as well as molecular analysis by means of ELISA and PCR. None of the grafted cassava plants showed any mosaic symptoms in the new shoots developed. PCR, ELISA and qPCR results revealed that the presence of SLCMV was only confirmed to the control plants (susceptible cv. H-226) and were absent in the breeding lines tested. This confirmed the 15 breeding lines screened are resistant to cassava mosaic disease caused by SLCMV. CMD resistant cassava varieties have an effective role in minimizing the damage caused by the virus. The success of grafting suggests this technique as the most efficient one for virus transmission and the resistant screening programme. The rapid selection of CMD resistance lines can be offered by this technique. The CMD resistance breeding lines have a better role in on-farm production as well as in the breeding programme.Item Formulating fermented cassava food products(Department of Home Science, College of Agriculture, Vellayani, 1989) Sathyalakshmi, C; Chellammal, SItem In vitro mutagenesis and evaluation of somatic embryo derived plantlets in cassava (Manihot esculenta Crantz.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2016) Riya Antony; Jiji JosephItem Pre-harvest forecasting models and instability in production of cassava (manihot esculenta crantz.)(Department of Agricultural Statistics, College of Agriculture, Vellayani, 2017) Neethu Kumar, S; Brigit JosephItem Slow release nitrogen in cassava nutrition(Department of Agronomy, College of Agriculture, Vellayani, 1988) Vinod, G S; Muraleedharan nair, VAn investigation was undertaken at the College of Agriculture, Vellayani during the year 1985-86 to study the effect of slow-release nitrogen sources on cassava. The variety used for the trail was Sree Visakha. The treatments consisted of four sources namely urea, neemcake coated urea, urea super granule and rubber cake coated urea each at five levels of nitrogen (50, 75, 100, 125 and 150 kg/ha). The experiment was laid out in a 4 x 5 rectangular lattice design with three replications. Application of slow release sources of nitrogen like urea super granule and neem cake coated urea enhanced the growth characters of tapioca such as plant height, number of functional leaves, number of nodes and the leaf area index. Higher levels of nitrogen gave better results in the growth characters. The highest number of tubers, maximum tuber weight and the highest tuber yield were recorded by the urea super granule application, followed by neem cake coated urea. Among the levels of nitrogen tried, the level 150 kg/ha gave the highest yield. Starch content, crude protein content and the hydrocyanic acid contents were not affected by the slow-release source of nitrogen while higher levels of nitrogen application increased the hydrocyanic acid content and the crude protein content. Urea super granule recorded the highest nitrogen uptake and potassium uptake followed by neem cake coated urea. There was no significant difference in the total nitrogen content of the soil with the use of slor-release sources of nitrogen. The treatment combination of neem coated urea tried at 150 kg N/ha resulted in the maximum net return. Though urea super granule gave the maximum yield its cost of cultivation was higher than that of the other sources. So it is more economical to use neem cake coated urea than urea super granule. So in general, the slow-release sources of nitrogn like urea super granule and neem cake coated urea resulted in a better performance than prilled urea.Item Integrated nutrient management for short duration cassava in lowlands(Department of Agronomy, College of Agriculture, Vellayani, 2003) Pamila Vimal Raj; Kumari Swabia, OAn investigation entitled "Integrated nutrient management for short duration cassava in lowlands" was undertaken in the Instructional Farm, College of Agriculture, Vellayani from September 2002 to April 2003 to develop an integrated nutrient schedule for short duration cassava in lowlands and to work out the economics of cultivation. The treatments consisted of factorial combinations of two varieties of cassava (Sree Vijaya and Kariyilapothiyan), three sources of organic manure (farmyard manure, poultry manure and coir pith compost) and three levels of nitrogen (50, 75 and 100 kg N ha-I). The trial was laid out in 32 x 2 asymmetrical confounded factorial design with two replications confounding VMN in replication J and MN in replication II. A uniform dose of 50 kg P20S ha' and 100 kg K20 ha-' was applied to all the plots. In general, the local var. Kariyilapothiyan recorded superior values of growth characters like plant height, leaf number and leaf area index. Among organic manures, farmyard manure produced higher values of growth characters. But total dry matter production was not influenced either by varieties or by sources of organic manure. Levels of N had profound influence on growth characters and 75 kg N ha-' was found superior in the case of both varieties. Varieties exhibited no variation in yield components except length of tuber. The improved var. Sree Vijaya produced longer tubers than the local variety. The yield components except tuber weight per plant did not vary with the source of organic manure. Poultry manure recorded the highest value of tuber weight per plant. Nitrogen @ 75 kg N ha" recorded higher values of yield components. The performance of both varieties In terms of tuber yield, top yield and utilization index was found similar. Among organic manures, the highest tuber yield was recorded by poultry manure which was on par with farmyard manure but superior to coir pith compost. At the same time the effect of farmyard manure was on par with coir pith compost. The top yield was not influenced by the source of organic manure but utilization index exhibited the same trend as that of tuber yield. The tuber yield increased when N level was increased from 50 to 75 kg N ha-I but decreased with further increase in the level of nitrogen. Top yield increased with increase in the level of nitrogen. Application of75 kg N ha" registered the highest utilization index. Neither varieties nor sources of organic manure recorded any significant variation in starch content of the tuber. But the local variety recorded higher protein content and lower HeN content than the improved variety. Poultry manure treated plants registered the highest protein content and the lowest HeN content. Application of 75 kg N ha" was sufficient for obtaining higher starch and protein contents. The HeN content increased with increase in the level of nitrogen though it was within permissible limits. The improved var. Sree Vijaya obtained higher scores for taste than the local variety. The taste of the tuber was not affected by the source of organic manure. Maximum score for taste was recorded by 75 kg N ha'. The cooking quality of the tuber of both varieties was judged as good. Uptake of Nand K was not influenced by varieties. But in the case of P uptake, the var. Sree Vijaya recorded higher P uptake than the local variety. Nutrient uptake did not vary with the source of organic manure. Maximum uptake of nutrients was observed when 75 kg N ha-I was applied. Significant variation In available Nand K status of the soil after the experiment was observed only due to source of organic manure. Farmyard manure applied plots showed higher status of these nutrients compared to poultry manure and coir pith compost applied plots. Higher status of available P was observed in the soil when the improved variety was raised irrespective of the source of organic manure. Nitrogen @ 75 kg N ha-I registered higher available P content in the soil after the experiment. The study revealed that application of farmyard manure @ 12.5 t ha" or poultry manure @ 5 t ha" along with 75:50:100 kg NPK ha" resulted in higher returns from Sree Vijaya and Kariyilapothiyan, two short duration varieties of cassava, in lowlands. No variation between varieties was observed in their response to N levels as well as to the sources of organic manure. The results suggested the suitability of poultry manure as an alternative to farmyard manure for cassava cultivation in lowlands. Coir pith compost can also be used as an alternate source of organic manure provided it is made cost effective.