1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Characterisation and management of sugarcane bacilliform virus (SCBV) causing leaf fleck disease in sugarcane(Department of Plant Pathology, College of Agriculture Vellanikkara, 2021) Sanju Balan; Anita CherianSugarcane (Saccharum officinarum) is a monocotyledonous perennial cash crop cultivated worldwide both under tropical and sub tropical conditions. It is being cultivated in more than 120 countries in the world. Like any other crops, it is also susceptible to biotic stress. Of which, diseases caused by viruses not only pose serious threat to sugarcane cultivation but also result in deterioration and exclusion of elite varieties of the germplasm. One of the major viral disease which affects global exchange of sugarcane germplasm is leaf fleck disease caused by Sugarcane bacilliform virus (SCBV). The research project entitled ‘Characterization and management of Sugarcane bacilliform virus causing leaf fleck in sugarcane’ was initiated with purposive sampling surveys in selected sugarcane fields in districts of Kerala and Tamil Nadu in order to document the symptoms under natural conditions, to assess the disease incidence, severity and to collect infected samples for further studies. The per cent disease incidence of the leaf fleck disease in Kerala ranged from 12 to 51 per cent whereas severity ranged from 10 to 36.5%. In Tamil Nadu the per cent disease incidence ranged from 28 to 56 per cent while severity ranged from 28 to 50.41%. Major symptoms observed on leaves were mottling, chlorotic flecks, chlorotic patches streaks and stripes with general yellowing of the canopy. In the case of severely affected clones, there was reduction in tillering, internodal length, number of internodes and appearance of deep longitudinal cracks. In highly susceptible clones, stunted growth with bunchy top appearance was noticed. On the basis of phenotypic variability of symptom expression, genotypes were classified into five groups. The development of the symptoms was also studied under artificial condition through insect transmission of the virus using pink mealy bug, Saccharicoccussacchari. Morphological characterisation of the virus done using electron microscopy revealed the presence of bacilliform virus particles of size 30 X 130–150 nm which indicated that the virus belongs to genus BADNA and family Caulimoviridae and the etiology of the disease was confirmed as Sugarcane bacilliform virus. The molecular detection of SCBV was also standardized through polymerase chain reaction (PCR). PCR amplification of RNaseH/RT gene was done using BADNA specific and SCBV129 specific primers. The amplicons were sequenced and in silco analysis of sequences showed sequence homology of 99 to 100 percent identity to SCBV. Widespread occurrence of the disease was observed even in the early generation of varietal development and in newly developed varieties. The transmission of the virus was suspected through true seed (fluff) developed by biparental crossing during sugarcane varietal development programme. Hence, the study was conducted to establish possible transmission of the virus from sugarcane parents to their progenies and the role of maternal and paternal parents in disease transmission through true seeds to the progenies. Samples from eight months old seedlings, three months old seedlings and parental clones were tested positive to the virus in PCR assays. Real time PCR was also standardized to assay these clones. Immunodiagnostic technique was validated using DAC ELISA. The technique of immunocapture PCR was also standardized. Minimal dilution of antisera with which SCBV could be detected was 2:1000 (V/V). Plant extract (antigen) at a dilution of 1:5 was found to be optimal for the detection of SCBV. Molecular detection of SCBV from mealy bug vector was also standardized. Both phenotypic and molecular methods were utilized to identify potential sources of natural resistance against SCBV. Based on the severity of symptom expression and PCR assays these were further classified as highly susceptible (HS), moderately susceptible (MS) moderately resistant (MR) and resistant (R). For generation of RNAi hair pin construct, initially forward (SF) and reverse primer (SR) were used to amplify 700 bp fragment of RT/RNase H gene to be cloned in sense orientation of the vector, pHANNIBAL. The linearized vector and the insert were ligated, and the ligation mixture was used to transform competent cells of Escherichia coli and the transformants were selected. Later antisense forward (AF) and reverse (AR) primer pairswere used to amplify 700 bp fragment of RT/RNase H gene to be cloned in antisense orientation. PCR product ligated into antisense direction of the vector and transformed into competent cells of E. coli. The recombinant pHANNIBAL vector was digested with restriction enzymes. The recombinant pHANNIBAL vector harbouringRNase H /RT gene was released from the vector through Not I site and subcloned into plant expression binary vector. Thus, cassette for RNA silencing was prepared.130 Meristem tip culture was also standardized with antiviral chemical tenofovir. Recovery percentage of meristem varied from 70 to 75 per cent and the viral load was quantified using real time PCR. The outcome of the study would facilitate early detection and elimination of the source of infection and prevent the spread of the disease in the field. Information generated in the study could be utilized while planning biparental crossing and reduce the spread of the virus in varietal development programmes. The hair pin construct developed in this study could be further utilized to generate transgenic disease resistant plants.Item Irrigation and integrated nutrient management for sustainable sugarcane production(Department of Agronomy, College of Agriculture, Vellayani, 2001) Thomas Mathew; Kuruvilla VarugheseTwo field experiments were conducted at Sugarcane Research Station, Thiruvalla in Pathanamthitta district of Kerala state to standardise the surface methods of irrigation with and without trash mulching and to study the potential of integrated nutrient management in sugarcane for sustainable cane production. The study was carried out for a period of two years in plant crops during 1998-1999 and 1999-2000. The influence on growth, yield attributes, yield, quality, nutrient uptake and physico-chemical properties and biological properties of the soil were investigated. . In Experiment No. I viz., 'Standardisation of irrigation management in sugarcane' the methods of irrigation with and without trash mulching was investigated. The treatment comprised of 4 methods of irrigation viz., all furrow, alternate furrow, skip furrow and irrigation once in a month (farmer's practice) under mulched and unmulched situations. The results revealed that all furrow irrigation in combination with trash mulching had positively influenced all the growth-characters, yield attributes, nutrient uptake and appreciably increased the cane, sugar and jaggery yield. It was comparable with alternate furrow irrigation with trash mulching. While cane growth and sugar production was reduced in skip furrow irrigation with or without trash mulching. Trash mulching also improved physical conditions, fertility status, microbial population and enzymatic reactions in the soil. It had also shown better retention and conservation of soil moisture and reduced the soil temperature as compared to unmulched treatments. Since the combination of trash mulching with all furrow and alternate furrow irrigation had recorded comparable values for cane I ~ yield, B : C ratio; it could be possible to economise the use of irrigation water by . following alternate furrow irrigation with trash mulching during the formative phase of sugarcane. It was revealed that a water economy to the tune of 41 per cent was possible in alternate furrow irrigation with trash mulching as compared to all furrow with trash mulching. By mulching alone an increase of 10 per cent in cane yield was observed in alternate furrow irrigation. While in all furrow, skip furrow or irrigation once in a month the beneficial effect of mulching was not visible to such an extent as in the case of alternate furrow irrigation. Alternate furrow irrigation under trash mulching had recorded the highest WUE, energy use efficiency and energy productivity which again suggest the effective and efficient utilisation of resources with better conservation. In Experiment No. II viz., 'Integrated nutrient management in sugarcane', studies with the integrated use of organic sources like press mud, _ trash, green manuring with cowpea, Acetobacter and Azospirillum inoculation with mineral nutrition at 50, 75 and 100 per cent dose of NPK and mineral nutrition alone were carried out. The results revealed that integrated use of press mud at 5 t ha:' with mineral nutrition at 100 per cent of the recommended dose of NPK had explicitly increased the growth characters, yield attributes and uptake of nutrients producing the highest cane, sugar and jaggery yield. However, it was comparable with the conjunctive use of press mud at 5 t ha" with 75 per cent of the recommended dose of NPK. Soil inoculation of Azospirillum at 10 kg ha-! with mineral nutrition at 100 per cent or 75 per cent had also produced significant impact on growth, yield attributes, yield and quality of cane. It also increased the B:C ratio as compared to the integrated use of mineral nutrition with green manuring, Acetobacter inoculation or trash application. Application of NPK at 50 per cent of the recommended dose along with Azospirillum inoculation had shown higher B:C ratio as compared to the integration of other organics with 50 per cent of the recommended dose of NPK. Mineral nutrition without organics even at full dose had produced lesser cane sugar and jaggery yield as compared to the integrated use of press mud, Azospirillum, green manuring or Acetobacter along with mineral nutrition at 50 per cent of the recommended dose of NPK. The conjunctive use of press mud either with 100 or 75 per cent of the recommended dose of NPK had shown comparable values for B:C ratio, energy use efficiency and energy productivity besides improving physico- chemical properties and biological properties of soil. Hence, it is possible to save 25 per cent of the recommended dose of NPK by applying press mud at 5 t ha:'. It can be concluded from the study that alternate furrow irrigation under trash mulching had resulted in substantial savings in irrigation water during the formative phase without any reduction in yield or quality. While in integrated nutrient management, it was concluded that press mud application at 5 t ha' along with mineral nutrition at 75 per cent of the recommended dose of NPK had increased the cane yield with a saving of 25 per cent of the recommended dose of NPK. Mineral nutrition alone even at its full dose recorded comparatively lesser cane yield and B:C ratio than all other combinations with organics.Item Biology, Bionomics and control of coconut cockchafer Leucopholis coneophora Burm.(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1983) Abraham, V A; Mohan Das, MThe biology of the coconut cockchafer Leucopholic coneophora Burm. was studied in detail for the first time. Techniques for rearing the pests from egg to adult in potted palnts kept in field were standardized. The egg laying behaviour of adults was observed. The morphological changes off eggs, different instars of grubs and pupae during development were studied in detail. The changes in immature stages of male and female insects were traced separately. The general morphology of different instars of the grubs was studied in full with a view to finding distinct identifying characters for each.Item Variability and heterosis in Intervarietal hybrids of sugarcane(Department of Plant Breeding, College of Agriculture, Vellayani, 1982) Alice Antony; Manikantan Nair, PItem Pre-harvest forecasting of sugarcane yield(Department of Statistics, College of Veterinary and Animal Sciences, Mannuthy, 1984) Alphi Korath; Prabhakaran, P VSeveral yield prediction models were tried to examine their suitability for the pre-harvest prediction of yield of two varieties of sugarcane namely CO-997 and CO-62175 in different months of plant growth using biometric characters based on the data collected from the Sugarcane Research Station, Thiruvalla. The methods of multiple regression analysis, path coefficient analysis and principal component analysis were used for the above purpose. Multiple regression analysis using plant biometric characters revealed that cane yield could be predicted on the basis of observations on height of the cane, girth of the cane find estimated total leaf area per cane or area of third leaf from the seventh month after planting onwards with an accuracy in the range of 59*5 to 81.9 per cent. The estimated cane yield when multiplied by the number of canes in the plot will give an advance estimate of the plot yield Linear models with five biometric characters viz., height of the cane, girth of the cane, width of the third leaf determined from the selected plants of each plot and number of canes/tillers and number of leaves determined on a whole plot basis were sufficient to predict the plot yield of the crop as early as in the fifth month of plant growth with an accuracy in the range 68 to 90 per cent. Path analysis revealed that height of the cane and girth of the cane were the t wo important characters contributing towards cane yield in all stages of plant growth. Using the forecasting models fitted with principal components as explanatory variables, yield could effectively be predicted with 81.4. per cent accuracy for variety CO-997 and with 76 per cent accuracy for variety 00-62175 in the Sixth month of plant growth.Item Virulence, variation and survival of colletotrichum falcatum went in Kerala(Department of Plant Pathology, College of Agriculture, Vellayani, 1989) Babu George; Wilson, KEleven ‘light type’ isolates of colletotrichum falcatum went from four common sugarcane varieties cultivated at different locations in Thiruvalla region were employed in the present study. The conidia of isolates I and XI were longer than most of the other isolates. Isolate VII produced shorter but broader conidia than the other isolates. Oat meal and potato dextrose agar media were found very good for the growth of all the isolates. Maximum sporulation of most of the isolates was obtained in oat agar medium.