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Kerala Agricultural University, Thrissur

The history of agricultural education in Kerala can be traced back to the year 1896 when a scheme was evolved in the erstwhile Travancore State to train a few young men in scientific agriculture at the Demonstration Farm, Karamana, Thiruvananthapuram, presently, the Cropping Systems Research Centre under Kerala Agricultural University. Agriculture was introduced as an optional subject in the middle school classes in the State in 1922 when an Agricultural Middle School was started at Aluva, Ernakulam District. The popularity and usefulness of this school led to the starting of similar institutions at Kottarakkara and Konni in 1928 and 1931 respectively. Agriculture was later introduced as an optional subject for Intermediate Course in 1953. In 1955, the erstwhile Government of Travancore-Cochin started the Agricultural College and Research Institute at Vellayani, Thiruvananthapuram and the College of Veterinary and Animal Sciences at Mannuthy, Thrissur for imparting higher education in agricultural and veterinary sciences, respectively. These institutions were brought under the direct administrative control of the Department of Agriculture and the Department of Animal Husbandry, respectively. With the formation of Kerala State in 1956, these two colleges were affiliated to the University of Kerala. The post-graduate programmes leading to M.Sc. (Ag), M.V.Sc. and Ph.D. degrees were started in 1961, 1962 and 1965 respectively. On the recommendation of the Second National Education Commission (1964-66) headed by Dr. D.S. Kothari, the then Chairman of the University Grants Commission, one Agricultural University in each State was established. The State Agricultural Universities (SAUs) were established in India as an integral part of the National Agricultural Research System to give the much needed impetus to Agriculture Education and Research in the Country. As a result the Kerala Agricultural University (KAU) was established on 24th February 1971 by virtue of the Act 33 of 1971 and started functioning on 1st February 1972. The Kerala Agricultural University is the 15th in the series of the SAUs. In accordance with the provisions of KAU Act of 1971, the Agricultural College and Research Institute at Vellayani, and the College of Veterinary and Animal Sciences, Mannuthy, were brought under the Kerala Agricultural University. In addition, twenty one agricultural and animal husbandry research stations were also transferred to the KAU for taking up research and extension programmes on various crops, animals, birds, etc. During 2011, Kerala Agricultural University was trifurcated into Kerala Veterinary and Animal Sciences University (KVASU), Kerala University of Fisheries and Ocean Studies (KUFOS) and Kerala Agricultural University (KAU). Now the University has seven colleges (four Agriculture, one Agricultural Engineering, one Forestry, one Co-operation Banking & Management), six RARSs, seven KVKs, 15 Research Stations and 16 Research and Extension Units under the faculties of Agriculture, Agricultural Engineering and Forestry. In addition, one Academy on Climate Change Adaptation and one Institute of Agricultural Technology offering M.Sc. (Integrated) Climate Change Adaptation and Diploma in Agricultural Sciences respectively are also functioning in Kerala Agricultural University.

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  • ThesisItemOpen Access
    Development of chilli (capsicum annuum l.) hybrids with leaf curl virus resistance, high yield and quality
    (Department of Vegetable Science, College of Agriculture , Vellayani, 2019) Vijeth, S; KAU; Sreelathakumary, I
    The investigation entitled “Development of chilli (Capsicum annuum L.) hybrids with leaf curl virus resistance, high yield and quality” was carried out at the Department of Vegetable Science, College of Agriculture, Vellayani, during the period of 2015-2018. The study was aimed at identification of sources for chilli leaf curl virus (ChiLCV) resistance, development of chilli hybrids with ChiLCV resistance, high yield and quality and studying the gene action of ChiLCV resistance. The investigation was conducted in four experiments. In experiment I (a), 70 chilli genotypes were evaluated for yield and quality traits. The best genotypes based on per se performance were CHIVAR-9 for plant height (73.33 cm), CHIVAR-4 for primary branches plant-1 (4.77), Jwalasakhi for days to first harvest (42.00 days), CHIVAR-7 for fruits plant-1(137.33), Vellayani Athulya for days to first flower (26.94 days), fruit length (8.50 cm), fruit girth (4.78 cm) and fruit weight (7.57 g), CA-32 for yield plant-1 and yield plot-1 (587.33 g and 16.10 kg/6.48m2 respectively), Punjab Sindhuri for vitamin C (120.33 mg 100 g-1) and Byadagi Kaddi for carotenoids (331.33 mg 100 g-1). Seven genotypes viz., CHIVAR-3 (L1), CHIVAR-7 (L2), CHIVAR-6 (L3), CA-32 (L4), Vellayani Athulya (L5), Keerthi (L6) and CHIVAR-10 (L7) were selected based on selection index ranking for utilization as lines in line (L) × tester (T) analysis. Among the 70 genotypes screened against ChiLCV under field condition [experiment I (b)], 23 were moderately susceptible, 12 each were susceptible and moderately resistant, ten were symptomless, six were resistant, five were highly resistant and two were highly susceptible. The selected ten symptomless and five highly resistant genotypes were subjected to artificial screening by using whitefly mediated and graft inoculations in experiment II (a). Six genotypes were symptomless under whitefly mediated inoculation, among which, four genotypes viz., Sel-3, Sel-4, Sel-6 and CHIVAR-1 showed highly resistant reaction under graft inoculation. The resistant genotypes identified under artificial inoculation by Polymerase Chain Reaction (PCR) using universal primers (AV494/AC1048) for the confirmation of ChiLCV. All the graft inoculated genotypes showed presence of virus. However, in the whitefly mediated inoculation, four genotypes viz., Sel-3 (T1), Sel-4 (T2), Sel-6 (T3) and CHIVAR-1 (T4) did not show any amplification for presence of virus. Hence, they were used as testers (male parent) in line (L) × tester (T) analysis. The overall disease score was higher with graft inoculation than whitefly mediated inoculation. The BLAST analysis of the amplified sequence showed 93 per cent similarity to Tomato leaf curl Karnataka virus (ToLCKV). Seven genotypes (lines) with high yield and quality attributes were crossed with four highly resistant genotypes (testers) in line (L) × tester (T) mating design in experiment III (a) to produce 28 F1 hybrids. These hybrids were evaluated along with parents and two checks (CH-27 and Arka Harita) for yield and quality attributes and ChiLCV resistance during summer in 2017 [experiment III (b)]. Based on per se performance most promising hybrids were L3 × T2, L6 × T1, L1 × T1, L7 × T1 and L3 × T1 for yield traits and L4 × T1, L4 × T2, L4 × T3 and L7 × T1 for quality traits. The superior crosses based on heterobeltosis, standard heterosis and SCA effects were L3 × T2, L1 × T1, L7 × T1, L6 × T1, L3 × T1, L2 × T4, L4 × T1, L5 × T3 and L5 × T4 for yield attributes; L4 × T1, L4 × T2, L3 × T1, L7 × T1, L3 × T2, L6 × T3 and L1 × T1 for quality traits; L6 × T1, L7 × T4, L3 × T2, L7 × T1 and L7 × T3 for ChiLCV resistance. Lines vs. testers showed significant differences for all the characters except for plant height. The GCA effects for testers were significant for all the traits except for days to first harvest. The ratio of σ2GCA/σ2SCA was less than unity for all the characters, which indicated the predominance of non-additive gene effects in the inheritance of these traits. The contribution of lines were more compared to testers for all the characters except for primary branches plant-1. The superior lines based on GCA effects were L1, L3, L7 and L6 for yield attributes; L2, L3, L4 and L7 for quality traits and L1, L2 and L4 for ChiLCV resistance. Among testers, T1 and T2 were best general combiners for yield and quality traits, and T1 and T3 for ChiLCV resistance. The hybrids viz., L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2, L5 × T3, L5 × T4, L7 × T3 were most promising with desirable SCA effects, heterosis and per se performance for yield and quality attributes and they were moderately resistant to ChiLCV except L5 × T3 and L5 × T4. The hybrid L1 × T1 and L7 × T1 had both parents with high GCA effects for yield plant-1. All the four testers were symptomless and among seven lines, two were moderately resistant and five were moderately susceptible. Among 28 F1 hybrids, 12 showed moderate resistant reaction, 11 were moderately susceptible and five susceptible. The check hybrids CH-27 and Arka Harita were moderately resistant and susceptible respectively. Three superior crosses identified from line (L) × tester (T) analysis viz., cross 1 (L1 × T1), cross 2 (L3 × T2) and cross 3 (L7 × T1) were utilized for generation mean analysis. The six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were developed and evaluated during 2018 summer. Both simple and joint scaling tests were significant for all the characters in all the crosses indicating the inadequacy of additive-dominance model and involvement of digenic or higher order non-allelic gene interactions. Duplicate type of epistasis was observed for plant height, days to first flower, days to first harvest, fruit length, fruit girth, vitamin C, carotenoids and ChiLCV resistance (cross 1); plant height, primary branches plant-1, days to first harvest, fruit girth, fruit weight, fruits plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 2); primary branches plant-1, days to first flower, days to first harvest, fruit girth, fruit weight, fruits plant-1, yield plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 3). These crosses can be improved by biparental mating between recombinants in early segregating generation and delaying the selection in the advanced generations. Complementary type of epistasis was noticed for fruits plant-1, yield plant-1 and yield plot-1 (cross 1); fruit length, yield plant-1 and yield plot-1 (cross 2); plant height and yield plot-1 (cross 3). Additive, additive × additive or complementary gene interactions are fixable, thus, these crosses can be exploited effectively through pedigree method of selection. For ChiLCV resistance dominance (h) gene action, additive × additive (i), additive × dominance (j) and dominance × dominance (l) type of gene interactions are significant. Among them, the former three are in negative desirable direction. The four ChiLCV resistant genotypes identified in this study could be used as potential parents for ChiLCV resistance breeding programme. The 93 per cent similarity of the amplified sequence to ToLCKV suggests that, it could be a strain of ToLCKV responsible for ChiLCV disease. The parents L1, L3, T1 and T3 were superior on the basis of GCA effects for most of the economic traits studied. The hybrids L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2 and L7 × T3 were most promising for yield and quality traits, and were moderately resistant to ChiLCV. The dominance (h) gene action and dominance × dominance (l) epistasis were predominant for yield and quality traits indicating the importance of heterosis breeding in varietal improvement of chilli. The ChiLCV resistance could be improved through recombinant breeding or recurrent selection.
  • ThesisItemOpen Access
    Aggrading lateric soils (ultisol) using biochar
    (Department of Soil Science, College of Horticulture, Vellanikkara, 2019) Rajakumar, R; KAU; Jayasree Sankar, S
    The present investigation was undertaken at College of Horticulture, Vellanikkara and Agricultural Research Station, Mannuthy during 2016-2018. The study consisted of production and characterization of bioehar from coconut based materials, an incubation experiment, and two field experiments. The incubation experiment was conducted for 15 months to study the dynamics of C and N in soil over time and the soil samples were analyzed for C and N fractions at three months' interval. Two field experiments were carried out sequentially, wherein Chinese potato was raised to study the direct effect of bioehar and vegetable cowpea was the test crop to study the residual effect of bioehar applied to the first crop. Three levels of bioehar (5, 7.5, 10 t ha"'), FYM 10 t ha"', soil test based POP + bioehar 10 t ha"' and soil test based POP were the treatments, for both incubation and field experiments. Soil test based POP consisted of NPK and FYM 10 t ha"'. Control plots without the addition of biochar/fertilizers were also maintained. Recovery of bioehar from coconut husk and shell (1:1) on pyrolysis was 22 per cent. The produced bioehar had an alkaline pH (10.01), high EC (3.42 dS m"'), C (64.14 %), CEC (15.78 cmol (+) kg"'), and C: N ratio (113:1). Total N, P, K, Ca, Mg and S contents were 0.567, 0.982, 4.175, 1.19, 0.456 and 0.244 per cent, respectively. Regarding physical properties, bioehar had low bulk density (0.128 Mg m"^), very high porosity (84.63 %) and WHC (307.3 %). Basicity and acidity of bioehar were 2.02 and 0.08 mmol g"', respectively. The surface morphology and chemistry studied using SEM, TEM, FT-IR and Raman spectroscopy revealed the porous, aromatic and recalcitrant nature of bioehar and the presence of functional groups mainly carboxyl, hydroxyl and carbonyl. Results of incubation experiment revealed that the content of organic carbon - (OC), water soluble carbon (WSC) and microbial biomass carbon (MBC) increased up to 6 months of incubation and decreased thereafter. In the case of permanganate oxidizable carbon (POXC) and hot water soluble carbon (HWSC), a decreasing trend was noticed. While the highest value of WSC and HWSC were recorded in FYM 101 ha"', all other C fractions were higher in the treatments viz. soil test based POP + bioehar 10 t ha"' and bioehar 10 t ha"'. With an increase in levels of bioehar, the labile C fractions viz. POXC and MBC increased. The labile C fractions in soil were in the order POXC > HWSC > MBC = WSC. As regards the N fractions, NH4-N declined steadily at 3 months, then increased up to 9 months of incubation after which it decreased till the incubation ended. The NO3-N and amino acid N increased up to 12 months of incubation and slightly declined thereafter. Increase in total hydrolysable N was noticed up to 6 months of incubation and thereafter, a progressive decrease was noticed. While the total N content decreased over the incubation period, the KMn04-N increased. With an increase in levels of biochar, the NO3-N and KMn04-N increased. The treatments soil test based POP + biochar and soil test based POP were equally superior to other treatments with respect to N fractions. Results of field experiments revealed the superiority of biochar 10 t ha"' in increasing soil pH and NH4OAC-K and reducing the exchangeable acidity. The treatments soil test based POP + biochar and soil test based POP were superior with respect to most of the soil properties. Application of biochar at 10 t ha"', either alone or in combination with POP improved the soil properties viz. OC, dehydrogenase activity, CEC, MWHC and hot water soluble B. With an increase in levels of biochar, the soil properties viz. pH, CEC, WHC, dehydrogenase activity, NH4OACK, Ca, HCl-Zn and humic acid increased. With respect to the growth parameters and yield of Chinese potato, application of soil test based POP + biochar and soil test based POP were comparable. The same treatment soil test based POP + biochar that faired in terms of direct effect proved good in residual effect as well, as reflected from the plant growth and yield of cowpea. Path analysis had shown that the soil properties viz. OC, MBC, Bray-P, NH4OAC-K, Ca and EC directly influenced the tuber yield, reinstating the role of biochar in yield improvement. The nutrient content in plant parts and its uptake varied among treatments and corroborated the trend. Considering the quality attributes of Chinese potato, the treatments biochar 10 t ha"' and soil test based POP + biochar recorded higher CHO content. Protein content was highest in the treatments soil test based POP and soil test based POP + biochar. The advantage of biochar on increasing protein content and decreasing crude fibre content was visible in the succeeding crop of cowpea also, thus establishing its high residual effect. The study revealed the potential of biochar as an amendment in the highly weathered, nutrient-poor acidic laterite soils of the tropics. Its application brought about increase in soil pH, addition of basic cations, improvement in CEC and WHC, and gradual release of nutrients to the growing plants. The overall improvement in physical, chemical and biological soil conditions through biochar could promote plant growth, yield as well as quality. The positive effect of biochar could be observed in combination with soil test based fertilizer application also.
  • ThesisItemOpen Access
    Calibration and validation of ceres rice crop simulation model
    (Department of Agronomy College of Agriculture, Vellayani, 2018) Anju, V S; KAU; Girija Devi, L
    The project entitled ‘Calibration and validation of CERES-Rice crop simulation model’ was conducted in the Department of Agronomy, College of Agriculture, Vellayani from 2016 to 2018 with the objectives to calibrate and validate CERES-Rice model to generate the genetic coefficients of the rice variety Prathyasa, to study the crop- weather relationship and to quantify the yield gap of the variety by running simulations. The field experiment was conducted at Upanniyoor Panchayat in farmer’s field for four seasons (Virippu 2016 and 2017 and Mundakan 2016 and 2017) and it was laid out in randomized block design. The treatments consisted of five dates of sowing each in Virippu (D1 - May 31, D2 –June 15, D3 –June 30, D4 –July 15 and D5 – July 30) and five dates of sowing each in Mundakan (D1 -Oct 14 / Sept 26, D2 – Oct 30 /Oct 10, D3 – Nov 14/ Oct 25, D4 –Nov 30/Nov 9 and D5 – Dec 14/Nov 24). The sowing dates in Mundakan seasons of 2016 and 2017 varied due to the delayed onset of rainfall in 2016. The plot size was 5 x 4 m2 with three replications. Routine observations on height, leaf area, dry matter production (DMP), number of tillers, panicles, spikelets per panicle, filled grains per panicle, 1000 grain weight, straw yield and grain yield were recorded apart from phenological observations. Soil analysis was conducted before and after the experiment. The soil and crop data collected from the experimental field and weather data from the Department of Agrometeorolgy were used as inputs for running the model. Study on phenology revealed that the crop duration decreased from 111 to 100 and 117 to 107 days respectively in Virippu 2016 and 2017. A similar decreasing trend was observed in Mundakan 2016, but in Mundakan 2017, it increased from 114 to 117 days in early sowing and decreased drastically from 117 to 105 days in delayed sowing. The height of the plant was found varying at different stages, D1 produced the tallest plants at harvest in Virippu seasons of both the years, while it was the highest in D3 in Mundakan 2016 at different stages and D5 in Mundakan 2017. The number of tillers was the highest in D2 and D1 respectively in Virippu in both the years and D2 and D1 respectively in Mundakan 2016 and 2017. The DMP was the highest in D2 and D1 respectively in Virippu and Mundakan 2016 and 2017. The grain yield was the highest in D2 in both the seasons in 2016 and D1 in both the seasons in 2017. The yield attributes such as productive tillers m-2 was the highest in D2 in both the seasons in 2016 and D1 in both seasons in 2017. The number of spikelets per panicle was the highest in D1 during Virippu 2016 and 2017 and Mundakan 2017 and D2 in Mundakan 2016. D1 in Virippu 2017 was on par with D2, and D2 in Mundakan 2016 was on par with D1. The number of filled grains per panicle was higher in D1 in Virippu 2016 and Mundakan 2017, while D2 recorded higher filled grains per panicle in Virippu 2017 and Mundakan 2016. D1 in Virippu 2016 was on par with D2 and D2 in Mundakan 2016 was on par with D1. The harvest index (HI) was higher in D1 in Virippu 2016 and 2017 and Mundakan 2017, while D2 recorded higher HI in Mundakan 2016. D1 in Virippu 2016 was on par with D2 and D5, and D1 in Virippu 2017 was on par with D2. In Mundakan season, D2 was on par with D1 and D5 in 2016 and D1 was on par with D2 in 2017. In Virippu and Mundakan 2016, N uptake was the highest in D1 while P and K uptake were the highest in D2, whereas in Virippu and Mundakan 2017, N, P and K uptake were the highest in D1. The organic carbon content of the soil was found influenced only after Virippu 2016 with D5 recording the highest value. In the case of available N, P and K status of the soil, only the N status was found affected and that was only after Mundakan 2017 with D2 recording the highest value. Crop weather relationship was studied by computing the different heat units such as Growing degree days (GDD), Heliothermal units (HTU), Photothermal units (PTU) and Heat unit efficiency (HUE) at different stages such as sowing to active tillering (P1), active tillering to panicle initiation (P2), panicle initiation to booting (P3), booting to heading (P4), heading to 50% flowering (P5), 50% flowering to physiological maturity (P6), vegetative stage (P7), reproductive stage (P8) and ripening stage (P9). These heat units computed were the highest in D1 and showed positive correlation with yield for GDD at P1, HTU at P5 and P6, PTU at P1 in Virippu, while in Mundakan positive correlation was obtained with GDD at P1 and P7, HTU at P2, PTU at P1 and P7. Negative correlation was obtained with GDD at P3, P8 and P9 and PTU at P4, P8 and P9 in Virippu and with HTU at P2 and P3 and PTU at P6 and P9 in Mundakan. The correlation between yield and yield attributes with weather parameters revealed positive correlation for minimum temperature at P3, P4 and P8, RH I & RH II at P1 and P7, BSS at P2, P3, P4 and P6, rainfall and rainy days at P1 and P7, pan evaporation at P6, P8 and P9 and wind speed at P6 and P9 in Virippu season. Negative correlation was observed with minimum temperature, pan evaporation and wind velocity at P1, rainfall at P3, P4, P6, P8 and P9, rainy days at P6, P8 and P9, RH I at P6, P8 and P9, RHII at P5, P6 and P9 in Virippu season. In Mundakan season positive correlation was obtained with maximum temperature from P1 to P9 except P6, RH I at P2, P4, P5, P7, P8 and P9 and rainy days at P1 and negative correlation with maximum temperature at P1, P2 and P6, minimum temperature at P6, BSS at P2, rainfall at P6, pan evaporation at P3, P5, P6, P7, P8 and P9. The genetic coefficients for the variety Prathyasa was generated by calibrating the CERES-Rice model by using the data of Virippu rice 2016 and validated by using the data of Mundakan 2016, Virippu and Mundakan 2017 respectively and the genetic coefficients generated were P1-720, P2R-33.7, P5-21.3, P2O-12, G1-38.7, G2-0.028, G3-1, G4-1 respectively. Model simulated results showed that there was close association between observed and simulated yield and the error percentage varied from -16.90 to 16.55 for Virippu 2016 and from -1.26 to 64.77 in Virippu 2017. In Mundakan, error per cent ranged from -13.43 to 16.63 in 2016 and from -11.09 to 12.58 in 2017. The error percentage for panicle initiation day varied from 1.96 to 18.37 in Virippu 2016, while it varied from -5.88 to 10 in Virippu 2017 and for Mundakan it varied from -8.16 to 0 in 2016 and from -8 to 1.96 in 2017. Similarly the error percentage for anthesis day varied from 8.54 to 11.25 and 4.88 to 9.88 in Virippu 2016 and 2017 and from 4.88 to 9.88 and 3.66 to 8.43 in 2016 and Mundakan 2017. The error percentage of physiological maturity day varied from -1.96 to 18 in Virippu 2016, while it deviated from -7.84 to 0.99 in Virippu 2017. During Mundakan season, error percentage ranged from -1.98 to 6.54 in 2016 and from -2.91 to 4.81 in 2017. Regression equations for grain yield were developed for certain phenological stages in Virippu and Mundakan from highly correlated weather parameters. The yield gap quantification revealed that the highest total and sowing yield gaps were in delayed sowing (D5), management yield gap in early sowing(D1), and the lowest in D3 and D4 (delayed sowing) and D2 (early sowing) respectively for the same parameters. Thus, the study enabled to generate the genetic coefficients of variety ‘Prathyasa’ and simulated the grain yield and panicle initiation, anthesis and physiological maturity days with minimum error percentage. The study also helped to quantify various yield gaps such as total, management and sowing gaps due to different dates of sowing, from the potential yield generated by the model along with the attainable and actual yield data supplied from the field experiment and farmers’ field. The various correlations worked out between yield, weather parameters and heat units provided an insight into the crop weather relationship. Finally, and the foremost implication of the study is that delayed sowing reduces the yield considerably in rice crop in both the seasons irrespective of other factors.
  • ThesisItemOpen Access
    Characterization of Mycosphaerella spp. causing sigatoka leaf spot disease complex of banana in Kerala and its management
    (Department of Plant Pathology College of Horticulture, Vellanikkara, 2019) Milsha George; KAU; Anita Cherian, K
    Sigatoka leaf spot disease complex caused by Mycosphaerella spp. is a serious constraint to banana cultivation in Kerala. The present study was undertaken to characterize the associated pathogen and to develop an integrated management package against this disease. The project initiated with purposive sampling surveys conducted in various districts representing different agroclimatic zones of Kerala viz. Malappuram (Northern zone), Palakkad (Northern zone), Thrissur (Central zone), Ernakulam (Central zone), Wayanad (High range zone) and Trivandrum (Southern zone). The percent disease severity (PDS) ranged from 3.33 to 43.90%. The correlation analysis of PDS with weather parameters showed a positive correlation with rainfall however, it was found to be negatively correlated with temperature. The study on symptomatology revealed that there were six types of symptoms noticed on banana var. Nendran (AAB), two types each on Palayankodan (AAB) and Njalipoovan (AB), while only one type of symptom was recorded on Robusta (AAA) and Kadali (AA). Isolation of the pathogen could be achieved on potato dextrose agar medium after 10- 12 days of incubation at very specific conditions. The fungal colony was slightly raised with irregular margin and greyish velvety appearance. Studies on morphological structures revealed that the conidia were hyaline to olivaceous brown in colour which measured about 24.29 - 71.89 µm length x 0.91 - 2.40 µm width with 3-8 septations. The sexual structures were flask shaped perithecia containing long asci bearing eight ascospores. Based on cultural and morphological characters, the pathogen was identified as Mycosphaerella eumusae. The identity of the pathogen was further confirmed by PCR based molecular characterization. In silico analysis of the sequences of the isolates showed 99 -100% homology to Mycosphaerella eumusae. Hence, it is concluded that the pathogen associated with Sigatoka leaf spot disease of banana in Kerala is identified as Mycosphaerella eumusae Crous & Mourichon (anamorph Pseudocercospora eumusae Crous & Mourichon). The screening of accessions maintained in the Germplasm of Banana Research Station, Kannara was done to assess their disease reaction and were grouped into six categories. Five resistant varieties viz., Pisang Lilin, BRS 1, BRS 2, FHIA 01 and FHIA 23 and susceptible varieties viz., Nendran, Grand Naine, Robusta, Moris and Kadali were further selected to investigate the anatomical, biochemical and molecular basis of host plant resistance. Anatomical studies revealed that the resistant varieties were characterized by thicker cuticle, epidermis and mesophyll tissues compared to the susceptible varieties. The number of stomata and the stomatal pore width were more in susceptible varieties compared to the resistant varieties. The biochemical basis of resistance was assessed by quantifying phenols, reducing sugars, non reducing sugars and the activity of defense related enzymes viz., peroxidase, polyphenol oxidase and phenylalanine ammonia lyase in both resistant and susceptible varieties. The results revealed that the phenols, reducing sugars and the defense related enzymes were higher in resistant varieties compared to susceptible ones. The amplification of genomic DNA of resistant and susceptible varieties using Sequence characterized amplified region (SCAR) markers yielded an amplicon of size 644bp in resistant cultivars while the bands were absent in susceptible cultivar. The BLASTn analysis of the sequence of the amplicons showed 90 per cent sequence homology to genomic sequences of Kanthali SCAR marker OPA1363 which is tightly linked to Sigatoka leaf spot disease resistance. Field experiments were conducted to evaluate the efficacy of chemical fungicides and organic / inorganic preparations for disease management. Among the various chemical fungicides, foliar spraying with trifloxystrobin (25%) + tebuconazole (50%), 0.4g/l) was found to be the best followed by copper hydroxide, hexaconazole (5%) + captan (70%), 2g/l) and Bordeaux mixture (1%), without leaving any toxic residues in the harvested fruits. The results of the experiment on disease management using organic / inorganic preparations revealed the effectiveness of PGPR mix II (consortium of Pseudomonas fluorescens and Bacillus subtilis), 2% followed by Pseudomonas fluorescens (2%) given as foliar spray. It is concluded that the present study has enlightened our knowledge on the etiology and management of Sigatoka leaf spot disease of banana cultivation in Kerala.
  • ThesisItemOpen Access
    Management and utilization of water hyacinth (Eichhornia crassipes ( Mart.) Solms)
    (Department of Agronomy College of Horticulture, Vellanikkara, 2018) Indulekha, V P; KAU; George Thomas, C
    Water hyacinth is one of the most productive plants on earth, but it is also considered as the world’s worst aquatic weed. The phytoremediation capacity of water hyacinth and its management through ecofriendly means like silage making, composting, and mulching were studied at the College of Horticulture, Vellanikkara. The phytoextraction capacity of water hyacinth was evaluated through a purposive sampling by collecting plant and water samples from 20 sites in central Kerala. These samples were analysed for various nutrients including heavy metals. To study the association of plant nutrients with water nutrients, cross tabulation was done and dependence of plant nutrient factor on water nutrient was measured through Chi-square. The Chi-square statistic was significant for N, P, Mg, and Ni indicating that the level of nutrients could be brought to a minimum through water hyacinth. The accumulation of heavy metals in water hyacinth was in the order Fe> Al> Mn> Zn> Cr> Ni> Co> Hg> Pb> As. Among them, Pb content in plant samples was within the permissible limit, but contents of Fe, Cu, Cr, Zn and Ni were beyond the safe limits. The quality and palatability of silage prepared with fresh and wilted water hyacinth with or without rice straw or guinea grass and using molasses, cassava flour, or rice bran as additives was investigated. Considering the quality parameters such as pH, odour, and palatability, wilted water hyacinth with molasses (5%) or cassava flour (10%) and wilted water hyacinth with cassava flour (10%) and rice straw (10%) or guinea grass (10%) are the best options for utilizing water hyacinth as silage. The composting experiment consisted of four methods viz., Bangalore method, Indore method, phospho-composting, and vermicomposting. All the prepared composts had neutral to slightly alkaline pH. The lowest C: N ratio was recorded with vermicompost (11.58) followed by Bangalore compost (12.68). Nitrogen content at 3 months after composting (MAC) was higher in vermicompost and Bangalore compost. The highest N content at 6 MAC was observed in vermicompost (1.75%). Phosphorus content was higher in phospho-compost at 3MAC and 6 MAC. There was no significant difference in K content of different composts at 3 MAC. Calcium, Mg and S contents were high in vermicompost. Micronutrients such as Zn, Cu, Co, and Ni were higher with Bangalore composting. Heavy metals such as As, Cd, and Pb were not detected in any of the composts. None of the composts contained heavy metals beyond safe limits. A field experiment involving three mulch materials–jack tree leaves, green water hyacinth, and coconut leaves–were compared with no mulching in turmeric for two years. All the mulch materials including water hyacinth had positive effects on most morphological and physiological parameters of turmeric such as plant height, number of leaves, leaf area index, leaf area ratio, and dry matter production. In both years, rhizome yield was also higher in plots mulched with organic debris compared to non-mulch control. Nutrient uptake by the crop was also higher with mulching compared to non-mulched plots. All the mulch materials substantially affected weed density and weed dry weight and reduced turmeric-weed competition for different growth factors.