PhD Thesis
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Item Andrographolide based biopesticide for the management of pest complex of vegetable cowpea Vigna unguiculata (L.) Walp(Department of Entomology, College of Agriculture ,Vellayani, 2024-08-16) Neethu, G Raj; Santhoshkumar, TThe present study entitled ‘Andrographolide based biopesticide for the management of pest complex of vegetable cowpea Vigna unguiculata (L.) Walp’. was carried out at Department of Entomology, College of Agriculture, Vellayani, during 2019-2023 with an objective to develop and standardize an “andrographolide” based biopesticide formulation against pests of vegetable cowpea V. unguiculata and its insecticidal and antifeedant effect on developmental stages of pests and natural enemy. Extraction and isolation of the bioactive compound from Andrographis paniculata, were isolated using the modified procedure of Pundarikakshudu et al., 2016 and resulting compound was further confirmed to be andrographolide through Fourier-transform infrared spectroscopy (FTIR) and Liquid chromatography-mass spectrometry (LC-MS) analysis. The effectiveness of isolated andrographolide based compound were studied on cowpea aphids (Aphis craccivora) and spotted pod borer (Maruca vitrata). The LC50 and LC90 were calculated at 24 hours after treatment and recorded concentration of 2064.51ppm and 3206.52ppm, respectively. A significant mortality was observed in the second and third instar larvae of M. vitrata. Studies were conducted to develop formulations showing stable emulsions (bloom test) and five combinations were found to be forming stable emulsions. Stable five combination were Andrographolide (70%) + Neem oil (20%) + Triton X 100 (10%), Andrographolide (70%) + Pungam oil (20%) + Triton X 100 (10%), Andrographolide (60%) + castor oil (30%) + Tween 80 (10%), Andrographolide (60%) + Palm oil (30%) + Tween 80 (10%) and Andrographolide (60%) + sunflower oil (30%) + Tween 20 (10%) and effectiveness of these five combinations were tested against A. craccivora at various concentration (3, 5 and 7%). The treatments Andrographolide (70%) + Neem oil (20%) + Triton X 100 (10%) (Formulation A) and Andrographolide (70%) + Pungam oil (20%) + Triton X 100 (10%) (Formulation B) were found to be superior among the other treatments. The invitro evaluation of formulations A and B against A. craccivora revealed that the LC50 values of formulations A and B were 1.51 and 1.42% respectively and the LC90 values of formulations A and B were recorded as 4.52 and 4.40%. Another study conducted to evaluate the safety of predatory 198 coccinellids, Cheilomenes sexmaculata and the result revealed that the formulations A and B exhibited a relatively safer profile with minimal adverse effects on the predatory coccinellid even at higher concentrations, as mortality rates remained below 50%. Observations on the orientation behaviour of M. vitrata and L. boeticus larvae revealed a significant decrease in mean larval orientation towards treated floral buds and pods with various concentrations of formulations A and B and this highlights the deterrent impact of the formulations on larval orientation. Antifeedant activity of formulations A and B towards 3rd instar larvae of M. vitrata and L. boeticus at 7% of the formulations showed extremely antifeedant activity followed by 5 and 3% of formulations. Larvae fed with treated flowers exhibited a reduction in size compared to the control. Both M. vitrata and L. boeticus larvae exhibited a shortened larval duration and extended pupal period when provided with different concentration of formulations A and B. Considering the adult emergence rate of M. vitrata minimum emergence recorded in 7% of formulation B (31.25%), which on par with 7% of formulation A (37.5%). Conversely, no significant difference in adult emergence was observed between treatments in L. boeticus. The antifeedant effect on pod bug, R. pedestris using different concentrations of formulations A and B recorded significant feeding deterrence effect. All the treatments showed significant antifeedant activity at 12 HAT, and at 7% of both formulations A and B recorded more than 95% of antifeedant activity, and were found to be on par with 5% of formulation B. The assessment of the repellent activity of formulations A and B against A. craccivora revealed a significant repellent activity on aphids and maximum repellency was recorded at 7% of both formulation A and B (98 and 96 per cent, respectively) at 24 HAT. The efficacy of formulations A and B at various concentrations on egg hatching and larval development in L. boeticus and R. pedestris were studied and the result revealed concentration-dependent effects of formulations A and B on the egg hatchability and developmental stages of both L. boeticus and R. pedestris, with lower hatching rates and prolonged incubation periods observed at higher concentrations compared to the untreated control.Item Nutrient use efficient technologies for enhancing productivity of cowpea[VIGNA UNGUICULATA (L.) WALP.](Department of Agronomy, College of Agriculture ,Vellanikkara, 2024-09-24) Vidhu Priyadarshini, P T.; Anitha, SCowpea, a vital leguminous crop in the semi-arid regions of tropics and sub tropics, plays a key role in sustainable agriculture and nutritional security. However, the productivity of cowpea remains low in various regions of India. There is a critical need to enhance the productivity of cowpea with limited resources to achieve nutritional security for the growing population. The research program entitled, ‘Nutrient use efficient technologies for enhancing productivity of cowpea [Vigna unguiculata ( L.) Walp.]’ was conducted from October 2021 to May 2023 at Instructional Farm, College of Agriculture, Vellanikkara, with the objective, to enhance the nutrient use efficiency and yield of cowpea through fertilizer microdosing, nano NPK and designer seeds. The investigation consisted of three experiments viz., standardization of fertilizer microdosing and seed treatment for cowpea, standardisation of nano fertilizer dose and seed treatment for cowpea and on field evaluation of nutrient use efficient technologies in two different cowpea varieties (Anaswara and PGCP 6) and the field experiments were repeated for three seasons (summer 2022, rabi 2022 and summer 2023). The experiment on standardization of fertilizer microdosing and seed treatments for cowpea consisted of five levels of fertilizer microdosing (25%, 50%, 75% NPK as per POP, NPK as per POP, and absolute control) and three levels of seed treatments (designer seeds, rhizobium treated seeds, and untreated seeds). Among fertilizer microdosing levels, microdosing (50%) exhibited the best growth and yield parameters followed by microdosing (25%). The percentage increase in grain yield with microdosing (50%) was 19% compared to NPK as per POP. Nutrient uptake and soil nutrient availability were higher in microdosing (50%). Partial factor efficiency (PFE), agronomic efficiency (AE) and apparent recovery efficiency (ARE) of N, P and K were significantly higher in microdosing (25%). Among seed treatments, designer seeds demonstrated superiority in terms of growth, yield and nutrient use efficiency. Designer seeds resulted in earlier flowering and led to a 114 per cent increase in grain yield compared to untreated seeds. Regarding interaction effect of treatments, microdosing (50%) with designer seeds showed the best performance followed by microdosing (25%) with designer seeds. Based on these results, microdosing 50% with designer seeds and microdosing (25%) with designer seeds were selected for field study. The experiment on standardization of nano fertilizer dose and seed treatment for cowpea consisted of six levels of nano fertilizers (2/3, 1/2, 1/3, 1/4 NPK as per POP applied as nano fertilizer (NF), NPK as per POP and absolute control) and three levels of seed treatments (designer seeds, rhizobium treated seeds, and untreated seeds). Among nano fertilizers, 2/3 NPK as per POP applied as NF showed significantly higher growth and yield parameters. This treatment resulted in a 14% increase in grain yield compared to NPK as per POP and a 137% increase compared to the absolute control. Significantly higher PFE and AE of N, P and K were recorded in 1/4 NPK as per POP applied as NF. Among seed treatments, designer seeds demonstrated the highest efficiency in terms of growth, yield, and nutrient use efficiency. Considering interaction effect, the application of 2/3 NPK as per POP applied as NF along with designer seeds resulted in 50 per cent increase in grain yield, while 1/4 NPK as per POP applied as NF along with designer seeds led to a 48 per cent increase in yield compared to the recommended dose of NPK as per POP of KAU with untreated seeds. Based on these findings, 2/3 NPK as per POP applied as NF with designer seeds and 1/4 NPK as per POP applied as NF with designer seeds were selected for field study. Experiment on field evaluation of nutrient use efficient technologies, consists of eight treatments viz., best two treatments from experiment I viz., microdosing (25%) with designer seeds, microdosing (50%) with designer seeds, best two treatments from experiment II viz., 2/3 NPK as per POP applied as NF with designer seeds, 1/4 NPK as per POP applied as NF with designer seeds, STCR equation based NPK with designer seeds, soil test based NPK with designer seeds, NPK as per POP with designer seeds and absolute control. Results on field evaluation of nutrient use efficient technologies using cowpea variety Anaswara revealed that microdosing (50%) with designer seeds showed increased growth parameters viz., plant height, number of branches, dry matter production per plant, crop growth rate and relative growth rate. Significantly highest grain yield was recorded in microdosing (50%) with designer seeds. Despite reducing the fertilizer dose to 50%, this treatment resulted in a 16% yield increase compared to the NPK as per POP with designer seeds. Total chlorophyll content at different growth stages and protein content in grains were higher in 1/4 NPK as per POP applied as NF with designer seeds. Soil parameters did not exhibit a consistent trend across treatments. Regarding nutrient use efficiencies, significantly higher partial factor efficiency and agronomic efficiency of N, P and K were recorded in 1/4 NPK as per POP applied as NF with designer seeds. While considering the economics, microdosing (50%) with designer seeds showed higher net returns and a better B:C ratio. Despite the higher yield observed with 2/3 of NPK as per POP applied as NF with designer seeds, the elevated cost of nano fertilizers rendered it less profitable. The field evaluation of nutrient use efficient technologies using cowpea variety, PGCP 6 revealed that microdosing (50%) with designer seeds and 2/3 NPK as per POP applied as NF with designer seeds performed best in terms of growth and yield parameters. The highest yield was recorded in microdosing (50%) with designer seeds followed by 2/3 NPK as per POP applied as NF with designer seeds. Reducing the fertilizer quantity by 50 per cent from NPK as per POP with designer seeds, microdosing (50%) with designer seeds resulted in an 86 per cent increase in yield. Throughout the growth stages, consistently higher total chlorophyll content and protein content in grains were observed with 1/4 of NPK as per POP applied as NF with designer seeds. Soil parameters did not show a consistent trend across treatments. Significantly higher PFE and AE of N, P and K were recorded with 1/4 NPK as per POP applied as NF with designer seeds. In terms of economics, microdosing (50%) with designer seeds demonstrated higher net returns and better B:C ratio. Despite achieving a higher yield with 2/3 of NPK as per POP applied as NF with designer seeds, the high cost of nano fertilizers made this treatment less profitable. From the results of field experiments conducted for both cowpea varieties (Anaswara and PGCP 6), microdosing (50%) with designer seeds can be recommended as an economically viable and nutrient use efficient technology for enhancing cowpea productivityItem Endophytic fungi for the management of spotted pod borer, Maruca vitrata Fab.(Lepidoptera:Crambidae) in cowpea.(Department of Agricultural Entomology, College of Agriculture.Vellanikkara, 2022) Smitha Ravi; Madhu SubramanianThe spotted pod borer, Maruca vitrata Fab. (Lepidoptera: Crambidae) is a major constraint in the production of legumes because of its wide host range, distribution and destructiveness. In cowpea, the loss due to pod borer infestation varies from 20 to 60 per cent, often reaching upto 80 per cent in severe cases. Application of pesticides can hardly be recommended in cowpea as the pods are harvested at alternate days. Biological control of M. vitrata using entomopathogenic microorganisms has received considerable attention in recent times. Previous studies have demonstrated the potential of entomopathogenic organisms to colonise an array of plants and confer protection from insect pests. In this context, a study entitled “Endophytic fungi for the management of spotted pod borer, Maruca vitrata Fab. (Lepidoptera: Crambidae) in cowpea” was undertaken with an objective of isolation and characterization of endophytic entomopathogenic fungi in cowpea, standardization of method of inoculation of entomopathogenic fungi in cowpea, and evaluation of selected endophytic fungi for management of the spotted pod borer, M. vitrata. Purposive sampling surveys were conducted in the major cowpea growing areas of Kozhikode, Thrissur, Kottayam and Thiruvananthapuram districts of Kerala. A total of 235 endophytic fungal isolates were obtained from the cowpea plant samples collected from 40 locations. This comprised of 103 isolates from roots, 63 from stems, 31 from leaves, 33 from pods and five from flowers. Nine accessions of cowpea with different levels of resistance were also screened for the isolation of fungal endophytes. All the accessions were found to harbor endophytic fungi and yielded 32 isolates. Among these accessions, Palakkadan thandan payar yielded the maximum number of seven endophytic fungi. Lola and Mysore local had the lowest number of isolates. In contrast to the results of survey, the leaves of cowpea plant harbored more endophytic fungi than other plant parts. A total of 267 isolates were obtained from survey samples and cowpea accessions. Three isolates were found to be pathogenic to M. vitrata. They were identified as Fusarium oxysporum (EEF 1) and two isolates of Purpureocillium lilacinum (EEF 4 and EEF 64) through morphological and molecular characterization. These isolates were evaluated along with Beauveria bassiana (NBAIR strain) for their bioefficacy against M. vitrata. The best two organisms in the bioefficacy studies, viz., B. bassiana (NBAIR strain) and P. lilacinum (EEF 4) were used for standardizing the inoculation technique for endophytic colonization in cowpea plant. Three different methods of inoculation viz., seed, soil and foliar inoculation were evaluated for identifying the best method for colonization of entomopathogenic fungi in cowpea plants. The effect of fungal colonization on infestation of spotted pod borer in cowpea was further assessed under field condition. Foliar inoculation with B. bassiana registered the lowest mean pod damage of 12.53 per cent. B. bassiana applied as foliar application resulted in the highest marketable pod yield of 152.83g plant-1 , followed by P. lilacinum as foliar application (149.33g plant-1 ). Based on the polyhouse and field studies, it was inferred that foliar application of B. bassiana was found to be the best treatment against the target pest, M. vitrata. In addition, the results of the current study suggested that that endophytic colonization in cowpea had little adverse impact on plant growth and yield. Foliar application of B. bassiana, which was identified as the most effective treatment against pod borer in the previous studies, was selected for comparative evaluation with the diamide insecticide, flubendiamide against M. vitrata. Cowpea plants treated with both flubendiamide and B. bassiana had significantly less number of infested pods than control, with 8.41 and 15.05 per cent infestation respectively. Control plants recorded the highest infestation of 21.28 per cent. Mean marketable pod yield showed significant difference between flubendiamide (166.14g plant-1 ) and foliar inoculation of B. bassiana (155.14g plant-1 ). Both these treatments also had significantly higher marketable pod yield compared to control plants (139.29g plant-1 ). In conclusion, the present study revealed that use of B. bassiana as an endophyte could be a useful tool in integrated pest management of pod borer in cowpea. However, further studies are needed to understand the mechanisms through which the endophytes protect plants from herbivores and promote plant growth and yield.Item Nutrients and tillage interactions in rice fallow cowpea (Vigna unguiculata L. Walp.) production(Department of Agronomy, College of Agriculture, 2020) Vandana G Pai; Prameela, PItem Bio-ecology and management of borer pests infesting yard lond bean, Vigna unguiculata subsp. sesquipedalis (L.) verdc.(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Sontakke Pritin Pramod; Amritha, V S