Browsing by Author "Deepa, S Nair"

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Bio-elicitation of Ashwagandha (Withania Somnifera (L.) Dunal) for improved growth, yield and secondary metabolite production
(Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture,Vellayani, 2024-10-10) Manisha Elza Jacob; KAU; Deepa, S Nair
The study titled “Bio-elicitation of Ashwagandha (Withania somnifera (L.) Dunal) for improved growth, yield and secondary metabolite production” was carried out in the Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture, Vellayani, during December 2019 to September 2023 with the objective to study the effect of individual application of chitosan and the root endophytic fungus, Piriformospora indica and their combined application on plant growth, yield and secondary metabolite production in Withania somnifera. The study was carried out in W. somnifera as four experiments (i) Biopriming of seeds using chitosan, (ii) Bio-elicitation by foliar application of chitosan, (iii) Bio-elicitation using P. indica, and (iv) Bio-elicitation by combined application of chitosan and P. indica. The second experiment consisted of two parts, preparation of chitosan nanoparticles and foliar application of chitosan. In the first experiment, seeds of Ashwagandha were primed with fourteen treatments, comprising of four different concentrations of chitosan (0.5 mg mL-1, 1 mg mL-1, 2.5 mg mL-1, and 5 mg mL-1) for three different durations (2 h, 4 h and overnight), along with overnight hydropriming and control (without priming). Different germination and seedling growth parameters of the seeds and seedlings were recorded. The highest germination per cent (76.00) and survival per cent (73.33) were observed in the priming treatment chitosan 5 mg mL-1 for 4 h. This was on par with the treatment chitosan 5 mg mL-1 for 2 h (69.33) and hydropriming treatment (70.67) with respect to germination per cent. Hydropriming recorded the highest germination index (1.79) and the treatment chitosan 2.5 mg mL-1 for 2h recorded the highest allometric index (0.91). Respective results were on par with the priming treatment chitosan 5 mg mL-1 for 4 h. Hydropriming recorded the lowest mean germination time (8.83 days). The highest values of seedling vigour indices I (8890.00) and II (45.15) were also recorded in the treatment chitosan 5 mg mL-1 for 4 h. The duration of priming had a significant effect on seedling growth parameters. Overnight priming treatments with chitosan were found to have an inhibitory effect on germination and seedling growth parameters with values on par with or lower than that of the control. Based on the results, seed priming with chitosan 5 mg mL-1 for 4 h, was selected as the best priming treatment for further experiments in the study. The preparation of chitosan nanoparticles was carried out by ionotrophic gelation method by dropwise addition of tripolyphoshate (TPP) solution to chitosan solution, under stirring at room temperature. Eighteen treatments formed by three levels of chitosan (1 mg mL-1, 2 mg mL-1 and 3 mg mL-1), three levels of TPP (0.5 mg mL-1, 0.75 mg mL-1 and 1 mg mL-1) and two speeds of rotation (700 rpm and 800 rpm) were tried for preparing the nanoparticles. The absorption spectra of the resultant solutions were observed at eight different wavelengths, i.e., 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, 320 nm and 340 nm. The factor combinations with chitosan 1 mg mL-1 and TPP 0.5 mg mL-1 at 700 rpm, chitosan 2 mg mL-1 and TPP 0.75 mg mL-1 at 700 rpm, and chitosan 3 mg mL-1 and TPP 1 mg mL-1 at 700 rpm had an absorption peak at 220 nm. These were further characterized for particle size and were observed to have mean particle sizes of 222.9 nm, 333.4 nm and 366.9 nm, respectively. As the particles formed by various chitosan - TPP combinations did not fall in the nanoscale range of less than 200 nm, the further experiments involving chitosan nanoparticles were carried out using commercially available chitosan nano particles of size 80 to 100 nm. In the experiment involving foliar application of chitosan, seeds primed with the best priming treatment selected (chitosan 5 mg mL-1 for 4 h) were sown in protrays and thirty-day old seedlings were transplanted to growbags. The eight treatments in this experiment consisted of chitosan and chitosan nanoparticles spray, each at three different concentrations (1 mg mL-1, 2.5 mg mL-1 and 5 mg mL-1). The primed and non-primed seeds (absolute control) without any foliar spray application served as the control treatments. The treatments were imposed as foliar spray at transplanting, 15, and 45 days after that. The treatment with chitosan 2.5 mg mL-1 was found to be the best in terms of parameters like plant height, number of leaves and leaf area, recording the values 123.67 cm, 178.83 leaves and 119.99 cm2 respectively, at harvest. The treatment with a higher concentration of chitosan nanoparticles (5 mg mL-1) recorded the lowest number of days to flowering from transplanting (30.67 days), and also a lesser number of days to fruitset from flowering (9.17 days). The highest number of branches (9.97) and flowering branches (8.15) at harvest were observed in the treatment, chitosan 1 mg mL-1. The treatment with the lowest concentration of chitosan nanoparticles (1 mg mL-1) recorded the lowest values in various growth parameters, viz., plant height, number of branches, number of flowering branches, leaf area and collar girth. With respect to biochemical parameters, the highest content of total proteins (7.12 mg g-1) and carbohydrates (22.41 mg 100 g-1) were observed in the treatment with chitosan nanoparticles 2.5 mg mL-1 at harvest. The treatment with chitosan 1 mg mL-1 recorded the highest peroxidase (32.35 U mg-1 protein), catalase (17.57 U mg-1 protein) and superoxide dismutase (1.68 U mg-1 protein) activities. Similar to growth parameters, chitosan 2.5 mg mL-1 recorded the highest leaf area index (25.75) and leaf area duration (1020.92 days). All the treatments involving chitosan as well as chitosan nanoparticles were observed to have significantly higher photosynthetic rate at harvest. The highest stomatal conductance (162.97 mmoles m-2 s-1) was observed in the treatment chitosan 1 mg mL-1, the highest proline content (44.03 μM g-1 tissue) was observed in the treatment chitosan nanoparticles 2.5 mg mL-1, and the highest cell membrane integrity (91.80 per cent) was observed in chitosan nanoparticles 5 mg mL-1 at harvest. This treatment also had the highest total chlorophyll content at harvest. The shoot weight was observed to be significantly higher in chitosan treatments over chitosan nanoparticles as well as the control treatments. However, with respect to the dry weight of shoot, the lowest concentration of chitosan nanoparticles (1 mg mL-1) was observed to be on par with chitosan foliar spray treatments. The treatments with chitosan nanoparticles were observed to give significantly higher berry weight and seed yield per plant over chitosan and control treatments. The root parameters, viz., root length, root diameter, root volume and root yield (fresh and dry) were also observed to be significantly higher in treatments with chitosan nanoparticles over that of chitosan and control treatments. Root being the officinal part of the plant, the secondary metabolite, withanolide content in it was recorded. The highest withanolide content was observed in the treatment chitosan 2.5 mg mL-1 (0.45 per cent), and was on par with the treatment chitosan 5 mg mL-1 (0.43 per cent). Withanolide yield per plant was the highest in the treatment chitosan nanoparticles 2.5 mg mL-1 (5.46 mg plant-1) which had 4.4 times increase in withanolide yield over control. This was on par with the treatment chitosan 5 mg mL-1 (4.99 mg plant-1) which had 3.9 times increase in withanolide yield over control. Among the foliar spray treatments, chitosan 5 mg mL-1 and chitosan nanoparticles 2.5 mg mL-1 were selected as the best two treatments in terms of higher withanolide yield, for proceeding to the combination trials. In the experiment involving application of P. indica, P. indica mycelium, culture filtrate and cell wall extract were applied to the plants raised from primed and non-primed seeds. The seedlings raised from the primed and non-primed seeds were transplanted at 30 days after sowing to growbags. P. indica mycelium was applied at transplanting; and P. indica culture filtrate and cell wall extract were applied as foliar spray at transplanting, 15 and 45 days after transplanting. With respect to growth parameters, the highest plant height (120.19 cm), number of flowering branches (7.25), leaf area (111.84 cm2) and collar girth (2.67 cm) were observed in the plants derived from primed seeds treated with P. indica mycelium. Significantly higher protein content and defense enzymes were observed in the plants raised from non-primed seeds treated with P. indica cell wall extract. Physiological parameters like leaf area index and leaf area duration were found to be the highest in the plants raised from primed seeds treated with P. indica cell wall extract (1.40 and 21.65 days) at harvest. The highest stomatal conductance (129.30 mmoles m-2 s-1), photosynthetic rate (26.60 μCO2 moles m-2 s-1), proline content (45.37 μM g-1 tissue) cell membrane integrity (70.06 per cent) and total chlorophyll content (2.44 mg g-1 fresh weight) were recorded in the plants raised from primed seeds treated with P. indica mycelium. Shoot weight per plant was found to be significantly higher in plants raised from both primed and non-primed seeds treated with P. indica mycelium. Number of berries per plant, berry weight and seed yield per plant were found to be significantly higher in plants raised from primed seeds treated with P. indica mycelium and culture filtrate. All the root parameters, root length, root diameter, root volume, root yield per plant (fresh and dry) were observed to be the highest in plants raised from primed seeds treated with P. indica mycelium. The withanolide content was observed to be significantly higher in the roots of plants raised from primed seeds treated with P. indica mycelium (0.35 per cent) and culture filtrate (0.37 per cent). The same treatments showed significantly higher withanolide yield of 4.05 mg (3.82 times increase over control) and 3.60 mg per plant (3.28 times increase over control), respectively. Thus, the plants raised from primed seeds treated with P. indica mycelium and culture filtrate were selected as the best two treatments in terms of higher withanolide yield, for proceeding to the combination trials. For the combined application of chitosan and P. indica, the best two treatments selected from the individual application of chitosan and P. indica were used for studying their combined effect on growth, yield and secondary metabolite production in W. somnifera. The highest plant height (91.86 cm), number of leaves (143.70), leaf length (17.01 cm), leaf breadth (9.48 cm), and leaf area (113.28 cm2) were observed in the combination treatment of chitosan 5 mg mL-1 and P. indica mycelium. The highest number of branches (8.25), flowering branches (7.60) and collar girth (2.42 cm) were observed in the combination treatment involving chitosan 5 mg mL-1 and P. indica culture filtrate. The same treatment recorded the highest protein content (8.45 mg g-1). The highest peroxidase activity (34.74 U mg-1 protein), catalase activity (14.67 U mg-1 protein) and superoxide dismutase activity (1.48 U mg-1) were observed in the treatment involving chitosan of 5 mg mL-1 and P. indica mycelium. The same treatment recorded the highest value with respect to physiological parameters, viz., leaf area index (19.53), leaf area duration (803.07 days), stomatal conductance (137.11 mmoles m-2 s-1), photosynthetic rate (33.73 μCO2 moles m-2 s-1) and total chlorophyll content (3.76 mg g-1 fresh weight). The highest proline content was recorded in the treatment involving chitosan nanoparticles 2.5 mg mL-1 and P. indica mycelium (34.22 μM g-1 tissue) and highest cell membrane integrity in the combination treatment of chitosan nanoparticles 2.5 mg mL-1 and P. indica culture filtrate (83.69 per cent). The shoot weight and all the root growth parameters, viz., root length, root diameter, root volume and root yield were found to be the highest in the combination treatment of chitosan 5 mg mL-1 and P. indica mycelium. The combination treatments involving chitosan nanoparticles 2.5 mg mL-1 and P. indica mycelium/culture filtrate had the highest number of berries, berry weight and seed yield per plant. Significantly higher withanolide content was observed in roots of the plants treated with chitosan 5 mg mL-1 and P. indica culture filtrate. Withanolide yield per plant was the highest in the treatment comprising chitosan nanoparticles 2.5 mg mL-1 and P. indica culture filtrate and was on par with the combination treatment of chitosan 5 mg mL-1 and P. indica mycelium/culture filtrate. In the study, it was observed that all the combination treatments gave better performance than the control in terms of root yield, withanolide content and withanolide yield per plant. The concentration of chitosan and exposure time of priming had a profound influence on seed germination and seedling growth parameters in W. somnifera. The bio-elicitors, chitosan/chitosan nanoparticles and P. indica when applied individually and in combination to chitosan primed seeds have been observed to enhance growth, yield and metabolite production in a dose dependent manner in W. somnifera.
Chitosan Mediated growth,yield and bioactivities of sweet basil [Ocimum basilicum (L.)]
(Department of Plantation Crops, Spices, Medicinal and Aromatic Crops, College of Agriculture, Vellayani, 2024-03-27) Amritha Lal,P.; Deepa, S Nair
The present study entitled “Chitosan mediated growth, yield and bioactivities of sweet basil (Ocimum basilicum L.)” was conducted at the Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala during 2022- 2023 with the objective to evaluate the plant growth and biological activities of Ocimum basilicum L. in response to foliar application of chitosan at varying concentrations and frequencies. The seeds of O. basilicum used for the study were sourced from from Indian Institute of Horticultural Research, Bengaluru. The seeds were sown in portrays filled with potting mixture comprising of coir pith and vermicompost in the ratio 3:1. The 30-day-old seedlings were transplanted to grow bags and maintained organically up to 120 days after sowing (DAS). Chitosan was applied at varying concentrations (0.5 g L-1, 1 g L-1 and 2 g L-1) and frequencies viz., 15 days after transplanting (45 DAS) and 30 days after transplanting (65 DAS) to growbags. The experiment was laid out in completely randomized block design with fifteen treatments and three replications. The treatment consisted of base solution (chitosan 0 g L-1) sprayed at 15 DAT (T1), at 30 DAT (T2), at 15 & 30 DAT (T3), chitosan 0.5 g L-1 sprayed at 15 DAT (T4), at 30 DAT (T5), at 15 & 30 DAT (T6), chitosan 1 g L-1 sprayed at 15 DAT (T7), at 30 DAT (T8), at 15 & 30 DAT (T9), chitosan 2 g L-1 sprayed at 15 DAT (T10), at 30 DAT (T11), at 15 & 30 DAT (T12), water sprayed at 15 DAT (T13), at 30 DAT (T14), at 15 & 30 DAT (T15). The plant growth parameters viz., shoot length, number of branches, leaf area, collar girth and number of flowering branches were recorded at 30, 60, 90 and 120 days after sowing (DAS). The growth parameters exhibited a significant variation among the treatments. At harvest (90 DAS), the plants treated with chitosan 2 g L-1 at 15 & 30 DAT (T11) recorded the highest shoot length (59.37 cm) and number of branches (42), The highest 114 leaf area (8892.96 cm2) was observed in chitosan 1 g L-1 at 30 DAT (T8) and was on par with T11. The highest number of flowering branches was observed in treatment chitosan 2 g L-1 at 30 DAT (T11). The treatment chitosan 2 g L-1 at 15 & 30 DAT (T12) recorded early flowering (57.67 days). The data on yield parameters on leaf biomass, stem biomass and herbage yield were recorded at 90 DAS. The seed yield parameters viz., seed yield per plant and thousand seed weight were recorded at 120 DAS. The treatment chitosan 1 g L-1 at 30 DAT (T8) exhibited higher fresh leaf biomass (254.40 g per plant), dry leaf biomass (12.54 g per plant-1), fresh stem biomass (216.73 g plant-1), dry stem biomass (19.0 g plant-1), fresh herbage (485.24 g plant-1) and dry herbage (32.06 g plant-1) yield. The oil yield (210.36 g plant-1), seed yield (66.08 g plant-1) and test weight (10.57 g) were also observed to be maximum in treatment chitosan 1 g L-1 at 30 DAT (T8). The effect of chitosan on biochemical parameter, plant pigments were recorded at 30, 60, 90 and 120 DAS. The treatment T11 exhibited the highest chlorophyll and carotenoid content. The biochemical parameter, secondary metabolites viz., total alkaloids, flavonoids, total phenol content and tannins were recorded at 90 DAS and was found to be significantly influenced by the application of chitosan. The treatment T8 exhibited highest phenol (33.75 ug GAE mg-1) and alkaloid content (91.61 ug AE mg-1). The highest flavonoid and tannin content were recorded in the treatment T11. In HPTLC comparative chemical profiling analysis, the leaf extracts of O. basilicum showed 38 phytochemical constituents corresponding to specific Rf values. T8 had more number, 19 phytochemical constituents out of 38 total constituents recorded during the analysis. This was followed by T10 and T11 , which were observed to show 16 constituents among the 38 constituents recorded in the analysis. The treatment T8 (chitosan 1 g L-1 sprayed at 30 DAT) selected as the best treatment in terms of herbage and oil yield was compared with the corresponding control treatment, T14 (water sprayed at 30 DAT) to study the effect of chitosan on bioactivities. The study revealed that the defatted ethanolic leaf extract of T8 showed better performance in terms of antifungal (against Colletotrichum capsici MTCC 9691), antioxidant and enzyme 115 (peroxidase and catalase) activities compared to T14. Both the treatment (T8) as well as the control treatment (T14) did not show any antibacterial property when tried against Escherichia coli MTCC 40. The T14 leaf extract gave better cytotoxicity against HCT 116 colon cancer cell lines compared to that of T8. Among the treatments T8 (chitosan 1 gL-1 sprayed at 30 DAT) exhibited the best results in terms of yield, secondary metabolites and bioactivities. This was followed by T11 (chitosan 2 gL-1 sprayed at 30 DAT) with respect to these parameters. From the study it can be concluded that one time spray of chitosan 1 g L-1 at 30 DAT could be selected as the best treatment for enhancing yield, secondary metabolites and bioactivities of O. basilicum.
Drought stress mitigation in Piper longum L.using chitosan
(Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture , Vellayani, 2024-12-12) Vishnu, V; Deepa, S Nair
Growth, yield and curcumin production in turmeric (curcuma longa L.) mediated by chitosan application
(Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture , Vellayani, 2024-03-27) Shibana, S N.; Deepa, S Nair
The research programme entitled “Growth, yield and curcumin production in turmeric (Curcuma longa L.) mediated by chitosan application” was carried out in the Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture, Vellayani, during 2021 to 2023 with an objective to evaluate the effect of different modes and frequency of application of chitosan (CTS) on plant growth, yield and secondary metabolite production in Curcuma longa. The present study was carried out as four experiments (i) Biopriming of rhizome bits using chitosan (ii) Effect of different modes and frequency of application of chitosan (iii) Effect of chitosan application on beneficial soil microflora and (iv) Effect of chitosan application on expression profile of curcumin synthase gene. All the experiments were tried in two varieties viz., Sobha and Sona. In the first experiment, single bud rhizome bits were treated with different concentrations of chitosan for specified periods. The experiment was laid out in Completely Randomized Design (CRD) with three replications. Each replication consist of 25 rhizome bits. The treatments included, T1: CTS 1 g L-1 for 30 min, T2: CTS 1 g L-1 for 1 h, T3: CTS 2 g L-1 for 30 min, T4: CTS 2 g L-1 for 1 h, T5: CTS 4 g L- 1 for 30 min, T6: CTS 4 g L-1 for 1 h and T7: Control (without priming). The treated rhizome bits were shade dried and sown in protrays and maintained for 45 days. The observations on growth parameters were recorded at 45 days after planting. The rhizome bits exposed to CTS 1 g L-1 for 1 h was observed to give better results in terms of growth parameters and vigour index in both the varieties. Chitosan treatment enhanced the shoot length of the plantlets by 58 % in Sobha and 83 % in Sona, over the control. The collar girth enhanced by 39 % and 19 % over the control in Sobha and Sona, respectively. However, the chitosan treatment did not significantly influence the days to sprouting, sprouting per cent and survival per cent in both the varieties. The plantlets obtained on priming of rhizome bits with CTS 1 g L-1 for 1 h was used to study the effect of different modes (foliar and soil application) and frequency of application of chitosan in the second experiment. The experiment was laid out in Randomized Block Design (RBD) with three replications. The foliar application treatments included, F1: CTS 1 g L-1 monthly, F2: CTS 2 g L-1 monthly, F3: CTS 3 g L- 1 bimonthly, F4: CTS 4 g L-1 bimonthly, F5: CTS 4 g L-1 trimonthly, F6: CTS 5 g L-1 trimonthly, Cp: Primed control and C: Unprimed control. Chitosan application significantly influenced growth, quality and yield parameters of turmeric over the control. Among the foliar treatments, monthly application of CTS 2 g L-1 (F2) was observed to give better results in terms of plant growth parameters viz., plant height, leaf area, shoot weight, rhizome spread and rhizome weight at 6 MAT. The cell membrane integrity and total chlorophyll content was observed to be significantly higher with monthly application of CTS 2 g L-1 (F2) in both the varieties. The activity of defense enzymes (peroxidase and polyphenol oxidase) were significantly higher in F2, in Sobha and Sona. F2 and F4 recorded low incidence of leaf blotch disease. Chitosan application significantly influenced the yield and yield attributing characters compared to untreated control. Trimonthly foliar application of CTS 4 g L-1(F5) and trimonthly foliar application of CTS 5 g L-1 (F6) recorded significantly higher dry yield per plot (1.93 kg) in variety Sobha, which was on par with all other chitosan foliar treatments. In variety Sona, bimonthly application of CTS 4 g L-1 (F4) recorded significantly higher dry yield per plot (2.21 kg) and on par with all other chitosan foliar treatments except F1. Foliar application of chitosan enhanced the dry yield in the range of 43 % to 69 % in Sobha and 56 % to 91 % in Sona over the control. Nutrient uptake also recorded a significantly higher value in F2 in both the varieties. In foliar spray treatment, F2, F4 and F6 recorded significantly higher volatile oil content in Sobha, while in Sona F2 and F4 recorded higher values. Oil content enhanced by 116 % to 137 % in Sobha and 144 % to 164 % in Sona over the control. F2 and F4 recorded significantly higher oleoresin content in both the varieties. Oleoresin content increased in the range of 76 % to 82 % in Sobha and 64 % to 72 % in Sona compared to control. F2 (6.63 %) and F4 (6.42 %) recorded higher curcumin content and enhancement ranged from 83 % to 89 % in Sobha. While in Sona, F2 recorded higher curcumin content (7.35 %) which recorded an enhancement of 54 % over the control. From the study it could be concluded that the best priming treatment of rhizome bits is with CTS 1 g L-1 for 1 h in terms of seedling growth and vigour index in both the varieties. All the chitosan treatments gave better performance in terms of yield over the control irrespective of mode of application in both the varieties. F2 and F4 gave better performance with respect to both yield and quality. Among these, the BC ratio was observed to be higher in F4 in both the varieties. Hence, F4 (bimonthly foliar application of CTS 4 g L-1) is selected as the best and economically feasible chitosan treatment for improving growth, yield and secondary metabolite production in turmeric. Chitosan application also improved the population of beneficial soil microflora, nitrogen fixing bacteria and phosphorus solubilising bacteria. Chitosan also enhanced the expression level of curcumin synthase gene.