1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Shade requirments for cut foliage plants (Dracaena Spp.)(Department of floriculture and landscaping, college of agriculture , Vellayani, 2023-12-06) Josmi John; Priya Kumari, IThe thesis work entitled “Shade requirement for cut foliage plants (Dracaena spp.)” was carried out in the Department of Floriculture & Landscaping, College of Agriculture, Vellayani from April 2022 to October 2022. The objective of the study was to evaluate different shade levels and colored shade nets for improving production and quality of commercially important cut foliages, Dracaena fragrans (L.) Ker Gawl., Dracaena reflexa Lam. and Dracaena sanderiana Sander ex Mast. The experiment was laid out in split plot design. The first experiment is conducted to study the effect of different shade levels. Main plot treatments were three different shade levels 50 % shade, 75 % shade and control (shade under coconut garden) and sub plot treatments were three commercially important cut foliage plants Dracaena spp. (Dracaena sanderiana ‘Gold’, Dracaena reflexa ‘Variegata’ and Dracaena fragrans ‘Massengeana’). There was a reduction of temperature under shade nets. Relative humidity was also lower under net houses compared to control condition. Light intensity under different shade levels was lower than outside environment. Different shade levels and colored shade nets had significant effect on production and quality of cut foliage Dracaena spp. Experiment on effect of shade levels revealed that higher shoot and root weight was observed under 75% shade level. Among the varieties highest shoot and root weight was observed for Dracaena sanderiana ‘Gold’ and Dracaena fragrans ‘Massengeana’ respectively. Among the interaction effect Dracaena fragrans ‘Massengeana’ under 75% shade net recorded higher shoot and root weight. Chlorophyll content was found to be higher under 50% shade level, Dracaena sanderiana ‘Gold’ recorded the highest value and their treatment combination also recorded higher values. Plants grown under 75% shade level recorded the highest plant height and leaf number; at 2 MAP it was on par with 50% shade level. Among the varieties highest plant height and leaf number was observed for Dracaena sanderiana ‘Gold’ and Dracaena reflexa ‘Variegata’ respectively. Highest leaf area was observed under 75% shade level at 4 and 6 MAP. 119 Among the varieties Dracaena fragrans ‘Massengeana’ recorded highest leaf area. Highest shoot length was recorded under 75% shade level at 4 and 6 MAP. Dracaena sanderiana ‘Gold’ recorded highest shoot length. The vase life of foliages was found to be superior under 50% shade level and Dracaena sanderiana ‘Gold’ recorded maximum vase life. Experiment on effect of shade net color revealed that higher shoot and root weight was observed under red shade net. Dracaena sanderiana ‘Gold’ recorded maximum shoot and root weight. Their treatment combination also gave higher value. Highest plant height was recorded under red shade net and at 4MAP it was on par with green shade net (50%). Dracaena sanderiana ‘Gold’ recorded maximum plant height and among the interaction effect for Dracaena sanderiana ‘Gold’ under red shade net recorded maximum plant height. Leaf number was maximum under red shade net and Dracaena reflexa ‘Variegata’recorded maximum leaf number and their treatment combination was also higher. Highest leaf area was observed under green shade net and at 4MAP it was on par with red shade net. Among the varieties Dracaena fragrans ‘Massengeana’ recorded highest leaf area. Shoot length was highest under red shade net and variety Dracaena sanderiana ‘Gold’ recorded maximum 37superior under black shade net and it was on par with green shade net. Dracaena fragrans ‘Massengeana’ recorded maximum vase life. Among the interaction effect Dracaena fragrans ‘Massengeana’ under black shade net had recorded maximum vase life. Shade net of 75% was found to be superior in improving most of the plant growth parameters like shoot weight (162.50g) , root weight (35.02g) , plant height (73.25 cm), leaf number (40), leaf area(143.50cm2) and shoot length (53.66 cm) for Dracaena sanderiana ‘Gold’, Dracaena reflexa ‘Variegata’, and Dracaena fragrans ‘Massengeana’ compared to 50% shade level and shade under coconut garden. Vase life (29.16 days) was recorded maximum under 50% shade level compared to 75% shade level and shade under coconut garden. 120 Red colored shade net was found to be superior in improving most of the plant growth parameters like shoot weight (131.21g) , root weight(29.63g) , plant height (77.11), leaf number(41), and shoot length(61.33) for Dracaena sanderiana ‘Gold’, Dracaena reflexa ‘Variegata’, and Dracaena fragrans ‘Massengeana’ compared to green , black , white and shade under coconut garden. Vase life (29.11 days) was recorded maximum under black and green shade nets compared to red, white and shade under coconut garden.Item Characterisation of Exacum bicolor Roxb.(KANNANTHALI) for aesthetic ,medicinal value and refinement of domestication practices(Department of Floriculture and Landscaping, College of Agriculture,Vellanikkara, 2024-07-01) Aswathi, S Vasu; KAU; Sreelatha,UIndia is blessed with a wide variety of endemic plant species due to the presence of four out of 34 biodiversity hotspots in the world. Endemic species with narrow geographical range of area are most likely to become extinct due to fragmentation of habitat, human interferences, deforestation, and expansion of agricultural land. Special attention must be given to such small natural populations before they get vanished. Many of such native plant species may also form an important source for sustainable landscaping and xeriscaping. Exacum bicolor which belongs to Gentianaceae family is an herbaceous perennial, endemic to peninsular India. The flowers which are a mix of colors imparted by the white petals with purple tips and bright, yellow-colored stamens, are the most beautiful part of the plant. Mature sturdy stem that ensures the non-lodging habit of Eaxcum bicolor even during heavy rainfall, makes the plant more suitable for gardening. The plant also holds enormous medicinal properties and was traditionally used by “vaidyas” for the treatment of various diseases. Though being frequently quoted by Malayalam literary writers, the plant is not that familiar to many common people due to its restricted occurrence. Exacum bicolor is an inhabitant of the dry grasslands of the lateritic hillocks and the shola grasslands in the high ranges of Kerala. The plant is enlisted as endangered due to its rapid shrinking population imposed by enmasse collection of the plants that happened decades back for herbal formulations, never ending, severe habitat destruction and also mass uprooting of the plant for its beauty. Discontinuous and isolated geographical situation of the habitats are other unique characteristics of the plant. The majority of the habitats in the lateritic hillocks are under private possession and are very likely to be exploited soon. Therefore, ex-situ conservation is of urgent need for conservation of Exacum bicolor. Evaluation of genetic variability among the available genotypes of the species and standardization of domestication practices are of utmost importance. In this context, the present study was undertaken with the objectives of morphological characterization of Exacum bicolor genotypes for aesthetic value, metabolite profiling for medicinal value, and standardization of propagation and management practices for popularization as a novel ornamental plant. The study was organized into three major experiments as morphological characterization, phytochemical analysis and standardization of domestication practices. In the first experiment, morphological characterization, eleven available genotypes of Exacum bicolor were collected and evaluated for various vegetative and floral parameters. A significant difference was noticed among the genotypes for both vegetative and floral characters. Plant characters such as stem girth (2.29 cm), number of primary branches (4.11), leaf length (8.76 cm), and floral characters such as number of flowers per plant (184.00) and duration of flowering (47.21 days) were found higher in the genotype KAU Ex 11. Qualitative characters like shape of the leaves, leaf tip as well as petal shape also differed among the genotypes. Most of the genotypes possessed linear-lanceolate leaves, whereas KAU Ex 7 and KAU Ex 14 (oblanceolate leaves), KAU Ex 9 (ovate-elliptic leaves) and KAU Ex 10 (ovate leaves) showed other leaf forms. Overall scoring of Exacum bicolor genotypes based on the number of flowers per plant and the duration of flowering resulted in the highest rank to KAU Ex 11, followed by KAU Ex 15. Wide variation in genetic parameters of various characters indicated occurrence of considerable diversity among the genotypes for these traits. The difference between phenotypic coefficient of variance (PCV) and genotypic coefficient of variance (GCV) was narrow for characters viz. number of leaves, leaf width, leaf length, number of flowers per plant and duration of flowering, indicating the impact of genetic makeup for these traits rather than influence of environment. High heritability (more than 90%) coupled with high GAM were recorded for number of leaves, leaf length, leaf width, days to bud initiation, duration of flowering which indicate the additive and dominance gene action for these characters and possibility of selection based on these traits for further crop improvement programmes. K-mean cluster analysis of eleven genotypes yielded three clusters. Four genotypes each were included in cluster 1 and cluster 2, and three genotypes in cluster 3. The clustering pattern indicated that, geographical origin had no influence on grouping of genotypes. Association among various vegetative and floral characters analyzed via genotypic and phenotypic correlation revealed that Genotypic correlation coefficients of all the attributes were greater than or equal to the phenotypic correlation coefficients which indicated that influence of environment is negligible on phenotypic variation. The second experiment was phytochemical analysis. With respect to phytochemical analysis, extractive yield in methanol, contents of total polyphenols, alkaloids, flavonoids and saponins were estimated. The extractive yield in methanol (18.98 g/100 g) and alkaloids (0.77%) were found higher in the genotype KAU Ex 7, total polyphenols were higher in KAU Ex 10 (397.03 mg GAE/100g), flavonoids in KAU Ex 16 (1541.50 mg QE/100 g) and saponins in KAU Ex 12 (3.19 %). Gas chromatography-mass spectrometry analysis of sequential extracts of two genotypes of Exacum bicolor yielded a number of possible compounds which possess various therapeutic properties. The presence of secoiridoid namely, gentiolacotne [1H,6HPyrano[ 3,4-c]pyran-1,6-dione, 5-ethyl-3,4,5,8-tetrahydro-5-hydroxy-, (.+-.)] was first reported in Exacum bicolor. The third experiment, refinement of domestication practices, was attempted on enhancement of seed germination, seedling growth, standardization of seed germination media, potting media, vegetative propagation through cuttings, spacing & pinching, elucidation of floral biology and assessment of seed dormancy. The seeds were subjected to treatments viz. priming with certain chemical/bio agents, heat scarification, and light stratification by exposing to fluorescent and ultraviolet (UV) light. Priming with GA3 at 750 mg/L for 24 h recorded higher seed germination (77.50%), seedling survival (69.25%), shoot length (23.03 mm), root length (25.63 mm), dry weight of seedlings (1.60 mg), vigour index I (3771.14) and II (124.04). Among heat scarification treatments tested, significantly highest seed germination (73.93%) and seedling survival (67.86%) was exhibited when the seeds were preheated at 120ͦC for 15 minutes. Preheating at 80ͦC for 15 minutes duration recorded significantly longest shoots (41.40 mm) and roots (21.24 mm). Exposure of seeds at 80 ͦC for 30 minutes recorded highest vigour index I (3149.54), and 100 ͦC for 15 (108.07) minutes and 120 ͦC for 15 minutes (99.90) duration of exposure yielded higher vigour index II. Light stratification using fluorescent light was found to be more beneficial for seed germination and seedling survival. Fluorescent light exposure at 12/12 h light/dark photoperiod for 6 days recorded higher seed germination (92.38%), seedling survival (92.14%), and vigour index I (7876.43) and II (296.72), whereas shoot length (41.09 mm), root length (67.01 mm), and seedling dry weight (4.80 mg) were found higher when seeds were exposed to UV light for 45 minutes. Analysing the germination media for seed germination in Exacum bicolor, seeds were sown in germination media comprised of various combinations of cocopeat, sand, FYM, perlite and vermiculite alone and along with arbuscular mycorrhizal fungus (AMF) and Phosphobacterium. Highest seed germination was observed in media composed of cocopeat and sand (1:1) (76.21%). Seedling survival, shoot length, root length and seedling dry weight were recorded higher in media containing cocopeat and sand (1:1) along with AMF (10g/pot), and cocopeat, perlite, vermiculite (3:1:1) along with AMF (10g/pot). Analysing the nutrient management for growth enhancement, seedlings were applied with nutrients viz. N: P: K as 30: 10: 10 and 19: 19: 19 and ‘Amino rich’ alone and in combination with different concentrations of plant growth regulators viz. GA3 and IAA. Foliar application of N: P: K as 30: 10: 10 alone in progressive doses (0.5 g/L in week 1 of germination; 1 g/L in week 2; 2 g/L from week 3 onwards) recorded highest seedling survival (70.12%), fresh weight (63.70 mg), and dry weight of seedlings (3.62 mg). Various combinations of growing media were tested to analyse the effect of different potting media on the growth and flowering of Exacum bicolor. Plant height was found highest in media composed of soil and AMF (10 g/ Kg medium) (39.36 cm), stem girth in soil + sand + vermicompost (1:1:1) + AMF (10g/kg medium), and number of leaves were found highest in soil + AMF (10g/kg medium) (25.44). Number of flowers per plant was found greatest in potting media comprised of soil + sand + vermicompost (1:1:1) (44.50). The potting media with soil alone (37.06 days) recorded longer duration of flowering. Larger flowers with longer petals were observed in potting media composed of cocopeat + perlite + vermiculite (3:1:1) + AMF (10g/kg medium). Based on the scoring and ranking of the twelve potting media treatments for vegetative and floral parameters, the media comprised of soil + sand + vermicompost (1:1:1) + AMF (10g/kg medium) recorded the highest rank (rank 1) followed by soil + sand + vermicompost (1:1:1) and coco peat + sand + vermicompost (3:1:1). Vegetative propagation of Exacum bicolor was performed through terminal stem cuttings treated with various concentrations of indole-3-butyric acid (IBA), charcoal powder, commercial hormone powder (Rootex). A significant difference was observed among the treatments, with 96.67 percent cuttings rooted when cuttings were treated with IBA at 5.0 mg/L. cuttings treated with IBA at 20.0 mg/L resulted in greatest number of roots (19.45) and IBA at 15.0 mg/L produced longer roots (42.86 cm). Influence of pinching and spacing on vegetative and floral parameters of Exacum bicolor was analyzed by adopting three levels of spacing viz. 20 × 20 cm, 30 × 20 cm and 30 × 30 cm and giving seven levels of pinching viz. no pinching, single pinching at 15, 30 and 45 days after transplanting (DAT), double pinching at 15 & 30, 15 & 45, and 30 & 45 DAT. Analysis of pinching and spacing on vegetative and floral parameters of Exacum bicolor showed significantly greater number of branches in all the double pinching treatments. However, plants spaced at 30 x 20 cm and double pinched on 15 & 45 days after transplanting (DAT) showed compact growth habit with stouter stem and a higher number of branches which are suitable for bedding plants. The treatment also recorded a greater number of flowers/plant (86.50) with longer duration of flowering (47.0 days). Floral biology and pollination behaviour of Exacum bicolor was studied analysing the anthesis time, pollen viability, stigma receptivity and mode of pollination. It was found that anthesis in Exacum bicolour was occurring between 4.00 am and 6.00 am with peak time of anthesis at 5.00 am (56.25%). Pollen viability gradually decreased with flower aging. Significantly higher viability of pollen grains was observed for flowers on the previous day of anthesis (D0), and flowers on the day of anthesis (D1) from 8.00 am to 1.00 pm, flowers on second day of anthesis (D2 flowers) up to 11.00 am, for third day of anthesis (D3) and fourth day of anthesis (D4 flowers) up to 9.00 am. The results of the stigma receptivity test revealed that pollinating flowers on the third day of anthesis at 9.00 am ensures successful seed set, capsule weight and seed weight per capsule. Pollination behaviour of Exacum bicolor was studied by assessing five methods of pollination such as controlled selfing, controlled out-crossing, forced open pollination, self-pollination (bagging) and open pollination. Cent percent fruit set was obtained in controlled selfing, controlled outcrossing and in open pollination indicating that the plant is both self and cross compatible. Lack of fruit set in self-pollination (bagging) is an indication of lack of the phenomenon of apomixis to promote natural self-pollination in this species. Seed dormancy was assessed by performing seed germination test immediately after seed extraction and on alternate days subsequent to seed extraction up to 35 days (D1, D3, D5,… D35) and thereafter at weekly intervals, until germination percentage reached greater than 50 percent. The germination test was performed without any seed treatment (control) and with seed priming using 750 mg/L GA3 for 24 h. Lack of seed germination in control even up to the 84th day of seed extraction indicated the occurrence of seed dormancy in this species. However, seeds treated with GA3 germinated from the first day seed extraction onwards. From the study, it could be concluded that Exacum bicolor can be effectively utilised as an ornamental potted plant, and standardisation of domestication practices ensures measures for successful cultivation of the plant for the plains in KeralaItem Phytochemical analysis and antioxidant profiling of ornamental flowers(Department of Floriculture and Landscaping, College of Agriculture,Vellanikkara, 2023-02-24) Logesh , M; Resmi , PaulThe present study entitled was undertaken with the objective of studying the physico-chemical, phytochemical and antioxidant properties, anti-nutritional factors and bioactive compounds of selected ornamental flowers viz., red hibiscus (both single and double), I. coccinea, I. singaporensis, R. damascena, marigold (T. erecta and T. patula), N. nucifera, N. rubra and C. sulphureus. The physico-chemical properties such as moisture, protein, fat, fibre, vitamin C, total ash and mineral contents (sodium, magnesium, calcium, iron, phosphorus and potassium) of the selected flowers were ascertained. Moisture content ranged from 45.51 (C. sulphureus) to 87.53 per cent (N. rubra). Protein content ranged between 2.03 (I. singaporensis) to 11.79 per cent (T. patula). Fat content of the ornamental flowers varied from 0.77 (single typed red hibiscus) to 10.77 per cent (T. erecta). The mean fibre content varied between 9.66 (single typed red hibiscus) to 20.00 (N. nucifera) per cent in the flowers. Ascorbic acid content of the ornamental flowers was observed to be in the range of 58.93 (T. patula) to 154.13 mg/100 g of DW (R. damascena). Total ash content of ornamental flowers studied ranged from 2.83 (N. rubra and C. sulphureus) to 10.00 per cent (N. nucifera). Sodium content of ornamental flowers ranged from 13.83 (double typed red hibiscus) to 16.23 mg/100 g of dry weight (single typed red hibiscus). Magnesium content varied from 5.61 (T. erecta) to 12.89 mg/100 g (single typed red hibiscus) in the flowers studied. Calcium content was in the range of 6.84 (R. damascena) to 31.24 mg per 100 g of DW (N. nucifera). Iron content of flowers ranged from 0.43 (R. damascena) to 2.31 mg/100 g (T. patula). Phosphorus content of the ornamental flowers ranged from 7.80 (I. coccinea) to 22.40 mg/100 g DW (T. patula). The mean potassium content varied from 40.86 (R. damascena) to 104.66 mg/100 g (N. nucifera). Phytochemicals in ornamental flowers such as carotenoids, anthocyanins, total flavonoids and phenols were also estimated. Total carotenoid content of the ornamental flowers ranged from 0.20 (R. damascena) to 8.13 mg per 100 g of DW (T. erecta). Anthocyanin content of ornamental flowers was in the range of 6.56 (T. erecta) to 187.43 mg/100 g (R. damascena). Flavonoid content ranged between 33.33 (N. nucifera) to 104.16 mg/100 g of DW (T. erecta). Phenol content of the ornamental flowers varied between 6.52 (R. damascena) to 49.80 mg/100 g of DW (C. sulphureus). Quantitative estimation of anti-nutritional factors such as tannin, oxalates and nitrates were done in the selected ornamental flowers. Tannin content of ornamental flowers ranged between 8.50 (N. nucifera) to 53.10 mg/100 g (R. damascena). Oxalate content was found to vary from 23.23 (N. nucifera) to 687.30 mg per 100 g of DW (single typed red hibiscus) of the flowers. Nitrate content varied between 6.30 (T. erecta) to 201.03 mg per 100 g DW (C. sulphureus) of the flowers. Free radical scavenging activity of the ten ornamental flowers was studied using DPPH and ABTS assays. Value of the DPPH assay ranged from 38.26 (R. damascena) to 269.32 µg/ml (double typed red hibiscus). ABTS radical scavenging activity ranged from 47.92 (R. damascena) to 738.60 µg/ml (T. patula). Estimation of physicochemical, phytochemical, anti-nutritional and antioxidant properties and bioactive compounds of the selected ornamental flowers revealed that the petals of N. nucifera recorded maximum fibre (20.00 %), total ash (10.00 %), magnesium (11.49 mg), calcium (31.24 mg) and potassium (104.66 mg) contents per 100 g DW with minimum anti-nutritional constituents such as tannins (8.50 mg) and oxalates (23.23 mg). T. patula recorded highest protein (11.79 %), fat (10.43 mg), sodium (15.30 mg), magnesium (10.61 mg), iron (2.31 mg), phosphorus (22.40 mg), potassium (79.40 mg) and flavonoid (101.00 mg) contents per 100 g DW but with lowest antioxidant properties in DPPH (257.57 µg/ml) ABTS (738.60 µg/ml) assay. Highest content of fat (10.77 mg), sodium (15.86 mg), carotenoids (8.13 mg) and flavonoids (104.16 mg) with lowest nitrate (6.30 mg) values per 100 g DW were noticed in T. erecta. R. damascena registered maximum sodium (15.23 mg), vitamin C (154.13 mg), anthocyanins (187.43 mg/100 g DW) and antioxidant properties in DPPH (38.26 µg/ml) as well as ABTS (47.92 µg/ml) assay, but having high tannin content (53.10 mg) per 100 g DW. H. rosa-sinensis (single) showed highest quantity of sodium (16.23 mg), magnesium (12.89 mg) and anthocyanins (184.82 mg) but with maximum oxalate content (687.30 mg) per 100 g DW. H. rosasinensis (double) showed highest quantity of magnesium (11.30 mg) and anthocyanins (186.63 mg) per 100 g DW but with least antioxidant property (269.32 µg/ml) as revealed in the DPPH assay. Petals of N. rubra registered maximum moisture content (87.53 %) and antioxidant properties in DPPH assay (47.04 µg/ml) with lowest nitrate (7.73 g) content per 100 g of DW. Cosmos recorded highest quantity of sodium (14.80 mg), iron (1.85 mg) and phenols (49.80 mg) but with maximum quantity nitrates (201.03 mg) per 100 g DW. I. coccinea recorded maximum sodium content (15.43 mg/100 g DW) among the ornamental flowers tested. GC-MS analysis of ten ornamental flowers revealed the various compounds present in its methanol extracts. Flowers of I. singaporensis contained more compounds (18) compared to rest of the flowers. The most abundant compound in I. singaporensis was (1R, 3R, 4R, 5R)-(-)-Quinic acid (70.60 %) whereas in I. coccinea, it was stigmast-5-en-3-ol, 3.beta (45.33 %). The most abundant compound in C. sulphureus was benzene, 1-chloro4-methoxy- (34.22 %) while in T. erecta -amyrin (42.37 %). Damask rose and red water lily contained eight compounds each. The most prevalent compound in Damask rose was 1, 2-benzenedicarboxylic acid (37.74 %) whereas in red water lily, it was heptacosane (44.27 %). Flowers of both single and double petalled hibiscus were found to contain seven -amyrin (83.41 %) was found in single petalled red hibiscus while 9-octadecenoic acid, 12-(acetyloxy) (25.56 %) and 9-octadecadienoic acid (25.51 %) were the most abundant in double petalled red hibiscus. Six different compounds were found in methanol extracts of both sacred lotus and T. patula. Most abundant compounds in the flower extracts of lotus were 9, 12, octadecadien-1-ol (34.74 %) and 9-octadecenoic acid, 12-(acetyloxy)-, methyl ester, [r-(z)]- (22.70 %). The predominant compound in T. patula was vitamin E (59.67 %). The present study revealed that the selected ornamental flowers are having nutritional value with high antioxidant properties and low anti-nutritional contents. The GC-MS analysis of ornamental flowers showed that they contained a variety of beneficial compounds that can act as nematicide, pesticide, anti-cancerous, antimicrobial, antifungal, antioxidant and anti-inflammatory agents. Some compounds identified in this study were reported to have anti-xanthine oxidase and anti-tyrosinase potentials. The compounds identified in the flowers could be used for the development of novel drugs also.Item Standardization of grafting techniques in african marigold (tagetes erecta L.) for combating bacterial wilt(Department of Floriculture and Landscaping, College of Horticulture, Vellanikkara, 2018) Athira Baburaj; Sreelatha, UThe present study entitled “Standardization of grafting techniques in African marigold (Tagetes erecta L.) for combating bacterial wilt” was taken up in the Department of Floriculture and Landscaping, College of Horticulture, during the year 2017-2018. The work was carried out under three experiments viz.,standardisation of grafting techniques, assay of enzyme activity and histological studies. The rootstock used in the study was the bacterial wilt resistant local collection M- and the wilt susceptible F1hybrid Maria 91 was used as scion. Grafting was done in the month of January. Three methods of grafting viz., cleft, splice and hole insertion were tried at different ages of rootstock (4, 5, 6 and 7 weeks after sowing) and different ages of scion (3, 4 and 5 weeks after sowing). Observation of graft survival was taken at 15 DAG (Days after grafting). It was observed that cleft grafting four week old scion on to six week old rootstock was found to be the best with a graft survival of 61 percent. It was also observed that there was no survival when grafting was done on four week old rootstock irrespective of age of scion and grafting method followed. Estimation of catalase and peroxidase was carried out to study the activity of these enzymes in graft union formation. Sampling was done at 4,8 and 15DAG. It was observed that, activities of both the enzymes increased from 4DAG to 15DAG. Highest catalase activity at 4th (0.85 EU/g), 8th (1.39 EU/g) and 15th (1.60 EU/g) DAG was observed in cleft grafting of four week old scion on to six week old rootstock. Similar results were also observed in peroxidase activity. Correlation of catalase and peroxidase activity with survival of grafts indicated that both the enzymes are positively correlated with graft survival. Histological studies of the grafts consisted of both anatomical studies and histochemical staining for lignin. It was observed that there was an intensification of the stain from 4DAG to 15DAG with advancement of lignification process in graft union. Histological studies also revealed the formation of necrotic layer in the graft union, as a result of wound repair and cell proliferation. Cleft grafting of four week old scion on six week old wilt resistant rootstock is the best method in African marigold for combating bacterial wilt.