Browsing by Author "Manju, A."

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    Diversity assessment, development of F1 hybrid and standardisation of micropropagation in drumstick (Moringa oleifera)
    (Department of Plant breeding and Genetics, College of Agriculture, Vellanikkara, 2024-12-20) Manju, A.
    The study entitled ‘Diversity assessment, development of F1 hybrid, and standardisation of micropropagation in drumstick (Moringa oleifera)’ was conducted as five experiments viz., characterisation of drumstick genotypes, development of F1 hybrids, evaluation of F1 progeny seedlings, standardisation of micropropagation protocols and in vivo induction of polyploidy in drumstick. The characterisation of drumstick germplasm established at NBPGR, Regional Station, Vellanikkara, aimed to study the diversity and to identify superior genotypes based on yield, biochemical and sensory characteristics. Morphological characterisation revealed that considerable variability existed among the 29 genotypes. Throughout the study, majority of the genotypes exhibited flowering and fruiting behaviour, except for IC632345, IC632353, IC632355 and Elamoringa, which exclusively produced leaves. Generally, two flowering peaks were observed from October to January and from April to June. The highest fruit weight was recorded in IC632358 (214 g), while Jaffna had the longest fruits (97.6 cm). Number of fruits per tree per year varied from 10 (IC632351 and IC632352) to 204 (IC632357). Top performing genotypes for fruit yield were IC632350 (18.70 kg) followed by IC632349 (16.52 kg), IC645217 (15.65 kg), Jaffna (15.59 kg) and IC632358 (15.29 kg). Estimation of biochemical characteristics for leaf and fruit on dry weight basis indicated that leaves were generally richer in nutrients than fruits. The highest nutrient content in leaves was recorded in Jaffna for calcium (370.5 mg/100g) and protein (25.80 g/100g), IC645256 for iron (22.50 mg/100g), IC632349 for β carotene (23.31 mg/100g) and Elamuringa for vitamin C (121.88 mg/100g). In fruits, the highest nutrient content was recorded in Jaffna for calcium (58.63 mg/100g), IC645217 for protein (8.97 g/100g), IC632356 for iron (11.11 mg/100g), IC632354 for β carotene (8.62 mg/100g), and IC632346 for vitamin C (93.39 mg/100g). The ranking of genotypes revealed that Elamuringa had the highest rank for leaf characters followed by PKM1 while, for fruit characters, Jaffna recorded the highest rank, followed by IC632356. During the organoleptic evaluation using Kendall's Coefficient of Concordance, the highest score and rank for overall acceptability was recorded in Elamuringa and Jaffna for cooked leaves and cooked fruits respectively. Significant positive correlation was observed for yield per tree with number of flowers and buds per inflorescence, pollen germination, number of fruits per bunch and number of fruits per tree. Principal component analysis (PCA) on quantitative characters revealed that the first four principal components accounted for 85.70% of the total variation, mainly contributed by pollen germination, no. of fruits per bunch, girth of fruit, thickness of flesh, no. of seeds per fruit and no. of fruits per tree. PCA on biochemical characters revealed that first three principal components accounted for 73.30% of the total variation, mainly contributed by protein, calcium, iron, β carotene and vitamin C content in fruit. The dendrogram based on morphological and biochemical characteristics categorised the 29 genotypes into six clusters. Cluster IV showed superior performance with higher numbers of fruits and yield per tree, along with higher β carotene content in leaves and fruits, and calcium content in fruits. Leafy types were grouped in clusters V and VI. Compared to other clusters, the cluster VI, which exclusively included Elamuringa, exhibited higher leaf yield and nutrient levels in leaves. Molecular characterisation of 18 selected drumstick genotypes based on morphological characters was conducted using 30 ISSR primers. Eighteen primers successfully amplified the DNA, produced 2 to 8.30 amplicons per genotype. Twelve primers showed 100% polymorphism, with ISSR 16 recording the highest polymorphic information content (0.41). A total of 16 ISSR primers generated 46 unique bands across 16 genotypes with specific band sizes. Based on molecular characterisation, the 18 genotypes were grouped into five clusters at 74% similarity. Cluster III included the leafy type Elamoringa and IC632355, showing 89% genetic similarity between them. Twelve genotypes were selected as parental lines for producing F1 hybrids in drumstick. All possible crosses were made based on the flowering pattern. A total of 50 F1 hybrid seedlings were developed from 18 crosses. Fourteen hybrid seedlings (H5P1, H5P2, H7P2, H7P3, H8P1, H8P4, H8P6, H9P1, H11P2, H14P2, H16P1, H16P2, H17P1 and H18P1) exhibited significant positive standard heterosis over PKM1 for seedling height, collar girth, stem volume index, no. of leaves, internodal length, leaf length, leaf breadth and no. of leaflets. An efficient micropropagation protocol for drumstick was developed using nodal segments from in vitro germinated seedlings of PKM1. Seeds treated with 15% sodium hypochlorite for 15 minutes achieved 94% germination with 88.4% contamination free cultures. MS basal medium with 4µM BAP produced 6.8 axillary shoots of 1.74 cm length. Root induction was optimal in half-strength MS medium with 4µM IBA (16 roots with 4.46 cm length). Acclimatisation in a sterile mixture of 1part vermiculite, 1part perlite, 1part cocopeat, and 1part soil resulted in 85% survival. This micropropagation protocol was successfully validated in Jaffna type also. Genetic fidelity analysis using ISSR primers confirmed the uniformity between in vitro propagated plants and their mother plant. In vivo induction of polyploidy in PKM1 drumstick explored the effects of colchicine at different concentrations ranging from 0.1% to 0.8% on young seedlings and axillary buds. As the concentration increases, a gradual reduction in plant height, leaf and leaflet number and internodal distance was observed. However, larger leaflets and stomata with decreased stomatal density in treated plants, indicated polyploidy. During flow cytometry analysis, sixteen plants showed mixoploidy with 7.9% to 16.4% tetraploid cells over the control (2.7%). Among these, five mixoploids (T1SP3, T3SP1, T3SP4, T3SP5 and T4 BP1) were identified with higher percentage of tetraploid cells and increased nutrient content for protein, β carotene and vitamin C.