Dr. Mukesh KumarCHETAN CHAUHAN2023-12-252023-12-252023-09https://krishikosh.egranth.ac.in/handle/1/5810204368Name of student : Chetan Chauhan Id.No. : PG/H-3680/20 Degree : Ph.D. (Horticulture) Major : Floriculture and Landscaping Architecture Minor : Agricultural Biotechnology Advisor : Dr. Mukesh Kumar (Prof. & Head) Thesis Title : Effect of different chemicals on vase life of dahlia flower, expression analysis of Senescence Associated Genes (SAGs) and their In-silico analysis ABSTRACT The present investigation was conducted to study effect of different chemicals on vase life of dahlia flower, expression analysis of senescence associated genes (SAGs) and their In-silico analysis. During two successive season 2021-22 and 2022-23 with different concentration viz. 100 ppm, 150 ppm and 200 ppm of SNP and GA3 as a foliar spray were applied on dahlia plant. The result indicated that plants treated with GA3 @ 200mgL−1 significantly increased that tallest plant (121.54 cm), number of branches per plant (12.50), Plant Spread (98.72 cm), number of flowers per plant (15.00), stalk length (19.90 cm) and number of tubers (11.00) while maximum stem diameter (15.67 mm) and highest tuber yield per plant was recorded in GA3 100 ppm and GA3 150ppm respectively. The most rapid flower bud initiation (50.21 DAP) and days to 50% flowering (75.21 DAP) occurred when plants were sprayed with GA3 at 200mgL-1. SNP gives better result compared than control but GA3 more improved the all attributes of dahlia plant. In regards the post-harvest studies of flowers like as relative fresh weight, solution uptake, pH, diameter, MSI and anthocyanin % observed lower across all days and the treatments, T15 (SNP 20mg/l + GA3 20mg/l) showed a higher activity on above all characters. The maximum vase life of cut flower (9.10 days) markedly extended by postharvest application of treatment T15 (SNP 20mg/l + GA3 20mg/l) and the control had the shortest vase life (5.45 days). SNP and GA3 has been proved to improved antioxidant activity in petals of dahlia cut flower as compared with untreated cut flower, the activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity increases while lipid peroxidation (MDA concentration) activity decreases. A comprehensive study of transcriptomics was conducted on all six samples, resulting in the generation of a total of 236,596,534 reads and from the total 371474 transcripts using BLASTx analysis a total of 3822 differentially expressed genes (p<0.05) were represented in the results, comprising 2628 upregulated unigenes and 1194 down-regulated unigenes. In in silico characterization 18 senescence associated XTH genes were discovered from the transcriptome assembly and their sequence alignment, phylogenetic structures, conserved domains, evolutionary relationships, subcellular localizations, protein structures, and codons were studied. For gene expression analysis out of 18 genes 5 genes were expressed in dahlia cut flower, in which 3 genes (DaXTH5, DaXTH7 and DaXTH14) were upregulated and 2 genes (DaXTH3 and DaXTH11) were downregulated in treated flower as compared with untreated flower. Mukesh Kumar Chetan Chauhan (Advisor/chairman) (Author)EnglishThesis