N Save Nature to Survive 8(4): 1489-1492, 2013 (Supplement on Genetics & Plant Breeding) www.thebioscan.in 1489 INDUCED MUTAGENESIS IN CHRYSANTHEMUM MORIFOLIUM VARIETY ‘OTOME PINK’ THROUGH GAMMA IRRADIATION KIRAN KUMARI, K. K. DHATT AND MANISH KAPOOR 1 * Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana - 141 004, Punjab, INDIA 1 Department of Botany, Punjabi University, Patiala - 147 002, Punjab, INDIA e-mail: jdmanishkapoor@yahoo.com INTRODUCTION Chrysanthemum, one of the top 10 cut flowers of the world, is member of the family Asteraceae. It is native to Northern hemisphere, chiefly Europe and Asia, (Anderson, 1987). The basic chromosome number of chrysanthemum is x=9, however a ploidy level ranges from 2n=36 to 45, 47, 51-57 (Nazeer and Khoshoo, 1983). Being a cross pollinated species many new chrysanthemum varieties were developed by hybridization. High degree of heterozygosity coupled with frequent polyploidy cause a complex inheritance of genetic factors, which pose serious handicap in conventional breeding. Chrysanthemum is easy to multiply through vegetative means and its higher ploidy level is suitable for inducing mutation through chemical as well as physical means. Induced mutations consequently have a high potential for bringing about further genetic improvement. Although a large number of varieties are available in market but due to ever increasing demand of new types, there is still a scope for the development of new varieties. The induction of mutation in chrysanthemum has attracted considerable attention as any mutation in the dominant gene is easily expressed in the first generation. Thus, the selection of mutants of directly perceptible characters like flower colour, shape and size etc. is generally very easy and can be directly put to commercial use. More mutations have been documented in the pink cultivars as compared to others (Datta and Banerji, 1993). The present study aimed to induce mutations for flower colour and form in chrysanthemum variety ‘Otome Pink’ through gamma irradiation and to study the different morphological and anatomical changes associated with gamma ray irradiation. MATERIALS AND METHODS The present investigation was carried out at the experimental farm of the Department of Floriculture and Landscaping, Punjab Agricultural University Ludhiana during 2010-11. Rooted cuttings of chrysanthemum variety ‘Otome Pink’ (Korean Double type) were irradiated with 0, 10, 15 and 20 Gy of gamma rays from a 60 Co source (Low Dose Irradiator 2000 ANSI-N4333.1) and immediately planted in the pots under open field condition. The experiment was laid out in CRD design with 3 replications for each treatment. Data were recorded on different vegetative and floral characters in the field and final plant height, number of branches, number of leaves and flower size were recorded at full bloom stage. To determine the pollen fertility (%), pollen grains collected soon after anthesis were stained with drop of acetocarmine and viewed under microscope (Leica Bright Field Research Microscope) at 200X. Uniformly stained and round pollens were considered as viable whereas unstained and broken as non-viable and percent pollen fertility was worked out. Size of well-stained pollen grains (in µm) was recorded under microscope. Size of guard cells (µm) and size of stomatal pores was measured by microscopic observation of the replica of the leaf epidermal surface. A drop of an adhesive (Quick fix) was applied to the abaxial (lower) surface of leaf and spread thoroughly over an area of 1-2 cm 2 during mid day (11:00 - 13:00 pm) while they are still attach to plant. When solidified, the replica containing impressions of epidermis and stomata ABSTRACT Rooted cuttings of chrysanthemum variety ‘Otome Pink’ were treated with 0, 10, 15 and 20 Gy of gamma rays and evaluated for various morphological, palynological and anatomical characters. Plant survival, plant height, number of flower heads, stems per plant, stem diameter and leaves per plant reduced after gamma irradiation. The delayed flowering and plant in vegetative stage were observed at 20 Gy gamma irradiation dose. Pollen fertility, number of chloroplasts per guard cell, flower head size and fresh weight also decreased as the dose increased. The leaf abnormalities were observed in terms of changes in leaf shape, leaf size, leaf margin and leaf apex. Flower head fasciation and asymmetrical development of flower heads increased with increased dose of gamma irradiation. Various changes in flower colour and shape were recorded after treatment in the form of chimeras. Two variants, one at 10 Gy having yellow colour and other at 15 Gy having quilled petals were obtained and further multiplied vegetatively. KEYWORDS Chrysanthemum Gamma irradiation Induced mutagenesis. Received on : 13.08.2013 Accepted on : 27.10.2013 *Corresponding author