Induction of genetic variability through gamma irradiation in mini marguerite (Chrysanthemum paludosum Poir.) and their RAPD-based genetic relationship

Abstract

The present investigation was conducted during the kharif season of 2010-2012 to study hormesis, morphological and biochemical attributes associated with mutation and purification of novel types in mini marguerite. The seeds of Chrysanthemum paludosum were exposed to gamma rays (source 60Co) at 20, 40, 60, 80 and 100 Gy dose treatments and sown along with control (un-irradiated seeds). Lower doses of irradiation resulted in hormesis and induced encouraging novelties, while the higher doses (100 Gy) induced elevated degree of abnormalities (6.41%), which consequently led to mortality (52.50%). Morphological characters, viz., plant height, plant spread (E-W and N-S), delayed flowering was observed in all the treatments. Biochemical characters, viz., chlorophyll a and b content as well as total chlorophyll content increased. The per cent abnormal plants, maximum deformed, per cent abnormal leaves, flower head fasciation/ asymmetrical flower heads was also observed all the treatments. Two promising mutants, viz., Star type (P1) at 40 Gy and Jasmine type (P2) at 60 Gy gamma irradiation treatment were tagged, screened and checked for stability of characters for genetic study and possible uses of the traits. The seeds of M2 and M3 generations were sown to observe their morphological characters and mutants in each population. RAPD molecular marker was used to study the genetic divergence and establishment of distinctiveness between the mutants developed, as a result of treatment of gamma rays. The results will aid in development of efficient germplasm utilization and management strategies.