Gamma irradiations induced morphological and biochemical variations in in vitro regenerated ginger (Zingiber officinale Rosc.)- an invaluable medicinal spice.

Abstract

PURPOSE\nTo evaluate the effect of gamma irradiations on morphological and biochemical variations of in vitro shoots, regenerated plants and rhizomes of ginger (Zingiber officinale Rosc.) var. Himgiri.\n\n\nMATERIALS AND METHODS\nIn vitro established shoot cultures were treated with different doses of gamma irradiations (10-100\u2009Gy). Non irradiated shoots were used as controls. Radio sensitivity of shoots and in vitro growth parameters were recorded. Surviving shoots along with controls were multiplied, rooted and hardened. Irradiation effect on chromosomes was evaluated by comparing with controls. Various morphological and biochemical observations were recorded in regenerated plants and rhizomes and compared to controls.\n\n\nRESULTS\nIrradiated shoots showed decline in survival percentage (95% in 10\u2009Gy to 12.33% in 100\u2009Gy) with increase in dose rate after 4 weeks of irradiation. Shoot survival significantly decreased with irradiation dose rate above 20\u2009Gy. Shoot multiplication rate showed an increase from 1:2 in 1st subculture to 1:9 after 5th subculture, in 10\u2009Gy irradiated cultures with 4.5\u2009cm average length of shoots and 8.19 number of leaves after 5th subculture. Average rooting showed an increase from 15.55% after 2nd subculture to 100% after 5th subculture, in 10\u2009Gy irradiated shoots however, no multiplication and rooting was observed in higher doses. In vitro rooted shoots were subjected to hardening with 100 percent survival in a mixture comprised of soil, cocopeat and FYM. One year old hardened plants when observed for morphological variations showed non-significant variations in comparison to controls. Rhizomes obtained from 10\u2009Gy irradiated plants showed enhanced concentration of 6-gingerol and reduced crude fibre content when compared with controls.\n\n\nCONCLUSIONS\nGamma irradiation doses upto 10\u2009Gy resulted in non-significant phenotypic variations, but can positively affect biochemical composition of rhizomes leading to development of biochemically improved mutant lines of ginger with increased 6-gingerol and lowered crude fiber content. Therefore, suggesting the lower doses of gamma irradiations for improvement of biochemical constituents in vegetatively propagated plants.