LETHAL DOSIS (LD50) DETERMINATION USING Co60 ON Agave tequilana var. Azul VITROPLANTLETS

Abstract

The agave crop (Agave tequilana Weber var. ‘Azul’) is the source for tequila. It has important social, cultural and economic impacts, particularly on employment needed to fulfill the activities around the crop and industry. Low genetic diversity is present in the cultivar; thus, induction of genetic variability via mutagenesis can be an option. In this research the mean lethal dose (LD₅₀) of Co⁶⁰ gamma rays for inducing genetic variability on agave in vitro callus and plantlets was quantified. Plantlets were obtained by incubating agave explants on a Murashige and Skoog (MS) medium containing growth regulators which promoted growth of axillary buds. Calli were irradiated six weeks after induction and plantlets at 12 weeks of development. In both cases, doses applied were: 0 (control), 10, 20, 30, 40 and 50 Gy. Statistically differences were obtained for plantlets and calli growth; significant effects appeared at radiation level above 20 Gy for calli and 30 Gy for plantlets. Linear and quadratic regression models between doses and variables were appropriate; R² for the linear model was 0.62, while the quadratic model had R² = 0.74. LD₅₀ was fixed between 20 and 25 Gy for plantlets and 16 Gy for callus, based on the quadratic model.