Resumen

HERNANDEZ-MUNOZ, Selene et al. DL₅₀ AND GR₅₀ determination with gamma rays (⁶⁰CO) on in vitro Laelia autumnalis protocorms. Agrociencia [online]. 2017, vol.51, n.5, pp.507-524. ISSN 2521-9766.

Laelia autumnalis is an orchid with high ornamental value in Mexico. Yet, their marketing is restricted because no commercial quality varieties exist. Mutagenesis radiation is an effective method for generating varieties. These depend on the radiosensitivity of the radiated tissues. The aim of the study was to determine the lethal and mean reductive dose to gamma rays in L. autumnalis protocorms treated with 0, 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 Gy. The experimental design was completely random, with three repetitions and 500 to 700 protocorms as the experimental unit. Fory five days after irradiation (DAR) survival rates photosynthetic protocorms, protocorms with pro-meristems and leaves, and protocorm fresh matter were quantified. At 214 DAR we evaluated the number of leaves and roots, root length, leaf and pseudo-bulbs, width and length, and, fresh biomass and seedling biomass we evaluated in 15 seedlings per treatment. The data were analyzed with ANOVA, Pearson correlation, Tukey test (p≤0.05) and linear regression. Radiation with 5 to 20 Gy did not affect protocorms survival, doses between 20 and 30 Gy stimulated the chlorophyll presence. The length of the seedlings from the 5 Gy treatment increased 32 %. From 40 Gy fresh biomass (44 %) and leaf width (25 %) decreased. The correlation between radiation levels and protocorms survival (-0.91), leaf formation (-0.90), weight of fresh matter of protocorms (-0.69) seedling (-0.56) and seedling length (-0.57) were highly significant. The LD50 for protocorm survival and the mean reductive dose for leaf formation were 53 and 28 Gy, each. The radiation dose to induce variability in Laelia autumnalis protocorm is between 28 and 53 Gy.

Palabras llave : Laelia autumnalis; breeding; mutagenesis; ionizing radiation; orchids.

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