GERMINACIÓN Y ASPECTOS MORFOLÓGICOS DE PLÁNTULAS DE Echinocactus platyacanthus Link & Otto TRATADAS CON RAYOS GAMMA

Background. The sweet biznaga (Echinocactus platyacanthus) is endemic to Mexico, whose seeds show low germination, viability, longevity, genetics, and latency; therefore, gamma irradiation is an alternative to stimulate the emergence and growth of seedlings, by causing variations in the chemical composition of DNA, which causes cytological, biochemical, physiological and morphological changes in plants. Objective. The objective of the present investigation was to evaluate the effect of different doses of gamma ⁶⁰Co radiation on seed germination and seedling vigor of E. platyacanthus. Methodology. E. platyacanthus seeds were irradiated at 0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500 and 550 Gy of ⁶⁰Co gamma rays, then they were sown in transparent plastic containers covered with filter paper and were distributed in a completely randomized design with four repetitions in a germination chamber, the percentage of germination and survival of seedlings in the container was recorded 30 days after sowing (das). The seedlings were transplanted at 30 das into black polyethylene bags with tezontle and established in a completely randomized design with 12 treatments and four replications, in a tunnel-type greenhouse. At 20 and 30 days after transplantation (dat) seedling vigor was measured based on height (cm), stem diameter (mm) and root length (mm) and at 20 dat survival was recorded (%) of seedling in the substrate. An analysis of variance and Tukey's test for comparison of means (p ≤ 0.05) were performed. Results. Gamma irradiation stimulated seed germination from 10 to 29%. In seedlings, root height and length were modified with intermediate doses of gamma rays (100 to 200 Gy); but higher doses negatively affected these indicators. Survival of containerized M₁ seedlings was up to 63% higher than the control, depending on the irradiation dose. Implications. Irradiation with ⁶⁰Co gamma rays improves seed germination, survival and vigor of E. platyacanthus seedlings. Conclusions. Irradiation with ⁶⁰Co gamma rays stimulated seed germination and improved some characteristics of vigor in E. platyacanthus seedlings, by modifying root height and length according to age. In addition, it increased the survival of containerized seedlings.