Uso de radiação gama para aumentar a variabilidade genética em capim-jaraguá

Spontaneous or induced mutations provide important genetic variability, useful to many plant species breeding programs. wit the objective to observe mutagenic effect of gamma radiation in Jaragua grass (Hyparrhenia rufa), seeds were irradiated with the dose of 400 Gy from 60Co source. The M1 generation was evaluated in the field. Different morphological characters were recorded, such as divergent racemes, awnless spikelets, low growth, narrow leaves, and chimerism. Vo variation in flowering time was observed. A preliminary progeny test with M2 off-type and control plants showed variation within progeny mainly for the character divergent racemes, which presented Mendelian segregation. Embryo sac analysis, by the clearing technique with phase contrast microscopy, showed the presence of single and multiple aposporous embryo sacs as well as a lower frequency of meiotic embryo sacs indicating the facultative apomictic breeding system of this species. Further investigation is needed to verify whether irradiation has caused a break in apomixis.