Variation of Pollen Viability in \u3ci\u3eBrachiaria\u3c/i\u3e Species and Opportunity in Increased Filled Seed Percentage

On pseudogamy process, pollen fertility affects endosperm development in Brachiaria apomictic hybrids. Also, it was well-known that self-incompatibility could affect the fertilization in cross pollination species. Evaluation of pollen viability and percentage of filled seed, and the demonstration of pollen induction technique for increasing filled seed percentage in Brachiaria spp. are presented in this paper. In the first experiment, 8 cultivars/breeding lines of Brachiaria, including 2 open-pollinated cultivars, an apomictic cultivar and 5 hybrids, were planted in randomized completely block design, with 3 replications at northeast Thailand. Each experimental unit consisted of 20 plants, 6 central plants were evaluated. Four anthers of each plot were collected, and pollen cells were stained by iodine-potassium iodide. The specimens were investigated under microscope, with stained cell was classified as viable pollen, whereas non-stained cell was non-viable one. Percentages of filled seed were determined by hand counting method. It was found that both traits showed variation significantly), however, there was no correlation between them. In the second experiment, a hybrid (tetraploid B. ruziziensis × B. decumbens) was planted with other genotypes in crossing cage, with 4 replications of completely randomized design. Because of the failure of inflorescence development in hybrid in some cages, hence, analysis of variance could not be performed. However, the data showed evidence that growing hybrid with tetraploid ruzigrass could improve filled seed percentage of hybrid