Abstract
This study aimed to evaluate the end-products of meiosis in sexual and apomictic hybrids of Urochloa decumbens, so as to identify genotypes with good production of viable pollen for use in breeding programs to increase yields of pure viable seed and reduce degree of seed shattering. From 457 intraspecific hybrids of U. decumbens arising from crosses between 3 artificially tetraploidized sexual plants and the apomictic cultivar Basilisk, 27 hybrids from non-shattered seed were selected. Slides were prepared by smearing anthers and staining to determine the presence of abnormalities. The abnormalities found were micronuclei, microcytes and polyads. The data were compared by the Scott-Knott test at P<0.05. Data obtained enabled separation of hybrids into 4 groups depending on the presence of micronuclei and formation of polyads and into 6 groups based on the presence of microcytes in the tetrads. Among the analyzed apomictic hybrids, R179 has the attributes for viable seed production to proceed to cultivar development. Among the sexual hybrids, R161, R181, R193 and S47 are recommended as female parents for use in crossing programs.
Highlights
Brazil has 221.8 million head of cattle and produced 9.71 million tonnes of meat, worth R$ 523.25 billion in 2017 (ABIEC 2018), making the country one of the main producers of beef in the world
This study aimed to evaluate the end-products of meiosis in sexual and apomictic hybrids of Urochloa decumbens, so as to identify genotypes with good production of viable pollen for use in breeding programs to increase yields of pure viable seed and reduce degree of seed shattering
Many abnormalities were observed in the final products of meiosis of hybrids of U. decumbens analyzed, the main ones being 1, 2, 3 and 4 micronuclei in the microspores (Figures 1a‒1d), microcytes (Figures 1e‒1f) and polyads (Figures 1g‒1i)
Summary
Brazil has 221.8 million head of cattle and produced 9.71 million tonnes of meat, worth R$ 523.25 billion in 2017 (ABIEC 2018), making the country one of the main producers of beef in the world. This is a result of the adoption of new technologies relating to genetics and the management and feeding of beef herds (Gomes et al 2017). Brazil occupies a prominent position in the world as a producer and exporter of tropical forage seed (Pereira et al 2011). While a number of cultivars have been released, most have some limitations, so further genetic improvement is warranted. Low seed yields and seed quality are significant issues for cultivars which have been released most recently, especially the hybrids
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