Effects of Selection on Morphological Characteristics in \u3ci\u3eSetaria sphacelata\u3c/i\u3e (Schumach.) Moss

Cattle production in Florida is limited by the lack of available warm-season forages adapted to the cool winters of the region. Setaria (S. sphacelata) has demonstrated green growth during cool conditions in subtropical climates around the world, and has the potential to fill this niche in cattle production in Florida. Four populations were selected in Gainesville and Ona, Florida: two cycles of selection for increased head number, one cycle for increased leaf width and one cycle for grazing tolerance. The objectives of this research were to compare these populations morphologically to determine changes due to selection. Selection for leaf width increased this trait while maintaining other morphological characteristics constant. Selection for head number decreased plant height and increased head number in each cycle, and decreased leaf width and inflorescence length in the second cycle. Selection for grazing regrowth resulted in reduced plant height and inflorescence length. Concern regarding susceptibility of Setaria to chinch bug and possible winter killing in Florida remain to be resolved before this species may be commercialized in Florida

Grass and Forage Plant Improvement in the Tropics and Sub-Tropics

The majority of tropical and subtropical forage grass genera and/or species have not yet been collected, or need further collection to be representative of their natural distribution. New biotechnological techniques will only result in the release of superior forage cultivars if supported by strong breeding programs. More funding and investment in the formation of strong public research teams in forage conservation and improvement are needed to guarantee the sustainability of tropical and subtropical pasture-based livestock systems in the future. The creation of a permanent international working group on tropical and subtropical forages is essential to assist the International Plant Genetic Resources Institute (IPGRI) in prioritising collection, conservation, evaluation and adoption in the tropical/subtropical world for the benefit of mankind

Grass and Forage Plant Improvement in the Tropics and Sub-Tropics

Key points 1. The majority of tropical and subtropical forage grass genera and/or species have not yet been collected, or need further collection to be representative of their natural distribution. 2. New biotechnological techniques will only result in the release of superior forage cultivars if supported by strong breeding programs. 3. More funding and investment in the formation of strong public research teams in forage conservation and improvement are needed to guarantee the sustainability of tropical and subtropical pasture-based livestock systems in the future. 4. The creation of a permanent international working group on tropical and subtropical forages is essential to assist the International Plant Genetic Resources Institute (IPGRI) in prioritising collection, conservation, evaluation and adoption in the tropical/subtropical world for the benefit of mankind

Evaluation of Guineagrass (\u3ci\u3ePanicum maximum\u3c/i\u3e Jacq) Hybrids in Brazil

Guineagrass (Panicum maximum Jacq.) is responsible for a high percentage of cattle finishing and milk production in Brazil, but presents problems of pasture degradability due to high soil fertility requirements and uneven production distribution. In order to search for new varieties to reduce these problems, over four hundred apomictic accessions of guineagrass and several sexual plants were introduced to Brazil in 1982. Agronomic evaluation took place at the National Beef Cattle Research Center of the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle), in Campo Grande, MS, Brazil. Breeding of the apomictic species began in 1990 using sexual x apomictic crosses. Three sexual plants and five apomictic accessions were used in the crosses. Seventy-nine hybrids were evaluated in small plots, for forage yield, regrowth after cuts, flowering and vigor during three years. The best families were identified for each characteristic evaluated. Multivariate analysis using principal components grouped the hybrids into six clusters according to their production. Due to superior performance, hybrids in groups 6 and 2 (22 hybrids) were indicated for future regional trials in small plot evaluations and grazing studies, aiming at releasing new cultivars for pasture diversification in Brazil

Potential of \u3cem\u3ePanicum maximum\u3c/em\u3e as a Source of Energy

The use of plant biomass as a source of energy presents many advantages, mainly that it is a renewable, clean source of energy. Many tropical grasses have excellent po-tential as energy crops. The main one in Brazil is Pennisetum purpureum (elephant grass) owing to its very high yields. However, it is vegetatively propagated, thus more difficult to establish than seed propagated species. The use of Panicum maximum (guinea grass) is a possible alternative for use as a source of energy, due to its high yields as well as seed propagation. The objective of this research was to evaluate the potential of different P. maximum genotypes for use as energy crops, in comparison with elephant grass

De Novo Transcriptome Assembly For The Tropical Grass Panicum Maximum Jacq.

Guinea grass (Panicum maximum Jacq.) is a tropical African grass often used to feed beef cattle, which is an important economic activity in Brazil. Brazil is the leader in global meat exportation because of its exclusively pasture-raised bovine herds. Guinea grass also has potential uses in bioenergy production due to its elevated biomass generation through the C4 photosynthesis pathway. We generated approximately 13 Gb of data from Illumina sequencing of P. maximum leaves. Four different genotypes were sequenced, and the combined reads were assembled de novo into 38,192 unigenes and annotated; approximately 63% of the unigenes had homology to other proteins in the NCBI non-redundant protein database. Functional classification through COG (Clusters of Orthologous Groups), GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses showed that the unigenes from Guinea grass leaves are involved in a wide range of biological processes and metabolic pathways, including C4 photosynthesis and lignocellulose generation, which are important for cattle grazing and bioenergy production. The most abundant transcripts were involved in carbon fixation, photosynthesis, RNA translation and heavy metal cellular homeostasis. Finally, we identified a number of potential molecular markers, including 5,035 microsatellites (SSRs) and 346,456 single nucleotide polymorphisms (SNPs). To the best of our knowledge, this is the first study to characterize the complete leaf transcriptome of P. maximum using high-throughput sequencing. The biological information provided here will aid in gene expression studies and marker-assisted selection-based breeding research in tropical grasses.8e7078

Reciprocal Recurrent Selection in the Breeding of \u3cem\u3eBrachiaria decumbens\u3c/em\u3e

Pastures of Brachiaria decumbens cv. Basilisk radically changed the scenario of livestock production in central Brazil in the early 1970s and in fact, promoted the development of this vast region. However, despite the reasonable biomass yields and nutritional value when grown on these tropical acid soils, its susceptibility to grassland spittlebugs has limited its use. The breeding of B. decumbens in Brazil has been restricted to interspecific crosses using cv. Basilisk as a pollen donor due to the lack of compatible sexual ecotypes within this species. Recently, the successful chromosome duplication of a sexually reproducing diploid accession produced 3 successful events (Simioni and Valle 2009), enabling intraspecific crosses. This paper reports the onset of the research to obtain superior apomictic hybrids in B. decumbens using reciprocal recurrent selection (RRS), a cyclic breeding strategy

Development of \u3ci\u3eMegathyrsus maximus\u3c/i\u3e Genotypes for Intensification of Cattle Rearing in Brazil

Megathyrsus maximus is a forage species used over 30 million hectares in Brazil and in the surrounding countries for intensification of the cattle production systems. Due to the large area and distinct biomes in which it is used, there is a need to continuously develop more productive and adapted cultivars to each biome and use. Three apomictic accessions were crossed with five sexual plants at Embrapa Beef Cattle in Campo Grande, MS, Brazil in 2014. More than 1100 hybrids were planted in a spaced-plant field and evaluated visually for regrowth after cuts and for disease and pest damage. In 2016, the best 154 hybrids together with the parentals and standards were planted in small plots with replication, and evaluated for two years for forage production and quality under a harvest cutting regime. From the nine harvests performed, the best twenty-three hybrids and four standards were planted to a field on 12 m2 plots with three replications on February 2019. These genotypes were evaluated under cuts every 35 days in the rainy season and at the end of the dry season in a total of 10 harvests. Leaf dry matter yield varied from 6.0 to 15.1 tons ha-1 with a dry season percentage of 5.7 to 12.8%. Leaf percentage varied from 59 to 92% and seed yield from 50 to 158 kg ha-1. The genotypes were grouped taking into account production, quality and morphological characteristics. Selection of the best ones is presented and discussed viewing evaluation under grazing before release in the market