Brazil creates its first Brachiaria ruziziensis grass cultivar

The forage genetic improvement program conducted by Embrapa developed the first cultivar of Urochloa ruziziensis or Brachiaria ruziziensis, as the grass was scientifically called. This cultivar was developed for the soil and climate conditions in Brazil and was named BRS Integra because it is intended for crop, livestock and forest integration systems (ILPF).

According to Embrapa Dairy Cattle researcher Fausto Souza Sobrinho, who conducted the studies, compared to the cultivar currently available on the market (cv. Kennedy), BRS Integra presents greater forage production in the off-season, when the grass is single in the area. “This difference, during the dry period, makes the cultivar more suitable for ILPF, and can contribute to increasing the productivity of these systems”, explains Souza Sobrinho.

Before BRS Integra, cv. Kennedy was the ruziziensis cultivar available on the forage seed market. The problem is that it was not developed specifically for Brazilian soil and climate conditions. For the researcher, despite having good adaptation to the country's different environmental conditions, the Kennedy cultivar presents lower forage production compared to cultivars of other brachiaria species such as brizantha or decumbens. “This happens mainly in winter, during the off-season of crops, when in integrated cultivation systems, forage crops are found alone in the area or accompanied only by the forestry component”, explains Souza Sobrinho.

By maintaining high productivity in winter, BRS Integra can be used both as forage for cattle feeding during the off-season, and as straw for the next planting of crops. The scientist also explains that, although brizantha and decumbens have a larger cultivated area In the country, ruziziensis has been increasing its space with the increase in ILPF. “The species has been widely used in these systems due to its better adaptation to overseeding compared to the others. Fellow Embrapa researcher Alexandre Brighenti points out another advantage. “Ruziziensis is more sensitive to herbicides, requiring lower doses in the pre-sowing desiccation of crops in no-till systems.” Furthermore, the species' seed production is uniform, as it only flowers once a year, making it easier to control.

Brachiaria's new name: Urochloa

Originally from Africa, it has good adaptability to low fertility soils and different climates and latitudes, in addition to being aggressive in competing with weeds and providing good animal performance. These qualities have made the brachiaria genus almost synonymous with pasture. Cultivated in tropical regions, the grass has a hundred species. In addition to ruziziensis, others that are well known and used in Brazil are decumbens, brizantha and humidicola.

Of a total of 180 million hectares of pastures in the country, 80% belong to the Brachiaria genus. Or belonged. Recently, scientists reclassified almost all brachiariae to the genus Urochloa. Reclassification follows taxonomic criteria (classification standards) whose function is to organize plants and animals, facilitating the study and identification of living organisms. In this way, each plant or animal has a name (genus) and surname (species), but changes can occur to facilitate the work of scientists.

That's what happened with Brachiaria. However, for legal reasons, since the last taxonomic reclassification, the scientific nomenclature for “brachiaria grass” is now “Urochloa (synonymy, Brachiaria)” or “Brachiaria (synonymy, Urochloa)”. The luck is that, for the producer, nothing changes and “brachiaria” can continue to be called brachiaria, as we did in this report. The same goes for idiomatic expressions and no one needs to “leak in urochloa” if they want to quickly leave somewhere. “Leaking in brachiaria” is still a valid way to withdraw.

Embrapa recommendations for the cultivation of BRS Integra

Composed of vigorous, medium-sized plants, with a height between 80 cm and 110 cm, BRS Integra has good soil coverage capacity and growth tends to be upright. Its leaves have an arched final third and measure an average of 25 cm (length) and 1,5 cm (width). The plant has thin stems and a high rate of tillering, both basal and axillary (aerial tillers). In the experimental field at Embrapa Gado de Leite, in Coronel Pacheco (MG), flowering occurs in February and March and seed maturation occurs in April and May. Compared to cv. Kennedy, the production of total forage and straw from the new cultivar in autumn/winter (dry period in much of the country) is greater. Suitable for the Atlantic Forest Biome, BRS Integra adapts to soils of medium to high fertility, and can be cultivated from sea level to 1.800 meters of altitude.

Researchers recommend avoiding planting in humid floodplain areas or areas subject to flooding. If sowing is exclusive, that is, for the formation of pasture, the soil must be prepared conventionally, carrying out plowing and harrowing, according to the needs and condition of the land. When sowing, special attention is required to control weeds so as not to compromise the establishment and longevity of the pasture. In the case of intercropped plantings, in integrated cultivation systems, sowing may be carried out simultaneously with crops. Another way is to carry out planting, with a delay of a few days in relation to the crop, in order to avoid or reduce initial competition with it and, also, through overseeding close to the crop's harvest.

- Liming – must be carried out at least 60 days in advance of the scheduled sowing date, based on the results of the soil analysis, aiming to achieve 50% base saturation, using dolomitic limestone, under conditions of low Mg content +2 applied before plowing the soil, thus increasing the efficiency in correcting acidity.

- Fertilization for establishment or planting – needs to be based on the results of the soil analysis. In tropical conditions, the biggest limitations in relation to soil fertility are related to low phosphorus levels and soil acidity. Therefore, it is only recommended to apply phosphate fertilizer, based on 100 kg/ha of P2O5, distributed at the bottom of the furrows, or broadcast. The application of potassium should be carried out when the exchangeable potassium content in the soil is less than 50 mg/dm3, at a dose of 80 to 100 kg/ha of potassium chloride (KCl).

- Maintenance/topping fertilization – it must be carried out 60 days after sowing, with the application of 200 kg of N and K2O and 50 kg of P2O5 per hectare/year being recommended, divided into three equal applications (beginning, middle and end of the rainy season). Phosphate fertilizer can be applied once at the beginning of the rainy season. Fertilization must be carried out throughout the rainy season, when soil moisture conditions are favorable.

- Seeding - Sowing can be carried out either with machines or broadcast, using high quality seeds between two and ten kilos/ha of viable pure seeds. When the purpose is direct sowing, aiming only at straw production, smaller quantities of seeds are normally recommended. Broadcast sowing requires larger quantities of seeds, which must be increased when the objective is the formation and rapid establishment of a pasture.

- Pasture leafhoppers – BRS Integra is susceptible to grasshopper leafhoppers, as is cv. Kennedy.

The development of BRS Integra

The fact that there was only one ruziziensis cultivar available on the seed market, without detailed information about its forage potential, made it difficult to expand the cultivated area. “Associated with the increasing increase in the area cultivated with ruziziensis, the problem led Embrapa to research new cultivars capable of meeting the demand of Brazilian livestock,” says Souza Sobrinho. According to him, the development of the species focused on obtaining cultivars with high productivity and good forage quality. The possibility of use in ILPF systems, which have expanded in the last decade, marked the path for the development of BRS Integra.

“The breeding program’s strategy was recurrent phenotypic selection, which is based on cycles of evaluation, identification and selection of the best individuals and their recombination to obtain new improved populations, that is, with higher frequencies of desirable alleles”, he explains. the researcher. The existence of genetic variability between progenies or plants of ruziziensis for all characteristics evaluated, observed in the first cycles, has boosted the species' genetic improvement program and shown the possibility of selecting superior genotypes.

At the end of the third selection cycle, 14 improved populations were obtained for further evaluation. These groups were identified basically by their superiority in relation to productivity and forage quality. The population called "REC 2" stood out in subsequent evaluations, including tests to determine the value for cultivation and use (VCU) under cutting, carried out between 2013 and 2016. The genetic material was also tested under grazing following the standards of VCU of the Ministry of Agriculture, Livestock and Supply (Mapa), in the years 2016 to 2018. In these grazing trials, the "REC 2" population was similar to the commercial cultivar (Kennedy) both in forage productivity and performance animal.

Similarities between the two cultivars were also verified in comparative trials of the milk productivity of crossbred cows. In this case, although animal productivity was similar, BRS Integra confirmed the results obtained in the VCU tests under cutting, producing greater amounts of forage and leaves and lower amounts of dead material in the dry season of the year, in addition to presenting a better relationship between leaves and stems most of the year, compared to Kennedy.

The "REC 2" population, after confirming its superiority in the VCU trials, was registered in MAPA as a new cultivar under number 40794, on 29/04/2019, being called U. ruziziensis “BRS Integra”. This new cultivar received, from MAPA, cultivar protection certificate number 20210042 on 21/01/2021.