Urochloa Ruziziensis Research Articles

Secondary metabolites of Urochloa ruziziensis on growth, nodulation, and spectral responses of soybean

Ruzigrass (Urochloa ruziziensis) is a widely cultivated plant alongside soybeans, particularly in integrated crop and livestock systems, due to its fast growth and adaptability to different conditions. This study aimed to assess the impact of secondary metabolites found in ethanolic extract from ruzigrass on soybean growth, nodulation, spectral responses, and soil microbiological attributes. The ethanolic extract of ruzigrass presents total concentration of flavonoids (852.5 µg g−1), including naringenin and kaempferol. Increasing doses (100, 200, 300, and 400 kg ha−1) of the extract were then applied to the soil in a greenhouse to cultivate soybean plants. The spectral analysis indicated that higher doses of ruzigrass extract enhanced photochemical reflectance, chlorophyll absorption, and total chlorophyll indices. However, the normalized differential vegetative index decreased in response to the treatments. Generally, increasing doses of ruzigrass extract led to linear improvements in plant height, leaf area, shoot dry mass, pod count, nodule count, nitrogen content, and soil microbial activity. On the other hand, root dry massand relative chlorophyll content decreased with higher doses of the extract. In conclusion, the application of Urochloa ruziziensis extract, containing secondary metabolites caused a reduction in root development and an increase in spectral indices related to abiotic stresses in soybeans. There was an increase in the biological attributes of the soil with a significant, increasing linear adjustment in the doses of ruzigrass extract applied, as well as in the soybean production components.

Optimal Time for Haymaking and Potential Production of Grass Hay on Soybean Overseeding in Brazilian Savanna

The objective of this research was to determine the potential for hay production of Quenia guinea grass (Megathyrsus maximus cv. BRS Quenia), Congo grass (Urochloa ruziziensis), and Xaraes palisade grass (Urochloa brizantha cv. Xaraes) following soybean cultivation (Glycine max) in the Brazilian Cerrado. The experimental field was divided into 12 plots, with 4 replicates of each grass species. Chemical composition, forage mass (FM), and the potential for milk and carcass production were determined for the three grasses. Principal component analysis showed that the total digestible nutrients (TDN) had the most significant influence on milk and carcass potential. Quenia guinea grass reached maximum forage accumulation at 134 days after soybean harvest, representing 4191.51 kg ha−1 of FM. Congo grass and Xaraes palisade grass produced 4033.51 kg ha−1 and 4437.22 kg ha−1, respectively, in cuts made at 154 and 138 days. Quenia guinea grass had 20.71% soluble protein in its composition when harvested at 115 days. Regarding milk production potential, Congo grass, on the other hand, showed a linear reduction in milk production as the number of days after soybean harvest increased. As for carcass production potential, Congo grass demonstrated the highest carcass production potential (110.65 kg Mg−1 FM) at 107 cutting days. Xaraes palisade grass had the highest FM production, while Quenia guinea grass stood out in soluble protein. Conversely, Congo grass showed greater potential for hay production when overseeding in soybeans, as it excelled in carcass production potential. Therefore, for this grass, the ideal point for haymaking should occur within up to 107 days after sowing.

Soybean yield, seed protein and oil concentration, and soil fertility affected by off-season crops

The main cropping system in Brazil is soybean-maize off-season, particularly in tropical climate regions. However, there is a lack of information about the effects of alternative off-season crops on soybean performance and soil chemical fertility. The objective of this study was to evaluate, in a long-term experiment, the effects of off-season crops on soybean yield, seed protein and oil concentration, and soil chemical fertility under a no-tillage system. A seven-year experiment was conducted in Londrina, Paraná, Brazil. Treatments comprised six crop systems in the soybean off-season: (i) maize with nitrogen (N) fertilizer topdressing (80 kg N ha−1, (ii) maize without N fertilizer topdressing, (iii) wheat without N fertilizer topdressing, (iv) ruzigrass (Urochloa ruziziensis) without fertilizers, (v) showy rattlebox (Crotalaria spectabilis) without fertilizers, and (vi) unplanted fallow. Maize and wheat were used as cash crops and ruzigrass and showy rattlebox as cover crops. Ruzigrass had the highest straw production (average of 6.8 Mg ha−1 year−1) and improved soil fertility, especially organic carbon and potassium concentrations in the superficial soil layer. Ruzigrass and wheat off-season provided the highest soybean yields in succession (4311 and 4228 kg ha−1, respectively), whereas maize without N and fallow resulted in the lowest soybean yields (3841 and 3825 kg ha−1, respectively). Ruzigrass off-season provided the greatest yield stability of soybean and the fallow the lowest yield stability (coefficients of variation of 14.70 % and 23.78 %, respectively). The highest soybean seed protein concentration was observed with ruzigrass (368 g kg−1) and the lowest with fallow (353 g kg−1). The highest seed oil concentration was observed in maize with N and showy rattlebox (224 g kg−1 for both off-season crops) and the lowest with wheat (216 g kg−1). The ruzigrass provided the highest soybean seed protein and oil yields (1586 and 945 kg ha−1) and fallow the lowest (1352 and 845 kg ha−1). The ruzigrass used as soybean off-season cover crop improved the soil chemical fertility and soybean grain yield.

Atributos físico-químicos de um latossolo vermelho distroférrico submetido a sucessões de culturas

ABSTRACT No-till farming is the practice closest to the concept of sustainable agriculture. The minimum soil movement and continuous contribution of crop residues to the farming system reduce erosion, mitigate the greenhouse effect, increase the organic matter content, and improve the physical and chemical quality of the soil. This study aimed to assess the effect of five-year succession cropping on the physical and chemical attributes of oxisol. The crops were sown for five consecutive years in the same plots, using a randomized block design in split plots with four replicates. The plots were crops grown in succession to soybean, namely Congo grass (Urochloa ruziziensis syn. Brachiaria ruziziensis), Congo grass intercropped with maize (Zea mays L.), pearl millet (Pennisetum glaucum), sorghum (Sorghum bicolor L.), maize, and slender leaf rattlebox (Crotalaria ochroleuca). The subplots were the following sampled soil layers: 0-5, 5-10, and 10-20 cm. The physicochemical attributes of these three soil layers were evaluated. Pearl millet cycled K efficiently, providing the soil with K concentrations equivalent to those of the K fertilization treatments. No single crop or intercrop increased the soil P concentration. Congo grass stood out for its ability to increase the Mg concentration. The 0-5 cm soil layer had the best physicochemical attributes based on the accumulated organic matter.

Performance of soybean cultivated following intercropped corn under varying nitrogen levels

The intercropping of second-crop corn with ruzigrass or showy rattlebox associated with an increase in the nitrogen (N) rate can improve the performance of soybean in succession. This study aimed to evaluate the soybean performance in succession to second-crop corn cultivated under N application rates, with or without intercropping with ruzigrass (Urochloa ruziziensis) or showy rattlebox (Crotalaria spectabilis). The experimental design was a complete randomized block design with a split-plot scheme with four replicates. The plots were composed of the cultivation of either sole corn (AG 9010 PRO) or corn intercropped with ruzigrass or showy rattlebox, and the subplots consisted of different N topdressing rates (0, 60, 120, 180, and 240 kg ha-1). Soybean (BRS 1003 IPRO) was grown in succession to corn under a no-tillage system (NTS). The evaluated variables were growth and yield. The increase in N rate in second-crop corn, with or without intercropping with ruzigrass or showy rattlebox, increased the growth and yield of soybean in succession under NTS. Second-crop corn intercropped with ruzigrass provided a greater amount of straw under NTS than sole corn or intercropped with showy rattlebox. However, intercropped systems did not influence the growth and yield of soybean grown in succession. Therefore, the corn intercropped with ruzigrass promotes the sustainability of NTS and the N fertilization in second-crop corn, which subsequently improves soybeans performance

Potential interaction of soybean-grass intercropping with residual nitrogen for a no-tillage system implementation

Combinations between crop intercropping and forage production in a no-tillage system are not well established for environments under low water retention and soil fertility conditions. Our study aimed to evaluate the potential interactions between soybean-grass intercropping with residual nitrogen in a no-tillage system. The experimental design was a randomized block with four replications in a subdivided plot scheme. The main plots in the summer season were: 1) soybean monoculture; 2) soybean - Aruana Guinea grass (Megathyrsus maximus cv. Aruana) intercropping, and 3) soybean - Congo grass (Urochloa ruziziensis cv. Comum) intercropping. The subplots were the nitrogen rates of 0, 50, 100, and 150 kg ha-1, applied as side-dressing in maize and grasses during the autumn-winter season. Here, the results of the summer seasons are shown. To do so, the parameters evaluated were soybean agronomic traits, dry biomass production, and macronutrient concentrations of plants intercropped. The main effects and interactions were studied. Our findings showed that soybean-Aruana Guinea grass intercropping is an alternative to no-tillage system implementation. Moreover, residual nitrogen from the autumn-winter season directly interfered with the dry biomass production of grasses intercropped with soybeans in the summer season. In short, the systems studied seem suitable for implementing a no-tillage system, which aims to neutralize degraded pastures and produce forage for ensilage. Despite the changes in macronutrient concentrations within the intercropping system and residual nitrogen, and among intercropped crops over the years, Congo grass intercropped with soybeans in the summer season showed great capacity for phosphorus, potassium, and magnesium cycling.

Phytophthora Root Rot in Rangpur Lime Cultivated in Soil Managed with Ecological and Conventional Mower

Root rot and gummosis caused by Phytophthora spp. are considered one of the most important citrus diseases in Brazil. Symptoms of Phytophthora spp. infection in citrus plants are associated with lesions on the bark at the base of the plant, roots, and even lower branches. Inappropriately performed cultural practices, such as excessive irrigation and practices that result in reduced aeration and soil drainage, favor the disease. The objective of this study was to evaluate the effect of Urochloa ruziziensis mulching provided by an ecological mower on the severity of Phytophthora nicotianae root rot and the development of citrus plants and their root system. The experiments were carried out under controlled conditions on Rangpur lime seedlings kept in pots containing soil from ‘Hamlin’ orange orchards with the use of an ecological mower or a conventional mower in the management of inter-row vegetation for six years. Urochloa ruziziensis mulching (9 t ha−1) was added or not to the pots. The inoculation of P. nicotianae in the roots occurred through infection of the soil with a solution containing mycelium and sporangia of the pathogen. A 2 × 2 × 2 factorial scheme was used, with the following factors A: soil type, B: inoculation of P. nicotianae and C: mulching of U. ruziziensis. The attributes of plant development, such as root growth, average number of leaves, leaves and dry mass of shoots and roots, in addition to assessments of the severity of disease in the roots, were evaluated. The mulch of U. ruziziensis did not promote an increase in root rot. The soil resulting from this management promoted the better development of Rangpur lime plants. Therefore, vegetation management of inter-row with an ecological mower is not associated with increased symptoms of Phytophthora root rot.

Association between seed production traits in Urochloa spp.

AbstractUrochloa spp. are excellent perennial forages and are among the best grasses for livestock production. The seed yield is an important trait because it impacts the seed production cost and, consequently, the cost of establishing pastures. The objective of this study was to estimate the genetic correlation between traits related to seed production in Urochloa spp. The experiment was evaluated in 2019 and 2020. Eight traits related with seed production were evaluated for 23 tetraploid progenies obtained by crossing Urochloa brizantha × Urochloa ruziziensis. There were positive correlations of high magnitude between the characters, allowing indirect selection. Two progenies showed better results in traits directly related to seed production. Days to flowering can influence the rate of seed production. The highest value for grain percentage was 20.31%.

Short-term impacts of different intercropping times of maize and ruzigrass on soil physical properties in subtropical Brazil

Intercropping maize (Zea mays L.) with ruzigrass (Urochloa ruziziensis) is a strategy for improving soil physical quality. However, effects of ruzigrass sowing time on soil physical properties with maize intercropping are unknown. Therefore, this study aimed to evaluate the short-term effects of intercropping times of maize and ruzigrass over three years (2019/2020–2021/2022) on the soil physical properties and grain yield of maize and soybean (Glycine max L.). The study was conducted in southern Brazil, in an Oxisol (602 g kg−1 of clay) under no-tillage. Under rainfed conditions, different intercropping times were evaluated during fall-winter, (i) ruzigrass sown before maize, (ii) sown at the time of maize sowing, (iii) sown 15 days after maize, and (iv) no intercropping (sole maize). Soybeans were grown every year during summer. The physical properties of the soil were evaluated during the six growing seasons. In the short-term, the bulk density in the 10–20 cm layer was 10% lower in the intercropping of ruzigrass sown before maize than that of sole maize. Macroporosity was 17% greater when ruzigrass was sown before maize compared with sowing performed 15 days after maize and it was 33% greater compared with no ruzigrass (sole maize) between the rows of maize. Although intercropping improved soil physical conditions, the soybean grain yield was not affected in two of the three years and was not correlated with the physical soil properties. In contrast, the maize yield was 17% higher when ruzigrass was intercropped 15 days after sowing maize than in the intercropping before maize sowing. The results suggest that the benefits of intercropping maize with ruzigrass on soil physical quality were greater when ruzigrass was sown before or at the time of maize sowing. The intercropping of maize with ruzigrass can be recommended as a management practice that improves the physical quality and other ecosystem services of the soil.

Plantas de cobertura e agentes de biocontrole no manejo de nematoides na cultura da soja

ABSTRACT In the Brazilian Cerrado, phytonematodes, phytonematodes are a challenge for agriculture, and the association of forms of control is the best strategy to be used in coexistence with this pathogen. Faced with this problem, this study aimed to evaluate the efficiency of cover crops and biocontrol agents in the management of nematodes in soybean. For each nematode species under study (Meloidogyne incognita and Pratylenchus brachyurus), two experiments were carried out under greenhouse conditions in a completely randomized design arranged in a 6 × 2 factorial scheme with eight replications. Six cover crops (millet ADRG 9050, millet ADR 300, Urochloa ruziziensis, Crotalaria ochroleuca, C. spectabilis, and corn hybrid DKB 290) and two treatments (treated or not with Bacillus subtilis and B. methylotrophicus - 1×106 CFU per seed) were evaluated. The cover crops were sown in soil infested with nematodes and then soybeans were sown under the straw, and cultivated for 45 and 60 days, for M. incognita and P. brachyurus, respectively. Fresh root mass, total nematode population, and the number of nematodes per gram of root were evaluated. The association of microorganisms with C. spectabilis, U. ruziziensis, and millet ADR 300 conferred an additional effect in reducing the population of P. brachyurus. For M. incognita, the association was successful only for combining C. spectabilis with B. methylotrophicus. DKB 290 corn, when treated with B. methylotrophicus, had the nematode population per gram of soybean root reduced by 90% compared to plants that did not receive biological treatment.

Protein and carbohydrate fractionation of Urochloa spp. and Megathyrsus maximus forages after intercropping with soybean in an integrated crop-livestock system

ABSTRACT The objective was to evaluate the protein and carbohydrate fractionation of forage plants of the Urochloa spp. and Megathyrsus maximus after intercropping with soybean in crop-livestock integration, in the off-season. The experimental design used was entirely randomised, with four repetitions, in a 4 × 5 factorial scheme. The treatments consisted of four forages: Xaraes palisadegrass (Urochloa brizantha cv. Xaraés), Ruziziensis grass (Urochloa ruziziensis), Mombaça guinea grass (Megathyrsus maximus cv. Mombaça), Tamani guinea grass (Megathyrsus maximus cv. BRS Tamani) and five grazing cycles (each grazing cycle was carried out every 28 days). Forage samples and protein and carbohydrate fractionation were obtained using destructive methods. The results showed that Tamani guinea grass and Xaraes palisadegrass presented higher fractions A of protein and carbohydrates and lower fraction C, being more suitable for integrated systems during the offseason. For all forages, there was a reduction in the protein and carbohydrate A fractions and an increase in the C fraction as grazing cycles advanced. Tamani guinea grass and Xaraes palisadegrass showed the best potential to be used for grazing in the off-season, by being planted as a replacement for soybean, and can be an alternative of quality food to be fed during the dry season.

Tropical Grasses—Annual Crop Intercropping and Adequate Nitrogen Supply Increases Soil Microbial Carbon and Nitrogen

In Brazil, grain crops in no-till soybean–maize succession have reduced biodiversity and carbon input into soil. Intercropping is a promising approach to address these problems. This study aimed to evaluate the microbiological quality of soil in conventional and intercropping systems in soybean–maize succession, depending on tropical grass and nitrogen fertilizer uses. The treatments were arranged in a randomized complete block design and a split plot scheme, with four replications. The main plots consisted of the following cropping systems: soybean monoculture–maize monoculture; soybean intercropped with Aruana Guinea grass (Megathyrsus maximum cv. Aruana)–maize intercropped with Aruana Guinea grass; and soybean intercropped with Congo grass (Urochloa ruziziensis cv. Comun)–maize intercropped with Congo grass. The subplots consisted of nitrogen rates (0, 50, 100, and 150 kg ha−1) applied as side-dressing in rows of maize and tropical grass in the autumn–winter season. Our results showed that maize or soybean intercropped with tropical grasses and adequate nitrogen rates favored the entry of microbial carbon and nitrogen, stimulated enzymatic activity, and reduced C-CO2 loss. However, the excess nitrogen supply can nullify the benefits of the intercropping systems. We concluded that the intercropping systems can improve soil microbiological quality in a short time with adequate nitrogen supply.

DOES THE USE OF COVER CROPS OPTIMIZE THE USE OF MINERAL NITROGEN IN SWEET PEPPER CULTIVATION?

The present study aimed to evaluate the effect of the combination between nitrogen rates and the management of straw mulches for the cultivation of peppers. The treatments comprised three managements of straw on the ground (no straw, Urochloa ruziziensis, and millet) and five nitrogen rates (0, 50, 100, 150, and 200% of the recommended dose of 120 kg ha-1). Mulch presence results in better physiological activity in the plants, while the rates of N positively affect the physiological and biometric characteristics of the plants up to 127.50% and 181.21%, respectively. Rates up to 145.62% increased fruit length in the treatment composed of U. ruziziensis straw, while rates relative to 154.65%, 127.98%, and 138.55% for the control, U. ruziziensis and millet treatments provided productive gains of 202.52%, 267.44%, and 473.18%. We concluded that straw mulching improves the physiological condition of sweet pepper plants and the application of nitrogen fertilizer; using straw from millet plants, combined with the dose of 138.55% N, results in greater yield gains.

Economic Results of Forage Species Choice in Crop–Livestock Integrated Systems

Crop–livestock integrated production systems (CLISs) combine cash-crop production and forage production in succession. There are plenty of options of forage cultivars with differences in production aspects and seeds cost, and there is little information on how the choice of forage cultivar can affect the results of a CLIS. We hypothesized that different forage cultivars can have important economic impacts on production systems. Thus, we evaluated the two-year economic results of using three forage species in a CLIS: (1) Urochloa ruziziensis; (2) Megathyrsus maximus cv. BRS Zuri e; and (3) Megathyrsus maximus cv. BRS Tamani. The system was evaluated during 2018 and 2019 with no-tillage soybean (Glycine max) cultivation from November to March and grazing of cattle from May to August. The seed costs were, on average, USD 25.27 ha−1 for Ruziziensis grass, USD 39.97 ha−1 for Zuri guinea grass, and USD 64.13 ha−1 for Tamani guinea grass. Animal production varied from 96.4 to 147.5 kg of live weight per hectare per year and mean two-year soybean yields varied from 3849 to 4217 kg per hectare, both without differences between forage cultivars. However, the lowest values for animal and soybean yields were obtained with Ruziziensis grass, and the highest were obtained with Zuri grass. Thus, Zuri guinea grass presented a net income (NI) of USD 1039.87 ha−1 with an annual return on equity (ROE) equal to 11.19%, while Ruziziensis grass obtained an NI equal to USD 612.65 ha−1 with an ROE of 6.47%, demonstrating the economic impact of forage resource choice in CLISs. Therefore, the choice of forage cultivars adequate for the conditions of an individual farm can correspond to an increase of 69.7% in net income, which highlights the importance of continuing efforts to develop new cultivars and the simultaneous evaluation of these cultivars in different production scenarios in order to better recommend forage genetic resources for particular production environments.

Can Soil Moisture and Crop Production Be Influenced by Different Cropping Systems?

The different conditions of soil vegetation cover combined with irrigation management and/or agricultural production systems can influence soil moisture content and crop yields. This study investigated the impact of agricultural production systems and center pivot irrigation management on soil moisture content during the cultivation of soybean and off-season corn crops. Two field experiments were conducted during the 2018–2019 growing season in tropical Cerrado soil conditions; one experiment consisted of the application of three irrigation water depths (0%, 50%, and 100% of the crop evapotranspiration) during soybean cultivation in a no-tillage system under ruzigrass (Urochloa ruziziensis) straw, and the second experiment consisted of the intercropped or nonintercropped cultivation of corn hybrids with ruzigrass in an agricultural area with and without the influence of eucalyptus reforestation. The volumetric soil moisture was measured using an electronic soil moisture meter (Hidrofarm), and the 1000-grain mass and yield of the soybean and corn were measured in the two trials. Irrigation and the no-till system did not influence soybean yields. The soybean cultivars NA 5909 RG and TMG 7067 IPRO presented TGM above 180 g, and this represented on average a 22% higher TGM than the BMX DESAFIO RR and CD 2737 RR. The presence of eucalyptus forest promoted a 1.5% increase in soil moisture in the corn crop. Soil management systems, such as irrigation, use cover crops, which may not increase the productivity of soybean and corn crops as expected.

Plantas de cobertura com potencial de reduzir a população do ácaro-rajado na soja

Abstract The objective of this work was to evaluate the potential of cover plants in reducing the population of the two-spotted spider mite, Te t r a n y c h u s urticae, in soybean. Seven host plants – cotton (Gossypium hirsutum), Urochloa ruziziensis, crotalaria (Crotalaria juncea), corn (Zea mays), radish (Raphanus sativus), soybean (Glycine max), and sorghum (Sorghum bicolor) – were evaluated for their effect on T. urticae biological parameters (oviposition, development stages, and survival) and preference for volatile odors (using a Y-tube olfactometer). Tetranychus urticae preferred cotton and showed a higher population growth rate on this host plant. The survival and oviposition of T. urticae was prolonged in radish and crotalaria plants, whereas juveniles did not complete their immature development on U. ruziziensis leaves. No preference was observed between the volatile odors of U. ruziziensis, radish, and crotalaria. Urochloa ruziziensis can reduce T. urticae populations in soybean plants.

Genome-wide family prediction unveils molecular mechanisms underlying the regulation of agronomic traits in Urochloa ruziziensis.

Tropical forage grasses, particularly those belonging to the Urochloa genus, play a crucial role in cattle production and serve as the main food source for animals in tropical and subtropical regions. The majority of these species are apomictic and tetraploid, highlighting the significance of U. ruziziensis, a sexual diploid species that can be tetraploidized for use in interspecific crosses with apomictic species. As a means to support breeding programs, our study investigates the feasibility of genome-wide family prediction in U. ruziziensis families to predict agronomic traits. Fifty half-sibling families were assessed for green matter yield, dry matter yield, regrowth capacity, leaf dry matter, and stem dry matter across different clippings established in contrasting seasons with varying available water capacity. Genotyping was performed using a genotyping-by-sequencing approach based on DNA samples from family pools. In addition to conventional genomic prediction methods, machine learning and feature selection algorithms were employed to reduce the necessary number of markers for prediction and enhance predictive accuracy across phenotypes. To explore the regulation of agronomic traits, our study evaluated the significance of selected markers for prediction using a tree-based approach, potentially linking these regions to quantitative trait loci (QTLs). In a multiomic approach, genes from the species transcriptome were mapped and correlated to those markers. A gene coexpression network was modeled with gene expression estimates from a diverse set of U. ruziziensis genotypes, enabling a comprehensive investigation of molecular mechanisms associated with these regions. The heritabilities of the evaluated traits ranged from 0.44 to 0.92. A total of 28,106 filtered SNPs were used to predict phenotypic measurements, achieving a mean predictive ability of 0.762. By employing feature selection techniques, we could reduce the dimensionality of SNP datasets, revealing potential genotype-phenotype associations. The functional annotation of genes near these markers revealed associations with auxin transport and biosynthesis of lignin, flavonol, and folic acid. Further exploration with the gene coexpression network uncovered associations with DNA metabolism, stress response, and circadian rhythm. These genes and regions represent important targets for expanding our understanding of the metabolic regulation of agronomic traits and offer valuable insights applicable to species breeding. Our work represents an innovative contribution to molecular breeding techniques for tropical forages, presenting a viable marker-assisted breeding approach and identifying target regions for future molecular studies on these agronomic traits.

Tiller Number and Flowering Ability on BC1F1 Progeny of Interspecific Hybridization in Ruzigrass (Urochloa ruziziensis)

The objective of this study focusing on production BC1F1 progeny of interspecific hybridization in ruzigrass (Urochloa ruziziensis) were to evaluate potential of pentaploid BC1F1 hybrid for seed propagation by associating with their tiller number, flowering, and shattering ability. In addition, we evaluate the function of various nitrogen dose on vegetative stages. Eight different genotypes were examined: B. ruziziensis ‘Kennedy’, B. decumbens ‘Basilisk’, pentaploid BC1F1 line derived from B. ruziziensis and Mulato (RM), pentaploid BC1F1 line derived from diploid B. ruziziensis and tetraploid B. ruziziensis (RR), and pentaploid BC1F1 lines derived from B. ruziziensis and B. decumbens (RD 1-4). The experimental plants treated with three level of nitrogen fertilizer (0, 4, and 8 kg/10a). Compared with parental line, RM line had high tiller number along with increasing level of nitrogen. For the flowering and shattering ability, the first lines to flowered and shattered was the pentaploid BC1F1 (RD 1-4), RR, and B. decumbens. Pentaploid BC1F1 lines derived from B. ruziziensis and B. decumbens (RD 1-4) had potential for seed propagation by associating with their flowering and shattering ability, while pentaploid BC1F1 line derived from B. ruziziensis and Mulato (RM) had the potential biomass production and yield ability by associating with its tiller number production.

Estratégias de manejo químico e cultural de capim-amargoso resistente ao glifosato no Brasil Central

Abstract The objective of this work was to evaluate different chemical treatments, associating herbicide combinations with the maintenance of forage species in the off-season, for the management of glyphosate-resistant sourgrass (Digitaria insularis) in a soybean crop. The experimental design was a randomized complete block in a 4×5 split-plot arrangement, with four replicates. The treatments consisted of: four combinations of the clethodim, glyphosate, haloxyfop-p-methyl, glufosinate ammonium, and s-metolachlor herbicides in the plots; green covers with the Massai, BRS Tamani, and BRS Zuri cultivars of Panicum maximum and with Urochloa ruziziensis, as well as fallow, in the subplots; and a control with the isolated application of glyphosate at the desiccation and post-emergence of the soybean crop infested with sourgrass and weeded. The herbicides tested before sowing and at post-emergence of soybean promoted a control above 90% of adult sourgrass plants until grain harvest. After harvest, there was a new emergence of sourgrass, mainly in the plots without green cover in the off-season. Overseeding soybean with forage species allowed of the establishment of these plants, which consequently interfered in sourgrass emergence and growth. The chemical treatments with herbicide combinations associated with the maintenance of forage species in the off-season are effective for the control of adult glyphosate-resistant sourgrass plants.

Forage production, morphogenetic and structural components, and nutritional value of tropical grasses in the semiarid condition

The objective of this study was to evaluate the forage mass, morphogenetic and structural characteristics, and nutritional value of tropical forage grasses in semiarid conditions. Nine grasses were evaluated, namely, three cultivars of Urochloa brizantha (Marandu, MG4, and Piatã); Urochloa decumbens cv. Basilisk; Urochloa humidicola cv. Llanero; Urochloa ruziziensis cv. Kennedy; and three cultivars of Megathyrsus maximum (Massai, Mombaça, and Tanzania). The experiment was laid out in a randomized complete block design in a split-plot arrangement in which the main factor were the grass cultivars and the secondary factor the seasons, with five replications per treatment. The statistical model included the fixed effect of treatment (grass), whereas the season was included as a random effect within treatments. Urochloa brizantha cvs. Marandu, MG4, and Piatã and Urochloa decumbens cv. Basilisk produced on average 858 kg ha-1 more forage mass than cvs. Kennedy and Basilisk. Megathyrsus maximum cv. Mombaça produced 40% more forage mass than the other cultivars of M. maximum (4205 vs. 3001 kg ha-1). Urochloa ruziziensis cv. Kennedy showed the lowest water use efficiency (36%). Urochloa ruziziensis cv. Kennedy exhibited the lowest leaf weight among the Urochloa cultivars (740 vs. 1319 kg ha-1). There was no treatment effect for leaf weight in the M. maximum cultivars. Urochloa ruziziensis cv. Kennedy showed the highest values of total digestible nutrients and dry matter digestibility (1.84 and 2.34%, respectively) among the other Urochloa cultivars. The M. maximum cultivars showed little differences in nutritional values. Cultivars Marandu, Piatã, and Massai exhibited better productive responses in the edaphoclimatic conditions of this study. However, future studies must be conducted evaluating the adaptation of the forage grass under semiarid conditions. Considering the settings of this study, the grasses Urochloa brizantha cvs. MG4, Marandu, and Piatã, as well as Megathyrsus maximum cvs. Massai and Mombaça, can be used in the semiarid condition.