Brachiaria Brizantha Research Articles

Effect of Amazonian tree species on soil and pasture quality in silvopastoral systems

ABSTRACT With the expansion of livestock in the Amazon region, a high percentage of pasture areas are degraded and unproductive. Novel strategies are needed, including the use of native tree species, to simultaneously achieve economic and ecosystem benefits. This study aimed at assessing the effects of five multipurpose native tree species on soil fertility and forage quality of Urochloa brizantha pastures in the southern Amazon. Soil and forage samples were collected under the crown and adjacent to 25 isolated trees belonging to five species during a dry and a rainy season. The presence of native trees positively affected the level of potassium, calcium and manganese in the soil, as well as the mineral matter and crude protein of the forage, especially in the dry season, suggesting a protective effect against the seasonal drought. The tree species had variable effects on soil fertility and forage quality. Soil under Apeiba tibourbou had higher potassium levels, while the forage under Handroanthus serratifolius had higher protein and fiber content. Our results indicate that it is important to diversify silvopastoral systems in the Amazon through the use of native tree species, contributing to the design of novel silvopastoral strategies in the region. Common multipurpose tree species with widespread natural distribution could be used as a complementary aspect of pasture management to provide a protective effect against drought, contribute to enhanced nutrient cycling and even increase forage quality.

Morphogenesis of stockpiled Marandu, Piatã, Xaraés and Paiaguás brachiariagrass cultivars

ABSTRACT The objective this study was to identify differences in the morphogenic patterns of four Urochloa brizantha cultivars (marandu, piatã, xaraés and paiaguás grasses) during the stockpiling period. A completely randomized design was used, with three replications, in experimental plots of 9m². The evaluations took place over 2 years. The grasses were stockpiled for 92 (Year 1) and 95 (Year 2) days. The leaf appearance rate of paiaguás grass was higher, compared to other grasses. In Year 1, the stem elongation rate of xaraés grass was higher than other grasses. At the end of stockpiling period of Year 1, the tiller population density (TPD) was higher in the paiaguás grass, intermediate in the xaraés and marandu grasses and lower in the piatã grass. At the end of the stockpiling period in Year 2, TPD was higher in the paiaguás grass canopy, intermediate in the marandu and piatã grasses canopies, and lower in the xaraés grass canopy. Paiaguás grass has greater leaf growth during the stockpiling period and is therefore suitable for use under stockpiled grazing. Xaraés grass has high stem elongation during the stockpiling period, which is why its use under stockpiled grazing must be accompanied by adjustments in pasture management.

Crop coefficient estimated by degree-days for ‘Marandu’ palisadegrass and mixed forage

Considering profitability in pasture-based systems, investigating parameters affecting crop coefficients for irrigation management becomes important. In this experiment, we determined the crop coefficient of ‘Marandu’ palisadegrass based on accumulated degree-days and estimated plant water consumption under single (‘Marandu’ alisadegrass) and mixed (‘Marandu’ palisadegrass + black oats + Italian ryegrass) cropping regimes. The research was conducted at the Luiz de Queiroz College of Agriculture in Piracicaba, São Paulo, Brazil, between 2016 and 2017. Evapotranspiration was assessed using weighing lysimeters while crop evapotranspiration was calculated using mean weight variation. Reference evapotranspiration and degree-days were estimated. Data were obtained from an automated weather station. Equations and regression models relating crop coefficient with accumulated degree-days were generated for two seasons (spring/summer and autumn/winter) and evaluated for two year-cycles, from 2015 to 2018. The results showed better prediction accuracy for the single cropping system in spring/summer 2017–18. Highlights The model for determinating crop coefficient (Kc) by accumulated degree-days showed efficient for use in determination local. The use of the degree days for determination Kc is more vantage because only necessary to measure the air temperature (maximum and minimum). The equations for determining crop coefficient by accumulated degree days for the spring/summer season in Marandu palisade grass cultive show more precision that in mixture forage system.

Tillering dynamics in spring and summer of marandu palisade grass pastures previously used under deferred grazing

ABSTRACT This work was conducted to evaluate the effect of deferred pasture condition of Brachiaria brizantha cv. Marandu in the late winter on tillering during the growing season. The treatments were three pasture conditions at late winter: short pasture, tall pasture and tall/mown pasture. In September and October, tiller appearance rate (TApR) and tiller mortality rate (TMoR) were greater in the tall/mown pasture. In November and December, tall pasture presented greater TApR. From November to January the TMoR was greater in the tall pasture. The tiller stability index of short and tall/mown pastures were greater in October. The short pasture presented a greater tiller number than the tall and tall/mown pastures during the entire experimental period. Deferred and short pasture of marandu palisade grass at late winter presents in general lower tiller mortality and higher population density of tillers from the early spring onwards, in comparison to tall pasture. The mowing of marandu palisade grass with high forage mass at the late winter, although it only temporarily compromises the population stability of tillers, also stimulates its fast tillering from spring on.

ALLELOPATHIC POTENTIAL OF AQUEOUS EXTRACT OF LEAF AND ROOT SESAME ON SICKLEPOD AND BRACHIARIA SEEDS

Sicklepod is an important weed in Brazil pastures, but control measures are not yet effective. Thus, allelopathy can be an alternative, due to its ecological importance and for being able to provide new structures sources for agrochemicals production. This research aimed to verify the allelopathic potential of sesame (Sesamum indicum L.) on germination and seedling development of sicklepod (Senna occidentalis L.) and brachiaria (Brachiaria brizantha). The treatments were root and leaf extract of sesame, and control (distilled water). Germination percentage, speed of germination, hypocotyl and radicle length were evaluated. Speed of germination, germination percentage and radicle length had no interference from the aqueous extracts. However, in brachiaria these traits had lower values than sicklepod. Hypocotyl length was not influenced by the extracts, however, the leaf extract showed lower growth of this feature. Allelopathy did not affect germination and speed of germination in both species, but interfered in brachiaria development.

Comparative analysis of exchangeable aluminum in a tropical soil under long-term no-till cultivation

Aluminum toxicity is a key determinant of crop yield for acid soils. Techniques used to characterize a soil’s exchangeable Al content often yield discordant results, thus impeding the implementation of corrective measures. We critically compared three such techniques – back-titration, ICP-AES, and 27Al NMR – for a tropical Oxisol under long-term (8-years) no-till cultivation involving four different cropping-systems and three pH control regimens. ICP-AES was superior in terms of accuracy, level of quantification (LOQ), practicable pH range, speed, cost, and versatility. By comparison, back-titration consistently overestimated exchangeable Al, whereas 27Al-NMR, though accurate, had a higher LOQ and is inherently non-quantitative between pH 5.4 and 6.3 owing to extreme quadrupolar broadening of Al(OH)n(H2O)6−n(3̶−n)+ (n = 1–3) signals. The only Al species detected by NMR in any of the soil extracts was the toxic Al hexaaqua cation, Al(H2O)63+, despite an appreciable presence of dissolved organic matter. Application of either dolomitic lime or calcium-magnesium silicate (CMS) as a pH corrective significantly decreased exchangeable Al in the upper soil layers. None of the decrease, however, was attributable to insoluble aluminosilicates having formed as a consequence of CMS dissolution. Rotation crops of wheat (T. aestivum) and showy rattlebox (C. spectabilis) depleted exchangeable Al in the upper soil layers, whereas palisade grass (Brachiaria brizantha) had no discernable effect on Al availability. Plots which incorporated any one of the three rotation crops provided equally high yields of soybean in year-8 when pH (1 M KCl) exceeded 4.9 ± 0.2 and Al saturation was less than 25 ± 5% (AlICP ≤ 22 ± 21 mg kg−1), on average, in the 0–20 cm soil horizon.

Genetic Transformation of Apomictic Grasses: Progress and Constraints.

The available methods for plant transformation and expansion beyond its limits remain especially critical for crop improvement. For grass species, this is even more critical, mainly due to drawbacks in in vitro regeneration. Despite the existence of many protocols in grasses to achieve genetic transformation through Agrobacterium or biolistic gene delivery, their efficiencies are genotype-dependent and still very low due to the recalcitrance of these species to in vitro regeneration. Many plant transformation facilities for cereals and other important crops may be found around the world in universities and enterprises, but this is not the case for apomictic species, many of which are C4 grasses. Moreover, apomixis (asexual reproduction by seeds) represents an additional constraint for breeding. However, the transformation of an apomictic clone is an attractive strategy, as the transgene is immediately fixed in a highly adapted genetic background, capable of large-scale clonal propagation. With the exception of some species like Brachiaria brizantha which is planted in approximately 100 M ha in Brazil, apomixis is almost non-present in economically important crops. However, as it is sometimes present in their wild relatives, the main goal is to transfer this trait to crops to fix heterosis. Until now this has been a difficult task, mainly because many aspects of apomixis are unknown. Over the last few years, many candidate genes have been identified and attempts have been made to characterize them functionally in Arabidopsis and rice. However, functional analysis in true apomictic species lags far behind, mainly due to the complexity of its genomes, of the trait itself, and the lack of efficient genetic transformation protocols. In this study, we review the current status of the in vitro culture and genetic transformation methods focusing on apomictic grasses, and the prospects for the application of new tools assayed in other related species, with two aims: to pave the way for discovering the molecular pathways involved in apomixis and to develop new capacities for breeding purposes because many of these grasses are important forage or biofuel resources.

Maize and sorghum root growth and yield when intercropped with forage grasses

AbstractIntegrated crop–livestock systems that intercrop forage crops with grain crops are effective for increasing forage production and improving nutrient cycling and soil health. However, the potential for root competition when maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] are intercropped with forages in sandy soils is unknown. The objectives of this study were (a) to evaluate the root growth and production characteristics of maize and sorghum intercropped with forage grasses and (b) quantify above‐ and belowground biomass in a tropical integrated cropping system. Two 3‐yr experiments were conducted in which maize and sorghum were intercropped with forage grasses: guineagrass (Panicum maximum Jacq.), ruzigrass [Urochloa ruziziensis (Germ. & Evrard) Crins], palisade grass [Urochloa brizantha (Hochst ex A. Rich.) R. Webster], or an Urochloa hybrid. Monocropped maize and sorghum were used as controls. Fine roots (≤3 mm) were sampled in the monocropped and intercropped systems at soil depths of 1.0 m. Intercropping guineagrass and palisade grass with maize and sorghum resulted in 40% greater dry matter production than intercropping with ruzigrass and the Urochloa hybrid. The positive effect of intercropping forage grasses in the low‐fertility sandy soil was greater for sorghum than for maize because of lower root growth competition. On average, intercropping maize and sorghum with forages increased the total above‐ and belowground biomass by 30 and 50%, respectively, compared with monocropping. In summary, intercropping maize and sorghum with forage grasses is a viable option to enhance biomass during the off‐season in tropical integrated crop–livestock systems.

Effect of Tree Shade on the Yield of Brachiaria brizantha Grass in Tropical Livestock Production Systems in Mexico

Trees play an important role in livestock grazing lands, but the effect of tree shade on grass productivity has not been studied widely. In this study, we evaluated the effect of tree shade on grass yield in pasturelands with dispersed trees in the humid tropics of Mexico. We sampled two livestock grazing systems: 1) scattered native trees in paddocks composed of Cordia alliodora and Cedrela odorata trees with Brachiaria brizantha cv. ‘Xaráes’ grass; and 2) scattered trees in paddocks composed of C. alliodora, C. odorata, and Guazuma ulmifolia, with B. brizantha cv. ‘Marandú’ grass. We established isolation cages at different distances from trees: 1) under the tree canopy, 2) on the border of the tree canopy, and 3) out of reach of the tree canopy, to measure grass yield, grass height, dry matter content, and senescent biomass from April to September. The effect of tree shade on grass yield was significant, with the highest grass production under the tree canopy compared with grasses that grew on the border of the tree canopy and in full sun. We found the highest forage yield in June for B. brizantha cv. Xaráes and the lowest yield in September for the same grass. During July and August, B. brizantha cv. Xaráes yielded the greatest average height, with the lowest values during April and May for B. brizantha cv. Marandú. The greatest dry matter content was recorded in September for B. brizantha cv. Xaráes. Additionally, the most senescent mass was recorded in June and the lowest in April for the same grass. Native trees that persist in grasslands positively influence forage yield during the dry season. Increasing the productivity of the grasslands by agroforestry practices may represent a valuable alternative to mitigate the negative effects of deforestation caused by extensive livestock farming.

First record of Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) in the state of Acre, Brazil

Spittlebugs are among the main insect pests of forage grasses in Brazil. In February 2021, a spittlebug infestation was verified in Xaraés palisadegrass (Brachiaria brizantha cv. Xaraés) in the municipality of Senador Guiomard, Acre state, Brazil. The specimens were captured with an entomological sweep net and identified as Notozulia entreriana (Berg) and Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae). Notozulia entreriana is frequently captured in studies with spittlebugs in Acre state, though this is the first record of M. spectabilis in the state. This new record expands the species known geographical distribution in Brazil and the number of species of Mahanarva occurring in Acre state.

Methodologies for the application of calcium compounds in agropastoral systems: Effects on crop yields

AbstractSoil acidity (pH <4.4) restricts exploration by the root system and impairs crop yield. To contribute to the development of alternative methodologies for correcting acidity in the surface and subsurface layers of soil, the present study evaluated the effects of seven combinations of application technique (surface, incorporation under soil tillage, or subsurface) and calcium (Ca) compounds (limestone [LS], phosphogypsum [PG], and hydrated lime [HL]) on soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) grain yields and on the absorption of macronutrients and dry matter yield of palisade grass (Urochloa brizantha syn. Brachiaria brizantha ‘Marandu’) in a Typic Hapludalf in an agropastoral system in Brazil. The experimental design was randomized complete blocks with four replications. The results support the following conclusions: (a) applying HL plus PG is a viable alternative to applying LS plus PG for soybean and maize crops, (b) incorporating LS by plowing and harrowing is not a viable alternative to applying LS on the surface, (c) applying HL plus PG on the subsurface is superior to applying HL plus PG on the surface for soybean and palisade grass cultivation, (d) incorporating LS plus PG followed by annually applying LS on the surface improves palisade grass crop yield, (e) annually applying LS plus PG 2 yr before and annually applying LS plus PG increase palisade grass crop yield, and (f) annually applying LS or HL plus PG increases the absorption of Mg and S by palisade grass.

Legacy Effects of Intercropping and Nitrogen Fertilization on Soil N Cycling, Nitrous Oxide Emissions, and the Soil Microbial Community in Tropical Maize Production

Maize-forage grasses intercropping systems have been increasingly adopted by farmers because of their capacity to recycle nutrients, provide mulch, and add C to soil. However, grasses have been shown to increase nitrous oxide (N2O) emissions. Some tropical grasses cause biological nitrification inhibition (BNI) which could mitigate N2O emissions in the maize cycle but the reactions of the N cycle and the microbial changes that explain the N2O emissions are little known in such intercropping systems. With this in mind, we explored intercropping of forage grasses (Brachiaria brizantha and Brachiaria humidicola) with distinct BNI and yield potential to increase N cycling in no-till maize production systems compared to monocrop with two N rates (0 and 150 kg ha−1) applied during the maize season. These grasses did not strongly compete with maize during the period of maize cycle and did not have a negative effect on grain yield. We observed a legacy of these grasses on N mineralization and nitrification through the soil microbiome during maize growth. We observed that B. humidicola, genotype with higher BNI potential, increased net N mineralization by 0.4 mg N kg−1 day−1 and potential nitrification rates by 1.86 mg NO3-N kg−1 day−1, while B. brizantha increased the soil moisture, fungi diversity, mycorrhizal fungi, and bacterial nitrifiers, and reduced saprotrophs prior to maize growth. Their legacy on soil moisture and cumulative organic inputs (i.e., grass biomass) was strongly associated with enhanced mineralization and nitrification rates at early maize season. These effects contributed to increase cumulative N2O emission by 12.8 and 4.8 mg N2O-N m−2 for maize growing after B. brizantha and B. humidicola, respectively, regardless of the N fertilization rate. Thus, the nitrification inhibition potential of tropical grasses can be outweighed by their impacts on soil moisture, N recycling, and the soil microbiome that together dictate soil N2O fluxes.

Discrimination of Urochloa seed genotypes through image analysis: Morphological features

AbstractThe tropical forage species seed market, including signalgrass (Urochloa), is expanding. There is demand for fast, automated methods that can be implemented for quality control of the seeds produced, with the aim of evaluating physical purity. In this respect, seed morphological features obtained by processing radiographs with the Tomato Analyzer software and of red–green–blue obtained and processed on the Groundeye device were used to test differentiation of materials of the Urochloa genus. Seeds of Urochloa brizantha (A.Rich.) R.D.Webster cvv. BRS Piatã, Marandu, and Xaraés MG‐5; Urochloa ruziziensis (R.Germ. & C.M.Evrard) Crins cv. Ruziziensis; and Urochloa decumbens (Stapf) R.D.Webster cv. Basilisk were evaluated. Morphological features obtained by Tomato Analyzer allowed differentiation of Urochloa seeds at an accuracy level greater than 80% for all the materials evaluated. Seed area was one of the features that allowed this differentiation. The Groundeye system also showed high efficiency in distinguishing Urochloa seeds, except for Piatã and Xaraés, which exhibited morphological similarity, and lower accuracy levels in distinguishing their seeds (<50%). Additional studies should be conducted to evaluate Urochloa seed lots from other origins to validate the use of image analysis techniques for the purpose of obtaining morphological features and to assist in determining the physical purity of the materials.

APSIM model performance in simulating Piatã palisade grass growth and soil water in different positions of a silvopastoral system with eucalyptus

CONTEXTSilvopastoral systems aim to be more sustainable than conventional systems, increasing total productivity, diversifying agricultural production, and improving resource use efficiency. However, very few studies were performed to adapt crop models to simulate these systems. OBJECTIVEThis study investigates the current capacity of the APSIM Next Generation model to estimate Piatã palisadegrass growth and soil water in different positions in a silvopastoral system with eucalyptus by looking at the impact of modelling belowground and aboveground competition separately. METHODSA field experiment was conducted from December 2014 to January 2016 in a silvopastoral system with eucalyptus trees arranged in single rows, in East-West orientation, with 15 m between rows and 2 m between trees in the rows. This experiment was conducted under grazing management and rainfed conditions, during 11 growth cycles, with pasture variables, soil moisture and microclimatic conditions assessed at four distances from the eucalyptus north row (0.00 m, 3.75 m, 7.50 m and 11.25 m). APSIM testing was performed in two ways: focusing on belowground competition for soil water and nitrogen, using a multi-root-zone approach, and focusing on competition for solar radiation, using the measured data of solar radiation at each position. RESULTS AND CONCLUSIONSThe APSIM-Tropical Pasture model was effective in simulating pasture growth when only competition for solar radiation was considered (R2 from 0.75 to 0.86, Agreement index (d) from 0.88 to 0.96, and Nash-Sutcliffe efficiency (NSE) between 0.32 and 0.85). These simulations are promising taking into account the difficulties to simulate pasture growth in silvopastoral systems with grazing; however, in systems with strong belowground competition for soil water and nutrients, this approach has strong limitations. Simulations of pasture growth were not as effective when using the multi-root-zone approach (R2 between 0.57 and 0.87, d between 0.53 and 0.74, and NSE from −5.32 to −1.20), despite reasonable simulations of soil water for the positions between the tree rows (R2 between 0.70 and 0.80, d from 0.91 to 0.94, and NSE between 0.60 and 0.77). In view of these results, improvements should be performed in APSIM to better simulate silvopastoral systems, mainly for solar radiation transmission and tree roots growth and distribution. SIGNIFICANCEThis study allowed identifying the key drivers of competition within the studied environment and to inform where the main efforts should be targeted in building a more effective model for silvopastoral systems. This is important to help model development teams in organising and optimising their efforts.

Endophytic Fungi Assures Tropical Forage Grass Growth by Water Stress Tolerances.

Forage plants is the base of beef and dairy cattle production. While water stress limits agricultural production worldwide, endophytic fungi can play a beneficial role for plants, such as tolerance to biotic and abiotic stresses. The objective of this work was to evaluate the effect of inoculation of the endophytic fungi Paraconiothyrium estuarinum (CML 3695, CML 3696, CML 3699) and Paraconiothyrium cyclothyrioides (CML 3697, CML 3698) on agronomic characteristics of two forage species, Brachiaria brizantha (A. Rich) Stapf. cv. Marandu and Megathyrsus maximus Jacq. cv. BRS Mombaça, under different available water capacities. The treatments simulated a long drought period (LDH) equivalent to 10% of the available water capacity (AWC) and simulated 7 (7 DH) and 14days of drought (14 DH) without water supply. The grasses were evaluated for length and dry weight of shoots and roots. All treatments reached humidity below the permanent wilting point (PWP) and the highest variation in soil moisture was observed at 14 DH, for both grass species. The endophytic fungi promoted an average 15% increase in shoot length (SL) for B. brizantha and an increase of 34% for SL, 266% for Dry Shoot Mass (SDM), and 340% for Dry Root Mass (RDM) for M. maximus treated with P. estuarinum (CML 3699) at 7 DH. Paraconiothyrium estuarinum (CML 3699) guaranteed the highest tolerance to water deficit and sustainable growth performance to both tested grasses.

Bromatological composition and ruminal degradability of Xaraés palisade grass under grazing in integrated systems

To evaluate the bromatological composition and ruminal degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of Xaraés palisade grass (Urochloa brizantha ‘Xaraes’ syn Brachiaria brizantha) under grazing in integrated crop, livestock (ICL), and forest (ICLF) systems, we conducted an in situ degradability trial in randomized blocks with three non-lactating 3/4 Gyr × 1/4 Holstein cows, provided with ruminal cannula. The management of Xaraés palisade grass was similar in both systems, differing only regarding shading in the ICLF system provided by eucalyptus trees (average 65% crown cover). Grass samples were incubated for 0, 3, 6, 9, 12, 24, 36, 48, 72, and 96 hours. Considering the passage rate 2% h-1, the Xaraés palisade grass of ICL system had greater NDF effective degradability in relation to ICLF (46.38% vs 44.98%). However, the palisade grass CP potential degradability was greater in the ICLF than in the ICL system (68.92% vs. 65.40%). The presence of trees in the pasture has effect on nutritional traits of the Xaraés palisade grass, increasing its protein content and degradability and reducing its fiber degradability.

Cover crop and early nitrogen management for common bean in a tropical no‐till system

AbstractCommon bean (Phaseolus vulgaris L.) has been grown under no‐till (NT), but nitrogen (N) management remains unclear when a previous cover crop is part of the farming system. In this study, we hypothesized that N applied to living cover crops, preceding the main grain crop of the rotation, can increase productivity and N‐use efficiency of the grain crop. Common bean was grown after palisade grass [Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster] and ruzigrass [Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins] cover crops combined with N management [application to living cover crops 35 days before common bean seeding (DBS), 1 DBS, conventional, and control (zero‐N application)] in four experiment‐years. Dry matter (DM) and N content for palisade grass was consistently greater at termination relative to ruzigrass. Nitrogen application 35 DBS increased cover crop DM, N content, and the decomposition rate relative to the other N treatments. Greater common bean yield occurred following palisade grass than ruzigrass, and N application 35 DBS increased common bean yield compared to 1 DBS and conventional in one out of four experiment‐years. Only minor differences in the agronomic efficiency (AE) of applied N to cover crops were detected between 35 DBS and 1 DBS, and only for one experiment‐year, when palisade grass resulted in greater AE than ruzigrass. Applying N early to living crops such as palisade grass is an alternative N management strategy to the traditional approach for N fertilization in common bean.

Development of the cultivar xaraés under different concentrations of teak sawdust

Tectona grandis L.f. (Teak) is a highly cultivated forest species in Brazil. When industrially processed, it generates a large amount of sawdust, a waste that has limited reuse and accumulates in the industrial yards. The aim of this study was to evaluate the effect of fresh teakwood sawdust on the development of Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster cv. Xaraés in a nursery. The treatments consisted of concentrations of 0, 5, 10, 20, 33 and 50% of sawdust, arranged in four randomized blocks in split-plots. At 45, 75 and 120 days, plant heigh (h), average tillers diameter (d), number of live (nll) and dead leaves per plant, fresh and dry mass of shoots and roots, and Dickson's quality index (dqi) were measured. There was a decrease in h growth, d, nll, fresh and dry mass of shoots and roots and in the dqi of the cv. Xaraés as it increased to concentration of wood sawdust in the substrate. This negative effect can be attributed to the high C/N ratio of sawdust (196/1), which influences the decomposition of organic matter. In addition, the possible Teak allelopathic effects, which are the subject of other studies, should be considered. Unlike the other variables, number of live leaves was not influenced by the treatment with 5% sawdust. Teakwood sawdust has negative effects on the U. brizantha cv. Xaraés development.

Ewe performance in the post-weaning phase and structural characteristics of Brachiaria brizantha cultivars in the dry season

The objective of this study was to examine the performance of ewes in the post-weaning phase and the structural characteristics of Brachiaria brizantha cultivars in the dry season. The treatments were represented by four Brachiaria brizantha cultivars (Piatã, Marandu, Paiaguás, and Xaraés), which were evaluated in a randomized-block design with two replicates for the forage variables and eight replicates for the animal performance variables. Canopy height, masses of forage and morphological components and chemical composition of morphological components were evaluated. Thirty-two ½ Santa Inês and ½ Dorper sheep with an initial body weight (BW) of 22.7 ± 1.2 kg were used. Average daily gain (ADG – kg animal-1 day-1), stocking rate (in animal units [AU] = 30 kg of body weight) and weight gain per area (kg ha-1 day-1) were measured. There was no cultivar effect (p > 0.05) on the structural characteristics of the pasture. The highest crude protein content in the leaf blade (11.8%) were found in cultivar Marandu. Average daily gain was higher in the animals that grazed on cultivar Marandu (0.08 kg animal-1 day-1) as compared with cultivars Xaraés (0.05 kg animal-1 day-1) and Piatã (0.04 kg animal-1 day-1), whereas the ewes that grazed on cultivar Paiaguás showed intermediate ADG values (0.06 kg animal-1 day-1). There was no difference between the cultivars for stocking rate (9.2 AU). Weight gain per area was highest in cultivar Marandu (0.33 kg ha-1 day-1) and lowest in cv. Piatã (0.16 kg ha-1 day-1). Brachiaria brizantha cultivars Piatã, Marandu, Paiaguás and Xaraés proved to be forage options for the post-weaning phase of ewes supplemented with concentrate in the dry season.

Allelopatic effects of Waltheria indica L.: Biocontrol potential in ecological restoration

In Brazil, most degraded areas are occupied by exotic and invasive species, which require alternatives for their management. We evaluated the allelopathic effects of Waltheria indica in the laboratory from aqueous extracts of leaves and roots on the germination of the species Lactuca sativa L. (lettuce), Urochloa brizantha (Hochst. ex A.Rich.) RDWebster (brachiaria) and Handroanthus chrysotrichus (Mart. ex DC.) Mattos (yellow Ipe). We collected adult one-year-old Waltheria indica shrubs in ecological restoration areas by direct seeding. We used two treatments with aqueous extracts of leaves and roots and a control without extract, with ten repetitions of 10 seeds per treatment, totaling 600 seeds per test species. Germination and use of tetrazolium assays to evaluate the potential respiratory activity of the roots were used. The aqueous extract of W.indica leaves affected the number of germinated seeds of all test species, while the aqueous extract of roots affected only L. sativa and H. chrysotrichus. There were no significant differences between treatments (leaf and root extracts) in species germination. The aqueous extracts of Waltheria indica leaves and roots affected germination and cellular respiration of the studied species, mainly in Lactuca sativa. The identification of W. indica allelopathic compounds may be an initial step so that in the future new bioherbicides are produced from extracts of this species, or even that its seeds can be sown together with non-sensitive native species, aiming for control of exotic species in ecological restoration projects.