Estructura del pasto forrajero con cultivares de Urochloa brizantha bajo sombra

This study evaluated the structure of swards planted with Urochloa brizantha cv. BRS Paiaguas and BRS Piata under the eucalyptus shading system, fertilized via foliar at the beginning of the dry and rainy seasons. The experiment followed a randomized block design with a 4×2×2 (4 leaf fertilizer levels × 2 systems × 2 seasons) factorial arrangement. The results were analyzed using the GLIMMIX PROC of SAS University while means were compared by the T-test at 5%. Foliar fertilizer had a significant (P≤0.05) effect on cv. BRS Paiaguas stem mass under shading while the 3 and 6 L/ha levels produced the lowest (P≤0.05) masses. The forage and root masses were not significantly affected (P≥0.05) by the systems and seasons whereas the dead material mass was not influenced by the seasons. The shading system resulted in (P≤0.05) significantly lower dead material mass for both cultivars and higher (P≤0.05) leaf and stem masses for the cv. BRS Piata. In the rainy season, leaf and stem masses were greater (P≤0.05). Foliar fertilization up to 6 L/ha favored the stem control in cv. BRS Paiaguas under shading. The resulting masses of forage, dead material, and root allow concluding that the cultivars adapted well to the shading and dry season.

Plant structural and nutritional responses to drought differ among common pasture species

In the face of a changing climate, research indicates that more frequent and severe drought conditions are critical problems that will constrain production of high-quality forage and influence the performance of grazing animals in the future. In addition, the duration of drought and potential trade-offs between plant morphology and nutritional composition may influence plant drought adaptation strategies across pasture species, and the consequences for forage quality are not well understood. Here we present the results of a study investigating the effects of drought on biomass productivity, dead material, leaf:stem biomass allocation and nutritional composition (whole-plant and tissue-specific) across nine diverse pasture species. For this, we conducted a field experiment exposing species to a 6-month period of simulated severe drought (60% rainfall reduction during winter and spring) and samples were collected at multiple harvests. We found that drought had different, harvest-specific effects on plant biomass structure and nutritional composition among pasture species. The severity of drought impacts on productivity, but not on nutritional quality, increased with drought duration. In general, drought strongly reduced productivity, increased the percentage of dead material and had mixed effects (increases, decreases and no effect) on leaf:stem ratio and concentrations of crude protein, non-structural carbohydrates, neutral detergent fibre and lignin. Changes in plant-level nutritional quality were driven by simultaneous changes in both leaf and stem tissues for most, but not all, species. Our findings may be especially helpful for selection of adapted species/cultivars that could minimize potential drought risks on forage, thereby optimising pasture performance under future drought scenarios.

Canopy characteristics of ‘Mavuno’ hybrid brachiariagrass and ‘Marandu’ palisadegrass harvested at different harvest intensities

‘Mavuno’ is a newly released brachiariagrass (Urochloa hybrid) cultivar with limited information available in the literature. The objective of this study was to compare forage characteristics of this cultivar and ‘Marandu’ palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster cv. Marandu] harvested at 2 different stubble heights during 2 growing seasons (January‒April). The study was conducted in Araguaína, TO, Brazil in 2017 and 2018. Treatments were the factorial arrangement of 2 brachiariagrass cultivars, Mavuno and Marandu, harvested at 2 harvest intensities, 5 and 15 cm stubble height, distributed in a randomized complete block design with 4 replicates. Response variables were canopy height, forage accumulation, proportion of leaf, stem and dead material, and concentration of crude protein (CP) and in vitro digestible organic matter (IVDOM). Mavuno and Marandu did not differ (P>0.05) in forage accumulation (mean = 3,800 kg DM/ha/harvest) and IVDOM concentration (mean = 637 g/kg); however, Mavuno had lower CP concentration (101 vs. 110 g/kg), greater proportion of stems (16 vs. 13%) and less dead material (4 vs. 6%) than Marandu (P<0.05). Harvesting at 5 cm stubble height rather than 15 cm increased herbage accumulation per harvest (4,100 vs. 3,500 kg DM/ha) with decreased proportion of leaves (77 vs. 84%) and CP concentration (101 vs. 115 g/kg) (P<0.05). Our data suggest that Mavuno is a useful addition to the range of brachiaria grass cultivars for sowing in tropical regions and further studies are needed to evaluate the long-term persistence of Mavuno under different management practices in a range of environmental situations. While harvesting at 5 cm stubble height rather than 15 cm increased forage accumulation but reduced CP concentration, regardless of cultivar, longer-term effects on the stability of these pastures with these harvest frequencies and heights are open to question and studies should be continued for longer periods to assess longevity of stands under the 2 management strategies. Applying maintenance fertilizer during the growing season might have prevented the marked decline in dry matter accumulation as the season advanced and this hypothesis should be tested.

Intensive Production and Management of Marandu Palisadegrass (Urochloa brizantha ‘Marandu’) Accelerates Leaf Turnover but Does Not Change Herbage Mass

Pasture intensification through higher stocking rates, nitrogen fertilization and intensified grazing management in beef cattle production optimizes pasture use by increasing the forage harvested. We aimed to assess its effects on the morphogenesis and canopy structure of Urochloa brizantha ‘Marandu’ (marandu palisadegrass) pastures. The treatments consisted of marandu palisadegrass pastures managed under continuous stocking and a canopy height of 25 cm, with different levels of intensification: extensive, semi-intensive, and intensive systems N-fertilized with 0 kg, 75 kg, and 150 kg N ha−1 year−1, respectively, as ammonium nitrate (32% of N), with four replicates (paddocks) in a completely randomized design. Phyllochron (9.8 days) and leaf lifespan (34.7 days) were shorter in intensified pastures, whereas herbage mass was similar among treatments. Extensive pastures had a higher proportion of senescent material; thus, more intensive systems showed higher proportions of leaves and stems, although the leaves-to-stem ratio remained similar across production systems. The defoliation interval was lower in intensive (14.4 days) and higher in extensive (18.7 days) treatments. Thus, pasture intensification accelerates leaf appearance, decreases leaf lifespan, shortens the tiller defoliation interval and increased herbage accumulation rate but does not change herbage mass. The extensive system produces excessive forage losses due to dead material.

An examination of the effect of autumn closing date on over-winter herbage production and spring yield

Altering autumn management affects the herbage mass available in spring. An experiment was established to determine the effect of five autumn closing dates (CDs) on herbage production, herbage quality, leaf, stem and dead proportions and tiller density over winter. In the study 50% of the herbage available in spring was accounted for by autumn CD. Each 1 d extra a sward was closed from 25 September to 9 December increased herbage mass by 16 kg DM/ha in spring. Swards closed earlier (25 September–26 October) had consistently higher herbage masses in spring (1,301 kg DM/ha) compared to swards closed later (11 November–9 December; 703 kg DM/ha). Later closed swards had greater herbage quality compared to earlier closed swards (organic matter digestibility = 852 and 825 g/kg DM, respectively) due to increased stem and dead material in the grazing horizon of earlier closed swards. There was no effect of autumn CD on sward quality in the subsequent defoliation in spring. However, following the initial spring grazing there was an effect of autumn CD on subsequent grass growth rates; swards closed in October had a lower growth rate (33 kg DM/ha per day) compared to swards closed in November and early December (49 kg DM/ha per day). Results indicate that earlier autumn closing is beneficial to meet high-feed demand in spring but can affect sward quality and growth rates in spring.

A Review Over the effect of Heavy Metal in Metabolism of Brassica juncea (L.) and Myristica fragrans

Brassica juncea (L.) and Myristica fragrans are common plants found in India where the concentration of heavy metals in water and soil is observed more frequently and in sufficient amounts to cause bad effects to the living entity. In plants various kinds of bad effects such as dwarfness, yellowish leaves, dead leaves, brownish and dead stem. These are kinds of symptoms that one can observe in plants suffering from the bad effects of heavy metal absorption. At a specific time, they should be identified and treated for the same otherwise this may cause an increase in dead material in the plant, day by day. This review summarizes the bad effects of heavy metals in plants like these two.

Caracterização dos Estratos Verticais de Pastagens Urochloa brizantha cv. Marandu Manejadas em Diferentes Alturas

A estrutura da pastagem é uma característica determinante tanto da dinâmica de crescimento da planta quanto do comportamento ingestivo dos animais. O objetivo do trabalho foi descrever a densidade da forragem e a proporção dos componentes morfológicos da planta, nos estratos verticais de pastagens de capim Marandu, submetido ao pastejo em diferentes alturas. O delineamento utilizado foi o inteiramente casualizado e as análises de variância e de regressão. Durante o experimento, as alturas médias dos seis piquetes utilizados foram de 10, 17, 18, 29, 32 e 50 cm. O material coletado foi separado, em lâmina foliar, colmo verde e material morto, que foram analisados quanto ao teor de matéria seca, proteína bruta e fibra em detergente neutro. Os estratos verticais apresentaram diferentes composições em relação aos componentes morfológicos de acordo com a altura do pasto. Os estratos próximos ao solo apresentaram maior densidade de forragem com valores de 370 a 543 kg/ha.cm, maior proporção de colmos verdes (30 a 53%) e material morto (25 a 52%) e menor de lâminas foliares (10 a 35%). Independente da altura do pasto, os estratos superiores são mais sensíveis aos efeitos do animal e do ambiente, e apresentaram maiores teores de PB e FDN para lâminas foliares e colmos. Nos estratos acima de 15 cm, os valores de PB e FDN das lâminas foliares verdes variaram entre 10,3 e 13,6% e 49,3 e 54,2%, respectivamente. O manejo em diferentes alturas altera as características dos estratos verticais do pasto, principalmente, nos estratos acima de 15 cm. Palavras-chave: Altura do Pasto. Densidade Forrageira. Colmos Verdes. Material Morto. Lâmina Foliar. Abstract The pasture structure is a determining characteristic of both the plant growth dynamics and the animals ingestive behavior. The objective of the work was to describe the density and the proportion of the plant’morphological components, in the pastures vertical strata of Marandu grass, subjected to grazing at different heights. The design used was completely randomized and the analysis of variance and regression. During the experiment, the average heights of six paddocks used were 10, 17, 18, 29, 32 and 50 cm. The collected material was separated into leaf blade, green stem and dead material, which were analyzed as to the dry matter content, crude protein and fiber in neutral detergent. The vertical strata presented different compositions in relation to the morphological components according to the height of the pasture. The near-soil strata showed higher forage density with values from 370 to 543 kg/ha.cm, higher proportion of green stems (30 to 53%) and dead material (25 to 52%) and smaller number of leaf blades (10 to 35%). Regardless of the height of the pasture, the upper strata are more sensitive to the animal and the environment effects, and presented higher levels of CP and NDF for leaf blades and stems. In the strata above 15 cm, the values of PB and NDF of the green leaf blades varied between 10.3 and 13.6% and 49.3 and 54.2%, respectively. The management of different heights change the characteristics of the pasturevertical strata, mainly in the strata above 15 cm. Keywords: Height of the Pasture. Forage Density. Green Stems. Dead Material. Leaf Laminas.

Establishment of paiaguas palisadegrass in monoculture or in an integration system with other crops

The objective of this study was to evaluate the productive and structural characteristics of Paiaguas palisadegrass established in monoculture and intercropped with agricultural crops in 2018 and 2019. The evaluated treatments were: Paiaguas palisadegrass (PP) in monoculture, PP intercropped with maize, PP intercropped with sorghum, and PP intercropped with soybean. The experimental design used was a randomized block, with 4 replications (plots of 160 m²). Sward height, tiller density, dry mass production, and bulk density of total dry matter, of leaves, of stems, and of dead material were evaluated. The data were analyzed using the Tukey test at 5% probability. The total dry mass was higher in intercropping than in monoculture. Paiaguas palisadegrass intercropped with maize showed lower productions of total dry mass, leaf blade, and stems. The percentage of leaf blades was higher in Paiaguas palisadegrass intercropped in 2018 and in monoculture and intercropped with maize and soybean in 2019. Higher percentages of stems were registered in Paiaguas palisadegrass in monoculture in 2018 and in intercropping with sorghum in 2018 and 2019. In general, higher heights were found in Paiaguas palisadegrass in monoculture and smaller when intercropped with maize. The highest tiller densities were observed in Paiaguas palisadegrass in monoculture and the lowest in Paiaguas palisadegrass intercropped with maize and sorghum. Intercropping with agricultural crops reduces the production of Paiaguas palisadegrass. The accompanying agricultural crops alter the composition of the forage produced by the Paiaguas palisadegrass.

Structure and nutritional value of BRS Zuri grass under shading

ABSTRACT The objective was to determine the structural and nutritive parameters for Panicum maximum cv. BRS Zuri under a Eucalyptus shading system, in rainy and dry seasons. At the beginning of each season, the treatments (foliar fertilization levels of 0, 3, 6 and 9 L ha-1) were applied and evaluated at 28, 56, and 84 growing days. The treatments did not affect significantly (p ≥ 0.05) the evaluated parameters. The systems (shading and full sun) and seasons did not change (p ≥ 0.05) forage and root masses. The leaf crude protein content was higher (p ≤ 0.05) in the dry season. Height, leaf mass, stem and dead material, neutral and acid detergent fiber contents, and in vitro dry matter digestibility were affected (p ≤ 0.05) by the system x season. The growing days did not affect (p ≥ 0.05) forage mass. The mass of dead material decreased (p ≤ 0.05) over the evaluated intervals. The other parameters were affected (p ≤ 0.05) by system × growing days. Based on the results, the forage and root masses show that the cv. BRS Zuri is adapted to the shading in the proposed experimental conditions. These masses added to the crude protein content indicate adaptation to low rainfall, inherent to the dry season, while foliar fertilization applied at the beginning of seasons did not affect the structural and nutritive parameters of BRS Zuri grass.