Alternatives for the recovery and renewal of degraded pastures

This review aimed to approach the dynamics of pasture degradation, relating its causes and forms of recovery and/or renewal. Despite being based on extensive systems, Brazilian agriculture faces serious problems related to pasture degradation. The reduction in forage productivity directly affects the production system, having negative impacts on the economy and the ecosystem. Factors such as the choice of forage species, grazing management and the use of fire are the main factors responsible for the degradation of pastures in Brazil, causing an environmental and productive imbalance. However, it is possible to stop the progress of degradation and resume system productivity using pre-defined techniques in accordance with the objective of the production system. Furthermore, pasture recovery techniques are efficient for the resumption of productivity, and environmental protection, by helping to reduce greenhouse gases. Nevertheless, more research is needed to prove and consolidate pasture recovery techniques in the environmental, economic, and social scope.

Expanding the Benefits of Tnt1 for the Identification of Dominant Mutations in Polyploid Crops: A Single Allelic Mutation in the MsNAC39 Gene Produces Multifoliated Alfalfa

Most major crops are polyploid species and the production of genetically engineered cultivars normally requires the introgression of transgenic or gene-edited traits into elite germplasm. Thus, a main goal of plant research is the search of systems to identify dominant mutations. In this article, we show that the Tnt1 element can be used to identify dominant mutations in allogamous tetraploid cultivated alfalfa. Specifically, we show that a single allelic mutation in the MsNAC39 gene produces multifoliate leaves (mfl) alfalfa plants, a pivot trait of breeding programs of this forage species. Finally, we discuss the potential application of a combination of preliminary screening of beneficial dominant mutants using Tnt1 mutant libraries and genome editing via the CRISPR/Cas9 system to identify target genes and to rapidly improve both autogamous and allogamous polyploid crops.

Linking Metabolites in Eight Bioactive Forage Species to Their in Vitro Methane Reduction Potential Across Several Cultivars and Harvests

An in vitro study was conducted to analyze the fermentation end-products from 17 cultivars of eight polyphenol containing forage species. The polyphenol composition and proanthocyanidin (PA) structural features of all cultivars were analyzed with UPLC-MS/MS in leaves of vegetative or generative plants. All samples were incubated with and without polyethylene glycol (PEG, a tannin-binding agent) to separate the tannin-effect on methane (CH4) production from that of the forage quality. Sulla and big trefoil, two particularly PA rich species, were found to have the highest CH4 reduction potential of up to 47%. However, they showed simultaneous and almost equal reductions in gas production (GP; a proxy for digestibility). The addition of PEG led to an increase in both GP and CH4 production, confirming the role of tannins on CH4 reduction. Moreover, PA structural features and concentration were found to be an important source of variation for CH4 production from PA containing species. Despite having low polyphenol concentrations, chicory and plantain were found to reduce CH4 production without reducing GP. Generally, the variation across cultivars from the same species was found to be lower than interspecies variability, and the results were found to be consistent across growth stages, indicating the findings representativeness.

CONTRIBUTION OF THE GENETIC IMPROVEMENT OF TALL FESCUE (Festuca arundinacea SCHREB.) IN ARGENTINA: SYNTHESIS OF ACHIEVEMENTS AND ADVANCES

Tall fescue (Festuca arundinacea Schreb.) is represented in Argentina by adapted populations of the continental morphotype, which are long persistent. It is the main perennial forage species cultivated in the temperate region of the country, producing forage for extensive grazing. The development of fescue plant breeding and its contribution to the achievement of higher productivity and better nutritional value with modern synthetic cultivars was the aim of this project. The characters considered were: adaptation and persistence in adverse environments, digestibility, leaf softness and tolerance to rust. The most representative cultivars of the stages and selection criteria considered in this work were: Pergamino El Palenque MAG, Palenque Plus INTA, Brava INTA, Baguala and Luján INTA. Key words: tall fescue, plant breeding, cultivars, germplasm.

Population dynamics of the pasture leafhopper complex (Hemiptera: Cercopidae) in brachiaria and mombasa grass

Pasture leafhoppers are considered highly important pests in forage grasses in Brazil due to their widespread occurrence. This insect is one of the most relevant pests in pasture degradation. In order for the control of spittlebugs to be efficient, it is important to know the population behavior of the species of this insect, identify the period of greatest occurrence, as well as the climatic and environmental conditions that favor the development of the pest. Thus, this study aimed to evaluate the population dynamics of spittlebugs, at a quantitative level, in Brachiaria decumbens and Panicum maximum pastures, associating the results with meteorological data from the municipality of Conceição do Araguaia, Southeast Pará. To study the population dynamics of spittlebugs, samples were taken every two weeks, in two types of pastures aged between 5 and 7 years, kept under rotational grazing, with a stocking of 1.5 animal units. The method of monitoring nymphs and adults of leafhoppers was adopted, through walking within the observation area. The level of infestation of spittlebugs in both forage species was evaluated and all results were submitted to analysis of variance by the F test. It was found that the species B. decumbens had a greater number of adults and nymphs when compared to the forage species P. maximum. The population dynamics of spittlebugs occur gradually according to climatic conditions, and the period with not-so-high temperatures (22 ºC to 34 ºC) and good rainfall provide an infestation of this insect pest in the pasture.

Production and quality of tropical grasses at different regrowth intervals in the Brazilian semiarid

The objective of this study was to evaluate the production and chemical composition of three forage species at different regrowth intervals. A 3 x 4 randomized-block factorial design with three forage species (Andropogon, Buffel, and Massai) and four regrowth intervals (21, 35, 49, and 63 days) was used. There was no interaction (p > 0.05) between forage species and regrowth interval on any of the chemical components evaluated. The crude protein content decreased but the contents of neutral detergent fiber, acid detergent fiber and hemicellulose increased with increasing regrowth interval (p > 0.05). Only the contents of crude protein and ether extract were similar (p > 0.05) among grasses. A significant interaction was observed (p < 0.05) between forage species and regrowth interval on forage mass. Andropogon grass had the highest forage mass at 63 days (3,270.1 kg ha-1 DM cut-1) and the highest productivity regardless of the regrowth interval (19.1 t ha-1 DM year-1). Therefore, Andropogon grass was the most productive forage among the tested species. Pastures should be managed with shorter growth intervals due to the highest crude protein level and the lowest contents of neutral detergent fiber and acid detergent fiber.

Bromatological Analysis of the Fodder Marketed in the Peri-Urban Areas of Bujumbura (Burundi): Towards Spontaneous Fodder Conservation by Transformation into Silage

Peri-urban areas of Bujumbura host a significant number of dairy cattle, which consequently ensure a substantial production of milk consumed in the Burundian capital. The presence of these cows in peri-urban areas has led to the emergence of an atypical market for spontaneous forage species. The present study seeks to determine the food and nutritional value of this fodder. A test on its conservation by transformation into silage was also carried out. Botanical field investigations and plant samples collection were carried out under the guidance of fodders suppliers. Based on the bromatological value deficiency thresholds for cattle, the results showed that the content of digestible nitrogenous matter and major elements (Ca, P, K, and Mg) in the forage is within acceptable limits. The final product obtained after fermentation, based on its color, its smell, and its consistency, is indeed silage. The chemical composition of fermented fodder showed that the nutritional quality has remained almost the same. Further research on digestibility of this forage is necessary. A study of the environmental determinants of spontaneous forage distribution at multiple sites and over a wide range of parameters may contribute to a better understanding of the importance of this fodder particularly in times of fodder deficit.