Comparación de la fibra detergente neutra en gramíneas, calculada mediante algoritmo de análisis de imágenes rojo, verde y azul vs espectroscopia del infrarrojo cercano

El trabajo estuvo orientado a evaluar la precisión del algoritmo de análisis de imágenes Red, Green, Blue (RGB) incluido en el software TaurusWebs V2017® para el cálculo del porcentaje de fibra detergente neutra (FDN) en la materia seca de gramíneas, a partir de imágenes de las praderas tomadas por un dron con cámara RGB. Los resultados fueron comparados con los valores de FDN calculados con espectroscopia del infrarrojo cercano (NIRS). Se tomaron 42 muestras para NIRS: 18 de gramíneas de trópico alto en Cundinamarca: kikuyo (Pennisetum clandestinum), falsa poa (Holcus lanatus) y pasto brasilero (Phalaris arundinacea) y 24 de trópico bajo en Tolima, Colombia: pangola (Digitaria decumbens), pará (Brachiaria mutica), bermuda (Cynodon dactylon) y colosuana (Bothriochloa pertusa). Los resultados se compararon contra 180 evaluaciones hechas con el algoritmo de las imágenes de las mismas gramíneas donde se tomaron las muestras para NIRS. Las pruebas de correlación de Kendall y de Spearman fueron significativas (p<0.05), con una asociación de rho=0.81 para la prueba de hipótesis de Kruskal Wallis (p> 0.05). No hubo diferencias significativas en los valores de FDN bajo las dos metodologías y según la prueba de Wilcoxon las medianas de la FDN calculada por NIRS vs. las del algoritmo son iguales. En conclusión, la información generada con el algoritmo se puede utilizar para trabajos de análisis del FDN en gramíneas.

Root-Associated Mycobiomes of Common Temperate Plants (Calluna vulgaris and Holcus lanatus) Are Strongly Affected by Winter Climate Conditions

Winter temperatures are projected to increase in Central Europe. Subsequently, snow cover will decrease, leading to increased soil temperature variability, with potentially different consequences for soil frost depending on e.g. altitude. Here, we experimentally evaluated the effects of increased winter soil temperature variability on the root associated mycobiome of two plant species (Calluna vulgaris and Holcus lanatus) at two sites in Germany; a colder and wetter upland site with high snow accumulation and a warmer and drier lowland site, with low snow accumulation. Mesocosm monocultures were set-up in spring 2010 at both sites (with soil and plants originating from the lowland site). In the following winter, an experimental warming pulse treatment was initiated by overhead infrared heaters and warming wires at the soil surface for half of the mesocosms at both sites. At the lowland site, the warming treatment resulted in a reduced number of days with soil frost as well as increased the average daily temperature amplitude. Contrary, the treatment caused no changes in these parameters at the upland site, which was in general a much more frost affected site. Soil and plant roots were sampled before and after the following growing season (spring and autumn 2011). High-throughput sequencing was used for profiling of the root-associated fungal (ITS marker) community (mycobiome). Site was found to have a profound effect on the composition of the mycobiome, which at the upland site was dominated by fast growing saprotrophs (Mortierellomycota), and at the lowland site by plant species-specific symbionts (e.g. Rhizoscyphus ericae and Microdochium bolleyi for C. vulgaris and H. lanatus respectively). The transplantation to the colder upland site and the temperature treatment at the warmer lowland site had comparable consequences for the mycobiome, implying that winter climate change resulting in higher temperature variability has large consequences for mycobiome structures regardless of absolute temperature of a given site.

Producción de leche real vs la calculada a partir de la ENL estimada por el algoritmo de análisis de imágenes red-green-blue de gramíneas

ABSTRACT: Knowledge about the net lactation energy (NLE) contained in the dry matter of grasses is necessary to make decisions about forage and the balance of diets for grazing cattle. Its determination is made in laboratories using wet or dry chemistry methods, which are costly, delayed, and sometimes present sampling- or process-related reliability problems. An algorithm, which analyzes the red-green-blue (RGB) images of grasses taken by drone, has been developed as a technological alternative. This has allowed us estimating the NLE level, reducing costs, and changing the sampling system and analysis method. The objective of the present study was to compare the milk production, which was calculated from the NLE and estimated using the algorithm for analysis of RGB images of grasses (included in the TaurusWebs® software), vs the actual milk production. The study was conducted in 15 dairy farms belonging to the dairy control system of the Colácteos dairy cooperative, which are located in the upper tropical region (Department of Nariño, Colombia). The prairies evaluated were composed of mixtures of Kikuyo (Pennisetum clandestinum), Raigrás (Lolium spp), and False Poa (Holcus lanatus). The result was analyzed using a linear regression model (R²=0.86; R=0.93). In the Student´s t-test, the actual and estimated milk production averages were equal (P>0.05). In conclusion, the NLE calculated using the algorithm satisfactorily explains the study livestock production, and the information generated by the algorithm can be used to calculate the NLE of grasses.

Germination and Early Development of Three Spontaneous Plant Species Exposed to Nanoceria (nCeO2) with Different Concentrations and Particle Sizes

This study aimed to provide insight regarding the influence of Ce oxide nanoparticles (nCeO2) with different concentrations and two different particle sizes on the germination and root elongation in seedlings of spontaneous terrestrial species. In a bench-scale experiment, seeds of the monocot, Holcus lanatus and dicots Lychnis-flos-cuculi and Diplotaxis tenuifolia were treated with solutions containing nCeO2 25 nm and 50 nm in the range 0–2000 mg Ce L−1. The results show that nCeO2 enters within the plant tissues. Even at high concentration, nCeO2 have positive effects on seed germination and the development of the seedling roots. This study further demonstrated that the particle size had no influence on the germination of L. flos-cuculi, while in H. lanatus and D. tenuifolia, the germination percentage was slightly higher (+10%) for seeds treated with nCeO2 25 nm with respect to 50 nm. In summary, the results indicated that nCeO2 was taken up by germinating seeds, but even at the highest concentrations, they did not have negative effects on plant seedlings. The influence of the different sizes of nCeO2 on germination and root development was not very strong. It is likely that particle agglomeration and ion dissolution influenced the observed effects.

Mycorrhizal colonisation in roots of Holcus lanatus (Yorkshire Fog) in a permanent pasture under conditions of reduced precipitation.

The UK climate is projected to become warmer, with more frequent hotter, drier summers. Many governments and international organisations are concerned about how climate change will affect food production and security. Mycorrhizal fungi are an essential part of agricultural systems and yet little is known about how climate change will affect mycorrhizal fungi. We investigated the effect of reduced precipitation on levels of arbuscular mycorrhizal (AM) colonisation in the top 10 cm of soil in the grass Holcus lanatus L. (Yorkshire Fog) in a permanent pasture in South Gloucestershire, UK. Incident rainfall was reduced, by approximately 50 %, using clear gutters supported on steel frames. Over three growing seasons we observed little difference in levels of AM colonisation and numbers of intra-root fungal structures between the roots of H. lanatus grown with reduced or full incident rainfall. Time of year when water stress occurred had a stronger effect on levels of colonisation than the absolute amount of precipitation received. In H. lanatus, growing in a permanent pasture, levels of AM colonisation were around 40 - 50%, across a range of precipitation, from 18% above to 36% below the long-term average. The results highlighted the complex relationship between mycorrhizal fungi, host plant and abiotic stress.

Evaluation of the grassland sward floristic composition of the Wadowice commune

The quality of the botanical composition of meadows and pastures is decisive in the profitability of livestock farming. The aim of this study was to examine the floristic composition of meadows and pastures of the Wadowice commune and to assess their feed value. Field explorations were carried out in June 2016 throughout the commune. Floristic lists were made on 51 designated plots using the estimated Klapp method. Four groups of similar plots with the following dominant species were distinguished in the analysed area: I – plots with Phleum pratense and Vicia cracca, II – plots with Dactylis glomerata and Trifolium repens, III – plots with Holcus lanatus, and IV – plots with Arrhenatherum elatius. The results of the research showed that, in the area of this commune, meadows and pastures were characterised by average and good pasture values, which favours their use for agricultural purposes. Improving the quality of the botanical composition of plots of medium fodder value could be achieved through proper care and sustainable use.

Use of Predicted Behavior from Accelerometer Data Combined with GPS Data to Explore the Relationship between Dairy Cow Behavior and Pasture Characteristics

Our aim in this study was to investigate whether the behaviors of dairy cows on pasture, predicted with accelerometer data and combined with GPS data, can be used to better understand the relationship between behaviors and pasture characteristics. During spring 2018, 26 Holstein cows were equipped with a 3D-accelerometer and a GPS sensor fixed on a neck-collar for five days. The cows grazed alternatively in permanent and in temporary grasslands. The structural elements, soil moisture, slope and botanical characteristics were identified. Behaviors were predicted every 10 s from the accelerometer data and combined with the GPS data. The time-budgets expressed in each characterized zone of 8 m × 8 m were calculated. The relation between the time-budgets and pasture characteristics was explored with a linear mixed model. In the permanent grassland, dairy cows spent more time under a tree to ruminate (p < 0.001) and to rest (p < 0.001) and more time to graze in areas with Holcus lanatus (p < 0.001). In the temporary grassland, behavior was influenced by the external environment (presence of other animals on the farm; p < 0.05). Thus, this methodology seems relevant to better understand the relationship between the behaviors of dairy cows and grazing conditions to develop precision grazing.

Plants increase silicon content as a response to nitrogen or phosphorus limitation: a case study with Holcus lanatus

Aims Silicon (Si) has been shown to beneficially affect plant performance under stressful environmental conditions, such as water or nutrient deficiency. Here we tested the effects of two important plant nutrients, nitrogen (N) and phosphorus (P), on Si content in different plant organs in the grass species Holcus lanatus. Methods We studied trait responses to N limitation, balanced nutrient availability and P limitation. Single plant individuals were grown in sand-filled pots in a greenhouse for 2 months. Nitrogen, phosphorus, carbon and silicon contents were determined in leaves, stems and roots, as were leaf and roots traits, biomass production and root enzyme activity. Results Si content was lowest under balanced nutrient supply in all plant organs. Under P limitation Si content was highest in leaves and stems, in roots it was highest under N limitation. Si:C ratios were lowest under balanced conditions, and highest under nutrient limitation. Root phosphatase activity was highest under P limitation and chlorophyll content was lowest under N limitation. Conclusions Our model species assimilated less ‘high cost C’ and took up more ‘low cost Si’ under nutrient limitation, especially under P deficiency. Si potentially plays an important role in different environments, such as nutrient or light limitation, which in turn may be related to different plant strategies, for example higher stem rigidity in high Si plants versus higher stem flexibility in low Si plants. More research is needed to further elucidate the role of silicon in different concepts of trait-environment relationships.