Nitrogen signals and their ecological significance for seed germination of ten psammophilous plant species from European dry acidic grasslands

The presented study evaluated effects of potassium nitrate (KNO3), ammonium nitrate (NH4 NO3) and ammonium chloride (NH4Cl) on the germination-related characteristics of 10 species from European dry acidic grasslands. Germination was studied under controlled laboratory conditions. The seeds were subjected to KNO3, NH4 NO3 and NH4Cl in four doses (1, 10, 50 and 100 mM) and to distilled water. Final germination percentage, index of germination velocity and index of germination synchrony were determined. Content of nitrogen in the soil probed from the site of seeds collection was also analyzed. Significant effects of type of the nitrogen compounds and their concentrations were observed. High concentrations of nitrogen-containing salts inhibited completion of germination in almost all species. Helichrysum arenarium and Hypericum perforatum showed preference for NH4+ over NO3‒, whereas Arnoseris minima, Alyssum montanum, Jasione montana and Spergula morisonii showed preference for NO3‒ over NH4+. Centaurea scabiosa, C. stoebe and Hypochaeris radicata had no preference and wide tolerance to the type of nitrogen-containing compound. Echium vulgare showed differential response hard for interpretation. A. montanum and J. montana showed stenotopic behavior in terms of nitrogen-related conditions. It is proposed that nitrogen-rich soil gaps favor establishment of more nitro-tolerant plant species (e.g. C. scabiosa, C. stoebe and H. radicata) as compared to nitrogen-poor ones.

Homeowner preferences drive lawn care practices and species diversity patterns in new lawn floras

Households intensively manage lawns to create uniformly green, low diversity plant communities. Because lawns occupy a large proportion of urban green space, they are a crucial case for understanding how people manipulate urban vegetation. In this study, I focused on 58 homeowners who purchased a newly constructed home and yard in the Seattle Metropolitan Statistical Area, USA, to see how preferences, lawn care regimes and new lawn floras develop within a multi-scalar urban environment. A typical homeowner watered 3 times in spring, watered 24 times in summer, applied fertilizer twice, mowed 21 times and edged 15 times. Most new lawn turfgrasses were Lolium perenne, Poa pratensis and/or Festuca spp. Mean species richness was 6.5 ± 5.3 species. The most frequent species were non-native and cosmopolitan (turfgrasses, Hypochaeris radicata, Taraxacum officinale and Trifolium repens). Five variables increased the probability of homeowners managing their lawns as turfgrass monocultures: living in a neighborhood with larger yards, summer watering frequency, fertilizer frequency, valuing space for children and valuing wildlife habitat. Valuing an easy to manage yard decreased the turfgrass monoculture probability. In polyculture yards, having a larger lawn was positively correlated with non-turfgrass species richness, but elevation was negatively correlated. Homeowners who valued space for children appeared to have more intensive lawn care regimes than those who valued wildlife habitat or easy to manage yards. Although lawn floras result from complex interactions of the environment and households, urban characteristics appeared to be weaker drivers of diversity than homeowner preferences and lawn care.

Evaluation of chemical composition and inhibitory effects of Hypochaeris radicata L. extracts on seed germination and growth of Echinochloa crus-galli L.

Allelopathy is a common plant-resistance mechanism in nature, this mechanism demonstrates the growth of this plant that may affect the growth and development of other nearby plant species through the production of secondary compounds. In this study, the allelopathic ability of ethanol extracts from Hypochaeris radicata L. on Echinochloa crus-galli L. was investigated in laboratory conditions. The extracts from stems of Hypochaeris radicata L. at the concentration of 5 mg/mL showed highest inhibition (73.33%) on seed germination of barnyard-grass (Echinochloa crus-galli L.). In this study, total polyphenol and flavonoids in Hypochaeris radicata L. were determined by spectrophotometry. Polyphenol and flavonoids present in all parts of the Hypochaeris radicata L. were investigated. The highest polyphenol content in leaves was 9.67 mg/g extract and the flavonoid content in roots was 29.56 mg/g extract. Phenolic acids in extracts from leaves, flowers, and roots were identified by HPLC. The results showed the presence of 7 phenolic acids including chlorogenic, syringic, vanillic, synaptic, p-coumaric, benzoic and ellagic in the extracts. The findings highlighted that Hypochaeris radicata L. is a wild plant species with great potential for allelochemicals.

Attachment-based mechanisms underlying capture and release of pollen grains

Successful insect pollination can be achieved by a sequence of numerous attachment and detachment events at various biological surfaces. However, the quantitative measurements of pollen adhesion on biological surfaces have been poorly studied so far. We performed atomic force microscopy adhesion measurements of pollen on two most important floral parts for Asteraceae in a course of pollination: the stigma and style of Hypochaeris radicata plant . The results indicated distinct adhesive properties of them—the pollen adhesion on stigmatic surfaces drastically increased over prolonged contact time, while the pollen adhesion increase on stylar surfaces was rather restrained. Based on the observation with cryo-scanning electron microscopy, we explained the experimental results by the presence of morphological features in form of flexible stigmatic papillae that may play a crucial role in enhancing both capillary attraction and van der Waals forces. The distinct adhesive properties seemingly originate from the unique adhesive tasks that each of the floral parts requires to achieve successful pollination. The insights into the adhesive interaction between pollen and the floral parts, obtained in the present study, may lead to better understanding of pollination mechanisms, which are strongly related to our food production. Additionally, the novel pollen adhesive mechanisms learned from the stigma of the studied Asteraceae plant can inspire biomimetic designs of spontaneous gripping systems.

EVALUACIÓN DE LA PRODUCCIÓN Y CALIDAD FORRAJERA DE UN SISTEMA SILVOPASTORIL ALTOANDINO EN NARIÑO

Teniendo en cuenta las adversidades climáticas que limitan la producción animal y su oferta alimentaria, es necesario reorientar la producción forrajera hacia sistemas ganaderos arborizados que brinden abundancia, calidad y estabilidad en épocas críticas, y que garantice armonía con el entorno. La investigación se realizó en la vereda Meneses, Villamoreno, Buesaco, Nariño, Colombia, con temperatura promedio de 15ºC, precipitación de 1.035 mm anuales y una altitud de 2.483 msnm. El objetivo de la investigación fue evaluar la oferta forrajera de un sistema silvopastoril (SSP), en zona de bosque húmedo montano bajo (bh-MB), con la inclusión de especies forrajeras arbustivas, distribuidas en tres tratamientos; T1: Acacia decurrens × A. decurrens, T2: A. decurrens × Tithonia diversifolia, T3: A. decurrens × Sambucus nigra, y el testigo (T0): una pastura convencional compuesta en su mayoría por Cenchrus clandestinus, Agrostis scabrifolia, Holcus lanatus e Hypochaeris radicata. Se evaluaron algunas propiedades físicas, químicas y biológicas del suelo, composición florística y fenología, determinación de diversidad y abundancia de especies mediante índices de Simpson y Shannon, producción de biomasa comestible, calidad nutricional mediante métodos de la AOAC y Goering y Van Soest, y presencia de metabolitos secundarios. Los factores físicos, químicos y biológicos tuvieron resultados similares entre tratamientos, con mayor producción de materia seca en T1 y T2, mejorando la oferta alimentaria con la incorporación de arbustivas. Los resultados estadísticos arrojados por SPSS de IBM, mostraron diferencias significativas entre los tratamientos en producción de materia seca. T1 y T2, por prueba de Tukey; éstos fueron los tratamientos de mayor beneficio forrajero, con producciones de 2,223 y 1,978 Ton/MS/año, respecto a T0, con 1,651 Ton/MS/año. La resistencia del suelo, en todos los tratamientos, fue alta y de limitación severa: T0: 1,91 Mpa, T1:1,85 Mpa, T2:1,92 Mpa y T3: 1,97 Mpa, causando dificultades en el desarrollo radicular de las especies arbustivas implementadas.

Traditional Salads and Soups with Wild Plants as a Source of Antioxidants: A Comparative Chemical Analysis of Five Species Growing in Central Italy

The interest and demand for nutraceuticals are rapidly increasing in many industrialized countries due to the emergence of health risks associated with the increased consumption of processed foods. Several wild Mediterranean plants used as traditional foods are an extraordinary source of nutraceutical substances with antioxidant properties. This study has two main aims: (1) to quantify the antioxidant properties of traditional wild food plants and (2) to determine if their use in soups (i.e., the cooking process) can alter their beneficial properties. We have evaluated the antioxidant capacity (ABTS, DPPH) and the Total Phenolic Content (Folin-Ciocalteu) of five herbaceous plants traditionally consumed in several areas of Central Italy: (A) Reichardia picroides (L.) Roth, (B) Hypochaeris radicata L., (C) Cichorium intybus L., (D) Tordylium apulum L., and (E) Helminthotheca echioides (L.) Holub. Our analyses show good levels of antioxidant capacity for all plants, with Reichardia picroides and Helminthotheca echioides having the highest levels. There is a high correlation between the antioxidant activity and the Total Phenolic Content especially in Reichardia picroides (R2=0.92) and Hypochaeris radicata (R2=0.93). Boiling the species caused a general decrease in the antioxidant activity and polyphenols. Our study confirms the health benefits of consuming wild plants, especially raw ones in salads. It also supports the use of ethnobotanical information to study and then promote the consumption of wild food plants.