Natürliche Mechanismen der Unkrautunterdrückung in ‚Elstar‘-Apfelanlagen

ZusammenfassungIm Rahmen einer Masterarbeit sollte untersucht werden, warum der Baumstreifen in ausgewachsenen Elstar-Anlagen wesentlich weniger Aufwuchs aufweist als bei anderen Apfelsorten auf der gleichen Unterlage am gleichen Standort. Daher wurde die Vegetation in Baumstreifen von ‘Elstar’-Anlagen im Vergleich zu drei anderen Apfelsorten in 150 Vegetationsaufnahmen an drei Terminen in einjährigen Untersuchungen am Campus Klein-Altendorf bonitiert. Daneben wurde die Lichtdurchlässigkeit der Baumkrone mittels 300 Ceptometer- und 100 Schachbrettmessungen der Sonnenflecken im Baumstreifen im Juni und September – nach der Herbizidapplikation im Mai 2019 – ermittelt.Die mit der Schachbrettmethode bzw. mit dem Ceptometer ermittelte Lichteinstrahlung durch die Baumkrone auf den Baumstreifen unter den ‘Elstar’-Apfelbäumen war im September um ca. 35 % bzw. ca. 10 % signifikant geringer als unter Bäumen gleichen Alters der Sorte ‘Golden Delicious’ in der Nachbarreihe auf der gleichen Unterlage M 9.Der Baumstreifen unter ausgewachsenen ‘Gala’- und ‘Braeburn’-Apfelbäumen wies einen statistisch signifikant höheren Bodenbedeckungsgrad mit Beikräutern mit Boniturnoten von 3,8–4,3 im Vergleich zu 1,7–1,9 bei ‘Elstar’ auf (auf der Skala 1–5) – auf zwei nach IP-Richtlinien und einer biologisch bewirtschafteten Fläche, d. h. die Art der Baumstreifenbehandlung (chemisch oder mechanisch) hatte keinen Einfluss auf das Phänomen der Beikrautunterdrückung bei ausgewachsenen ‘Elstar’-Apfelbäumen.Sowohl Kreuzkraut (Senecio spp.) als auch Gänseblümchen (Bellis perennis) traten in den Baumstreifen unter ausgewachsenen ‘Elstar’-Apfelbäumen mit wesentlich geringerer Stetigkeit auf als unter ‘Golden Delicious’ in der benachbarten Reihe. Die in der Literatur beschriebene indirekte Selektion durch langjährige Glyphosatanwendung auf Vogelmiere (Stellaria media) und Kreuzkraut (Seneccio spp.) durch Auskeimen der Samen nach der Herbizidapplikation wurde bestätigt; im vorliegenden Versuch traten jedoch Behaartes Schaumkraut (Cardamine hirsuta) und Rispengräser (Poa spp.) stärker auf.Keimtests in Aussaatschalen – aufgestellt in den Baumstreifen – unter den Apfelbäumen der beiden Apfelsorten ‘Elstar, Michielsen’ und als Vergleich ‘Golden Delicious’ mit einem Licht- (Lepidium sativum) und einem Dunkelkeimer (Borago officinalis) zeigten keinen Unterschied in der Keimrate. Keimtests mit Kressesamen (Lepidium sativum) in mit Falllaub vermischtem Substrat in Aussaatschalen im Gewächshaus zeigten keine keimhemmende und damit keine allelopathische Wirkung des Falllaubes der Sorte ‘Elstar’.Die vorliegenden Ergebnisse der Beikrautunterdrückung im Wiederaufwuchs nach Beikrautbekämpfung stimmen mit denen unter starkwüchsigen ‘Ingrid Marie’ auf M 2 aus der Literatur überein. Diese Wirkung ausgewachsener Apfelbäume der Sorte ‘Elstar, Michielsen’ auf M 9 ist durch die Schattierung dieser wüchsigeren Bäume bedingt und hängt nicht von der Bewirtschaftungsform (IP mit Herbizideinsatz oder Öko mit mechanischer Beikrautbekämpfung), aber eventuell noch von weiteren Faktoren, ab.

Efficiency of Methodologies Used in the Evaluation of the Weed Seed Bank under Mediterranean Conditions

The objective of this study was to compare the efficiency of two methodologies, seed germination (SG) and seed physical extraction SPE), to assess the weed community from two locations with different soil and climatic conditions: M, with dry and low soil fertility, and S with high soil humidity and fertility. Over three years of study, the analysis of both methodologies confirmed differences in seed bank composition. In M, fewer seeds were recorded by SG than SPE (13.5% and 86.5% respectively), while in S, the difference between percentages was less (31.58% by SG and 68.41% by SPE). Our findings confirmed that Portulaca oleracea L., Amaranthus blitoides S. Watson and Chenopodium album L. were abundantly found in M. Anacyclus clavatus (Def.) Res. seeds were also found, mainly detected by SG. In S, Stellaria media (L.) Vill. was widely found. All species found in S were similarly detected by SG and SPE. The results confirmed that climatic and soil conditions influenced the efficiency of the methodology used to assess the seed bank. M conditions led to an increased seed reservoir, and both methodologies were necessary to obtain the seed bank composition. In S conditions, the seed bank was continuously renewed, and either one of methodologies defined the seed bank composition equally well.

Skuteczność chwastobójcza wybranych herbicydów stosowanych w jęczmieniu jarym

Celem prowadzonych badań była ocena skuteczności chwastobójczej wybranych herbicydów stosowanych w jęczmieniu jarym, odmiana Poldek. Doświadczenie przeprowadzono w latach 2012–2014. W doświadczeniu stosowano następujące kombinacje herbicydowe: kontrola (bez odchwaszczania), Pike 20 WG (metsulfuron metylu), Aurora 40 WG (karfentrazon etylu), Tayson 464 SL + Pike 20 WG (2,4-D + dikamba + metsulfuron metylu), Pike 20 WG + Aurora 40 WG (metsulfuron metylu + karfentrazon etylu), Galmet 20 SG + Galaper 200 EC (metsulfuron metylu + fluroksypyr), Granstar Ultra SX 50 WG (tifensulfuron metylu + tribenuron metylu). Ocenę skuteczności zwalczania najliczniej występujących gatunków chwastów przeprowadzono 30 dni po zastosowaniu preparatów metodą szacunkową. Dodatkowo dwa tygodnie przed zbiorem jęczmienia oceniono wtórne zachwaszczenie łanu metodą botaniczno-wagową, określając skład florystyczny, liczebność poszczególnych gatunków oraz powietrznie suchą masę chwastów. Gatunkami dominującymi w uprawie jęczmienia były: Galinsoga parviflora, Polygonum lapathifolium subsp. lapathifolium, Galium aparine, Matricaria maritima subsp. inodora, Chenopodium album i Stellaria media. Najbardziej skuteczne w zwalczaniu dominujących w jęczmieniu gatunków chwastów były kombinacje herbicydowe Tayson 464 SL + Pike 20 WG oraz Pike 20 WG + Aurora 40 WG, Galmet 20 SG + Galaper 200 EC. Po aplikacji tych kombinacji herbicydowych uzyskano również najwyższy plon ziarna jęczmienia.

Evaluation of In Vitro Wound-Healing Potential, Antioxidant Capacity, and Antimicrobial Activity of Stellaria media (L.) Vill

The healing of skin wounds remains an important concern in medicine, especially in chronic wounds caused by various diseases such as diabetes. Using herbs or herbal products to heal skin wounds is a therapeutic challenge for traditional medicine. In this context, the main aim of our work was to highlight the in vitro healing potential of Stellaria media (L.) Vill. (SM) extract using the scratch assay on normal human dermal fibroblasts (NHDF). The ability to stimulate cell migration and proliferation under the influence of different concentrations of SM extract (range between 12.5 and 200 µg/mL) was determined compared to the control (untreated in vitro-simulated wound) and positive control (allantoin 50 µg/mL). Our results showed that the concentration of 100 µg/mL SM extract applied on the simulated wound recorded the strongest and fastest (24 h) migration (with wound closure) and proliferation of NHDF compared with the control. In addition, the SM extract was characterized in terms of bioactive compounds (total phenols and flavonoids content), antioxidant capacity (FRAP (The Ferric-Reducing Antioxidant Power) assay and electrochemical method), and antimicrobial activity. The results show that the SM extract contains a considerable amount of polyphenols (17.19 ± 1.32 mg GAE/g dw and 7.28 ± 1.18 mg QE/g dw for total phenol and flavonoid content, respectively) with antioxidant capacity. Antimicrobial activity against Gram-positive bacteria (S. aureus) is higher than E. coli at a dose of 15 µg/mL. This study showed that Stellaria media is a source of polyphenols compounds with antioxidant capacity, and for the first time, its wound healing potential was emphasized.

The Genomic Architecture of Competitive Response of Arabidopsis thaliana Is Highly Flexible Among Plurispecific Neighborhoods

Plants are daily challenged by multiple abiotic and biotic stresses. A major biotic constraint corresponds to competition with other plant species. Although plants simultaneously interact with multiple neighboring species throughout their life cycle, there is still very limited information about the genetics of the competitive response in the context of plurispecific interactions. Using a local mapping population of Arabidopsis thaliana, we set up a genome wide association study (GWAS) to estimate the extent of genetic variation of competitive response in 12 plant species assemblages, based on three competitor species (Poa annua, Stellaria media, and Veronica arvensis). Based on five phenotypic traits, we detected strong crossing reaction norms not only between the three bispecific neighborhoods but also among the plurispecific neighborhoods. The genetic architecture of competitive response was highly dependent on the identity and the relative abundance of the neighboring species. In addition, most of the enriched biological processes underlying competitive responses largely differ among neighborhoods. While the RNA related processes might confer a broad range response toolkit for multiple traits in diverse neighborhoods, some processes, such as signaling and transport, might play a specific role in particular assemblages. Altogether, our results suggest that plants can integrate and respond to different species assemblages depending on the identity and number of each neighboring species, through a large range of candidate genes associated with diverse and unexpected processes leading to developmental and stress responses.

Five undervalued edible species inherent to autumn-winter season: nutritional composition, bioactive constituents and volatiles profile

Background Wild edible herbs have historically been used as local nutritional and medicinal sources. These plants grow spontaneously, depending on the season. They adapt well to different edaphoclimatic conditions, generating a diversity constituent beneficial to health. They impart compounds needed in the human diet in regard to macro and micronutrients. When consumed raw, they keep their properties intact and provide health benefits. Five undervalued edible plants: Stellaria media (L.) Vill, Tropaeolum majus L., Sonchus oleraceus L., Chenopodium album L. and Diplotaxis erucoides (L.) DC are characteristic of the autumn-winter season in the Valencian coastal region and could have new sustainable agro-ecological potential for the local commercial sector. However, little information is available from the nutritional quality and bioactive composition viewpoint for these species. Concurrently, the volatiles compounds profiles describing the characteristic flavors are unknown. Methods Nutritional characteristics, bioactive compounds, and other chemical components of the fresh leaves were analyzed. In addition, the volatiles composite profile was performed. The analyzed species come from the soil reservoir; their wild growth is adjusted to the autumn season. The proximate analysis was carried out by Association of Official Analytical Chemists methods. Total antioxidants were measured as 2.2-diphenyl-1-picrylhydrzyl hydrate (DPPH) and total polyphenols content via the Folin-Ciocalteu procedure. Volatiles profile was determined by gas chromatography-mass spectrometry. The vegetative part analyzed was the tender leaves with edible potential. Results A high variability has been obtained in the composition of the species studied. The proximate analysis found a considerable content of fiber (1.22–5.4 g·100 g−1), potassium (157.7–1,250.6 mg·100 g−1), iron (0.6–2.0 mg·100 g−1), and a low caloric value (16.1–43.02 kcal·mg·100 g−1). In bioactive compounds analysis, a high level of antioxidants was highlighted (1,604.3–4,874.6 μmol·100 g−1), followed by chlorophylls. Volatiles profile revealed that the species were rich in benzenoids (33.8–89.9%) as the majority family. The pyrazines class was characteristic only in D. erucoides L. Discussion Fresh edible leaves of the undervalued plants show considerable nutritional potential and a high bioactive components level, which highlight the antioxidant capacity. Leaves of C. album L. stand out due to their higher concentration of nutritional compounds, while D. erucoides L. is noted for its higher antioxidant capacity. Aromatic descriptor of pyrazines detected in the leaves of D. erucoides L. is associated with the slightly spicy flavors that characterize this species. Results suggest that studied species could be of great relevance in introducing these five edible herbs as a source of new grown material, postulating them as healthy food ingredients with attractive flavors for the gourmet cuisine industry.

Allelopathic Properties of Hemp

Summary Allelopathic effects of different plant allelochemicals have become the focus of studies that aim to determine new pesticidal compounds. Plant extracts with different chemical compositions can be obtained using different methods of extraction, whereas studies dealing with allelopathic properties use biotests to obtain fast and precise results. Such studies were undertaken after noticing the allelopathic effects of industrial hemp (Cannabis sativa L.) on the surrounding crops. Trials that involve the application of hemp extracts obtained by different methods resulted in determining the hemp allelopathic effects on Stellaria media (L.)Scop., Beta vulgaris ssp. vulgaris var. vulgaris, Lupinus albus L., corn (Zea mays L.), Cyperus rotundus L., Matricaria recutita L., Lepidium sativum L., lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), rye (Secale cereal M. Bieb.), Ambrosia artemisiifolia L., Chenopodium album L., and Sorghum halepense L..

Resistance to post-emergent herbicides is becoming common for grass weeds on New Zealand wheat and barley farms

To estimate the prevalence of herbicide-resistant weeds, 87 wheat and barley farms were randomly surveyed in the Canterbury region of New Zealand. Over 600 weed seed samples from up to 10 mother plants per taxon depending on abundance, were collected immediately prior to harvest (two fields per farm). Some samples provided by agronomists were tested on an ad-hoc basis. Over 40,000 seedlings were grown to the 2–4 leaf stage in glasshouse conditions and sprayed with high priority herbicides for grasses from the three modes-of-action acetyl-CoA carboxylase (ACCase)-inhibitors haloxyfop, fenoxaprop, clodinafop, pinoxaden, clethodim, acetolactate synthase (ALS)-inhibitors iodosulfuron, pyroxsulam, nicosulfuron, and the 5-enolpyruvyl shikimate 3-phosphate synthase (EPSPS)-inhibitor glyphosate. The highest manufacturer recommended label rates were applied for the products registered for use in New Zealand, often higher than the discriminatory rates used in studies elsewhere. Published studies of resistance were rare in New Zealand but we found weeds survived herbicide applications on 42 of the 87 (48%) randomly surveyed farms, while susceptible reference populations died. Resistance was found for ALS-inhibitors on 35 farms (40%) and to ACCase-inhibitors on 20 (23%) farms. The number of farms with resistant weeds (denominator is 87 farms) are reported for ACCase-inhibitors, ALS-inhibitors, and glyphosate respectively as: Avena fatua (9%, 1%, 0% of farms), Bromus catharticus (0%, 2%, 0%), Lolium spp. (17%, 28%, 0%), Phalaris minor (1%, 6%, 0%), and Vulpia bromoides (0%, not tested, 0%). Not all farms had the weeds present, five had no obvious weeds prior to harvest. This survey revealed New Zealand’s first documented cases of resistance in P. minor (fenoxaprop, clodinafop, iodosulfuron) and B. catharticus (pyroxsulam). Twelve of the 87 randomly sampled farms (14%) had ALS-inhibitor chlorsulfuron-resistant sow thistles, mostly Sonchus asper but also S. oleraceus. Resistance was confirmed in industry-supplied samples of the grasses Digitaria sanguinalis (nicosulfuron, two maize farms), P. minor (iodosulfuron, one farm), and Lolium spp. (cases included glyphosate, haloxyfop, pinoxaden, iodosulfuron, and pyroxsulam, 9 farms). Industry also supplied Stellaria media samples that were resistant to chlorsulfuron and flumetsulam (ALS-inhibitors) sourced from clover and ryegrass fields from the North and South Island.