Enhancement of bioactive compounds in baby leaf Amaranthus tricolor L. using short-term application of UV-B irradiation.

Baby-leaf vegetables are a trade name for leafy vegetables sold as leaves with petioles at the seedling stage. Amaranth (Amaranthus tricolor L.) is a nutritious baby-leaf vegetable containing many bioactive compounds. The effects of short-term ultraviolet B (UV-B) treatments on the growth and quality of baby leaf amaranth were studied, including the conditions of a 24-h recovery period after irradiation, and different irradiation intensities (3.0-9.0 W m-2), irradiation periods (4-16 h), and cumulative energies (130-170 kJ m-2). A recovery period experiment was conducted to observe the changes in the growth and quality of leaves at 0 and 24 h after UV-B irradiation. The results showed that the concentrations of phenolic compounds, flavonoids, anthocyanin, and ascorbic acid in the leaves, as well as the leaf antioxidant capacity increased 24 h after UV-B irradiation. Increases in target compound concentrations and antioxidant capacity without negative growth and appearance effects were observed in leaves irradiated with UV-B at 3, 6, and 9 W m-2 for irradiation periods of 12 and 16, 8 and 12, and 4 h, respectively. The highest bioactive compound concentration was found in leaves irradiated with UV-B at 6 W m-2 for 7 h (cumulative energy: 150 kJ m-2). It was concluded that UV-B irradiation at 6 W m-2 with a cumulative energy of 150 kJ m-2 and a 24 h post-irradiation recovery period could be an appropriate treatment to increase bioactive compounds in baby leaf amaranth without causing appearance abnormalities.

Germination and seed persistence of Amaranthus retroflexus and Amaranthus viridis: Two emerging weeds in Australian cotton and other summer crops.

Redroot pigweed (Amaranthus retroflexus L.) and slender amaranth (Amaranthus viridis L.) are becoming problematic weeds in summer crops, including cotton in Australia. A series of laboratory and field experiments were performed to examine the germination ecology, and seed persistence of two populations of A. retroflexus and A. viridis collected from the Goondiwindi and Gatton regions of Australia. Both populations of A. retroflexus and A. viridis behaved similarly to different environmental conditions. Initial dormancy was observed in fresh seeds of both species; however, germination reached maximum after an after-ripening period of two months at room temperature. Light was not a mandatory prerequisite for germination of both species as they could germinate under complete darkness. Although both species showed very low germination at the alternating day/night temperature of 15/5 C, these species germinated more than 40% between ranges of 25/15 C to 35/25 C. Maximum germination of A. retroflexus (93%) and A. viridis (86%) was observed at 35/25 C and 30/20, respectively. Germination of A. retroflexus and A. viridis was completely inhibited at osmotic potentials of -1.0 and -0.6 MPa, respectively. No germination was observed in both species at the sodium chloride concentration of 200 mM. A. retroflexus seedling emergence (87%) was maximum from the seeds buried at 1 cm while the maximum germination of A. viridis (72%) was observed at the soil surface. No seedling emergence was observed from a burial depth of 8 cm for both species. In both species, seed persistence increased with increasing burial depth. At 24 months after seed placement, seed depletion ranged from 75% (10 cm depth) to 94% (soil surface) for A. retroflexus, and ranged from 79% to 94% for A. viridis, respectively. Information gained from this study will contribute to an integrated control programs for A. retroflexus and A. viridis.

Chemical Composition and Phytotoxic Activity of Artemisia selengensis Turcz. Volatiles.

The chemical profile and allelopathic action of the volatiles produced by Artemisia selengensis were studied. Artemisia selengensis was found to release volatile chemicals to the environment to influence other plants' growth, which suppressed the root length of Amaranthus retroflexus and Poa annua by 50.46 % and 87.83 % under 80 g/1.5 L treatment, respectively. GC/MS analysis led to the identification of 41 compounds (by hydrodistillation, HD) and 48 compounds (by headspace solid-phase microextraction, HS-SPME), with eucalyptol (15.45 % by HD and 28.09 % by HS-SPME) being detected as the most abundant constituent. The essential oil (EO) of A. selengensis completely inhibited the seed germination of A. retroflexus and P. annua at 1 mg/mL and 0.5 mg/mL, respectively. However, eucalyptol displayed much weaker activity compared with the EO, indicating that other less abundant constituents might contribute significantly to the EO's activity. Our study is the first report on the phytotoxicity of A. selengensis EO, suggesting that A. selengensis might release allelopathic volatile agents into the environment that negatively affect other plants' development so as to facilitate its own dominance; the potential value of utilizing A. selengensis EO as an environmentally friendly herbicide is also discussed.

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials.

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.

Salinity differently affects antioxidant content and amino acid profile in two cultivars of Amaranthus cruentus differing in salinity tolerance.

BACKGROUND: Amaranthus cruentus is a promising leafy vegetable with high nutritional value and is able to cope with salt stress but the impact of sodium chloride (NaCl) on its main properties have not been studied in detail. Plants from two contrasting cultivars (Rouge: salt-tolerant and Locale: salt-sensitive) were exposed to NaCl (0, 30, 60 and 90 mmol L-1 ) in nutrient solution for 2 weeks. Plant growth, mineral content, oxidative status and antioxidant concentration, salicylic acid concentration, protein content and amino acid profile were analyzed in the harvested leaves. RESULTS: Low dose (30 mmol L-1 NaCl) increased plant growth while Na+ accumulated to higher extent in salt-sensitive Locale than in salt-tolerant Rouge. A total of 30 mmol L-1 NaCl increased magnesium (Mg), phosphorus (P) and iron (Fe) content, as well as total antioxidant activity, ascorbate, phenolics, α-tocopherol and carotenoids content to higher extent in cultivar (cv.) Rouge than in cv. Locale. Low (30 mmol L-1 ) and moderate salinities (60 mmol L-1 ) increased γ-tocopherol and total protein in cv. Locale. They also increased lysine, valine, methionine and proline concentration as well as chemical score of protein in this cultivar. The highest NaCl (90 mmol L-1 ) dose had a detrimental impact on both cultivars. CONCLUSIONS: It is concluded that A. cruentus is a promising plant species for saline agriculture since moderate doses of salt improve both quantitative and qualitative parameters in cultivar dependent manner. © 2021 Society of Chemical Industry.

Enantioselective and Synergistic Herbicidal Activities of Common Amino Acids Against Amaranthus tricolor and Echinochloa crus-galli.

Amino acids have a wide range of biological activities, which usually rely on the stereoisomer presented. In this study, glycine and 21 common α-amino acids were investigated for their herbicidal property against Chinese amaranth (Amaranthus tricolor L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). Both d- and l-isomers, as well as a racemic mixture, were tested and found that most compounds barely inhibited germination but moderately suppressed seedling growth. Various ratios of d:l-mixture were studied and synergy between enantiomers was found. For Chinese amaranth, the most toxic d:l-mixtures were at 3:7 (for glutamine), 8:2 (for methionine), and 5:5 (for tryptophan). For barnyard grass, rac-glutamine was more toxic than the pure forms; however, d-tryptophan exhibited greater activity than racemate and l-isomer, indicating the sign of enantioselective toxicity. The mode of action was unclear, but d-tryptophan caused bleaching of leaves, indicating pigment synthesis of the grass was inhibited. The results highlighted the enantioselective and synergistic toxicity of some amino acids, which relied upon plant species, chemical structures, and concentrations. Overall, our finding clarifies the effect of stereoisomers, and provides a chemical clue of amino acid herbicides, which may be useful in the development of herbicides from natural substances.

Suitability and benefits from intercropped sorghum-amaranth under partial root-zone irrigation.

BACKGROUND: The production of sufficient animal feed in arid and semi-arid regions plays a significant role in food security in these areas. The present study was conducted based on the hypothesis that intercropping of sorghum and amaranth, comprising relatively drought tolerant forages, will enhance the yield and quality of the feed under limited irrigation water availability. RESULTS: Implementation of fixed alternate furrow irrigation (FFI) and alternate furrow irrigation (AFI) resulted in a saving of 22.5% and 19.7% of irrigation water, respectively. However, the water saving declined both yield and quality of forage. In conventional furrow irrigation (CFI), the highest dry matter (DM) yield was 15.5 Mg ha-1 , obtained from S50 -A50 treatment. In FFI and AFI, sole sorghum produced the highest DM. However, their maximum yields (11.2 and 12.6 Mg ha-1 , respectively) were not significantly different from yields in S75 -A25 intercropping ratios. Irrigation water use efficiency (IWUE) was similar in CFI and AFI and considerably higher than FFI. Sorghum monoculture and the S75 -A25 intercropping had the highest IWUE (3.4 and 3.3 kg m-3 ), whereas IWUE of the sole amaranth was 1.7 kg m-3 . The partial land equivalent ratio and monetary advantage index of amaranth and sorghum indicated that sorghum would benefit from intercropping as long as its ratio in the intercropping is more than 25%. CONCLUSION: When sufficient irrigation is available, intercropping of sorghum and amaranth can considerably improve yield and quality of emergency feed. However, the benefits from intercropping faded under the two partial root-zone irrigation methods used in the present study. © 2021 Society of Chemical Industry.

Soil pH and Microbial Properties as Affected by Integrated Use of Biochar, Poultry Manure and Urea.

BACKGROUND AND OBJECTIVE: The use of biochar, a charred organic material, is becoming a sustainable technology that leads to the improvement of highly weathered tropical soils. A study was conducted at the Teaching and Research Farm of the University of Calabar to compare the effects of integrated use of Biochar (B), Poultry Manure (PM) and urea on the pH and microbial properties of soil-grown with Amaranthus cruentus. MATERIALS AND METHODS: A total of 15 treatments consisting of a sole and combined use of biochar, poultry manure, urea and control were fitted on a randomized complete block design with 3 replications. The organic amendments were applied 2 weeks before sowing while urea was applied 2 weeks after sowing. Composite soil samples (0-15 cm) were taken before and after the experiment for pH and microbial analysis. RESULTS: Soil pH was raised from a strongly acidic level to values ranging from 5.73-6.8 (moderately acid-slightly acid, respectively) pH level after the experiment with the highest obtained in Full B+½PM amended soil. The fungal population was maximum in PM (sole and combinations) (18×103-20×103 CFU g-1) and minimum in sole biochar and control (×-10×103 CFU g-1). The bacterial population exhibited a similar trend with the maximum value in PM (sole and combinations) (98×106-148×106 CFU g-1) and minimum in control (×-36×106 CFU g-1). CONCLUSION: This suggests that biochar addition alone did not cause any apparent alteration to the microbial population and diversity compared to its complementary use.

1H-NMR and LC-MS Based Metabolomics Analysis of Wild and Cultivated Amaranthus spp.

Amaranthus crops are important for their use as food and nutritional sources, as well as for their medicinal properties. They are mostly harvested from the wild, and cultivation of Amaranthus species is still rare, and therefore, attempts are being made to commercialize and market this important crop. This research investigated the effect of cultivation and environment on the chemical profile of both cultivated and wild A. cruentus and A. hybridus by multivariate statistical analysis of spectral data deduced by Nuclear Magnetic Resonance (NMR). Furthermore, wild samples of A. cruentus and A. hybridus were subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) for further analysis. Through NMR analysis, it was found that maltose and sucrose increased in both cultivated A. cruentus and A. hybridus. Moreover, the amino acid, proline was present in cultivated A. cruentus in high quantity whereas, proline and leucine were prominent in A. hybridus. Other compounds that were found in both wild and cultivated A. cruentus and A. hybridus are trehalose, trigonelline, lactulose, betaine, valine, alanine, fumarate, formate and kynurenine. LC-MS analysis revealed the presence of rutin, 2-phenylethenamine and amaranthussaponin I in both wild A. cruentus and A. hybridus, while chlorogenic acid was identified only in cultivated A. hybridus. On the contrary, L-tryptophan, kaempferol, phenylalanine and quercetin were detected only in wild A. cruentus. Amaranth is not only rich in macro and micronutrients, but the leaves also contain phytochemicals that vary between species and cultivated plants, and might, therefore, affect the medicinal properties of the material.

Chemical Profile and Phytotoxic Action of Hibiscus trionum Essential Oil.

The chemical profile and phytotoxic action of Hibiscus trionum essential oil (EO) was studied. In total 17 compounds were identified via GC/MS, representing 94.18 % of the entire oil, with phytol (40.37 %) being the dominant constituent. Bioassay revealed that the EO inhibited root elongation of Medicago sativa and Amaranthus retroflexus by 32.66 % and 61.86 % at 5 mg/mL, respectively; meanwhile, the major component phytol also exhibited significant phytotoxic activity, suppressing radical elongation of Pennisetum alopecuroides, M. sativa and A. retroflexus by 26.08 %, 27.55 % and 43.96 % at 1 mg/mL, respectively. The fact that the EO showed weaker activity than phytol implied that some constituents might trigger antagonistic action to decrease the oil's activity. Our study is the first on the chemical profile and phytotoxic effect of H. trionum EO.

Multi-criteria suitability analysis for neglected and underutilised crop species in South Africa.

Several neglected and underutilised species (NUS) provide solutions to climate change and creating a Zero Hunger world, the Sustainable Development Goal 2. Several NUS are drought and heat stress-tolerant, making them ideal for improving marginalised cropping systems in drought-prone areas. However, owing to their status as NUS, current crop suitability maps do not include them as part of the crop choices. This study aimed to develop land suitability maps for selected NUS [sorghum, (Sorghum bicolor), cowpea (Vigna unguiculata), amaranth and taro (Colocasia esculenta)] using Analytic Hierarchy Process (AHP) in ArcGIS. Multidisciplinary factors from climatic, soil and landscape, socio-economic and technical indicators overlaid using Weighted Overlay Analysis. Validation was done through field visits, and area under the curve (AUC) was used to measure AHP model performance. The results indicated that sorghum was highly suitable (S1) = 2%, moderately suitable (S2) = 61%, marginally suitable (S3) = 33%, and unsuitable (N1) = 4%, cowpea S1 = 3%, S2 = 56%, S3 = 39%, N1 = 2%, amaranth S1 = 8%, S2 = 81%, S3 = 11%, and taro S1 = 0.4%, S2 = 28%, S3 = 64%, N1 = 7%, of calculated arable land of SA (12 655 859 ha). Overall, the validation showed that the mapping exercises exhibited a high degree of accuracies (i.e. sorghum AUC = 0.87, cowpea AUC = 0.88, amaranth AUC = 0.95 and taro AUC = 0.82). Rainfall was the most critical variable and criteria with the highest impact on land suitability of the NUS. Results of this study suggest that South Africa has a huge potential for NUS production. The maps developed can contribute to evidence-based and site-specific recommendations for NUS and their mainstreaming. Also, the maps can be used to design appropriate production guidelines and to support existing policy frameworks which advocate for sustainable intensification of marginalised cropping systems through increased crop diversity and the use of stress-tolerant food crops.

The identification of phytoextraction potential of Melilotus officinalis and Amaranthus retroflexus growing on copper- and molybdenum-polluted soils.

The contamination of soils by heavy metals from the mining industry nowadays is one of the greatest threats to environment and human health. The cleaning of polluted soils using cost-effective and eco-friendly methods such as phytoextraction has wide public recognition. Considering the above-mentioned ones, the objectives of the present study were the identification of Cu and Mo accumulation capability and the phytoextraction potential of Melilotus officinalis and Amaranthus retroflexus as well as the determination of the influence of ammonium nitrate and EDTA on phytoextraction effectiveness. The contaminated soil samples for phytoremediation experiments under ex situ conditions were collected from the surroundings of the Zangezur Copper and Molybdenum Combine, Armenia. During the studies, it was found out that M. officinalis and A. retroflexus are capable of growing in polluted soils. M. officinalis grown in polluted soil had greater ability to accumulate heavy metals in roots, while the ability to transport the copper to aboveground parts was more pronounced in A. retroflexus. During the growing of these plant species for phytoextraction of soils contaminated by copper, it is necessary to use chelates, in particular the EDTA, for the enhancement of the effectiveness of phytoextraction process. EDTA due to chelating influence increased the availability of copper for plants and its mobility in them that lead to greater accumulation of this metal in shoots. The application of chelates did not have a significant impact on molybdenum accumulation intensity in plants; therefore, in case of this metal, it is unreasonable to use additional chelating compounds.

Anti-inflammatory and antioxidant effects of peptides released from germinated amaranth during in vitro simulated gastrointestinal digestion.

Amaranth (Amaranthus hypochondriacus) is an ancestral nutritional grain and good source of bioactive compounds as peptides. In this study, the effect of in vitro simulated gastrointestinal digestion (SGD) of germinated amaranth on the release of antioxidant and anti-inflammatory peptides was evaluated. The germinated amaranth peptides generated during SGD were released after 90 min of incubation with pancreatin and fractioned to F1 (>10 kDa), F2 (3-10 kDa), and F3 (<3 kDa). Among germinated amaranth peptides fractions tested, F2 had the highest antioxidant activity, while F1 and F2 exhibited a high anti-inflammatory response caused by lipopolysaccharide-induced in RAW 264.7 macrophages. A total of 11 peptides sequences were identified in the fractions evaluated, and they exhibit potential biological activity against non-communicable diseases. The findings from this study showed first time report on bioactive peptides, especially anti-inflammatory, from germinated amaranth released by in vitro gastrointestinal digestion.

Toxicity and Antimicrobial Activities of Amaranthus caudatus L. (Amaranthaceae) Harvested From Formulated Soils at Different Growth Stages.

This study examined the toxicity and antimicrobial effects of ethanol and aqueous extracts from Amaranthus caudatus grown on soils formulated from parent particles of silt, sand and clay in a glasshouse. Four different soils namely; sandy clay loam, loam, clayey loam and silty clay loam from were formulated were used for cultivation with the unfractionated soil which was the control. Crude extracts obtained from the plant shoots harvested at different growth stages were tested on some certain gram-negative and gram-positive bacteria and some fungi via agar dilution assay. The toxicity of the water and ethanol extracts was also examined via Artemia salina assay and the level of lethality was measured against Clarkson's lethality scale. All aqueous samples, as well as ethanol extracts of flowering and pre-flowering harvests of control soil tested, were non-toxic (LC50 > 1 mg/mL). At post flowering, the ethanolic extracts were highly toxic mostly in clayey loam, control, sandy-clayey loam soils (LC50 < 0.5 mg/mL). Also, antifungal effects of the plant revealed that extracts inhibited the growth of Candida albicans significantly with mild effect on Candida glabrata, Penicillium chrysogenum and Penicillium aurantiogriseum suggesting that the plant is a promising pharmacological candidate in the treatment of candidiasis. For an optimal yield of non-toxic supplement for household consumption which may also serve as pharmacological precursors, clayey loam soil is recommended for cultivation and harvesting may occur at pre-flowering or flowering stage using ethanol and water as solvents of extraction.

Phenolic profiles and antioxidant activities in selected drought-tolerant leafy vegetable amaranth.

Four selected advance lines of drought-tolerant leafy vegetable amaranth were characterized for phenolic profiles, vitamins, and antioxidant activities. The selected advance lines exhibited differences in terms of genotypes with remarkable phenols, vitamins, flavonoids content, and potential radical quenching capacity. We identified twenty-five phenolic and flavonoid compounds including protocatechuic acid, salicylic acid, gentisic acid, gallic acid, ß-resorcylic acid, vanillic acid, p-hydroxybenzoic acid, chlorogenic acid, ellagic acid, syringic acid, ferulic acid, kaempferol, m-coumaric acid, trans-cinnamic acid, quercetin, p-coumaric acid, apigenin, caffeic acid, rutin, sinapic acid, isoquercetin, naringenin, myricetin, catechin, and hyperoside. The selected advance lines VA14 and VA16 had abundant phenols, vitamins, flavonoids, and antioxidants potentiality. The selected drought-tolerant leafy vegetable amaranth showed high antioxidant potentiality as phenols, vitamins, flavonoids of these lines had a significant positive correlation with antioxidant capacities equivalent to Trolox using 2,2-diphenyl-1-picrylhydrazyl and ABTS+. Therefore, drought-tolerant leafy vegetable amaranth VA14 and VA16 can be grown in semi-arid and drought-prone areas in the world to attaining vitamins and antioxidant sufficiency. The phenolic and flavonoids compounds identified in drought-tolerant leafy vegetable amaranth demand a comprehensive pharmacological study. The baseline data on phenolic and flavonoids compounds obtained in the present study will contribute to the scientist forum for the scientific evaluation of these compounds in vegetable amaranth.

Agricultural adaptation in the native North American weed waterhemp, Amaranthus tuberculatus (Amaranthaceae).

There is increasing interest in documenting adaptation of weedy plant species to agricultural ecosystems, beyond the evolution of herbicide resistance. Waterhemp (Amaranthus tuberculatus) is a native plant of the Midwestern U.S. that began infesting agricultural fields in the 20th century within the central portion of its range. We hypothesized that the vegetative growth and reproductive traits of waterhemp from this heavily infested central region provide differential fitness benefits in agricultural environments. We collected seeds from across the species' native range, representing regions with varying degrees of waterhemp infestation, and planted them together in common garden soybean plots. A 2010 common garden experiment was conducted within the range of agriculturally weedy waterhemp (in Missouri), and a 2011 common garden experiment was conducted outside of this range (in Ohio). Days to flowering and flowering plant height, mature plant size data (height, number of branches, and length of the longest branch), and above-ground biomass were measured to estimate relative fitness. In both common garden locations, plants from regions where waterhemp occurs as an agricultural weed - including those from the heavily infested Mississippi Valley region (Iowa, Illinois, and Missouri) and the less severely infested Plains region (Nebraska, Kansas, and Oklahoma) - had higher relative performance in almost all fitness-related measures than plants from the Northeast region (Ohio, Michigan, and Ontario), which had little to no agriculturally weedy waterhemp at the time of our study. Further analysis revealed that fewer days to flowering in the Northeast populations can be largely accounted for by latitude of origin, suggesting a strong genetic influence on this reproductive trait. These findings suggest intraspecific variation in agricultural adaptation in a native U.S. weed, and support the use of agricultural weeds to study adaptation.

Herbicidal and Antifungal Xanthone Derivatives from the Alga-Derived Fungus Aspergillus versicolor D5.

Fungi have been proved as promising and prolific sources of functional secondary metabolites with potent agricultural applications. In this study, 14 xanthone derivatives (1-14), including six new ones, versicones I-N (1-4, 7, 11), and a biogenetically related derivative (15), were isolated from the alga-derived fungus Aspergillus versicolor D5. Their structures were elucidated by comprehensive spectroscopic methods. Versicone L (4) exhibited a broad antifungal spectrum and prominent inhibitory effects on Botrytis cinerea at a minimum inhibitory concentration (MIC) of 152 µM, 7-fold stronger than that of the positive control, carbendazim (MIC = 1.05 × 103 µM). Dihydrosterigmatocystin (13) showed strong antifungal activity toward B. cinerea at MIC = 38.3 µM, almost 30-fold stronger than that of carbendazim. Meanwhile, 13 exhibited potent herbicidal activity toward Amaranthus retroflexus L. with an MIC of 24.5 µM, approximately 4-fold stronger than that of the positive control, glyphosate (MIC = 94.7 µM). Additionally, 13 also displayed remarkable activity against other weeds belonging to Amaranth sp. Analysis of the structure-herbicidal activity relationship indicated that the bifuranic ring played an important role in xanthone phytotoxicity and the presence of a double bond in the furan ring could decrease phytotoxicity. This study indicated that xanthones can be served as promising candidates for lead compounds of agrochemicals.

Indigenous plant species and invasive alien species tend to diverge functionally under heavy metal pollution and drought stress.

The functional similarity between indigenous plant species (IPS) and invasive alien species (IAS) governs the invasion process of successful IAS because IPS and coexisting IAS suffer alike or even same ecological selection pressures. The aggravated condition created by heavy metal pollution (HMP) and drought stress may generate a noticeable impact on the invasive competitiveness and invasion process of IAS possibly via the variations in the functional similarity between IPS and IAS. Consequently, it is necessary to illumine the functional similarity between IPS and IAS under HMP and drought stress to clarify the mechanisms underlying the successful invasion of IAS. This study aims to estimate the functional similarity between IPS Amaranthus tricolor L. and IAS A. retroflexus L. under the condition with the alone and combined effects of HMP with different kinds (e.g., Cu and Pb) and drought stress [simulated by polyethylene glycol-6000 (PEG) solution]. HMP notably declines A. tricolor growth but has no remarkable effect on A. retroflexus growth. A. retroflexus displays a strong competitive intensity than A. tricolor under HMP. Further, HMP makes a greater stress intensity on A. tricolor growth than A. retroflexus growth. Therefore, HMP can accelerate A. retroflexus invasion. A. retroflexus displays a poor competitive intensity under drought stress. Thus, drought stress can hinder A. retroflexus invasion. However, drought stress causes a greater stress intensity on A. tricolor growth than A. retroflexus growth. Thus, the continued drought stress may converse the adverse effects of drought stress on A. retroflexus invasion potentially. The two Amaranthus species tend to diverge functionally under the combined HMP and drought stress. Further, A. retroflexus shows a strong competitive intensity than A. tricolor under the combined HMP and drought stress. Moreover, the combined HMP and drought stress induces a greater stress intensity on A. tricolor growth than A. retroflexus growth. Thus, the combined HMP and drought stress can facilitate A. retroflexus invasion. Meanwhile, the competitiveness for sunlight acquisition and leaf photosynthetic capacity may play a key role in the successful invasion of A. retroflexus under the combined HMP and drought stress.

Late-season surveys to document seed rain potential of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) in Texas cotton.

Weed escapes are often present in large production fields prior to harvest, contributing to seed rain and species persistence. Late-season surveys were conducted in cotton (Gossypium hirsutum L.) fields in Texas in 2016 and 2017 to identify common weed species present as escapes and estimate seed rain potential of Palmer amaranth (Amaranthus palmeri S. Watson) and waterhemp [A. tuberculatus (Moq.) J.D. Sauer], two troublesome species with high fecundity. A total of 400 cotton fields across four major cotton-producing regions in Texas [High Plains (HP), Gulf Coast (GC), Central Texas, and Blacklands] were surveyed. Amaranthus palmeri, Texas millet [Urochloa texana (Buckley) R. Webster], A. tuberculatus, ragweed parthenium (Parthenium hysterophorus L.), and barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] were reported as the top five weed escapes in cotton fields. Amaranthus palmeri was the most prevalent weed in the HP and Lower GC regions, whereas A. tuberculatus escapes were predominantly observed in the Upper GC and Blacklands regions. On average, 9.4% of an individual field was infested with A. palmeri escapes in the Lower GC region; however, 5.1 to 8.1% of a field was infested in the HP region. Average A. palmeri density ranged from 405 (Central Texas) to 3,543 plants ha-1 (Lower GC). The greatest seed rain potential by A. palmeri escapes was observed in the upper HP region (13.9 million seeds ha-1), whereas the seed rain potential of A. tuberculatus escapes was the greatest in the Blacklands (12.9 million seeds ha-1) and the upper GC regions (9.8 million seeds ha-1). Seed rain from late-season A. palmeri and A. tuberculatus escapes is significant in Texas cotton, and effective management of these escapes is imperative for minimizing seedbank inputs and impacting weed species persistence.

Speed breeding short-day crops by LED-controlled light schemes.

KEY MESSAGE: A simple and rapid speed breeding system was developed for short-day crops that enables up to five generations per year using LED lighting systems that allow very specific adjustments regarding light intensity and quality. Plant breeding is a key element for future agricultural production that needs to cope with a growing human population and climate change. However, the process of developing suitable cultivars is time-consuming, not least because of the long generation times of crops. Recently, speed breeding has been introduced for long-day crops, but a similar protocol for short-day crops is lacking to date. In this study, we present a speed breeding protocol based on light-emitting diodes (LEDs) that allow to modify light quality, and exemplarily demonstrate its effectiveness for the short-day crops soybean (Glycine max), rice (Oryza sativa) and amaranth (Amaranthus spp.). Adjusting the photoperiod to 10 h and using a blue-light enriched, far-red-deprived light spectrum facilitated the growth of short and sturdy soybean plants that flowered ~ 23 days after sowing and matured within 77 days, thus allowing up to five generations per year. In rice and amaranth, flowering was achieved ~ 60 and ~ 35 days after sowing, respectively. Interestingly, the use of far-red light advanced flowering by 10 and 20 days in some amaranth and rice genotypes, respectively, but had no impact on flowering in soybeans, highlighting the importance of light quality for speed breeding protocols. Taken together, our short-day crops' speed breeding protocol enables several generations per year using crop-specific LED-based lighting regimes, without the need of tissue culture tools such as embryo rescue. Moreover, this approach can be readily applied to a multi-storey 96-cell tray-based system to integrate speed breeding with genomics, toward a higher improvement rate in breeding.