Nutritional diversity in leaves of various amaranth (Amaranthus spp.) genotypes and its resilience to drought stress

The nutritional diversity in leaves of twelve accessions of four amaranth species (Amaranthus caudatus, A. cruentus, A. hybridus, A. hypochondriacus) was studied in a randomized complete block design (n = 5). The accessions revealed high contents of the macronutrients K, Ca, Mg, and P, while the micronutrients Fe and Zn were comparatively low (542 – 717, 304 – 497, 131 – 230, 74 – 166, 0.9 – 1.3, 0.4 – 0.9 mg 100 g-1 fresh weight, respectively). Protein contents were found to be higher (23 – 32%) compared to other commonly consumed leafy vegetables in Sub-Saharan-Africa. Phenolic acid and flavonoid contents strongly varied between accessions and to some extent were lower in comparison to those reported in literature. Amaranth is reported to be drought tolerant, thus, one accession of each species was subjected to two different drought stress conditions (moderate – 35 – 45% field capacity, severe – 15 – 25% field capacity, n = 3). Well-watered plants were used as control (60 – 70% field capacity). A significant reduction in plant height and fresh matter occurred in all accessions with increasing drought stress, whereas contents of nutritional compounds increased. Phenolic acids and flavonoid contents in all accessions/species were not affected by drought stress except for A. cruentus where total phenolic acids significantly increase

Hemp Waste as a Substrate for Hermetia illucens (L.) (Diptera: Stratiomyidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae) Rearing

The article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin.The proper treatment of cannabis agricultural wastes can reduce the environmental impact of its cultivation and generate valuable products. This study aimed to test the potential of cannabis agricultural wastes as a substrate for the rearing of black soldier fly larvae (BSFL) and yellow mealworms (MW). In the case of BSFL, replacing the fibre component (straw) in the substrate with the hemp waste can increase the nutritional value of the substrate and led to bigger larvae. The bigger larvae had lower P and Mg, and higher Fe and Ca. Crude protein also varied based on the size of larvae and/or the content of protein in the initial substrate, which was boosted by replacing straw with hemp material. No other cannabinoids than cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), and cannabidiol (CBD) were found in significant amounts in the larvae. In the case of MW, the larvae grew less on the hemp material in comparison to wheat bran. Replacing wheat bran with the hemp material led to smaller larvae with higher Ca, Fe, K, and crude protein content, but lower Mg and P values. No cannabinoids were detected in the MW fed with the hemp material.Peer Reviewe

Soilless Tomato Production: Effects of Hemp Fiber and Rock Wool Growing Media on Yield, Secondary Metabolites, Substrate Characteristics and Greenhouse Gas Emissions

Replacement of rock wool by organic substrates is considered to reduce the environmental impact, e.g., through energy savings during production and waste prevention, caused by hydroponically produced crops. A suitable substrate for plant production is characterized by an optimal composition of air- and water-filled pores. In our study, we used hemp fibers as an organic alternative to rock wool in order to cultivate tomato plants in hydroponics for 36 weeks. The leaf area, plant length, and yields, as well as the quality of fruits including soluble solid contents, dry weight content, mineral composition, and contents of phenolic compounds caused by both substrates, were similar. Carotenoids were significantly increased in fruits from plants grown in hemp at some measuring dates. Nevertheless, higher emission rates of greenhouse gases such as N2O, CO2, and CH4 caused by hemp fiber compared to those emitted by rock wool during use are rather disadvantageous for the environment. While hemp proved to be a suitable substrate in terms of some physical properties (total pore volume, bulk density), a lower volume of air and easily available water as well as very rapid microbial decomposition and the associated high nitrogen immobilization must be considered as disadvantages.Peer Reviewe

Survey of bioactive metabolites in selected cultivars and varieties of Lactuca sativa L. under water stress

Plants respond to water stress with a variety of physiological and biochemical changes, but their response vary between species, varieties and cultivars. The present study focused on changes of bio-functional phytochemicals (phenolic compounds, chlorophyll, carotenoids, dietary fiber) in commercial cultivars and old, traditional varieties of lettuce under different water regimes (water-deficit, well-watered and water-logged).Results revealed lettuce varieties and cultivars with a different response behavior to water stress. Biomass production under drought conditions was reduced significantly. Carotenoid and chlorophyll contents decreased in both water extremes, while total phenols were accumulated under limited water availability. Dietary fiber content was not influenced by different water regimes. Water stress reduces biomass production and led to a change of phytochemicals in lettuce, however, old and traditional varieties did not show a different water stress adaptation compared to commercial cultivars

Phenolic compound abundance in Pak choi leaves is controlled by salinity and dependent on pH of the leaf apoplast

Onset of salinity induces the pH of the leaf apoplast of Pak choi transiently to increase over a period of 2 to 3 hr. This pH event causes protein abundances in leaves to increase. Among them are enzymes that are key for the phenylpropanoid pathway. To answer the questions whether this short-term salt stress also influences contents of the underlying phenylpropanoids and for clarifying as to whether the apoplastic pH transient plays a role for such a putative effect, Pak choi plants were treated with 37.5 mM CaCl2 against a non-stressed control. A third experimental group, where the leaf apoplast of plants treated with 37.5 mM CaCl2, was clamped in the acidic range by means of infiltration of 5 mM citric acid/sodium citrate (pH 3.6), enabled validation of pH-dependent effects. Microscopy-based live cell imaging was used to quantify leaf apoplastic pH in planta. Phenolics were quantified shortly after the formation of the leaf apoplastic pH transient by means of HPLC-DAD-ESI-MS. Results showed that different phenolic compounds were modulated at 150 and 200 min after the onset of chloride salinity. A pH-independent reduction in phenolic acid abundance as well as an accumulation of phenolic acid:malate conjugates was quantified after 200 min of salt stress. However, at 150 min after the onset of salt stress, flavonoids were significantly reduced by salinity in a pH-dependent manner. These results provided a strong indication that the pH of the apoplast is a relevant component for the short-term metabolic response to chloride salinity.BMBF research grantDeutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Peer Reviewe

Impact of postharvest osmodehydration treatments and drying processes on the nutritional quality, bioactive compounds and preservation of leaf amaranth (Amaranthus cruentus)

Amaranth leaves are rich in micronutrients and health-promoting secondary metabolites, but highly perishable. The effect of osmodehydration and drying on nutritional quality, health-promoting compounds and their postharvest preservation in Amaranthuscruentus leaves was investigated. The experimental set up consisted of four treatment variants with different levels of osmotic solution (NaCl) concentration, temperature and immersion time, i.e.; variant 1 (2.5%, 20 °C, 60 min), variant 2 (10%, 20°C, 60 min), variant 3 (10%, 40°C, 60 min), and variant 4 (10%, 40°C, 180 min). Osmodehydrated leaves were oven-dried at 30°C or 60°C, freeze-dried or stored at ambient temperature for 3 days, with non-osmodehydrated leaves as control. Results showed that proteins,minerals (Ca, Mg, Fe, Zn), carotenoids, flavonoids, and phenolic acids were preserved in osmodehydrated leaves with no significant changes, except proteins in freeze-dried and a significantly decreased chlorophyll content in both freeze- and oven-dried leaves of variant 4, corresponding to higher osmotic solution concentration, temperature and longer immersion time. During shelf-life, most nutrients and secondary metabolites were maintained with no significant changes, except protein that significantly increased while ascorbic acid and chlorophylls in both osmodehydrated and control leaves significantly decreased. Lower-temperature and shorter-time immersion resulted in better quality preservation

Replacing Mineral Fertilizer with Nitrified Human Urine in Hydroponic Lettuce (Lactuca sativa L.) Production

Source-separated, nitrified, and decontaminated human urine constitutes a promising plant fertilizer that contains a large share of the nitrogen and phosphorus in household wastewater, and other plant nutrients. However, human urine contains high levels of sodium and chloride that can affect salt-sensitive greenhouse crops. Replacing mineral fertilizer with nitrified urine fertilizer could reduce the environmental impact of lettuce production in hydroponic systems, if marketable yield, appearance, and produce quality are not affected. In the present study, a treatment combination of a nitrified urine fertilizer and mineral fertilizers was used to grow lettuce through the nutrient film technique. This was compared to a conventionally fertilized control treatment. No significant differences were observed regarding yield, phenotype, and contents of nitrate, heavy metals, phenolic acids, and chlorophyll in leaf tissue. Calcium content was significantly reduced and sodium was elevated in nitrified urine treatment. For the elements nitrogen, phosphorous, and potassium, a saving of 48%, 13%, and 15% was calculated, respectively. The calculated carbon footprint from the total fertilizer production was reduced by 34.25%, caused by the nitrified urine treatment. Based on these results, a nutrient solution composed of nitrified urine fertilizer combined with mineral fertilizer may be a promising alternative for growers to produce lettuce with a reduced environmental impact without loss of plant quantity and quality.city of BerlinPeer Reviewe

Chemoprofiling as Breeding Tool for Pharmaceutical Use of Salix

Willow bark is traditionally used for pharmaceutical purposes. Evaluation is so far based on the salicylate content, however, health promoting effects of extracts might be attributed to the interaction of those salicylates with other compounds, which support and complement their action. So far, only S. purpurea, S. daphnoides, and S. fragilis are included in pharmaceutical extracts. Crossing with other species could result in a more diverse secondary metabolite profile with higher pharmacological value. With the help of targeted inter- and intraspecific crossing, new chemotypes were generated, whereby nine different Salix genotypes (S. alba, S. daphnoides, S. humboldtiana, S. lasiandra, S. nigra, S. pentandra, S. purpurea, S. x rubens, S. viminalis) were included in the study. Based on substances known for their health promoting potential and characteristic for Salix (selected phenolic compounds including salicylates), a targeted metabolomics analysis and clustering of 92 generated Salix clones was performed revealing four different cluster/chemoprofiles. In more specific, one group is formed by S. daphnoides clones and inter- and intraspecific hybrids, a second group by S. viminalis clones and inter- and intraspecific hybrids, a third group generally formed by S. alba, S. pentandra, S. x rubens, and S. lasiandra clones and hybrids, and a fourth group by S. purpurea clones and inter- and intraspecific hybrids. Clustering on the basis of the selected phenolic compounds can be used for identifying Salix clones with a different compound profile. New combinations of secondary plant metabolites offer the chance to identify Salix crosses with improved effects on human health.Peer Reviewe

Identification of Salicylates in Willow Bark (Salix Cortex) for Targeting Peripheral Inflammation

Salix cortex-containing medicine is used against pain conditions, fever, headaches, and inflammation, which are partly mediated via arachidonic acid-derived prostaglandins (PGs). We used an activity-guided fractionation strategy, followed by structure elucidation experiments using LC-MS/MS, CD-spectroscopy, and 1D/2D NMR techniques, to identify the compounds relevant for the inhibition of PGE2 release from activated human peripheral blood mononuclear cells. Subsequent compound purification by means of preparative and semipreparative HPLC revealed 2′-O-acetylsalicortin (1), 3′-O-acetylsalicortin (2), 2′-O-acetylsalicin (3), 2′,6′-O-diacetylsalicortin (4), lasiandrin (5), tremulacin (6), and cinnamrutinose A (7). In contrast to 3 and 7, compounds 1, 2, 4, 5, and 6 showed inhibitory activity against PGE2 release with different potencies. Polyphenols were not relevant for the bioactivity of the Salix extract but salicylates, which degrade to, e.g., catechol, salicylic acid, salicin, and/or 1-hydroxy-6-oxo-2-cycohexenecarboxylate. Inflammation presents an important therapeutic target for pharmacological interventions; thus, the identification of relevant key drugs in Salix could provide new prospects for the improvement and standardization of existing clinical medicine.Peer Reviewe