This study investigated biochar production from stranded Sargassum biomass and its effects on lettuce (Lactuca sativa L.) growth and foliar elemental composition. Biochars were produced by laboratory-scale pyrolysis at 400, 500, and 600 °C and using an artisanal double-drum kiln. The resulting materials were alkaline and mineral-rich, with ash contents of 24.6–42.3 wt% and pH values of 8.4–8.7. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) revealed structural changes after pyrolysis, including the development of rough, porous surfaces. The SEM/EDS semiquantitative analysis indicated relatively high proportions of Na (4.55 wt%), K (4.31 wt%), Ca (2.46 wt%), and Mg (1.75 wt%) in the double-drum biochar, consistent with the mineral-rich composition of the original marine biomass. Lettuce responses varied with biochar application rate. Lettuce response depended strongly on biochar application rate. The 1 t ha−1 rate did not significantly affect plant growth, whereas 12 t ha−1 reduced shoot fresh mass by approximately 45% and decreased plant diameter, rosette diameter, leaf number, and leaf area. Foliar Na concentration increased from 4.95 in the control to 11.50 mg kg−1 at 12 t ha−1, while the Na/K ratio increased from 3.88 to 9.91. The highest application rate was therefore characterized by increased foliar Na and Na/K ratio together with reduced plant growth. These findings highlight the potential of Sargassum-derived biochar for biomass valorization and mineral recovery, while indicating that its high sodium content warrants careful consideration of application rates for lettuce cultivation.
Fresh Gastrodia elata tubers are highly perishable after harvest because pathogen infection accelerates quality deterioration and limits their storage and commercial utilisation. This study examined lesion development in wounded, pathogen-inoculated tubers held at 24 ± 1 °C and, in a separate experiment, quality and physiological changes in non-inoculated tubers stored at 4 ± 1 °C. In the inoculation assay, 1 mM salicylic acid (SA) reduced lesion development following inoculation with Fusarium sp. (isolate 1022-1-1) and Aspergillus sp. (isolate 1022-11). During cold storage, SA-treated tubers maintained higher soluble solid content and showed less weight loss, membrane permeability, and malondialdehyde accumulation than controls. SA application promoted the enzymatic activities and transcriptional expression of superoxide dismutase, catalase, and peroxidase. It also activated the ascorbate–glutathione cycle by promoting ascorbic acid and glutathione accumulation, along with increasing the enzymatic activities and transcript abundance of several cycle-related enzymes, including ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase. These responses limited superoxide anion production and excessive hydrogen peroxide accumulation, thereby alleviating oxidative damage. SA enhanced phenylpropanoid metabolism through the upregulation of phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, and 4-coumaroyl-CoA ligase at both enzymatic and transcriptional levels, contributing to increased levels of total phenolics, flavonoids, and lignin. Furthermore, SA contributed to ATP maintenance by upregulating hexokinase, succinate dehydrogenase, cytochrome c oxidase, H+-ATPase, and Ca2+-ATPase at both enzymatic and transcriptional levels. Overall, SA treatment reduced lesion development in inoculated G. elata tubers and helped maintain the quality of non-inoculated tubers during cold storage.
The study evaluated the effects of different LED light spectra on the morphological characteristics, photosynthetic pigments, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (DPPH) of endive microgreens, and identified biochemical parameters associated with light responses using correlation analysis, principal component analysis (PCA), and the Random Forest model. Microgreens were grown under different LED light spectra (blue, red, blue–red, cool white and darkness) in controlled growth chamber conditions under a long-day photoperiod (16 h light/8 h dark). Analysis of variance (ANOVA) demonstrated that LED light quality significantly affected all morphological and biochemical traits. The highest fresh weight (0.246 g) and total chlorophyll content (8.475 mg/g FW) were obtained under the b-RED treatment, whereas the highest TPC was recorded under blue light (B; 4.497 mg GAE/g FW). The greatest antioxidant activity was observed under the combined red-blue spectrum (RB; 19.573 mg TXE/g FW), while red light and darkness resulted in the lowest values for most analyzed parameters. Correlation analysis revealed strong positive associations among photosynthetic pigments, phenolic compounds, and antioxidant potential, with the strongest correlation observed between TPC and DPPH (r = 0.858, p < 0.01). PCA explained 88.8% of the total variance and clearly separated treatments containing a blue light component from those exposed to red light or darkness. Random Forest analysis identified TPC as the most important discriminating variable among LED treatments, followed by stem length, DPPH, and Total Chl. Overall, blue-containing LED spectra, particularly in combination with red light, improved morphological (b-RED) and biochemical characteristics of endive microgreens (RB). The b-RED treatment was the most effective in improving morphological characteristics and chlorophyll accumulation, while the red:blue treatment produced the highest antioxidant activity.
Berry fruits from Aristotelia chilensis (Molina) Stuntz are considered a “superfruit” because of their high antioxidant activity. Currently, most traded berries are wildcrafted from natural populations, threatening the resource’s sustainability, but some efforts are underway to domesticate the species, which may be very versatile in agroforestry and orchard systems. We assessed genotypic variability and stability of ecophysiological and fruit-related traits in A. chilensis clones established at two contrasting sites of northern-central (Panguilemo) and southern (Panguipulli) Chile. At both sites, we measured clones for growth, leaf morpho-physiological, and fruit traits seven years after planting. Overall, there was a significant genotype–environment interaction (G × E) for foliar area (FA) and fruit dry mass (FDM), mainly explained by the higher performance of some clones in the most fertile site at Panguilemo than at Panguipulli. Intrinsic water use efficiency (WUEint) was higher at the drier northern site (+79%) than in Panguipulli, while at the genotype level, it was higher in southern-origin clones. Clonal variation was observed in anthocyanin content (five-fold between the highest and lowest value), but not in polyphenol content. In Panguilemo, FDM was positively correlated with FA but tended to be negatively related to WUEint, indicating a disadvantageous trade-off for future selection. Relationships between gas exchange, twig growth, and fruit traits decoupled at Panguipulli, likely associated with the mild weather. Despite the low number of clones and sites tested, this study provides guidelines for future genotype and trait selection. Deploying orchards with selected clones can reduce pressure on wild populations, contributing to the sustainability of this resource.
