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The present study was intendant to evaluate variations among flaxseed varities in terms of fatty acid composition, phytochemical profiles, and antioxidant activities determined by oxygen radical absorbance capacity (ORAC), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferrous ion reducing antioxidant power (FRAP) assays. Significant variations in the fatty acid composition, phenolic acids and lignan were observed in flaxseed varieties from different countries. Among these flaxseed verities, the unsaturated fatty acids accounted over four fifths of total fatty acid contents. The highest ratio of linolenic acid of total fatty acid was observed in USPEA, whereas the lowest one was found in Yexiao. USPEA showed the most contents of total phenolics, as well as flaxseed lignans. In general, total phenolics appeared to be the main contributors in the antioxidant capacity of flaxseed, which presented significant positive correlation. Our study revealed that both cultivar and origin of seeds significantly affect fatty acid composition, phenolic acids, lignans and subsequent antioxidant activities in flaxseed. The results provide new aspects of breeding resources of flaxseed cultivars by presenting their quality specification and possible commercial value.

Cadmium (Cd) pollution in both water bodies and farmlands seriously threatens human health, removing Cd from these environments is of great importance. Previous studies have proved ramie has great potential to remediate Cd pollution, however, its remediation efficiency depends greatly on the varieties of ramie. Therefore, in the present study, 165 ramie germplasms were selected to investigate their responses to Cd stress and the potential to remediate Cd pollution via a hydroponic trial. Results showed that Cd stress significantly inhibited the growth of ramie, the average ramie plant height, stem diameter, root length, and biomass under Cd stress were significantly decreased compared with that under control treatment; Cd stress can elevate the nutrient contents (B, Fe, K, Mg, P) in the aboveground part of ramie to some extent, but significantly reduce the accumulations of these elements. The Cd content in the aboveground part of ramie under Cd stress ranged from 61.7 mg kg−1 to 643 mg kg-1 with an average of 231 mg kg-1, and the Cd uptake ranged from 0.001 mg plant−1 to 0.71 mg plant-1 with an average of 0.15 mg plant-1. Correlation analysis indicated that the enrichment of K and Mg can significantly reduce the Cd absorption in ramie but the enrichment of P seemed to enhance the Cd accumulation in ramie. Hence, ramie has great potential to be used for phytoremediation of Cd and further studies are needed to explore the suitability of these ramie germplasms for remediation of Cd-contaminated soil as well as the interactions between nutrient elements and Cd, and the results of this study can provide valuable references for finding the genes related to Cd-resistance and Cd-accumulation in ramie and for further breeding transgenic varieties with higher Cd-remediation efficiency.

Given the special pharmacological value of cannabidiol (CBD), industrial hemp (hemp) has become a real “hot” crop. Though indoor farming of hemp has been widely used, the effects of red and blue light-emitting diode (LED) acting as supplementary light on the CBD synthesis in hemp remains unclear. Herein, a pot experiment with six treatments [CK, high-pressure sodium as light source, (R:B (ratio of red light to blue light) 9.30:1, PPFD (photosynthetic photon flux density) 191); LED1 (R:B 9.20:1; PPFD 129); LED2 (R:B 1.61:1; PPFD 540); LED3 (R:B 6.47:1; PPFD 28.2); LED4 (R:B 7.15:1; PPFD 41.7); LED5 (R:B 16.8:1; PPFD 252)] was carried out to study the effects of LED light quality on the growth and cannabinoid synthesis of hemp. Results showed that LED2 and LED5 could well maintain hemp growth compared with CK in terms of plant height, stem diameter, and leaf numbers. Compared with CK, the treatment of LED1, LED4, and LED3 significantly decreased the aboveground biomass, while LED2 and LED5 notably improved the aboveground biomass with an increment of 15.2 % and 55.1 %; the biomass of hemp flowers for LED2 and LED5 was markedly increased compared with that for CK with increments of 238 % and 61.5 %, respectively, but the other LED light treatments significantly reduced the flowers yield; LED2 could significantly increase the CBD content of both leaves (1.81 %) and flowers (5.83 %) compared to CK (leaves 1.38 %, flowers 4.27 %) while LED5 only notably increased the CBD content of leaves; among the LED treatments, the theoretic CBD yield for a per plant of LED2 and LED5 was 26.8 % and 9.0 % higher than that of CK. In conclusion, different red and blue LED light intensity ratios would dramatically influence the growth and cannabinoid synthesis of hemp, LED2 and LED5 can be good choices for indoor farming of hemp targeted for higher CBD yield.