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Ramie is an important natural fiber. There has been little research on the molecular mechanisms of ramie related to the absorption, utilization and metabolism of nitrogen (N), phosphorus (P) and potassium (K). One approach to reveal the mechanisms of N, P and K (NPK) utilization and metabolism in ramie is comparative proteome analysis. The differentially expressed proteins in the leaves of ramie were analyzed by proteome analysis after 6 days of N- and K-deficient treatments and 3 days of P-deficient treatment using MALDI-TOF/TOF mass spectrometry and 32, 27 and 51 differential proteins were obtained, respectively. These proteins were involved in photosynthesis, protein destination and storage, energy metabolism, primary metabolism, disease/defense, signal transduction, cell structure, transcription, secondary metabolism and protein synthesis. Ramie responded to NPK stress by enhancing secondary metabolism and reducing photosynthesis and energy metabolism to increase endurance. Specifically, ramie adapted to NPK deficiency by increasing signal transduction pathways, enhancing the connection between glycolysis and photosynthesis, promoting the intracellular flow of carbon and N; promoting the synthesis cysteine and related hormones and upregulating actin protein to promote growth of the root system. The experimental results provide important information for further study on the high-efficiency NPK utilization mechanism of ramie.

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Light is an important variable affecting the plant growth. In present study, the effects of different color light-emitting diodes (mixed colors, red, blue, and orange light) on plant growth, gas exchange, and oxidative stress were investigated in Boehmeria nivea L., by means of measuring growth, photosynthesis, chlorophyll (Chl) content, reactive oxygen species (ROS), and activity of antioxidant enzymes under controlled conditions. Comparing to the mixed colors light, red light significantly increased shoot and leaf biomass, plant height, number of leaves per plant, and stem diameter by increasing the Chl content and therefore promoting the highest photosynthetic capacity. This might partially be explained by the decrease of malondialdehyde and proline contents as well as the activities of superoxide dismutase and peroxidase under red light, to keep a better internal environment of the cell. However, blue and orange light decreased plant growth, and increased the activities of antioxidant enzymes which suggest an environmental stress on plants. These results suggest that red light can enhance B. nivea growth by activating photosynthesis and reducing ROS accumulation.

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Optimum fertilization is one of the challenges to agricultural sustainability. Understanding the physiological and biochemical response of plants to available nutrients is important for optimization of crop management practices. Present study investigated the effects of different levels of N fertilizer (N0 = 0 kg ha−1 [Control], N1 = 140 kg ha−1 [Low], N2 = 280 kg ha−1 [Medium], and N3 = 420 kg ha−1 [High]) on growth, gaseous exchange, antioxidant capacity, and N metabolism in ramie (Boehmeria nivea L.) under greenhouse conditions in a completely randomized design (CRD) with three replications. Nitrogen application improved the plant growth, chlorophyll contents, and antioxidant activity of ramie; the maximum shoot fresh biomass (91 g), shoot dry biomass (13.7 g), number of leaves (46.5), and number of stems (6.4) were recorded at medium N rate. However, the growth was reduced under high N rate. Except for intercellular CO2 concentration, all the other gas exchange parameters were significantly affected by the N levels. Increasing N level improved the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), and enhanced the chlorophyll and soluble protein contents in ramie leaves. Thus, N fertilizer at medium rate is relatively more effective in the growth of ramie and biomass production.

The industrial hemp varieties 'Yunma 5' and 'Bamahuoma,' which demonstrate growth vigor and environmental adaptability, have been primarily cultivated in Yunnan and Guangxi, China, respectively, for fiber and seeds. The results of physiological measurements showed the phenotypic differences between the two varieties in response to salt stress. RNA-Seq analysis was first performed on leaves of both varieties sampled at four time intervals (0, 2, 4, 6 days) after treatment with salt (500 mM NaCl) We identified 220 co-up-regulated differentially expressed genes (DEGs) in the two varieties, while 26 upregulated DEGs and 24 down-regulated DEGs were identified exclusively in the single varieties after 2 days of salt stress. Among the 220 DEGs, we identified 22 transcription factors, including key transcription factors involved in salt stress, such as MYB, NAC, GATA, and HSF. We applied gene expression profile analysis and found that 'Yunma 5' and 'Bamahuoma' have variety-specific pathways for resisting salt stress. The DEGs of 'Yunma 5' were enriched in spliceosome and amino acid metabolism genes, while the DEGs of 'Bamahuoma' were enriched in fatty acid metabolism, amino acid metabolism, and endoplasmic reticulum protein processing pathway. Although there were common DEGs, such as genes encoding cysteine protease and alpha/beta-hydrolase superfamily, the two varieties' responses to salt stress impacted different metabolic pathways. The DEGs that were co-expressed in both varieties under stress may provide useful insights into the tolerance of cultivated hemp and other bast fiber crops to saline soil conditions. These transcriptomes also represent reference sequences for industrial hemp.