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Rising human population has increased the utilization of available resources for food, clothes, medicine, and living space, thus menacing natural environment and mounting the gap between available resources, and the skills to meet human desires is necessary. Humans are satisfying their desires by depleting available natural resources. Therefore, multifunctional plants can contribute towards the livelihoods of people, to execute their life requirements without degrading natural resources. Thus, research on multipurpose industrial crops should be of high interest among scientists. Hemp, or industrial hemp, is gaining research interest because of its fastest growth and utilization in commercial products including textile, paper, medicine, food, animal feed, paint, biofuel, biodegradable plastic, and construction material. High biomass production and ability to grow under versatile conditions make hemp, a good candidate species for remediation of polluted soils also. Present review highlights the morphology, adaptability, nutritional constituents, textile use, and medicinal significance of industrial hemp. Moreover, its usage in environmental conservation, building material, and biofuel production has also been discussed.

Light spectrum plays a crucial role in regulating the growth of hemp ( Cannabis sativa L.) plants and the biosynthesis of secondary metabolites. Several studies have demonstrated that additional red-light exposure increases biomass accumulation, while supplementary UV-A light stimulates cannabinoid synthesis. Nevertheless, the potential of stage-specific supplementation of red and UV-A light remains underexplored in its capacity to optimize cannabinoid yield in indoor hemp cultivation. In the present study, the effect of red light in combination with UV-A light on hemp biomass and cannabinoid accumulation was investigated using a high-CBD strain. There were four treatments: (1) white light throughout the growth period (control; V W R W ); (2) red light supplementation during the vegetative stage (V WR R W ); (3) UV-A supplementation (V W R WUV ) during the flowering stage; and (4) combined red and UV-A supplementation (V WR R WUV ) during the vegetative and flowering stages. Results showed that V WR R W promoted the number of effective branches (increased by 18.0%) compared to the control (V W R W ), resulting in an increase in inflorescence yield by 17.9%. V W R WUV increased CBG and CBD content by 52.7% and 12.1%, respectively, relative to the control. The effect of V WR R WUV on biomass and cannabinoid accumulation was the strongest among the treatments, with CBG and CBD yields reaching 0.53 g and 4.62 g per plant, representing significant increase of 91.8% ( p  < 0.01) and 44.1% ( p  < 0.01), respectively, compared to the control. However, there were no significant differences in CBD yield among the V WR R W , V W R WUV and V WR R WUV treatments, indicating that the combined supplementation of red and UV-A light did not have an additive effect on CBD accumulation. These findings highlight the potential of stage-specific spectral strategy to optimize both plant growth and phytochemical quantity.

The present study aimed to explore the effects of exogenous gibberellins (GAs) on seed germination and subsequent seedling growth of hemp (Cannabis sativa L.) under drought stress. Seeds of two industrial hemp cultivars i.e., ‘Yunma 1’, (YM) and ‘Bamahuoma’, (BM) were treated with different concentrations of GA3 solution (0, 200, 400, 600, 800 mg/L) at 20 °C for 8 h. The effect of pre-treatment was assessed on germination characteristics and physiological indexes on subsequent exposure to drought stress using 20% (m/v) polyethylene glycol (PEG) for 7 days. The results revealed that seed germination in hemp was sensitive to drought stress, as the germination indexes (germination rate and germination potential) decreased significantly, and seedling growth (hypocotyl length and radicle length) was impeded under 20% PEG-6000 condition. GA3 pre-treatment affected germination rate, germination potential, hypocotyl length and radicle length. With increasing GA3 concentration, these indexes first increased and then decreased. For seedling physiology characteristics in hemp, GA3-pretreatment remarkedly increased the osmotic regulating substances (soluble sugar and soluble protein contents) and the activities of antioxidant enzymes (SOD, superoxide dismutase and POD, peroxidase), while sharply decreased the lipid peroxidation (malondialdehyde, MDA) in seedlings grown under PEG-6000 induced drought stress. These results suggested that seeds pre-treated with GA3 could enhance the drought tolerance of hempseeds, and the optimal effect of GA3 for seed pre-treatment of YM and BM could be obtained when the concentration of GA3 solution reached 400 mg/L and 600 mg/L, respectively.

Interest in hemp ( L.) as a crop for the biobased economy is growing worldwide because hemp produces a high and valuable biomass while requiring low inputs. To understand the physiological basis of hemp's resource-use efficiency, canopy gas exchange was assessed using a chamber technique on canopies exposed to a range of nitrogen (N) and water levels. Since canopy transpiration and carbon assimilation were very sensitive to variations in microclimate among canopy chambers, observations were adjusted for microclimatic differences using a physiological canopy model, with leaf-level parameters estimated for hemp from our previous study. Canopy photosynthetic water-use efficiency ( ), defined as the ratio of gross canopy photosynthesis to canopy transpiration, ranged from 4.0 mmol CO (mol H O) to 7.5 mmol CO (mol H O) . Canopy photosynthetic nitrogen-use efficiency ( ), the ratio of the gross canopy photosynthesis to canopy leaf-N content, ranged from 0.3 mol CO d (g N) to 0.7 mol CO d (g N) . The effect of N-input levels on and was largely determined by the N effect on canopy size or leaf area index ( ), whereas the effect of water-input levels differed between short- and long-term stresses. The effect of short-term water stress was reflected by stomatal regulation. The long-term stress increased leaf senescence, decreased but retained total canopy N content; however, the increased average leaf-N could not compensate for the lost , leading to a decreased . Although hemp is known as a resource-use efficient crop, its final biomass yield and nitrogen use efficiency may be restricted by water limitation during growth. Our results also suggest that crop models should take stress-induced senescence into account in addition to stomatal effects if crops experience a prolonged water stress during growth.

Hemp ( L.) is a bast-fiber crop well-known for the great potential to produce sustainable fibers. Nevertheless, hemp fiber quality is a complex trait, and little is known about the phenotypic variability and heritability of fiber quality traits in hemp. The aim of this study is to gain insights into the variability in fiber quality within the hemp germplasm and to estimate the genetic components, environmental components, and genotype-by-environment ( × ) interactions on fiber quality traits in hemp. To investigate these parameters, a panel of 123 hemp accessions was phenotyped for 28 traits relevant to fiber quality at three locations in Europe, corresponding to climates of northern, central, and southern Europe. In general, hemp cultivated in northern latitudes showed a larger plant vigor while earlier flowering was characteristic of plants cultivated in southern latitudes. Extensive variability between accessions was observed for all traits. Most cell wall components (contents of monosaccharides derived from cellulose and hemicellulose; and lignin content), bast fiber content, and flowering traits revealed large genetic components with low × interactions and high broad-sense heritability values, making these traits suitable to maximize the genetic gains of fiber quality. In contrast, contents of pectin-related monosaccharides, most agronomic traits, and several fiber traits (fineness and decortication efficiency) showed low genetic components with large × interactions affecting the rankings across locations. These results suggest that pectin, agronomic traits, and fiber traits are unsuitable targets in breeding programs of hemp, as their large × interactions might lead to unexpected phenotypes in untested locations. Furthermore, all environmental effects on the 28 traits were statistically significant, suggesting a strong adaptive behavior of fiber quality in hemp to specific environments. The high variability in fiber quality observed in the hemp panel, the broad range in heritability, and adaptability among all traits prescribe positive prospects for the development of new hemp cultivars of excellent fiber quality.

As the Internet of Things devices are deployed on a large scale, location-based services are being increasingly utilized. Among these services, kNN (k-nearest neighbor) queries based on road network constraints have gained importance. This study focuses on the CkNN (continuous k-nearest neighbor) queries for non-uniformly distributed moving objects with large-scale dynamic road network constraints, where CkNN objects are continuously and periodically queried based on their motion evolution. The present CkNN high-concurrency query under the constraints of a super-large road network faces problems, such as high computational cost and low query efficiency. The aim of this study is to ensure high concurrency nearest neighbor query requests while shortening the query response time and reducing global computation costs. To address this issue, we propose the DVTG-Index (Dynamic V-Tree Double-Layer Grid Index), which intelligently adjusts the index granularity by continuously merging and splitting subgraphs as the objects move, thereby filtering unnecessary vertices. Based on DVTG-Index, we further propose the DVTG-CkNN algorithm to calculate the initial kNN query and utilize the existing results to speed up the CkNN query. Finally, extensive experiments on real road networks confirm the superior performance of our proposed method, which has significant practical applications in large-scale dynamic road network constraints with non-uniformly distributed moving objects.

Industrial hemp (Cannabis sativa L.) seedlings are sensitive to drought stress, which is a prevalent factor influencing its growth seriously. To explore the effect of ascorbic acid (AsA) on hemp seedlings under drought condition, a pot experiment was carried out to applicate AsA on two cultivars, ‘Yunma1’ (YM) and ‘Bamahuoma’ (BM). Three drought treatments were imposed: control (normal water), drought (50% substrate moisture) and drought + AsA (50% substrate moisture + 200 mg/L AsA). The results showed that drought stress significantly suppressed plant height and reduced plant fresh weight, with reductions of 59% and 75% observed in YM, and 43% and 67% in BM, respectively. Although foliar treatment with AsA had little effect on increasing plant fresh weight under drought conditions, it significantly enhanced the concentrations of photosynthetic pigments and the activities of antioxidant enzyme (superoxide dismutase, SOD and peroxidase, POD). The results suggested that harmful effects of drought stress on hemp seedlings were mitigated by exogenous application of AsA, which decrease the breakdown of photosynthetic pigments, enhancing antioxidant enzyme activities and strengthening the antioxidative defense system. Among these, compared to drought treatment the carotene content and SOD activity exhibited the most significant increases after AsA spraying. Specifically, exogenous AsA treatment increased the carotene content by approximately 108.40% in YM and 88.53% in BM. Meanwhile, POD activity increased by 33.33% in YM and 60.94% in BM. Furthermore, the study found that hemp plant response and tolerance to drought were cultivar-dependent. Overall, these results provide a theoretical basis for understanding the mechanism by which AsA alleviates drought stress.

Hemp is a multipurpose crop that is cultivated worldwide for fiber, oil, and cannabinoids. Nitrogen (N) is a key factor for getting a higher production of hemp, but its application is often excessive and results in considerable losses in the soil–plant–water continuum. Therefore, a rational N supply is important for increasing N efficiency and crop productivity. The main objective of this paper was to determine the responses of four hemp cultivars to different levels of exogenous-N supply as nutrient solution during the vegetative growing period. The experiment was conducted at Yunnan University in Kunming, China. Yunma 1, Yunma 7, Bamahuoma, and Wanma 1 were used as the experimental materials, and five N supplying levels (1.5, 3.0, 6.0, 12.0, and 24.0 mmol/L NO3-N in the nutrient solution) were set by using pot culture and adding nutrient solution. The root, stem, and leaf of the plant were sampled for the determination of growth indexes, dry matter and N accumulation and distribution, and physiological indicators. The plant height, stem diameter, plant dry weight, and plant N accumulation of four hemp cultivars were significantly increased with the increase in exogenous-N supply. Root/shoot dry weight ratios, stem mass density, and N use efficiency decreased significantly with the increase in exogenous-N supply. Nitrogen accumulation, chlorophyll content, soluble protein content, and nitrate reductase activity in leaves were increased with the increase in exogenous-N supply. Among the four indexes, the increase in N accumulation was more than the increase in NR activity. The activities of superoxide dismutase and peroxidase in leaves were increased first and then decreased with the increase in exogenous-N supply, with the maximum value at N 6.0 mmol/L, while the content of malondialdehyde in leaves increased significantly when the level of exogenous-N supply exceeded 6.0 mmol/L. These results revealed that increasing the exogenous-N supply could improve the plant growth, dry matter accumulation, and N accumulation in hemp during the vegetative growth period, but N supply should not exceed 6.0 mmol/L. Among four hemp cultivars, Wanma 1 performed well at 6.0 mmol/L N application.

Introduction: Hemp (Cannabis sativa L.) has gained worldwide attention for its emerging role as a valuable medicinal source, particularly for cannabidiol (CBD) extraction. Yunnan province is currently the only region in China where hemp grown for CBD production is legalized; yet information on optimal agronomic practices for maximizing CBD output in this region remains scarce.Methods: In the present study, field experiments were conducted in Yunan over two consecutive growing seasons (2019 and 2020) to evaluate CBD productivity and variations in CBD content between female and male plants, as well as among branches along the stem, using a local dioecious hemp cultivar, Yunma #7. Plants were grown under five treatments: a control (CK) with NPK fertilization; additional calcium magnesium phosphate (CK+CMP); and additional boron applied either as powdered boron at the basal stage (CK+CMP+PB1), powdered boron at the budding stage (CK+CMP+PB2), or liquid sugar-alcohol-chelated boron at the budding stage (CK+CMP+LB2).Results: The average inflorescence yield reached 4 Mg ha−1, with female plants producing 2.4 Mg ha−1. Inflorescence CBD content averaged approximately 1% (w/w), being 15% higher in female than male plants, and 30% higher in upper than lower inflorescences. Mg and B fertilization showed no statistically significant effects on inflorescence yield and CBD content, the average CBD yield across all fertilization treatments was 20.1 kg ha−1.Discussion: The study underscores the potential for increasing CBD content through breeding and optimizing harvest methods that distinguish between female and male plants, and separate upper and lower inflorescences.

The world’s arable land has been contaminated by heavy metals to a large extent, which has led to the decreasing availability of farmland. Thus, the remediation of heavy metal pollution deserves due attention, and phytoremediation is preferred. Hemp has been proposed as an ideal alternative crop for remediating heavy-metal-contaminated soil, owing to its well-developed roots, large biomass, and tolerance to heavy metals. Chelators can activate heavy metals to enhance plant absorption, but they may cause stress to plant growth. Therefore, it is very important to optimize the combination of chelator and plant (cultivar) for efficacious phytoremediation. The effects of different concentrations (2, 5, 10, 15, and 25 mmol·L−1) of the chelators disodium ethylene diamine tetra-acetate (EDTA) and citric acid (CA) on the seed germination and plant growth of hemp cultivars were investigated. Triple application of increasing concentrations of EDTA or CA two days apart gradually reduced the germination potential, germination rate, radicle length, and embryonic shoot length of hemp seed, although 2 mmol·L−1 of CA could even promote seed germination. Distinct varietal differences were found in the response of hemp to chelator stress. Under the scheme of four-time uses one week apart, both chelators caused a concentration-dependent linear decrease in the plant height, stem diameter, and biomass of hemp plants, but the growth inhibition due to CA was relatively milder. This could be partially explained by the change in tested physiological indices in hemp leaf. In conclusion, 2 mmol·L−1 of CA helped with seed germination and was almost nontoxic to plant growth; cultivar BM was more tolerant to the chelators than cultivar Y1.