Comparative Evaluation of Industrial Hemp Varieties: Field Experiments and Phytoremediation in Hawaii

Industrial Crops & Products 170 (2021) 113683

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Industrial Crops & Products

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Comparative evaluation of industrial hemp varieties: Field experiments and phytoremediation in Hawaii

Xu Wang a,b,*, Qing X. Li b, Melody Heidel b, Zhichao Wu a, Alan Yoshimoto b, Gladys Leong b, Dongjin Pan c, Harry Ako b a Institute of Quality Standard and Monitoring Technology for Agro-Products of Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China b Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA c Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, 530299, China

ARTICLE INFO ABSTRACT

Keywords: Industrial hemp (Cannabis sativa L.) is a fast-growing and high biomass producing plant species with wide usage Industrial hemp of its materials such as fiber, food, and fuel. There are many varieties containing low concentration of tetra Atrazine hydrocannabinol (THC). In the present study, it assessed the agricultural feasibility of three industrial hemp Water management varieties with different water management and nitrogen fertilizer treatments, and determined the best ones to Nitrogen fertilizer cultivate in Hawaii, then evaluated the effects of plant density on the yield and the potential phytoremediation Phytoremediation for the herbicide atrazine. The fieldexperiments indicated that it was difficultto grow the variety F75 in Hawaii with a final weight of 13 g and did not live for the full growth season. However, the subtropical fiber hemp variety CHG grew to height of about 190 cm and its weight varied from 150 g to 280 g between two planting densities (100 plants m 2 and 28 plants m 2, respectively). The subtropical seed hemp variety CHY was inter mediate at a mean height and weight of about 130 cm and 130 g, respectively. Estimated crop yields were 19 tons acre-1 year-1 (dry weight) for CHG stalks that could be used for building construction and 16 tons acre- 1 year-1 (dry weight) for leaves could be used as animal forage. Approximately, 1.7 tons of seeds could be har vested per acre per year from variety CHY. Little water consumption (10 mm week-1) was needed, which cor responds with drought resistance of CHG variety. Use of nitrogen fertilizer at a rate of 100 kg ha-1 did not improve growth of CHG variety more than the existing nitrogen levels in the soil. Phytoremediation potential of industrial hemp was also assessed by field pot studies, in which field soils were fortified with 0, 0.25 and -1 0.50 mg kg of atrazine. The half-life (t1/2) of atrazine in hemp watered pots was 15 days, whereas t1/2 was approximately 50 and 28 days in the no plant non-watered pots and the no plant watered pots, respectively, suggesting the degradation of atrazine in soils showed a higher efficiency planted with hemp under water irri gation condition. The CHG plants accumulated atrazine from soils, and the enrichment factor in CHG was increased over the course of 28 days (from 0.22 %–0.31 % to 0.63 %–0.89 %), then decreased after 49 days (0.28 %–0.30 %). Overall, these findingsrevealed that industrial hemp plants were useful for phytoremediation of soils contaminated with atrazine.

1. Introduction be used to make a variety of industrial products, including cloth and building materials from its fiber, oil and food from seeds, and anaes Hemp (Cannabis sativa L.), as an important crop, has a wide range of thetic from secondary metabolite (Das et al., 2017). Most recently this uses in the industrial field (Salentijn et al., 2015). However, it was includes cannabidiol (CBD), a non-psychoactive compound. It also has forbidden in the U.S. due to narcotic properties of Δ-9-tetrahydrocan some eminent traits, such as excellent gas permeability and antibacterial nabinol (THC) after World War II. Industrial hemp is considered as a character. It received widespread and sustained attention for its relisting non-psychoactive plant with a THC concentration of 0.3 % or less. It can of licit crop varieties (Branca et al., 2017; Tang et al., 2017a).

* Corresponding author at: Institute of Quality Standard and Monitoring Technology for Agro-Products of Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China. E-mail address: [email protected] (X. Wang). https://doi.org/10.1016/j.indcrop.2021.113683 Received 28 December 2020; Received in revised form 19 May 2021; Accepted 25 May 2021 Available online 29 May 2021 0926-6690/© 2021 Elsevier B.V. All rights reserved. X. Wang et al. Industrial Crops & Products 170 (2021) 113683

Under natural conditions, Industrial hemp can be grown in a wide range of environments. Due to the climate and industrial hemp’s growth cycle, Hawaii is an ideal place for growing industrial hemp (Dusek et al., 2015). However, the best genotypes to cultivate in Hawaii have yet to be determined, and the good management practices have not been reported so far. Therefore, in order to grow industrial hemp in Hawaii as a valuable crop, it is important to find out the suitable industrial hemp varieties and the key cultivation techniques. Furthermore, due to its fast growing and multiple-use nature, in dustrial hemp has phytoremediation potential for inorganic and organic contaminants (Liste and Prutz, 2006; Asgari et al., 2017; Kyzas et al., 2015). Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3, 5-triazine) has been widely used as herbicides for its high herbicidal efficacyand low cost (Huang et al., 2003, 2015), causing its residual in surface and groundwater worldwide (Nodler¨ et al., 2013; Albright and Coats, 2014). The contamination of atrazine and its metabolites has been linked to the possibly harmful effects on human health and sediment-water environment (Powell et al., 2011; Huang et al., 2015). For example, Souther et al. (2017) reported that atrazine has been implicated as causes of birth defects and have been found in places with a high gastroschisis incidence in Hawaii. Phytoremediation, the use of green plants to bioremediate polluted Fig. 1. Weather conditions during the experiment period. sites, is considered as a low cost and environmentally-friendly remedi ation technology in remediation of heavy metals or organic pollutant day length was 14 h to meet the requirement for vegetative growth of soils (Liste and Prutz, 2006; Citterio et al., 2003). It, however, has some temperate zone hemp. Rainfall was below typical this year and some disadvantages: 1) The phytoremediation plants are often growth with manual watering was required. small biomass with limited remediation efficiency; 2) The remediation period are quite slow and even decades; 3) During phytoremediation, 2.3. Field experiments and plant sampling the polluted sites cannot be utilized (Shi et al., 2012). Industrial hemp may be a good candidate crop for phytoremediation. For example, in The three industrial hemp varieties (F75, CHG and CHY) were dustrial hemp grew very fast with a high biomass, even in dense soil planted in starter trays with 6 × 72 cells and potting soil. The trays were environment. In addition, it is a metal and organic pollutant tolerant then watered manually, and placed in a greenhouse sprouting system organism. Finally, it is an economic crop, which its biomass and seed can that was automatically irrigated twice a day with misters. After 15-d the used for fuel and biodiesel production (Elisa et al., 2007; Citterio et al., industrial hemp plants were transplanted into the field.The experience 2003; Shi et al., 2012). Therefore, it is significant to identify industrial in the nursery suggested that sprouting required moist soil and fivedays hemp varieties that can remediate polluted soils and conquer the dis of rain or twice daily manual watering to be successful. In later trials, advantages of phytoremediation. seedlings were planted in the fieldduring a rainy period. On days which The purpose of this study were to: 1) compare the growth charac there was no rain, sprouts were manually watered twice a day over a teristics of three industrial hemp varieties under different agronomic period of 5 days. Spouting was good. Each variety was subjected to three factors (e.g., water and nitrogen fertilization) in Hawaii, 2) evaluate the treatments: control, irrigated and fertilized. The treatments were in plant density effect on dual-purpose industrial hemp cultivation, and 3) triplicate for a total of 27 plots. The control plants were irrigated with investigate phytoremediation potential of industrial hemp when atra 10 mm of water (rainfall plus artificial irrigation). The irrigated plants zine was used as a chemical model. It was hypothesised that the in were irrigated with 25 mm of water without fertilizer. The fertilized dustrial hemp was a potential species for phytoremediation polluted by group was treated with 100 kg ha 1 of urea. At the end of the experi atrazine. ment, the plants were harvested by cutting at the stalk as it emerged from the ground. The height and weight of plants were measured and 2. Materials and methods averaged.

2.1. Seeds 2.4. Plant density and utilization for CHG

Three varieties of industrial hemp seeds were obtained for research The variety CHG was planted under two growth densities (28 and purposes from EcofibreIndustries Operations Pty Ltd of Australia: CHG 100 plants m 2). The CHG variety was tested with enhanced irrigation (subtropical fiber and forage variety, originated from Southeast Asia), and fertilization. The utilization of the hemp hurd to make hempcrete CHY (subtropical seed variety, originated from Southeast Asia), and (with 1.1 part lime and 1.1 part water and 0.74 part hurd) was carried Futura 75 (F75, temperate variety, originated from France). The phy out. Physiological parameters like plant height, stalk and leaf weight, toremediation experiments were done with the CHG variety only. inflorescenceyield, seed yield and the characteristics of hemp and weed above ground biomass were recorded. 2.2. Field and pot experiments time and soil analysis 2.5. Pot experiments and sample collection The field and pot experiments were carried out in the University of Hawaii at Manoa, Honolulu. The soil pH was 6.2. The nitrogen con Soil samples were collected from the Waimanalo Research Station, centration was 0.21 %. The total carbon was 2.2 %. The cation exchange air dried and then sieved through a 4-mm mesh. Atrazine dissolved in capacity was 26.6 meq 100 g 1. P, K, Ca, and Mg concentrations were ethanol was evenly sprayed onto the soil and uniformly mixed to make 69, 578, 3064, and 1118 mg kg 1, respectively. The rainfall, day length, 0, 0.25, and 0.50 mg of atrazine per kg soil. An amount of 1.07 kg soil maximum and mean air temperature during the experiments were was placed in each 12 cm diameter pot. Each treatment had 45 pots and shown in Fig. 1. It is noteworthy that there was only one month when there were total 135 pots of three treatments. In each treatment, the first

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15 pots had no plants and were not watered (no plant non-watered). The 2.7. Data analysis second 15 pots had no plants but were watered daily (no plant watered). The final 15 pots had one plant (CHG) in each pot and watered daily Concentrations of atrazine in industrial hemps and soils were re (plant watered). Each pot was placed in a plate to receive the leachate. ported on a fresh weight and dry weight basis. The mean weight of in On day 0, 14 and 28, three pots were sampled at each sampling time dustrial hemp would be corrected for dry weight. The enrichment factor from each control treatment and plant treatment. The remaining six pots (Ef) of atrazine was calculated according to the equation of: Ef = of control and plant treatments were sampled on day 49, of which the (atrazine concentration in hemp) / (atrazine concentration in soil). All data were averaged with the appropriate day 49 control. data of this study was statistically analyzed by one-way analysis of The industrial hemp plants were washed with gently flowingwater, variance (ANOVA) followed by LSD test at significant level of P ≤ 0.05 dried with filter paper and then ground in liquid nitrogen for atrazine by using SPSS 20.0 software. The diagrams in the figureswere drawn by analysis. Each plate was rinsed with methanol twice (10 mL and 15 mL) Sigmaplot 12.5 software. to extract atrazine residues in the leachate from pot watering. Soil in each pot was thoroughly mixed and sampled approximately 200 g for 3. Results moisture determination and atrazine analysis. 3.1. Plant growth and photos of three hemp cultivars CHG, CHY and 2.6. Atrazine determination F75 grown for approximately 15 weeks in field

Moisture was determined for soil in each pot tested. Ten grams of wet To choose a genotype suitable for non-psychoactive cannabinoids soil were weighed, dried at 105 C in oven for 7 h, and then weighed uses and adapted to the particular environment is of paramount again to record the dry weight. Ten grams of wet soil and two grams of importance to the success of hemp cultivation in Hawaii. The height and industrial hemp plant (CHG) were weighed in conical glass flasks, fol weight of three industrial hemp varieties under different agronomic lowed by addition of 25 mL methanol, respectively. The sample was factors were shown in Fig. 2. F75 variety was short and small. It flowered shaken for 30 min and then ultrasonicated for 10 min. After the solvent when it grew to a height of about 52 cm and a mean weight of 13 g. F75 was decanted into a tube, a 25 mL aliquot of methanol was added into variety died in the grow-out period. The CHG variety grew fastest and the soil residue, followed by ultrasonication for 10 min. The extracts had the highest yields in Hawaii. It grew to a mean of 1.9 m in 15 weeks, were combined in a centrifuge tube. After centrifugation at 7000 rpm for and showed higher trends than the fertilized or irrigated group. The 10 min, the solvents were removed with a rotary evaporator at 40 C to photo depicts the various varieties at the end of the growth cycle. In near dryness. The residue was dissolved in 2 mL of the mobile phase addition, the results showed that after fertilized treatment, the weight of (8:2, methanol: 50 mM ammonium acetate solution pH 7.4), filtered the CHG was obviously increased while the height had no significant through a 0.2 μm PTFE filter(Thermo Scientific),and then analyzed by change. Additional irrigation (25 mm daily) treatment decreased the an Agilent 1100 series high performance liquid chromatograph (HPLC) height and weight of the CHG. The subtropical seed hemp variety CHY with an diode array detector (Agilent Technologies, Santa Clara, CA, was intermediate at a mean height and weight of about 130 cm and USA) and a C18 column (5 μm particle size, 4.6 mm × 250 mm, Phe 130 g, respectively. Moreover, the CHY variety could yield about nomenex, Torrance, CA, USA). The mobile phase was 80 % methanol in 1.7 tons of seed per acre per year. The field trials showed that CHG 1 50 mM ammonium acetate pH 7.4. The flowrate was 1.0 mL min . The variety grew well in Hawaii, so the remainder of the experiments were injection volume was 20 μL. The detection wavelength was 220 nm. The focused on it. limit of detection (LOD) was 3 μg L 1 and the limit of quantitation (LOQ) was 10 μg L 1. The calibration linear range was between 10 and 3.2. Plant tissue biomass and utilization of the hemp cultivar CHG 500 μg L 1 with r2 > 0.99. The average recoveries were 77–102 %. between two planting densities

CHG growth was compared between two planting densities of 28 and

Fig. 2. Comparison of height (A) and weight (B) of three hemp cultivars CHG, CHY and F75 and photo (C) of three hemp varieties CHG, CHY and F75 grown for approximately 15 weeks in field. Values (Means ± STDEV) with different lower case letters mean statistically significant differ ences by using on one-way ANOVA and LSD test (P ≤ 0.05, n = 4) of each three hemp cultivar among three treatments.

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100 plant m 2 (Fig. 3). The heights for densities of 28 and 100 plants atrazine in soil. m 2 had no significant difference. Leaf and stalk weights of CHG were observably higher in 28 plants m 2 density treatment than those in 100 3.4. Atrazine concentrations in the hemp cultivar CHG under 0.25 and plants m 2 density treatment. The total yield of both stalk and leaf 0.50 mg kg 1 atrazine treatments weight per acre in 100 plants m 2 density treatment was greater than that of 28 plants m 2 density treatment. As shown in Table 1, CHG hemp plants were grown in 0, 0.25, and Estimated CHG crop yields under 100 plants m 2 density density 0.50 mg kg 1 atrazine fortified soil. After 14 days, the atrazine con were about 19 tons dry weight acre-1 year-1 for stalks and 16 tons dry centrations in CHG were 3.40 ± 0.43 and 5.48 ± 0.45 mg kg 1 grown in weight acre-1 year-1 for leaves. As shown in Fig. 4, the Stalks from hemp the 0.25, and 0.50 mg kg 1 atrazine fortifiedsoil, respectively. The Ef of planted in 100 plants m 2 were used to make hempcrete with blending hemp was 0.22 0.31%. After 28 days, the atrazine concentrations were the commercially available lime, suggesting that this stalks planted in 4.44 ± 0.46 and 7.60 ± 0.55 mg kg 1 of CHG from 0.25 and 100 plants m-2 could be produced in Hawaii. However, the talks planted 0.50 mg kg 1 atrazine fortified soil, respectively. The Ef of CHG was in 28 plants m 2 were thicker and harder to break into small pieces, and 0.63 0.89%. After 49 days, the atrazine concentrations were a machine would be required to mechanically break into pieces. 1.20 ± 0.21 and 2.22 ± 0.31 mg kg 1 of CHG grown in the 0.25 and 0.50 mg kg 1 atrazine fortified soil, respectively. The Ef of hemp was 0.28 0.30%. The atrazine concentrations of hemp increased after 14 3.3. Comparison of the residue atrazine concentrations in soils planted 1 and 28 days and then decreased after 49 days consistent with meta with the hemp cultivar CHG under 0.25 and 0.50 mg kg atrazine bolism occurring within hemp plants. treatments

4. Discussion CHG hemps were grown in 0, 0.25, and 0.50 mg kg 1 atrazine for tified soil and soil was sampled periodically. As shown in Fig. 5, the 4.1. Suitable hemp varieties and agronomic management in Hawaii concentrations of atrazine decreased over time. After 14 days, the – – – atrazine concentrations in soil were 81 84 %, 54 65 %, and 44 48 % of Industrial hemp can be grown most of the world for its high envi both initially fortifiedconcentrations for the no hemp non-watered pots, ronmental suitability (Salentijn et al., 2015). As growing hemp means no hemp watered pots, and hemp watered pots, respectively. The atra that the interaction of the genotype, environment and crop management – zine concentrations in the hemp watered treatment soil was 36 37 % is relevant (Struik et al., 2000). In the present study, the genotype – and 10 17 % less than that of no hemp non-watered and no hemp F75 grew to the mean values with height of 52 cm and weight of 13 g, watered controls, respectively. After 28 days, the atrazine concentra flowered, and died in the grow-out period in Hawaii. F75 is a late – – – tions in soil were 63 66 %, 45 48 %, and 22 24 % of the initially for flowering genotype which is well adapted in Mediterranean environ tified concentration in the soil in no hemp non-watered pots, no hemp ments, its growth requires a day length longer than 14 h because it is a watered pots, and hemp watered pots, respectively. The atrazine con temperate zone variety (Tang et al., 2017b) and Hawaii does not satisfy – – centrations in hemp watered soil was 41 42 % and 23 24 % less than no this requirement. The poor growth of F75 proved that it is not suitable in hemp non-watered and no hemp watered treatments, respectively. After subtropical day lengths, while the other two varieties (CHY and CHG) – – 49 days, the atrazine concentration of soil were 50 51 %, 31 43 %, and were bred for good yields with 2 two-years yields of about 1.7 tons of – 15 17 % of the fortified concentration for no hemp non-watered, no seed per acre per year. This yield is a rough estimation, but such infor hemp watered, and hemp watered pots, respectively. The atrazine mation is needed for planning future research. Seed yield was based on – – concentrations in hemp watered soil was 34 35 % and 16 26 % less than the facts that only half of the plants had seeds with a quarter contained no hemp non-watered and no hemp watered treatment, respectively. about 5 g of seeds per plant while the remainder had 30 g of seeds per After 49 days, the atrazine concentrations in hemp watered soil was plant. CHG grew fast and had higher yields in Hawaii, which grew to a – – 30 34 % of no hemp non-watered treatment, and 64 84 % of no hemp mean value of 1.9 m for 15 weeks. These mean that three hemp varieties but watered treatments. Degradation of atrazine in soil followed pseudo can be harvested per year using Hawaii’s unique climate and environ first order kinetics and was consistent with slow disappearance of ment. Also it can be cross cultivated with corn (Zea mays L.) (Ehrensing, 1998). Little water consumption (10 mm week 1) corresponded with drought resistance of CHG variety. Nitrogen fertilization (100 kg ha 1) did not improve growth more than existing nitrogen levels in the soil. Other researches had shown that nitrogen fertilization played the negligible role on the yield of hemp (Struik et al., 2000; Prade et al., 2011) when soil fertility was high. In contrast, a significant increase of the stalk yield was also found with the increasing of nitrogen application from 0 up to 120 kg ha-1 (Finnan and Burke, 2013). The main reason to these differential results of shoot biomass of hemp varieties was responsible for sufficient level of nitrogen content in field soil (Tang et al., 2017a).

4.2. CHG plant density and utilization

The planting density has strong effect on its growth and stalk yield of hemp plants, with longer and thicker grown at low-and-suitable density Fig. 3. Comparison of per plant yield of the hemp cultivar CHG between two than those grown at high density (Bhattarai and Midmore, 2014). Plant planting densities (28 and 100 plants m 2). Values (Means ± STDEV) with different lowercase letters mean statistically height could be affected by interspecificcompetition and contributed to significant differences by using on one-way ANOVA and LSD test (P ≤ 0.05, the stalk elongation in high plant density in order to avoid the shade, n = 4) among two planting densities (28 and 100 plants m 2) of the hemp probably due to light scarcity (Burczyk et al., 2009). In the present 2 cultivar CHG. Weight means the sum value of the stalk weight and the study, the hemp CHG heights for both densities of 28 and 100 plants m leaf weight. were not significantlydifferent. Stalk and leaf weights of the hemp CHG

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Fig. 4. Photos of hempcrete made from hurd of 100 plants m 2 planting density of the hemp cultivar CHG.

1 for leaves (Fig. 3). Due to the thinner stalks at high plant density, it need less energy to make hempcrete. Additionally, a great amount of leafy materials from fiberhemp CHG provides the possibility of a home grown forage crop in Hawaii. Results indicated that CHG variety planted in 100 plants m 2 could achieve greater value in Hawaii.

4.3. Phytoremediation of atrazine-contaminated soils

The soil half-lives (t1/2) of atrazine could last for more than one year, and this is according to soil physicochemical property, moisture, tem perature, and its depth (Satpute et al., 2015), as well as the microor ganisms in soil which even could be metabolic into CO2 (Henderson et al., 2007). Atrazine would disappear more fastly in soil with the presence of plants. It was reported that forty-three percent of atrazine was degraded when planted with three different prairie grasses, and degraded more quickly in vegetated soils than unvegetated soil (Belden and Coats, 2004). Similar findingwas also observed that degradation of Fig. 5. Comparison of the residue atrazine concentrations of soils planted with atrazine showed a more quick rate in polluted soil planted with Zea mays the hemp cultivar CHG under 0.25 and 0.50 mg kg 1 atrazine treatments. than the non planted soil (Ibrahim et al., 2013). In the present study, when the soil had no water and no hemp, the half-life was greater than Table 1 50 d, and when the soil had water and no hemp, t1/2 was 28 d, while it Atrazine concentrations in the hemp cultivar CHG under 0.25 and 0.50 mg kg 1 was 15 d under the water and hemp circumstance. Thus, atrazine con atrazine treatments. centrations in soil would decrease under appropriate irrigation, which is 1) possibly due to microbial degradation under moisture conditions. Treatment period (day) Atrazine concentrations (mg kg Atrazine Ef In addition, growing hemps shortened t of atrazine in soil to an 1 1 1/2 0.25 mg kg 0.50 mg kg approximately half and one third relative to the no hemp non-watered 14 3.40 ± 0.43 b 5.48 ± 0.45 b 0.22 0.31 % 28 4.44 ± 0.46 a 7.60 ± 0.55 a 0.63 0.83 % control and the no hemp watered control, respectively. Results proved 49 1.20 ± 0.21 c 2.22 ± 0.31 c 0.28 0.30 % that degradation of atrazine in soil followed pseudo first order kinetics (Yuan et al., 2017) and was consistent with a slow disappearance of Values (Means ± STDEV) with different lowercase letters mean statistically significant differences by using on one-way ANOVA and LSD test (P ≤ 0.05, atrazine in soil (Fig. 5), which was accelerated by watering and was n = 4) of the hemp cultivar CHG among the treatment period. "Ef" was indicated presumably associated with microbial diversity and populations as well as "enrichment factor". as hemp plants.

plant were higher at 28 plants m 2 density than those at 100 plants m 2 4.4. Phytoremediation ability of hemp density. The hemp plants at 100 plants m 2 grew smaller with lower tissues biomass compared with at 28 plants m-2 as due to lower cortical Several researches has been evidenced that many plants could be surface and higher surface-area ratio (Campiglia et al., 2017), which can absorbed and accumulated atrazine, such as wheat, corn, soybeans, be used to produce high-quality fibers (Amaducci et al., 2015). Addi cotton, poplar trees and grass (Belden and Coats, 2004; Ibrahim et al., tionally, the stalks were more slender at higher planting density than the 2013). Switchgrass and big bluestem were two potential species for treatments of low or appropriate density, but this caused the increasing phytoremediation of atrazine, which were capable of removing atrazine of the cost of seed input, and as well as the risk of lodging (Legros et al., from soil due to their extensive root system and general hardiness 2013). (Albright III and Coats, 2014; Albright III et al., 2013). For example, As a good material for producing of hemp fiber,the hemp stalk could Khrunyk et al. (2016) showed that switchgrass could take up 40 % of – be cut into the small pieces and then used to form a contraction material atrazine in liquid hydroponic cultures added 20 33% sand. In the pre called hempcrete, and used to product building walls when mixed with sent study, after 49 days treatment, atrazine concentration in the water – lime. Hempcrete is termite resistant, insulates, is recyclable and there is hemp treatment soil were 30 34 % less than that in the no hemp – a great need for construction materials in Hawaii. In this study, the non-watered treatment, and 64 84 % less than that in the no hemp estimated CHG crop yields under 100 plants m 2 density were about watered. Atrazine was firstaccumulated in the CHG, and the enrichment – – 19 tons dry weight acre-1 year-1 for stalks and 16 dry weight acre-1 year- factor (Ef) in CHG were 0.22 % 0.31 %, 0.63 % 0.89 % and 0.28 %-0.30 % after 14 d, 28 d, and 49 d treatments, respectively. Hemp is highly

5 X. Wang et al. Industrial Crops & Products 170 (2021) 113683 capable of absorbing atrazine and remediate atrazine contaminated soil. Belden, J., Coats, J., 2004. Effect of grasses on herbicide fate in the soil column: fi Atrazine, after plant uptake, can be degraded to deethylatrazine (DEA), in ltration of runoff, movement, and degradation. Environ. Toxicol. Chem. 23, 2251–2258. https://doi.org/10.1897/03-422. deisopropylatrazine (DIA), and didealkylatrazine (DDA). These results Bhattarai, J., Midmore, D., 2014. Effect of industrial hemp (Cannabis sativa L.) planting suggest that industrial hemp plants are useful for phytoremediation of density on weed suppression, crop growth, physiological responses, and fibreyield in – soils polluted by atrazine in Hawaii. Additional researches are war the subtropics. Renew. Bioresour. 2, 1 7. https://doi.org/10.7243/2052-6237-2-1. Branca, C., Blasi, C., Galgano, A., 2017. Experimental analysis about the exploitation of ranted to reveal the mechanisms of uptake, migration and degradation industrial hemp (Cannabis sativa) in pyrolysis. Fuel Process. Technol. 162, 20–29. metabolism of atrazine in hemp plants, as well as the effects of senes https://doi.org/10.1016/j.fuproc.2017.03.028. cence on atrazine degradation in a phytoremediation system. Burczyk, H., Grabowska, L., Strybe, M., Knoczewicz, W., 2009. Effect of sowing density and date of harvest on yields of industrial hemp. J. Nat. Fibers 6, 204–218. https:// doi.org/10.1080/15440470902972588. 5. Conclusion Campiglia, E., Radicetti, E., Mancinelli, R., 2017. Plant density and nitrogen fertilization affect agronomic performance of industrial hemp (Cannabis sativa L.) in Mediterranean environment. Ind. Crop. Prod. 100, 246–254. https://doi.org/ Among the three hemp varieties, F75 flowered fast and died in the 10.1016/j.indcrop.2017.02.022. grow-out period because of its strict day length requirements. CHY grew Citterio, S., Santagostino, A., Fumagalli, P., Prato, N., Ranalli, P., Sgorbati, S., 2003. taller and heavier than F75, 2 crops a year CHY could be harvested and Heavy metal tolerance and accumulation of Cd, Cr and Ni by Cannabis sativa L. Plant Soil 256, 243–252. https://doi.org/10.1023/A:1026113905129. yields of about 1.7 tons of seed could be obtained per acre per year. CHY Das, L., Liu, E., Saeed, A., Williams, D., Hu, H., Li, C., Ray, A., Shi, J., 2017. Industrial may be the most lucrative if seeds could be made into candy bars or hemp as a potential bioenergy crop in comparison with kenaf, switchgrass and other foods for humans. CHG grew fast and had higher yields in Hawaii, biomass sorghum. Bioresour. Technol. 244, 641–649. https://doi.org/10.1016/j. which can reach a mean of 1.9 m in 15 weeks. It can take advantage of biortech.2017.08.008. Dusek, J., Dohnal, M., Snehota, M., 2015. 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