Industrial Crops & Products 170 (2021) 113683 Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop 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.