Comparison of stem and fiber yield: Industrial hemp varietal trial

Introduction

Cotton is the most widely produced natural fiber in the world. But as a crop, Gossypium hirsute L., as it is known scientifically, relies heavily on irrigation water and agrochemicals.

Hemp (Cannabis sativa L.) is one alternative with a smaller environmental footprint. Industrial hemp grows rapidly. It requires less water and fewer chemicals. Interest in hemp as a fiber crop has grown since its removal from the Controlled Substances Act following the passage of the 2018 U.S. Farm Bill, which regulated the crop as a traditional crop.

Industrial hemp must contain less than 0.3% tetrahydrocannabinol, or THC, a psychoactive compound found in other varieties of hemp.

Industrial hemp is widely recognized as a good source of fiber, particularly bast fiber. Bast fiber, used in textiles, is obtained from the outer cell layers of the stems. Hemp is also a source of hurd fiber, an absorbent material obtained from the pith.

Hemp production is greatly affected by cultivar, environment and management practices such as planting density, fertilization and irrigation. Identifying cultivars well adapted to local environmental conditions is key to optimizing bast fiber performance. Our research work evaluated hemp prospects as a suitable environmentally sustainable and economic alternative source of natural and bast fiber. This study sought to evaluate the fiber yield performance of three dioecious (NWG 2463, NWG 4113 and Jin Ma) and two monoecious (Bialobrzeskie and Henola) varieties of industrial fiber hemp. Monoecious varieties have both male and female sex organs, while the sex organs of dioecious plants occur in separate individuals.

Data collection

Prior to harvest, we measured plant height from the soil surface to the top of the canopy on three randomly selected plants from each plot. We harvested plants September 13–23, 2022, as individual varieties matured. Biomass yield was calculated on a per-plant basis. We measured 10 representative plants in each plot, marking stem diameter at the base of the third node from the soil surface using a caliper. We separated harvested plants into stems, leaves and inflorescences, and weighed each part. All plant parts were oven-dried at 60 °C for 72 hours until a constant dry weight was achieved. We analyzed data using PROC ANOVA procedure in SAS version 9.4 (SAS Institute, 2015) followed by LSD post-hoc analysis (p ≤ 0.05) for differences among varietal means for the measured parameters (Table 1).

Results and discussion

All measured parameters (Table 1) showed significant differences and were notably higher in this study compared to similar studies with dioecious varieties.

Plant height and stem diameter

Both plant height and stem diameter were highly influenced by variety (Table 1). These characteristics are not only highly correlated but are also good predictors of biomass and fiber yield. The mean plant height was 244.8 cm. The Jin Ma variety was the tallest at 309.9 cm. The shortest variety was Henola at 196 cm.

The difference in stem diameter was significant. Jin Ma stems measured 19.5 mm, while stems of the other varieties ranged from 10 mm to 13 mm (Table 1). Stem diameter is generally inversely proportional to plant density. Seeding rates can influence this, with subsequent effects on plant populations. Stem diameter in this study is notably higher than stem diameter reported in other areas.

Dry weight, leaf and stem yields

Variety had a significant effect on dry weight, leaf and stem yields (Table 1). In all cases, the Jin Ma (fiber type) variety produced significantly higher yields than the other varieties. This performance is consistent with a previous study in Georgia. Jin Ma produced the highest dry weight per plant (0.264 g/plant), while Bialobrzeskie produced the lowest (0.058 g/plant). Leaf yields averaged 3,742 lbs/acre and ranged from a low of 450 lbs/acre (Henola) to a high of 12,297 lbs/acre (Jin Ma).

For stem yield, the average ranged from 7,447 lbs/acre (Henola) to 37,062 lbs/acre (Jin Ma), with a mean of 17,669 lbs/acre. Stem yield is an important characteristic and shows a direct relationship with bast fiber yield. As expected, the varieties with the highest stem yields produced higher bast fiber yields (Table 1).

Fiber content and fiber yield

Hemp variety significantly affected both fiber content and fiber yields (Table 1), which is consistent with a previous study in Finland. Overall, bast fiber content averaged 24.1% among all varieties. Bialobrzeskie (fiber type) and the predominantly grain variety Henola produced significantly higher fiber content compared to the remaining three varieties. Conversely, Jin Ma (fiber type) produced the highest bast fiber yield at 6,295.8 lbs/acre compared to the remaining fiber (Bialobrzeskie) or dual-purpose varieties (Henola, NWG 4113, NWG 2463), which did not differ in their fiber yields.

Bast fiber yield is a product of stem yield and bast fiber content, and both are instrumental in overall bast fiber yields. Jin Ma, which produced the lowest bast fiber content, produced significantly more bast fiber yield compared to all other varieties due to its superior stem yield performance. Stem diameter was inversely related to fiber content (Figure 3). Generally, bast fiber content increases with decreasing stem diameter.

Conclusion

Results from this study clearly showed which varieties performed best at this location. Varieties differ in their ability to produce concentrations of bast fiber, one indication of fiber quality. The greatest bast fiber content was associated with Bialobrzeskie and Henola varieties, compared to the three other varieties, which were similar in their bast fiber content. These varieties showed good adaptability and can be considered for local adaptation and cultivation.

Conversely, when total fiber yield is the main consideration, Jin Ma excels. Jin Ma recorded the lowest bast fiber content, but owing to its considerably larger stem diameter, higher growth rates and stem yields, its fiber yield was greater. "Planting this variety earlier could also be a consideration due to its late maturing tendencies.

This varietal evaluation provides grounds to study other agronomic variables such as planting density, which is a major factor affecting hemp fiber yield and quality. Additionally, given this region’s limited supply of irrigation water, further studies should examine how different varieties respond to differing agronomic practices, such as changes in the amount and scheduling of irrigation.

For more information, visit the Global Hemp Innovation Center at Oregon State University.

Acknowledgment

Funding support provided by the Oregon State University Global Hemp Innovation Center and the Agriculture and Food Research Initiative, Sustainable Agricultural Systems, grant No. 13333755, project accession No. 1027531 from the USDA National Institute of Food and Agriculture.

References

Adesina, I., A. Bhowmik, H. Sharma and A. Shahbazi. 2020. A Review on the Current State of Knowledge of Growing Conditions, Agronomic Soil Health Practices and Utilities of Hemp in the United States. Agriculture 10, 129.

Coolong, T., T. Bagby, and E Elsner. 2020. An Introduction to Fiber Hemp Production in Georgia. University of Georgia Extension 32. Retrieved January 26, 2024.

Darby, H., 2022. 2022 Industrial Hemp Fiber Variety Trial. Retrieved January 26, 2024.

Duley, C., J. Clark, B. Halfman, A. Olson and K. Davis. 2022. Exploration of Hemp for Fiber Production and Quality in Wisconsin. Retrieved January 26, 2024.

Duque Schumacher, A.G., S. Pequito and J. PazourJ. 2020. Industrial hemp fiber: A sustainable and economical alternative to cotton. Journal of Cleaner Production 268, 122180.

Ekren, S., G. Ozturk, A. Gokçol, M. Ertekin, H. Geren and E. Ilker. 2023. Effect of nitrogen application rate and harvesting stage on yield and agronomic parameters of industrial hemp (Cannabis sativa L.). Crop Science 63, 3051–3064.

Franco, M.A., 2017. Circular economy at the micro level: A dynamic view of incumbents’ struggles and challenges in the textile industry. Journal of Cleaner Production 168, 833–845.

Kaur, G., and R. Kander. 2023. The Sustainability of Industrial Hemp: A Literature Review of Its Economic, Environmental, and Social Sustainability. Sustainability 15, 6457.

Richmond, M.D., 2021. Dual-Purpose Industrial Hemp Cultivar Trial in Tennessee 2021. Retrieved January 26, 2024.

Salas Fernandez, M.G., P.W. Becraft, Y. Yin and T. Lübberstedt. 2009. From dwarves to giants? Plant height manipulation for biomass yield. Trends in Plant Science 14, 454–461.

Sandin, G. and G.M. Peters. 2018. Environmental impact of textile reuse and recycling — a review. Journal of Cleaner Production 184, 353–365.

Sankari, H.S., 2000. Comparison of bast fibre yield and mechanical fibre properties of hemp (Cannabis sativa L.) cultivars. Industrial Crops and Products 11, 73–84.

Solomon, J.K.Q., A. Ogunleye, A. Opoku, F.H. Barrios-Masias, S. Huber and S. Foster. 2022. Industrial Fiber Hemp : An Early Initiative to Capture Varietal Response in Nevada. Retrieved January 26, 2024.

Tang, K., P.C. Struik, P.C., X. Yin, D. Calzolari, S. Musio, C. Thouminot, M. Bjelková, V. Stramkale, G. Magagnini, and S. Amaducci. 2017. A comprehensive study of planting density and nitrogen fertilization effect on dual-purpose hemp (Cannabis sativa L.) cultivation. Industrial Crops and Products 107, 427–438.

Williams, D.W., J.W. Turner, R. Hounshell, D. Neace. 2022. 2018 University of Kentucky Industrial Hemp Variety Trials for Dual‐Purpose Production. Retrieved January 26, 2024.