Evaluation of Weed Interference Effects on Yield and Yield Components of Hemp (Cannabis Sativa)

Document Type : Research Paper

Authors

1 Associate Professor, Department of Plant Production and Genetics, Faculty of Agriculture, University of Birjand, Birjand, Iran

2 MSc Graduated. Department of Plant Production and Genetics, Faculty of Agriculture, University of Birjand, Birjand, Iran

3 Lecturer, Department of Plant Production and Genetics, Faculty of Agriculture, University of Birjand, Birjand, Iran

Abstract

Introduction
Hemp (Cannabis sativa L.) is one of the oldest cultivated annual crops in the world belonging to the cannabaceae family and annual wind-pollinated broadleaf. It is originated in central Asia and considered a multi-purpose crop including stalk fiber (apparel, fabric, bags), stalk hard (animal bedding, mulch, biofuel, filter, and so on), seeds (nut, and snacks), oil (salad oil, cosmetic, shampoo, soap, oil paint, industrial oil, and solvent), leave and inflorescence (anti-microbe (hand soap), and agrochemical products (insecticide and herbicide). Weed competition for nutrients, water, and light led to decreased growth and yield of hemp. Mechanical and agronomical techniques are commonly used for weed management in hemp. Since mechanical and agronomical techniques are expensive and time-consuming, finding a new approach to save time and money is essential. Determination of weed critical period may facilitate arriving at this approach. The critical period of weed control (CPWC) refers to a part of the integrated weed management (IWM) program and is defined as a part of the crop growth cycle in which weeds must be removed for avoiding economic yield losses due to weed competition with crops for water, light, and minerals. On the other hand, CPWC is a period in which crops must be growth-free of weeds. Numerous agents' effects on CPWC include crop species and growth characteristics, crop density, crop variety, and crop planting pattern. The main goal of this study was to determine the effect of hemp density on CPWC and hemp yield and yield components' responses to the critical period of weed control.
 
Materials and Methods
A field trial was carried out in 2016 at the research field of Birjand University in South Khorasan Province, Birjand, Iran (latitude 32°, 86′, 49″ N, longitude 59°, 22′, 62″ E, and altitude 1491 m). Before sowing seeds, the field was fertilized with urea (250 kg ha-1) split at two times (sowing time, 2 mount after emergence), P2O5 (100 kg ha-1), and K2O (100 kg ha-1). The field was plowed with a mouldboard plough (30 cm depth), and then harrowing by a disk used for seedbed preparation twice, and finally, leveling the soil surface by leveler tools. Hemp has never been cultivated in this field. The hemp seeds were sown on May 4, 2016, in a cluster, 5 seeds in each hole with 60 cm between rows and 10 and 20 cm between plants in the row for 8 and 16 plants/m2, respectively. Sown depth was 3 to 4 cm. Crop emergence began about 2 weeks after planting. Two weeks after emergence (four weeks after planting), the plants were thinned to reach a determined density. The experiment was arranged in a randomized complete block design (RCBD) in a factorial arrangement with three replications. Each experimental plot was 6 m long, 3 m in width, and included 5 rows. Data were collected in three central rows. Treatments included six weed-infested periods (2 (WI2), 4 (WI4), 6 (WI6), 8 (WI8), and 10 (WI10) weeks after crop emergence (WAE)), in which weeds were allowed to grow to 2, 4, 6, 8, and 10 weeks after that control conducted by hand hoeing until harvest time. In weed-infested control (WIC), weeds were allowed to grow in all growing seasons duration. Six weed-free periods (2 (WF2), 4 (WF4), 6 (WF6), 8 (WF8), and 10 (WF10) weeks after crop emergence (WAE)), which weeds were hand hoeing control to 2, 4, 6, 8, and 10 WAE and then weeds were allowed to grow until harvest time. In weed-free control (WFC), weeds control in all season growth duration. The experimental treatments during the growing season of hemp are described in Figure 1. Seed hemp yield and yield components were determined at the end of the growing season.
 
Results and Discussion
Weed-infested and weed-free periods treatments have significant effects on the seed yield and yield components including flower number and seed number per plant of hemp (Table 1). Moreover, hemp density has a significant effect on the seed yield and yield components including flower number and seed number per plant of hemp (Table 1). Higher crop density led to limited CPWC since under weed-infested fields using higher crop density led to improved crop competition ability (Zimdal, 1993). (Hayat et al.,2003) reported that high crop density led to decreased seed yield of crops by increasing inter-species competition. (Purcell et al.,2002) demonstrated the seed yield of soybean depends on crop density whereas by increasing crop density firstly seed yield was increased but under high crop density seed yield was decreased. Therefore, using proper crop density is known as an important challenge to crop production. Flowers per plant, seed number per plant, and seed yield were affected by crop density. Results of this study demonstrated that under weed-infested fields using 16 plants/m-2 is more suitable than 8 plants/m-2 compared to weed-free in Birjand conditions (Dry climate)(Table 2).
 
Conclusions
A greater understanding of weed behavior can help with IWM strategies. The critical period of weed control determination is a key factor for IWM strategies that led to less introduction of herbicides into the environment, saving money and time, and so on. Data obtained from the results of this study revealed that more crop density led to a decrease in the duration of the critical period of weed control in hemp.

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Ahn, J. K., Hahn, S. J., Kim, J. T., Khanh, T. D., & Chung, I. M. (2005). Evaluation of allelopathic potential among rice (Oryza sativa L.) germplasm for control of Echinochloa crus-galli P. Beauv in the field. Crop Protection, 24(5), 413-419. https://doi.org/10.1016/j.cropro.2004.09.009
Amaducci, S., Zatta, A., Pelatti, F., & Venturi, G. (2008). Influence of agronomic factors on yield and quality of hemp (Cannabis sativa L.) fiber and implication for an innovative production system. Field Crops Research, 107(2), 161-169. https://doi.org/10.1016/j.fcr.2008.02.002
Crotser, M. P., & Witt, W. W. (2000). Effect of Glycine max canopy characteristics, G. max interference, and weed-free period on Solanum ptycanthum growth. Weed Science, 48(1), 20-26. https://doi.org/10.1614/0043-1745(2000)048[0020:EOGMCC]2.0.CO;2
Erman, M., Tepe, I. K., Buuml, B., Yergin, R., & Takesen, M. (2008). Critical period of weed control in winter lentil under non-irrigated conditions in Turkey. African Journal of Agricultural Research, 3(8), 523-530.
Evans, S. P., Knezevic, S. Z., Lindquist, J. L., Shapiro, C. A., & Blankenship, E. E. (2003). Nitrogen application influences the critical period for weed control in corn. Weed Science, 51(3), 408-417. https://doi.org/10.1614/0043-1745(2003)051[0408:NAITCP]2.0.CO;2
Gibson, L. R., & Liebman, M. (2003). A laboratory exercise for teaching critical period for weed control concepts. Weed Technology, 17(2), 403-411. https://doi.org/10.1614/0890-037X(2003)017[0403:ALEFTC]2.0.CO;2
Hamzei, J., Nasab, A.D.M., Khoie, F. R., Javanshir, A., & Moghaddam, M. (2007). Critical period of weed control in three winter oilseed rape (Brassica napus L.) cultivars. Turkish Journal of Agriculture and Forestry, 31(2), 83-90.
Hayat, F., Arif, M. & Kakar, K.M. (2003). Effects of seed rates on mungbean varieties under dryland conditions. International Journal of Agriculture and Biology, 5, 160-161.
Hourfane, S., Mechqoq, H., Bekkali, A. Y., Rocha, J. M., & El Aouad, N. (2023). A comprehensive review on Cannabis sativa ethnobotany, phytochemistry, molecular docking and biological activities. Plants, 12(6), 1245. https://doi.org/10.3390/plants12061245.
Knezevic, S. Z., Evans, S. P., Blankenship, E. E., Van Acker, R. C., & Lindquist, J. L. (2002). Critical period for weed control: the concept and data analysis. Weed science, 50(6), 773-786. https://doi.org/10.1614/0043-1745(2002)050[0773:CPFWCT]2.0.CO;2
Kornpointner, C., Martinez, A. S., Marinovic, S., Haselmair-Gosch, C., Jamnik, P., Schröder, K., Löfke, C., & Halbwirth, H. (2021). Chemical composition and antioxidant potential of Cannabis sativa L. roots. Industrial Crops and Products, 165, 113422. https://doi.org/10.1016/j.indcrop.2021.113422
Makarian, H., Bannayan Aval, M., Rahimiyan mashhadi, H., & Izadi Darbandi, E. (2003). Planting date and population density influence on competitiveness of corn (Zea mays L.) with redroot pigweed (Amaranthus retroflexus L.). Iranian Journal of Field Crops Research, 1(2), 271-279. (In Persian)
Martin, S. G., Van Acker, R. C., & Friesen, L. F. (2001). Critical period of weed control in spring canola. Weed Science, 49(3), 326-333. https://doi.org/10.1614/0043-1745(2001)049[0326:CPOWCI]2.0.CO;2
Masoudi, B., Bihamta, M. R., Babaei, H. R., & Peyghambari, S. A. (2008). Evaluation of Genetic Diversity for Agronomic, Morphological and Phenological Traits in Soybean. Seed and Plant Journal, 24(3), 413-427. (In Persian)
Mirshekari, B., Dabagh Mohammadi nasab, A., Noormohammadi, G., Rahimian mashhadi, H. (2006). Effects of redroot pigweed (Amaranthus retroflexus L.) density and time of emergence on yield and yield components of sunflower (Hybrid Hysun-33). Iranian Journal of Crop Science, 7(4), 365-377. (In Persian)
Mousavi, M., Zand, E. & Baghestani, M. A. (2005). Effects of crop density on interference of common bean (Phaseolus vulgaris L.) and weeds. Applied Entomology and Phytopathology, 73(1). (In Persian)
Piotrowski, S., & Carus, M. (2011). Ecological benefits of hemp and flax cultivation and products. Nova institute, 5, 1-6.
Purcell, L. C., Ball, R. A., Reaper, J. D., & Vories, E. D. (2002). Radiation use efficiency and biomass production in soybean at different plant population densities. Crop Science, 42(1), 172-177. https://doi.org/10.2135/cropsci2002.1720
Rehman, M. S. U., Rashid, N., Saif, A., Mahmood, T., & Han, J. I. (2013). Potential of bioenergy production from industrial hemp (Cannabis sativa): Pakistan perspective. Renewable and Sustainable Energy Reviews, 18, 154-164. https://doi.org/10.1016/j.rser.2012.10.019
Salentijn, E. M., Zhang, Q., Amaducci, S., Yang, M., & Trindade, L. M. (2015). New developments in fiber hemp (Cannabis sativa L.) breeding. Industrial crops and products, 68, 32-41. https://doi.org/10.1016/j.indcrop.2014.08.011
Singh, J., & Yadava, H. S. (2000). Factors determining seed yield in early generation of soybean. Crop Research (Hisar), 20(2), 239-243.
Swanton, C. J., Weaver, S., Cowan, P., Acker, R. V., Deen, W., & Shreshta, A. (1999). Weed thresholds: theory and applicability. Journal of Crop Production, 2(1), 9-29. https://doi.org/10.1300/J144v02n01_02
Van der Werf, H. M., &Turunen, L. (2008). The environmental impacts of the production of hemp and flax textile yarn. Industrial Crops and Products, 27(1), 1-10. https://doi.org/10.1016/j.indcrop.2007.05.003
Zimdahl, R. L. (1993). Fundamentals of Weed Science. Academic Press, San Diego, CA, USA.