The Effects of Irrigation, Topping, and Interrow Spacing on the Yield and Quality of Hemp (Cannabis sativa L.) Fibers in Temperate Climatic Conditions

Abstract

The study was aimed at determining the most suitable irrigation schedule program for hemp grown for fibers by using evaporation from the free water surface (Eo), measured by a Class A pan and related crop plant coefficient (Kc). The experiment, carried out in Vojvodina, a northern part of the Republic of Serbia, included three irrigation regimes: I1, I2, and I3 corresponding, respectively, to daily evaporation from an open water surface (Eo), two interrow spacings: RS1 (12.5 cm) and RS2 (25 cm), and topped (T) and not topped (NT) variants. The Kc values used for the calculation of daily evapotranspiration (ETd) were 0.42 for April and May and 1.00 (I1), 0.80 (I2), and 0.60 (I3) from June to the harvest. In addition, the nonirrigated (Io) control variant was also included in the trial. The dioecious fiber hemp variety Marina was used for the trials. Irrigation was carried out by a drip irrigation system and was scheduled based on the water budget method. It started when readily available water (RAW) in the soil layer of 0.4 m was completely depleted by the plants. In the first year of the study, irrigation did not influence the yield of hemp fiber, but in the second one, the best result was achieved for the irrigation variant I1. Interrow spacing did not have a statistically significant effect on both the hemp fiber yield and the quality. The topping of plants significantly decreased the yield of hemp, and it is not recommended when the hemp is cultivated for fibers. The quality of the hemp fibers was not influenced by irrigation, inter-row spacing, and topping. The rate of hemp evapotranspiration was in an interval of 312 mm (ETa) to 520 mm (ETm). The highest values of IWUE and ETWUE in both years and the bark yield in the first year were detected for the I3 irrigation variant, which suggested that the crop plant coefficient (Kc) of 0.6 could be recommended for the correction of Eo values in the calculation of the daily evapotranspiration of hemp (ETd) from June to August. The yield response factor (Ky) with values of 0.22 and 0.60 for the total growing season reveals that, in rainy years, hemp for fiber production could be grown without irrigation in the temperate climate of the Vojvodina region. However, such years are rare. Without doubt, irrigation of fiber hemp is recommended in the mentioned region in order to obtain high yields of good quality product.

Experimental Study on Mechanical Properties of Hemp Fibers Influenced by Various Parameters

“…However, Hackett [29] specified water stress as the greatest restricting factor influencing fiber yield and quality; for this reason, the authors carried out a short bibliographical research about the influence of the irrigation process specifically for growing hemp. Recently, Bajic et al [30] studied the effect of irrigation on the yield and quality of hemp. They verified that irrigation did not influence the yield of hemp fiber in the first year of harvest and had a small influence in the second year of harvest.…”

Water–yield Relations of Processing Potato Under Surface and Shallow Subsurface Drip Irrigation in Temperate Climatic Environment

“…Howell (2001), Pejić et al (2011a) indicated that care should be taken when comparing WUE values as many researchers have evaluated WUE in different ways (Viets, 1962;Bos, 1985;Stanhill, 1986;Payero et al, 2006;Molden, et al, 2010). It means that in climatic conditions where irrigation is supplementary WUE's calculation takes into account yields and plants evapotranspiration with and without irrigation (Bos, 1985;Erdem et al, 2006, Bajić et al, 2022, compared to arid regions where crop production cannot be realized in conditions of natural water supply. Thus in arid climate WUE's values are calculated as the ratio of yield and water added by irrigation or water used for plant seasonal evapotranspiration (Viets, 1962;Ati et al, 2012).…”