The Effect of Seeding Rate on Industrial Hemp Fiber Yield and Mortality in Manitoba
Parkland Industrial Hemp Growers
To understand the effect of seeding rate on plant/seed mortality and final fibre yield of industrial hemp.
All sites had a moisture deficit relative to historical averages with Carberry, Melita and Roblin receiving 43%, 8% and 84% of 10yr average rainfall in May and the April prior was only at 63%, 80%, & 37% of normal, respectively. Moisture conditions at seeding for all sites was rated satisfactory. Both Melita and Carberry were similar with small rain events occurring around seeding but otherwise relatively fair to dry conditions with moderate temperatures. The Roblin site however, had a large rain event following seeding and cool temperatures. Given these differences however it would be expected that Roblin should have seen the largest levels of mortality and equal mortality across all plant populations which did not occur.
Mortality rates for industrial hemp can vary from 10-70% [1]. Nevertheless, the crop demonstrates the ability to adapt to different plant densities by altering its architecture (e.g. tall and thin vs. shorter and branched). Consequently, plant density has an impact on stem length and thickness. Higher seeding rates are used when targeting a hemp fibre crop. Varieties suited to fibre production typically have long, “pencil-thin” stems, sometimes exceeding two metres in height. Stem thickness affects the ratio of bast (long, outer fibres) and hurd (short, inner fibres), with thicker stems producing more hurd. This in turn affects the industrial application of the fibres.