Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: Lauren E. Kurtz x
  • HortTechnology x
Clear All Modify Search

Hyperhydricity of shoots initiated in vitro, poor shoot extension, inability of shoot cultures to maintain good growth over an extended time, and unsuccessful ex vitro rooting have limited the development of a commercial scale micropropagation system for hemp (Cannabis sativa). We present a culture initiation method that prevents shoot hyperhydricity using vented-lid vessels with 0.2-µm pores and medium containing agar at 1% (w/v). To optimize shoot multiplication in vitro, a control medium (medium A) and four treatment media (medium B, C, D, and E), with varying inorganic nutrients and vitamins were tested. Control medium A consisted of 1× Murashige and Skoog (MS) with vitamins plus 3% (w/v) sucrose, 0.5 mg·L−1 metatopolin, 0.1 mg·L−1 gibberellic acid, and 0.8% agar (w/v) at pH 5.7. The four treatment media differed from the control medium as follows: medium B, 2.5× MS with vitamins; medium C, 1× MS with vitamins plus added mesos [calcium chloride (anhydrous), magnesium sulfate (anhydrous), and potassium phosphate (monobasic) nutrients]; medium D, 1× MS with vitamins plus added vitamins; and medium E, 1× MS with vitamins plus added mesos and vitamins. Medium C and medium E produced more microcuttings than the control at 6 weeks after the initial subculture with shoot multiplication media and all other treatments at 9 and 12 weeks. Shoots grown on these two media displayed optimal extension and leaf lamina development; however, they exhibited slight chlorosis by 12 weeks after subculture with shoot multiplication media. In a separate experiment, medium E was supplemented with ammonium nitrate at 0, 500, 1000, or 1500 mg·L−1, and cultures grown with 500 mg·L−1 produced the most microcuttings and exhibited the best combination of shoot extension and leaf lamina development. We provide a method of prerooting microshoots in vitro that has resulted in 75% to 100% rooting ex vitro in rockwool. Using 10 recently micropropagated plants, ≈300 retip cuttings (cuttings taken from new shoots from recently micropropagated plants) were harvested over 10 weeks. The average weekly rooting was more than 90%. Retipping can produce nine-times as many plants in a similar amount of floor space as stem cuttings derived from traditional stock mother plants. The micropropagation/retipping method proposed can be a more efficient way to generate clonal liner plants for commercial-scale production.

Open Access

Micropropagation of hemp (Cannabis sativa) is constrained by problems with hyperhydricity and culture decline of microshoots. These problems can be reduced by increasing agar and nutrients in the media during micropropagation stages 1 and 2, respectfully. Performance of microshoots of ‘Abacus’ and ‘Wife’ hemp cultured in Driver and Kuniyuki Walnut medium (DKW) for 15 weeks (6 weeks of stage 1 + 9 weeks of stage 2), with subculturing every 3 weeks during both stages 1 and 2, or in Murashige and Skoog with vitamins medium (MS) for 6 weeks (stage 1) followed by Lubell-Brand Cannabis medium (LBC) for 9 weeks (stage 2), with subculturing every 3 weeks during both stages 1 and 2, was evaluated. In a separate study, microshoot performance of ‘Abacus’ and ‘Wife’ in MS for 3 weeks (stage 1) followed by LBC for 6 weeks (stage 2), with subculturing every 3 weeks, using boxes (Magenta GA-7) with lids featuring a vent with a diameter of 10 mm and a pore size of 0.2 µM or using microboxes (Sac O2 O95/114 + OD95) with lids featuring a filter (Sac O2 #10) were evaluated. Shoot multiplication rate (SMR) and explant height were greater for ‘Abacus’ in LBC than DKW. For ‘Wife’, SMR at 9 weeks was greater in LBC, as LBC provided more nutrients and water than cultures had received in MS initially during stage 1. Culture medium did not influence ex vitro rooting success, which was 75% for ‘Abacus’ and ≥ 90% for ‘Wife’. Microboxes resulted in greater hyperhydricity of shoots and a lower ex vitro rooting percentage than boxes. For cultivars that are highly prone to developing hyperhydricity, like ‘Abacus’, the microboxes were not adequate to control this condition.

Open Access