Rooting and survival of Lobostemon fruticosus (L) H. Buek stem cuttings as affected by season, media and cutting position

The eight-day healing bush (Lobostemon fruticosus) belongs to the Boraginaceae family and is one of the oldest medicinal plants used in the Cape by Khoisan and early settlers. The natural populations of L. fruticosus are being destroyed by veld fires and overharvesting, leading to a need for propagation of plant material especially for commercial use. The objective of the study was to investigate the effect of season, plant growth regulator, growth media and cutting position on survival and rooting of L. fruticosus. A randomised complete block design was used with 2 block replications per season and 10 cuttings as an experimental unit. Treatments included four media, three plant growth regulator treatments and two cutting positions. Improved survival and better root quality was observed in cuttings planted in autumn (survival percentage 85.6% and root score 4.3) compared to spring (survival percentage 50.1% and root score 2.3). In autumn, cuttings planted in peat (91.25%) had the best survival percentage, however, only differed significantly from those planted in bark (77.5%), while in spring, cuttings planted in bark (68.33%) had significantly higher survival percentage compared to all other media {peat (52.92%); peatpol (51.67%) and sandpol (27.5%). Survival percentage was significantly higher in heel cutting planted in both bark (85.83%) and peat (78.33%) as compared to apical cuttings planted in the same growth media (bark 60% and peat 65.83%). While cuttings planted in peat consistently outperformed most other season-media treatment combinations in autumn an increase in rooting percentage, root length and root quality score was recorded in cuttings planted in bark during spring. Increased budding was recorded in cuttings planted in spring, except for cuttings planted in the sandpol media. Survival percentage, rooting percentage, root quality and budding leaves significantly increased in heel cuttings {survival percentage (61.46%); rooting percentage (41.88%); root score (3.25) and budding leaves (58.96%)} planted in spring as compared to apical cuttings {survival percentage (38.75%); rooting percentage (17.08%); root score (1.34) and budding leaves (38.54%)} of the same season. Rooting percentage (66.25%), root length (57.76 mm), root score (4.99) and budding leaf percentage were significantly higher in heel cuttings planted in bark as compared to apical cuttings. Application of PGR's produced a significantly better rooting percentage {Dip 'N Grow® (52.66%) and Seradix B® No. 2 (47.81%), significantly longer roots {Seradix B® No. 2 (36.23 mm) and Dip 'N Grow® (35.34 mm)} and a significantly better root quality score {Seradix B® No. 2 (3.64); Dip 'N Grow® (3.62)} compared to the control. Based on the current findings it is therefore recommended that, L. fruticosus stem cuttings can be propagated successfully using heel cutting type, Seradix B® No. 2 or Dip 'N Grow® as growth regulator application and, coco-peat as growth media if propagating during autumn or bark if propagating during spring.