The effects of ontogenetic maturation in <i>Pinus patula</i> – Part II: hedge cycling and field performance

Abstract

Early studies suggest that the juvenile period, during which favourable rooting can be achieved from Pinus patula seedling hedges, may be as short as 2 years from the date of sowing. If the effects of hedge maturation cannot be delayed, productivity from seedling hedges will be severely limited. The most common technique to postpone hedge maturation in some coniferous species is by rejuvenating the donor plant (ramet) through serial propagation or hedge cycling. This involves taking a cutting from the parent hedge and, once rooted, establishing a new donor hedge from the rooted cutting. Cuttings harvested from such cycled hedges have been reported to grow better than those from non-cycled hedges that have passed the point of ontogenetic maturation. This paper summarises the effects of cycling P. patula hedge plants in the nursery on subsequent field performance. Seedling comparisons were included in the field trial. The effects of cycling were measured for the first three years after planting. The field results indicate that cycling hedges within the first 24 months since sowing negatively affected early field growth in one treatment. Cuttings from the non-cycled three-yearold seedling hedge treatment performed similarly to the seedling controls in the field trial, which supports other studies. Based on these results, it is currently recommended that P. patula cuttings be produced from seedling hedges for a period of 36 months from sowing, without the inclusion of a hedge-cycling regime.

Keywords: cuttings, growth, ontogenetic maturation, survival, Pinus patula, stem form (tropism)

Southern African Forestry Journal Vol. 207 2006: 3-6