A review of the propagation of Pinus radiata by cuttings, with emphasis on juvenility

Abstract

Ritchie surveyed the production of forest trees from cuttings and reported that the annual world production at that time was more than 65 million rooted cuttings. He also noted that half of this production was in Japan where Cryptomeria japonica had been grown by this method for more than five centuries. Another 10 million or more cuttings of radiata pine (Pinus radiata) were reported to be grown in Australia and New Zealand at that time. Canada, Scandinavia, and the U.K. together were annually producing about 21 million cuttings of various spruce species. New Zealand sales of P. radiata cuttings in 1992 were 6.1 million and this rose to a peak of 24 million in 1996 and have steadied to 19.8 million sold in 1998. The propagation of P. radiata in New Zealand was for many years based solely on raising open-ground seedlings. Seed was initially collected from existing forest trees to provide bulk seed. Then in the early 1950s breeding programmes were commenced based on the selection of superior types, which were then collected together in separate open-pollinated seed orchards. Grafts were taken from trees that showed high quality due to such desirable characteristics as high growth rate, good tree form, few stem cones, etc. Control pollinated (CP) seed orchards were introduced in 1986. In this system bags are placed over the female cones and only specific previously collected pollen is used on individual trees. Good pollination is ensured by several applications of pollen resulting in seed which can have a large proportion ofpotential high-grade individuals. Although plants had been successfully raised from cuttings in New Zealand by the early 1930s , it was not an economic proposition until the cost of CP seed rose to high levels in the late 1980s. It was found that cutting production became economically viable when seed costs were greater than or equal to $1800 per kg.