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SYNOPSISPropagation of African sandalwood (Osyris lanceolata) by air layering (marcotting) was investigated at Sao Hill, Tanzania, aiming at providing an alternative propagation technique to the use of seeds or cuttings that germinate or root poorly. Air layers were initiated on the young shoots (1 -2 years old) of mature O. lanceolata trees growing at Sao Hill catchment Forest. After root initiation, which took 8 weeks, they were detached from the parents, potted in polyethylene tubes and reared at the nursery for a further three months. The factors assessed in this experiment were the effect of time at which air layers were initiated (i.e. February, June, September and December); and the influence of IBA as rooting promoter at three concentrations (50, 100 and 150 ppm). From the data collected it was observed that rooting success of up to 80% can be achieved from air layers, making this propagation technique a viable alternative to seedlings or cutting propagation. Rooting success was influenced by both the season and application of rooting hormone with optimal rooting being achieved during June and September with the addition of IBA at a rate of 50 ppm. The significance increase in rootability of air layers during June and September may be linked to the advantage of the dry season in Tanzania where reduction of plant development activities such as budding, leafing and flowering in the dormant dry season might have reduced resource competition and thus promoting the observed rooting.

SYNOPSISIdentification of the host plants of the hemi-parasitic African sandalwood (Osyris lanceolata) and the influence of some on its early growth performance was investigated at Image, Nundu, Sao Hill and Iringa in the southern highlands of Tanzania. The aim was to identify host plants that support the growth of O. lanceolata, and to evaluate the potential of some in promoting its early growth under artificial establishment. The results revealed that O. lanceolata parasitises a wide range of hosts although some were preferred. The preferred hosts were Rhus natalensis, Dodonaea viscosa, Tecomaria capensis, Catha edulis, Apodytes dimidiata, Brachystegia spiciformis, Maytenus acuminatus and Aphloia theiformis. Of the preferred hosts, Brachytegia spiciformis, Rhus natalensis and Casuarina equisetifolia promoted most effectively the early growth of O. lanceolata in terms of height, diameter and overall root and shoot biomass. Possibly the light crown of these host species and the nitrogen fixing ability of C. equisetifolia played a significant role in conferring this advantage. The species are thus recommended as appropriate host plants when raising O. lanceolata seedlings for planting. However, a decision on whether these hosts will support the growth of O. lanceolata at a later stage is subject to further experimentation as they may only be serving as initial or intermediate hosts as reported in a related species Santalum album.

SYNOPSISAfrican sandalwood (Osyris lanceolata) populations occurring in Tanzania were assessed to determine the current resource status and ascertain variation in quality existing among them. This will provide a guide inthe selection ofpopulations where conservation efforts and im provement programmes can be concentrated. The resource status was assessed through estimation ofthe species' density per unit area and measurements oftree dimensions. Quality variation was assessed by determining the amount of oil extracted from a given amount ofwood and the proportion composition ofsantalol, a prime determinant ofsandalwood oil quality. The study revealed that populations supporting O. lanceolata in Tanzania occur mostly in arid to semiarid areas with the majority being on stony and rocky soils. However, big sized trees are supported in humid climates, being favoured by relatively low soil pH and reasonable amounts of soil nitrogen. Tree density ranged from 38 individuals to 76 per hectare. The mean tree height was 3,8 m (2,1 to 6,5 m) while the mean diameter was 5,7 em (3,6 em to 8,6 em). The best quality and quantity of oil came from populations of relatively arid climates compared to those of humid climates. Populations differed significantly in both yield and quality. The highest yield obtained was 8,45 ± 0,54% from Gubali population while the highest santalol content (32,2 ± 1,2%) was from Bereko populations. Within trees, quantity and quality of oil was higher in wood portions close to the ground in both the root and shoot system. The amount decreased toward the root and shoot tip. The root and the shoot system were similar in quality and quantity of oil. The observed harvesting selectivity is thus primarily influenced by quality differences among populations while the large dimension and density differences among populations seem to be secondary. Inclusion of the root systems during harvesting is also a matter of maximizing the raw material to be collected rather than differences between the two portions. The exact factors controlling wood quality in the species have however remained uncertain. Probably, genetic factors alone or in combination with the environmental factors playa significant role.