Growth performance of Casuarina junghuhniana provenances in two sites in Kenya

Abstract

Two provenance trials of Casuarina junghuhniana were established in April 1999 in Uplands forest and Kiandongoro forest stations in Kenya on opposite sides of Aberdares Ranges as part of the ACIAR International Provenance Trial. The trials compared growth performance of 21 seed sources from the natural range of the species in Indonesia, and planted stands from Kenya and Tanzania. Fifteen provenances were common to the two sites while three additional different provenances were included at each site as the number of their seedlings was low. Assessments of the trials were carried out in April 2003 (for Uplands) and October 2005 (for Kiandongoro) for: height and diameter growth; axis persistence; stem straightness; density, thickness and angle of permanent branches; and length, thickness and stiffness of branchlets; results presented are for the growth parameters only. In 2015, health status of both trials was assessed including incidence and severity of pests and diseases. The growth characteristics differed significantly among the provenances and the land races. The average survival of the 18 provenances in Uplands was 53.4% while in Kiandongoro it was 78.3%. This is despite the fact that Kiandongoro trial was assessed at 6.5 years while the Uplands trial was assessed at 4 years. Provenance 18848 from Mt. Abang, Bali, Indonesia had the highest growth performance with 80%, 15 cm and 18.3 m (survival, diameter and height respectively). It was followed by 18844 from Mt. Tapak, Bali with 78.5 %, 13.0 cm and 12.8 m respectively. Other provenances worth considering for the Kenyan highlands include 18951 (Mt. Arjuno, East Java, Indonesia); 18846 (Mt. Pengalongan, Bali Indonesia) and 19239 (a land race from Muguga Kenya). The least adapted of the provenances was 18853 from Kwai Mission in Tanzania. However, the best performing provenances showed considerable within-provenance variation. There is therefore a need to establish stands of these suitable provenances and carry out selection of outstanding individual trees to optimize plantation productivity in future. The health status data revealed no major pests at either site but there was a significant difference in incidence of leaf blights between the two sites. The Kiandongoro site was severely affected by a leaf blight caused by a Fusarium species which seemed to negatively affect growth there.