Geographical and Ecological Distribution of Some Macadamia Genotypes in Kenya and Prospects for Increased Production

Abstract

Macadamia (Family Proteaceae) is the most important nut crop in Kenya, grown as a source ofhousehold income and foreign exchange. Kenya is the fourth largest producer of Macadamia nutscontributing about 10% of world’s total production. However, its production, expansion andcommercialization are hampered by various constraints, especially suitable varieties for the variousagro-ecological zones in Kenya. Selection and development of new varieties currently rely on existinggermplasms and introductions from other growing countries. Considering that genetic diversity is crucial to breeding efforts, studies were done to locate valuable germplasms using geographical positioning system (GPS) and evaluate ecological adaptation. A total of 39 accessions, including breeding linescurrently being tested under Kenya’s Macadamia breeding programme, some cultivars introduced from Australia and Hawaii and some new selections were evaluated. A total of 39 GPS points were recordedand data analyzed using ArcView GIS version 3.3. Results indicated that all accessions were locatedbetween 0 and 3 degrees south of the equator and between 36 and 37 degrees East of the Greenwich3Meridian. Only one accession was adapted to over 2000 meters above sea level while all the others wereadapted to between 1300 to 1920 meters above sea level. Mapping of the accessions on agro-ecologicalzones located them in six different agro-ecologies and four major soil types. Accessions hybridorigin showed adaptability to higher altitude with high rainfall distribution. Oresults suggest wideadaptability of Macadamia germplasm in Kenya and provide a basis for future expansion of Macadamia orchards.