Nigeria's Cola Genetic Resources: The Need for Renewed Exploration

Understanding the genetic resource status of an economic crop such as Cola is a very relevant pre- requisite for its improvement and advancing its research attention. This will, no doubt, also improve the adoption of these grossly under-utilized species of West African origin. Sterility, self and cross incompatibilities, unpleasantly tall trees and low nut yield are among the problems faced by growers of this crop. As the crop takes up to seven years to produce its first fruit, while some trees may not bear fruit within the first fifteen years of field establishment or even throughout life, many farmers have adopted other crops as their source of livelihood. This poses a great threat to the livelihood of the rural populace whose main occupation revolves around kola trading. Hand-pollinated experiments showed a yield of 3,000-10,000 nuts per tree per year, as against 250 nuts per tree per year usually obtained in open-pollinated plants. In Nigeria, recent efforts in Cola breeding and improvement include plant introduction, progeny trials, hybrid trials, clonal trials, root stock-scion compatibility trials and variability studies resulting in further plant selections. The highest diversity of Cola spp. has been observed in Nigeria 's boundary with Cameroon. This review is intended to beam the searchlight on Cola breeding in Nigeria and the availability of genetic diversity that can be assembled and utilized for the improvement of this all-important tree crop.