Abstract
Using data from several clone trials in Malaysia, and one in Cameroun, the reliability of clone trial results is reviewed, both in terms of variation in yield from year to year, and of differences between locations. It is concluded that at least five years' yield records may be needed to give a good indication of a clone's potential, but that if several trials are considered together, a shorter period might suffice. Evidence is presented indicating that cloe x location interactions may be important; thus each clone may have to be tested at a range of site. A simple financial analysis is used to estimate the extra yield necessary to make planting of clones profitable. It is suggested that a clone can be considered suitable for commerical planting, provided that ehre is at least an 80 percent probability that the required yield increse will be achieved. To estime the yield increase actually obtained, clones must compared with a standard. Because every seedling progeny is different, a simple comparison of clones with mixed seedling may not be very reliable. This problem will be minimised if results of several trials are combined, but standard clones may eventually be preferred to seedling controls. The performance of some individual clones is disucssed, but the conclusions drawn must be tentative, as they are based on relatively short periods of recording.Incluye 4 referencias bibliográficas.Using data from several clone trials in Malaysia, and one in Cameroun, the reliability of clone trial results is reviewed, both in terms of variation in yield from year to year, and of differences between locations. It is concluded that at least five years' yield records may be needed to give a good indication of a clone's potential, but that if several trials are considered together, a shorter period might suffice. Evidence is presented indicating that cloe x location interactions may be important; thus each clone may have to be tested at a range of site. A simple financial analysis is used to estimate the extra yield necessary to make planting of clones profitable. It is suggested that a clone can be considered suitable for commerical planting, provided that ehre is at least an 80 percent probability that the required yield increse will be achieved. To estime the yield increase actually obtained, clones must compared with a standard. Because every seedling progeny is different, a simple comparison of clones with mixed seedling may not be very reliable. This problem will be minimised if results of several trials are combined, but standard clones may eventually be preferred to seedling controls. The performance of some individual clones is disucssed, but the conclusions drawn must be tentative, as they are based on relatively short periods of recording.