THE USE OF BREEDING TRIALS TO ESTIMATE DISEASE-INDUCED YIELD LOSSES AND TO REFINE SELECTION STRATEGIES

Plant breeders conduct a range of yield trials each year to estimate the yielding potential of clones progressing through the breeding program. Only the highest yielding clones are selected for further testing with very small numbers being released as commercial canes. The tested clones vary enormously in disease susceptibility and various diseases impinge on the yield of these clones as they pass through the breeding program. Another routine part of the breeding program is the testing of clones for disease resistance. Data are routinely available on Pachymetra root rot resistance in northern clones. In this study, resistance to other diseases (yellow spot and orange rust) was also assessed in stage 3 breeding trials in the northern program. Analyses were conducted relating yielding ability of clones in stage 3 (FAT) trials to disease resistance. The results suggested that yellow spot, Pachymetra root rot and orange rust were each influencing the yield of clones in northern breeding trials. Yield loss estimates were calculated as well as the relationship between resistance and yield. This will provide valuable data for refining selection strategies so that the efficiency of the breeding program can be increased. These analyses may be undertaken each year with a minimum of further expenditure, providing ongoing estimates of disease-induced yield losses and further information to guide the selection program.