STAGE 4 - INITIAL TEST ORCHARD EVALUATION...
Initial Test Orchard Evaluation: The two trees in the foreground are shown in the winter between their fourth and fifth leaf. These genotypes will probably be eliminated from the program due to excessive vigor and low yield efficiency (cumulative yield / trunk cross sectional area). Note trees in the background with a higher proportion of fruiting wood and a more manageable size.
Elite Stoolbed Establishment: Liners of a rootstock genotype that performed well in an initial orchard trial have been recently planted in a trench at an angle, and then pinned to the ground with twine. Vertical shoots will arise from these mother plants and will be mounded with a rooting medium to produce a crop of rooted liners for intermediate stage trials.
Root cuttings are collected from disposable orchard trees with promising rootstocks in late winter, and then placed in sterilized flats with potting soil in the greenhouse to induce adventitious shoot growth (click photo for closer look). There is wide phenotypic variation in the ability of genotypes to regenerate shoots in this manner. Those that are successfully regenerated are transferred to the stoolbed field the following year for further propagation.