The Use of Cyclic Balanced Incomplete Block Designsf for Directional Seed Orchards

Abstract

The adaptation of cyclic balanced incomplete block designs for use with directional seed orchards is described, and some examples are given of their use in practice. Where the number of treatments v is of the form 3t + 1 such orchards need only 3t replicates, together with one or two extra replicatesfor pollinator trees only: when v = 3t or 3t + 2, 3(v - 1) replicates are needed, with a few extra replicates for pollinators. Most of the balanced incomplete block designs used are given, explicitly, in the literature, but those for 9 and 15 treatments, for 12t + 4 treatments, t, e 0, and for 6t treatments, are new: the method of construction of the new designs is described. Seed orchard designs are given for all numbers of treatments up to 20, and for those of the form 3t + 1 up to 40.