Outcrossing in early-stage spring wheat breeder seed development
Outcrossing (OC) during the initial stages of spring wheat (Triticum aestivum L.) breeder seed development ('head-rowing') may lead to off-types appearing in later generations of pedigreed seed. The objective of this research project was to measure OC in a simulated short (1.3 m) breeder row nursery of spring wheat. Rows of four cultivars known to differ in OC potential were grown at up to 12 distances (30–360 cm) from a blue aleurone pollen source in two directions in each of 2 yr. Pollen flow barriers consisted of varying numbers of border rows of wheat or the use of four rows of spring triticale (Triticosecale). The blue aleurone trait was used to estimate OC frequency. Triticale was equivalent to wheat as a pollen trap. Based on the results from this study, it would appear prudent to use a pollen barrier of at least 3.6 m between wheat germplasm of a low to moderate OC potential. Wider pollen barriers (>10 m) probably will be required for germplasm prone to OC.