Performance of true potato seed families. 1. Effect of level of inbreeding

Summary Successive generations of open pollinated (OP) true potato seed (TPS) families represent a low-cost planting material. This study was conducted to determine whether inbreeding occurred during two successive OP generations and, if so, whether it adversely affected the performance of transplant families from true seed. Potato seedling transplants from 4x×2x hybrid, OP₁, OP₂, S₁ and S₂ families were compared for plant vigour, flowering, pollen stainability, OP fruit set, tuber yield and specific gravity. Hybrids were consistently superior, while S₂ families were inferior. The performance of OP₁, OP₂ and S₁ families did not differ significantly for most traits. The accumulation of inbreeding in successive OP generations was limited by reduced OP seed production on selfed plants; thus, a synthetic TPS variety propagated by open pollination may be feasible. Paper no. 3162 from the Department of Genetics, University of Madison.