Cross-Compatibility of Cultivated Amaranthus Grain Lines with Wild Amaranthus Species.
David Brenner and Micheal Owen. Iowa State University, Plant Introduction Stn., Iowa State Univ.-g212 Agron., Ames, IA 50011-1170
The cultivated grain amaranth species (Amaranthus caudatus, A. cruentus, and A. hypochondriacus) have pollination cross-compatibility with wild Amaranthus species. The resulting hybrid progeny create difficulty in the maintenance of genetically clean seed stocks for commercial agricultural use. There is potential for plant breeders to select for cultivars that minimize cross-compatibility with wild Amaranthus species, resulting in cultivars that are easier to maintain genetically. Progress on improving the genetic purity of commercial amaranth varieties will depend on the development of practical out-crossing assessments for breeding lines with wild Amaranthus species. We propose systematic evaluation of Amaranthus grain lines for cross-compatibility with common Amaranthus weed species. In 2005 we produced seed lots contaminated by pollen primarily from weedy Amaranthus tuberculatus plants under defined field conditions. Populations grown from these seed lots were visually inspected for weedy-hybrid off-type plants. Weedy-hybrid progeny were 20% of PI 538321 (n= 40), 9% of PI 558499 (n= 153), and 2.8% of PI 604461 (n= 209). Surprisingly PI 538327 (n= 246) progeny were not contaminated. These preliminary data support the hypothesis that useful differences in out-crossing rates exist, and that development of commercial cultivars with minimal out-crossing potential is feasible.