David M. Brenner

Field evaluation of an Amaranthus genetic resource collection in China

A total of 229 genotypes of 20 Amaranthus species from the United States Department of Agriculture – Agricultural Research Service (USDA – ARS) National Plant Germplasm Amaranth Collection was evaluated in field experiments in Beijing and Wuhan, China, in 1994. Agronomic traits, including plant height, maturity, leaf number and color, stem color, seed color, branch number, 1000-grain-weight, yield per plant, and resistance to stresses (including diseases) were measured. The results indicated: 1. Many of the species were sensitive to daylength; 2. Cultivated genotypes generally had higher grain yield but were more seriously affected by diseases than non-cultivated species; 3. There was wide diversity in agronomic traits among Amaranthus species and among genotypes within the same species, and several genotypes were identified that appeared to carry favorable agronomic traits of immediate use in cultivar improvement; 4. For introduction of genotypes for use in plant breeding in China, selection should be partially based on matching the climates of the location of origin and the target area for production.

Crop–weed hybrids are more frequent for the grain amaranth ‘Plainsman’ than for ‘D136-1’

White-seeded cultivated amaranth [Amaranthus caudatus L., A. cruentus L., and A. hypochondriacus L.] grain is less valuable if contaminated with brown off-type seeds from the hybrid weedy progeny of spontaneous crop–weed crossing. Crop–weed crossing frequency was estimated by using two grain amaranth cultivars. Both cultivars were planted at the same nine locations in the Midwest United States and exposed to pollen from local weedy Amaranthus species. Harvested seeds were grown in a greenhouse, and the frequency of crop–weed hybrids was determined by observing dominant weed traits in the progeny. The cultivar ‘Plainsman’ was approximately tenfold more likely to hybridize with weedy amaranths than was ‘D136-1’. These are the first amaranth cultivars to be evaluated in this way. The reduced hybridization potential of ‘D136-1’ or similar material can be exploited to reduce the occurrence of off-type seed contamination in grain amaranths.