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Brenner, D.M. 2002. Non-shattering grain amaranth populations. p. 104106. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, Alexandria, VA.
Grain amaranths (Amaranthus spp., Amaranthaceae) are pseudocereals, with high-protein nutritious seeds. They are warm-season annuals that are primarily self pollinating. In the United States, they are grown for health food use; production is concentrated in Nebraska. In India, Mexico, Peru, and some other countries, amaranth grain is a traditional food (Brenner et al. 2000).
Shattering can cause serious losses in commercial grain production of amaranth (Fitterer et al. 1996). In Nebraska, amaranth grain is harvested after the plants are killed by frost and have dried. The predominant cultivar Plainsman is favored partly because it maintains good stem strength after frost has killed it (Baltensperger et al. 1992), however, it does shatter (Fitterer et al. 1996). In certain years, the mature plants must remain standing for weeks before the plants are killed and dry enough to harvest.
Each amaranth seed is held in a separate papery utricle. In standard grain production cultivars each utricle has a seam that opens at maturity allowing for circumscissile abscission along the utricles equator. Taxonomists including Sauer (1967) have observed that some populations of A. powellii S. Watson have non-circumscissile utricles. A. powellii is a wild and weedy species closely related to the grain amaranths. Non-circumscissile utricles have also been observed infrequently in cultivated amaranths (Hauptli et al. 1980 p. 119; Joshi 1981), and some populations are so indicated in the GRIN database (USDA, ARS 2001). Jain et al. (1986) used the notation, Dh and dh, in A. hypochondriacus, with dh representing a recessive non-circumscissile allele, and Dh representing the dominant circumscissile allele. They noted that the trait has potential for use in breeding programs. Brenner and Hauptli (1990) proposed breeding for non-shattering populations, described the abscission mechanisms, and suggested parental germplasm. The two germplasm releases described herein result from their proposal (Brenner and Hauptli 1990). Hauptli et al. (1980, p. 119) originated the idea of breeding for non-shattering in this way. Two distinct populations were developed because of the need to have cross-compatible germplasm for both grain species important in North America, A. cruentus L. and A. hypochondriacus L. Both of these non-shattering populations are adapted for seed maturity in the Midwestern United States.
For both populations, a weedy A. powellii accession from Germany (PI 572261) donated by the Institut fur Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, Germany, was used as the non-circumscissile parent. The utricles of PI 572261 abscise from the inflorescence below their tepals. Both populations DB 92226 and DB 9350 are derived from initial crosses made in 1991. DB 92226 is derived from PI 572261 × Plainsman, and bulked with the reciprocal. DB 9350 is derived from open pollinated PI 572261 cultivated in a diverse field planting at the NCRPIS. In 1992, F1 hybrid plants were distinguished from selfed progeny in a field planting by their growth form and morphology. Non-shattering plants were not observed in the F2 progeny but were recovered as single-plant selections in the F3 generation. Pollen sterility in the F1 generation, as has been observed in other F1 Amaranthus populations (Greizerstein and Poggio 1995), could have resulted in inadvertent high outcrossing in that generation and prevented the recovery of non-shattering plants in the F2 generation. Because of this outcrossing in a diverse Amaranthus germplasm field planting, the exact makeup of DB 9350 is uncertain.
DB 92226. Although of interspecific hybrid origin this population has affinity to A. hypochondriacus based on floral morphology. It crosses readily with PI 568125, A. hypochondriacus, a population closely related to Plainsman. Plants of DB 92226 branch from near the ground with three to five main branches up to 140 cm tall. Late in the season the branches frequently bend or break near the ground. The inflorescences are either red (56%), or green (44%). The seeds are white. In a cross with PI 568125, the non-shattering was inherited as a simple recessive trait, consistent with published observations of the Dh/dh trait in other A. hypochondriacus populations (Jain et al. 1986). The seed for distribution was produced with controlled pollination in a greenhouse.
DB 9350. Although also of interspecific hybrid origin, this population has affinity to A. cruentus as based on floral morphology and photoperiod insensitivity. It crosses readily with the A. cruentus population PI 566897. Plants of DB 9350 are single stemmed, non-branching, and about 180 cm tall. The inflorescence is pink with distinctive, very short pedicels, making the inflorescence arms unusually compact. It is very susceptible to seed damage by the tarnished plant bug Lygus lineolaris Palisot de Beauvois. The seed color, black or white, can be seen through the pale utricle walls. In seven crosses with PI 566897 the non-circumsissle character was inherited erratically with circumsissile to non-circumsissle ratios varying between 5.3:1 and 20:1 among the seven F2 populations. These data suggest that more than one genetic factor may be influencing this trait in A. cruentus. The seeds for distribution were produced with controlled pollination in a greenhouse, and are a mixture of 80% black, and 20% white seeds.
DB 98246 (Amaranthus cruentus) combines large growth (260 cm tall in Ames, Iowa) with strong stems that resist lodging. It is intended for forage or biomass production. In a 2000 small plot experiment this yielded 93% of the dry matter from PI 477913 (RRC 1011). The seeds are white and non-dormant. The plants are dark red. It has the non-shattering trait from DB 9350. It was selected for large size from a cross between DB 9350 and PI 566897. The seed for distribution was produced by open pollination in a field, however since it flowers later than other amaranths, it has some pollen isolation, and the seeds are observed to be true to type.
DB 92226, DB 9350, and DB 98246 are available from the Iowa State University Research Foundation, Inc., 310 Lab of Mechanics Bldg., Ames, Iowa 50011-2131 USA, or on the internet at: www.ag.iastate.edu/centers/cad/cadamaranth.html. Standard 200 seed samples are provided for research at nominal cost.
Three grain amaranth interspecific hybrid populations with non-shattering (seed retaining) utricles, Amaranthus hybrids DB 92226, DB 9350, and DB 98246 were developed at the North Central Regional Plant Introduction Station (NCRPIS), Agronomy Department, Iowa State University. These populations have little or no abscission at the equator of the utricle or beneath the utricle. The first two are intended to be crossed with standard cultivars and provide a source of shattering resistance in newly developed cultivars. DB 98246 is intended for biomass production. The populations were released by Iowa State University in 1999, and 2000.