Polyploidy has been induced, but results in only minor morphological changes.
Horticultural Varieties. Numerous landraces have been found in the Andes, generally distinguished by panicle form and the color of stem, leaves, fruit, and seed. True varieties have been selected in Peru. These include, in particular, “Noel Vietmeyer” and “Alan Garcia.” The first is tall; “rustic”; resistant to mycoplasms, sclerotinia, and alternaria; and yields 3–3.5 tons per hectare. Its seed is translucent and makes good flour and flakes. The second is short and susceptible to diseases, but yields 3–5 tons per hectare under good conditions.
Over 1,200 accessions are being maintained in the Andean region, with many duplicates in other areas.
Daylength. Most kiwicha varieties are short-day. Cultivars exist, however, that flower at daylengths ranging from 12 to 16 hours.
Rainfall. Grain amaranths have set seed in areas receiving as little as 200 mm. Some estimates place their moisture requirements at about equivalent to those of sorghum, or about half those of corn. Although kiwicha will tolerate dry periods after the plant has become established, reasonable moisture levels are critical for proper germination. Also, some moisture is needed during pollination.
Altitude. Kiwicha appears to be the only grain-amaranth species to thrive above 2,500 m. In the Andes, most is grown between 1,500 and 3,600 m. Commercial varieties are being successfully cultivated at sea level near Lima, Peru.
Low Temperature. Although more cold tolerant than most grains, it cannot tolerate frost. Some “cold-tolerant red lines” have been found that can stand temperatures of 4°C.13
High Temperature. 35–40°C. The plant grows best at 21–28°C.
Soil Type. Kiwicha grows well on soils containing widely varying levels of nutrients, although it does best in loose, sandy soils with high humus content. Genotypes that tolerate alkaline soils with pH as high as 8.5 have been discovered. In addition, some with an apparent ability to withstand mild salinity have been identified.14 Other Amaranthus species are renowned for their tolerance to acid soils and aluminum toxicity; kiwicha probably is similar.