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Color analysis of storage roots from the USDA, ARS sweetpotato (Ipomoea batatas) germplasm collection

Michael Jackson, D., Harrison, HowardF., Jarret, RobertL., Wadl, PhilipA.
Genetic resources and crop evolution 2018 v.65 no.4 pp. 1217-1236
Agricultural Research Service, Ipomoea batatas, color, colorimetry, field experimentation, genetic variation, germplasm conservation, greenhouses, introduced plants, periderm, plant genetic resources, plantlets, roots, stele, sweet potatoes, tissue culture, Georgia, South Carolina
The United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Plant Genetic Resources Conservation Unit in Griffin, GA maintains the United States germplasm collection for Ipomoea spp. (Convolvulaceae). During 2012–2014, 737 sweetpotato, Ipomoea batatas (L.) Lam., plant introductions (PI) were acquired as tissue-culture plantlets and then acclimated to greenhouse conditions at the USDA, ARS, U. S. Vegetable Laboratory (USVL), Charleston, SC. Single plants were transferred to plastic-covered plant beds to produce cuttings for replicated field trials. Storage roots were harvested from 690 PIs grown in the field and 695 PIs grown in pots. Color coordinates were obtained for each PI using a tristimulus colorimeter. Hue angle values (h*) ranged from 8.2° to 88.3° ([Formula: see text] = 54.9°) for the periderm (peel or skin) of field-grown storage roots (n = 690 PIs) and − 9.4° (= 350.6°) to 96.2° ([Formula: see text] = 51.3°) for pot-grown roots (n = 695 PIs). The red–green coordinate (a*) ranged from 0.8 to 30.7 ([Formula: see text] = 12.8) for the periderm of field-grown roots and − 2.0 to 44.9 ([Formula: see text] = 16.1) for pot-grown roots. The yellow–blue coordinate (b*) ranged from 2.8 to 33.1 ([Formula: see text] = 19.4) for the periderm of field-grown roots and − 7.4 to 38.1 ([Formula: see text] = 19.3) for pot-grown roots. Color saturation (chroma, C*) ranged from 13.7 to 35.8 ([Formula: see text] = 24.9) for the periderm of field-grown roots and 14.9–45.5 ([Formula: see text] = 29.3) for pot-grown roots. Lightness (white–black, L*) ranged from 32.6 to 81.7 ([Formula: see text] = 54.6) for the periderm of field-grown roots and 32.1–88.2 ([Formula: see text] = 64.0) for pot-grown roots. Hue angles ranged from − 13.1° (= 346.9°) to 100.9° ([Formula: see text] = 80.9°) for the stele (flesh) of field-grown storage roots (n = 672 PIs) and − 29.9° to 103.5° ([Formula: see text] = 81.6°) for pot-grown roots (n = 676 PIs); a* ranged from − 5.6 to 35.0 ([Formula: see text] = 8.0) for the stele of field-grown roots and − 6.0 to 41.0 ([Formula: see text] = 7.6) for pot-grown roots; and b* ranged from − 7.7 to 56.1 ([Formula: see text] = 34.6) for the stele of field-grown roots and − 12.6 to 56.1 ([Formula: see text] = 31.8) for pot-grown roots. C* ranged from 12.7 to 65.8 ([Formula: see text] = 37.2) for the stele of field-grown roots and 8.9–65.7 ([Formula: see text] = 34.5) for pot-grown roots; and L* ranged from 27.8 to 91.1 ([Formula: see text] = 77.7) for the stele of field-grown roots and 28.2–91.9 ([Formula: see text] = 80.4) for pot-grown roots. There were significant relationships between stele color (h*) and percent dry matter, with orange stele having a significantly lower % dry matter ([Formula: see text] = 25.6%, n = 183) compared with roots with cream/white stele ([Formula: see text] = 30.8%, n = 373). There appears to be wide genetic diversity for root color characteristics for the United States sweetpotato germplasm collection.
  Data from: Color Analysis of Storage Roots from the USDA, ARS Sweetpotato Germplasm Collection