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  • Author or Editor: W. W. Collins x
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Eight clones of sweet potato Ipomoea batatas L. were evaluated for resistance to the soil-borne pathogen Fusarium oxysporum (Schlecht) f. sp. batatas (Wr.) Snydor & Hanson and their reactions varied from extremely susceptible to extremely resistant. The 8 clones were used as parents in a modified diallel crossing design which generated 24 families each consisting of 10 full-sib clones. These 240 clones were evaluated for Fusarium wilt resistance in a randomized complete block design. They showed a gradation of resistance similar to the parents which is consistent with the theory of a quantitative mode of inheritance for this character. Diallel analysis of the 24 families revealed significant general and specific combining ability effects. Additive variance accounted for 87% of the total genetic variance while dominance variance accounted for only 13%. Broad-sense and narrow-sense heritabilities estimated for individuals and full-sib families from the diallel analysis were consistently greater than 70%. Narrow-sense heritability of individuals using the parent-offspring regression method was 50%. Results indicate that gains in Fusarium wilt resistance should be rapid and substantial in sweet potatoes.

Open Access
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Carbon dioxide enrichment of the greenhouse atmosphere, either in the period prior to tuberization or during the tuber development period of potato (Solanum tuberosum L.), increased tuber yield significantly at harvest, compared to yields from plants grown in a conventional atmosphere. Enrichment during the tuber development period provided the greatest increase in tuber dry weight. The data indicated that the increase in yield was attributable to an increase in the net assimilation rate of carbon dioxide enriched plants and a corresponding increase in the relative growth rate.

Open Access
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Abstract

‘Scarlet’ sweet potato [Ipomoea batatas (L.) Lam.], designated NCM-283 during testing, was released by the North Carolina Agricultural Research Service. ‘Scarlet’ is a dark-skinned sweet potato with orange flesh intended for growers and consumers desiring deep red to purple skin color. The major advantage of this cultivar over other red sweet potatoes is the greater intensity and stability of the dark skin color. The skin color is distinctly darker at harvest and more stable in storage than those of ‘Copper Skin Jewel’, the most widely grown red skin cultivar in North Carolina, and ‘Red Jewel’, a cultivar popular in other areas of the southeastern United States but not grown in North Carolina. Many characteristics of ‘Scarlet’ are similar to ‘Jewel’ (2); foliage growth habit, disease resistance, and insect resistance are all similar. However, ‘Scarlet’ has a distinct root shape and it scored significantly higher in baking trials.

Open Access
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Abstract

‘Pope’ is a new cultivar of sweet potato [Ipomoea batatas (L.) Lam] developed at North Carolina State University that is high-yielding and early-maturing with high resistance to Fusarium wilt, root-knot nematodes, and flooding damage in the field. ‘Pope’ is named for Daniel T. Pope, who was the sweet potato breeder at North Carolina State University until his retirement in 1975.

Open Access

Abstract

‘White Delite’ is a moist-type, white-fleshed sweet potato [Ipomoea batatas (L.) Lam] developed at North Carolina State Univ. in 1979 and tested as NC1135. There is a consistent but limited demand for white-fleshed sweet potatoes. These types are certainly not as widely grown in the United States as orange-fleshed types and usually are confined to sales at local farmers’ markets or for planting in home gardens. Cultivars presently available have little disease resistance and poor yield potential. This cultivar provides a high-yielding, excellent quality white-fleshed cultivar for local markets and/or garden types.

Open Access
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Abstract

Storage losses of apparently sound roots from flooded plots with vines mowed or completely removed were greater than intact vines for ‘Jewel’ but not ‘Centennial’ sweet potato [Ipomoea batatas (L.) Lam.]. Vine removal accentuated the detrimental effects of flooding, possibly by elimination of a possible route for ethanol removal from the roots. Ethanol concentration at harvest from flooded plots was greater in roots with vines removed than from roots with intact vines. Vine removal lowered yield of ‘Jewel’ and lowered percent dry matter of both ‘Jewel’ and ‘Centennial’.

Open Access

Abstract

‘Sweet Red’ is a moist-type sweet potato [Ipomoea batatas (L.)] developed at North Carolina State Univ. in 1976. It was evaluated as NC727 in regional yield trials by the National Sweet Potato Collaborator Group in 1981 (observational test), 1982, and 1983 (advanced tests). The release of ‘Sweet Red’ provides the industry with a high-yielding, high-quality, red-skinned sweet potato.

Open Access

Abstract

Storage roots of 10 sweet potato clones [Ipomoea batatas (L.) Lam.] were screened for resistance to Fusarium solani (Sacc.) Mart, emend. Snyd. and Hans. Clones were inoculated after 0, 6, and 36 days of postharvest storage and incubated in sterile moist chambers for 23 days. Resistance was evaluated by measuring volume of rotted tissue in each clone at the end of the incubation period. Clones tested (in increasing order of average rot volume over three screenings) were: NC 910, NC 925, NC 928, ‘NC Porto Rico 198’, ‘Centennial’, NC 825, NC 835, NC 818, W 125, and ‘Jewel’. Differences among clones for mean rot volume were highly significant within each storage period, and mean rot volumes generally increased in all clones as the length of the preinoculation storage period increased. The average rot volume of roots of resistant clones NC Porto Rico 198, NC 928, NC 910 and NC 925 was 19% that of ‘Jewel’ roots. Correlations between rot volume and postharvest quality factors in comparably stored healthy roots of the same genotypes were too low to be useful selection indices for F. solani resistance.

Open Access