Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 25, 2002
Publication Date: N/A
Internal heat necrosis is characterized by brown spots that occur in the potato tuber flesh. The presence of a charateristic called "high specific gravity" in tubers is hypothesized to relate to resistance to internal heat necrosis. It is a severe physiological disorder in potato tubers grown in warmer climates. The number one chipping cultivar in the United States, 'Atlantic', is particularly susceptible to this disorder. In this study, crosses were made between commercial potatoes and their closely related diploid relatives to transfer high specific gravity to the commercial level. These progeny were then evaluated for high specific gravity and susceptibility to internal heat necrosis in three mid-Atlantic states where internal heat necrosis is a recurring problem yearly. Many of the progeny had specific gravity as high as or even higher than the specific gravity of 'Atlantic' and were found resistant to internal heat necrosis. This genetic material will be extremely valuable to potato breeders, farmers and extension specialists in breeding new chipping cultivars to withstand high temperature stress.
Internal heat necrosis (IHN) is a severe physiological disorder of tubers, characterized by brown spots that first appear towards the apical end of the tuber parenchyma, although most of the parenchyma tissue is involved in severe cases. 'Atlantic' is the predominant potato (Solanum tuberosum L.) chipping cultivar grown in the mid-Atlantic United States despite its susceptibility to IHN. A lack of tetraploid germplasm genetically unrelated to 'Atlantic' with high specific gravity has hindered the breeding effort in developing new chipping cultivars for this area. The purposes of this study were to evaluate 4x-2x clones of S. tuberosum x S. phureja-S. stenotomum for specific gravity and incidence and severity of IHN in the mid-Atlantic states, and identify clones with a low incidence and severity of IHN and high specific gravity for future enhancement efforts in S. tuberosum. In 1999 and 2000, 26 and 88 4x-2x clones, respectively, and the check cultivar 'Atlantic' were grown in Plymouth, NC; Painter, VA; and Bridgeton, NJ in a randomized complete block design with two replications of 20 hills per plot. The crop was harvested two to three weeks later than normal harvest time to provide maximal development of IHN symptoms. All tubers were harvested and those >64 mm in diameter were quartered longitudinally and rated for IHN (1= severe IHN; 9= no IHN). Specific gravity was also recorded. The correlation between incidence and severity of IHN was very high for each location-year combination, but there was no correlation between IHN and specific gravity. There were significant differences among the clones for specific gravity, and incidence and severity of IHN. There were also significant clone x location interactions for specific gravity, and incidence and severity of IHN. Several 4x-2x clones were identified each year with a significantly lower incidence and severity of IHN, and higher specific gravity than 'Atlantic'. The majority of these clones were stable both before and after removal of environmental heterogeneity. These results indicate that S. phureja-S. stenotomum has the potential to expand the tetraploid potato breeding base for both resistance to IHN and high specific gravity in the mid-Atlantic states.