Stability of Internal Heat Necrosis and Specific Gravity in Tetraploid × Diploid Potatoes

Abstract

Internal heat necrosis (IHN) is a severe physiological disorder of potato (Solanum tuberosum L.) tubers, characterized by brown spots that first appear near the apical end of the tuber parenchyma, although most of the parenchyma tissue is involved in severe cases. The purposes of this study were to evaluate 4x‐2x clones of S. tuberosum × S. phureja Juz. & Bukasov–S. stenotomum Juz. & Bukasov (phu‐stn) for specific gravity (SG) and incidence and severity of IHN in the mid‐Atlantic states, and identify clones with low incidence and severity of IHN and high SG 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 North Carolina, Virginia, and New Jersey, in a randomized complete block design with two replications. At harvest, tubers > 64 mm in diameter were rated for IHN. The SG was also determined. The correlation between incidence and severity of IHN was very high; however, there was no correlation between IHN and SG. There were significant differences among the clones for SG and IHN. There were also significant clone × location interactions for SG and IHN. Several 4x‐2x clones were identified each year with significantly less IHN, and higher SG than Atlantic. The majority of these clones were stable both before and after removal of environmental heterogeneity. These results indicate that phu‐stn has the potential to expand the tetraploid potato breeding base for both high SG and resistance to IHN in the mid‐Atlantic states.