4x-2x Potato Clones with Resistance or Susceptibility to Internal Heat Necrosis Differ in Tuber Mineral Status

Internal heat necrosis (IHN) is a physiological disorder resulting in necrotic tissue in the pith of potato (Solanum spp.) tubers. Susceptibility is associated with localized Ca deficiency within the tuber, but Ca availability may be influenced by other nutrients. Studies in Virginia, North Carolina, and New Jersey in 2001 and 2002 determined the influence of soil-applied Ca on tuber yield, specific gravity (SG), IHN, and nutrient concentration. Furrow-applied Ca sulfate (448 kg ha-1 Ca) was applied to IHN resistant or susceptible interspecific 4x-2x S. tuberosum L. (tbr) x S. phureja Juz. & Bukasov-S. stenotomum Juz. & Bukasov hybrids. Tuber yield, SG, incidence and severity of IHN, and pith concentrations of P, K, Mg, Ca, S, Na, Zn, Mn, Cu, and Fe were determined. Clones differed significantly for yield, SG, and IHN expression. Resistant clones were lower in IHN incidence than susceptible clones, but the clone x Ca interaction was not consistently significant within location-years. Incidence was fit with a classification and regression tree (CART) model with the 10 nutrients as regressors, which revealed that IHN-resistant clones had higher tuber concentrations of Mn and S, but lower P. These results suggest that resistance or susceptibility to IHN is a complex function of tuber tissue mineral status. Mn, S, and P may make a more important contribution to clonal IHN resistance than Ca. Additional work is needed to verify the potential for minimizing IHN by either nutrient management or genetic enhancement.