Stability of high specific gravity genotypes of potatoes under high temperatures

An initial population of PHU-STN hybrid diploid potatoes was screened in 1978 at the Mountain Horticultural Crops Research Station, Fletcher, N.C. for high specific gravity and tuber production. Sixty clones were selected for testing under high temperatures at two North Carolina coastal locations. Twenty-seven clones maintained a relatively high specific gravity and acceptable tuber production under these high temperatures. The other 33 either were low in specific gravity or produced few, if any, tubers. Specific gravity was lower at the two coastal locations than at the Mountain Horticultural Crops Research Station. The 27 relatively stable, high specific gravity clones were retested in 1980 along with seven additional clones included for the first time. Severe high temperatures resulted in low survival rates and low specific gravity. However, eight clones maintained a relatively high specific gravity in relation to the rest of the population.