Heritability of Specific Gravity of Diploid Potato under High Temperature Growing Conditions

High temperatures encountered during the growing season reduce tuber dry matter content in commercial tetraploid potato (Solanum tuberosum L.). Variability in dry matter content as measured by specific gravity was observed in a diploid hybrid population of S. tuberosum Group Phureja and S. tuberosum Group Phureja and S. tuberosum Group Stenotomum grown under high temperatures. The objective of this research was to estimate heritability of specific gravity in this diploid hybrid population under high temperature growing conditions in North Carolina. Heritability was estimated by midparent offspring regression. Parents were grown at three high-temperature locations and offspring at eight. Analyses of variance on specific gravity for each of the eight offspring locations revealed heterogeneity of error variances, therefore data were not combined over years and locations for further analyses. Twenty-four estimates of heritability were obtained, 16 of which were unbiased (parents and offspring were grown in different years and different locations). The average unbiased estimate of heritability was 0.28 (range −0.07 to 0.77). Four estimates were biased because parents and offspring were grown at similar locations in different years. The average of these estimates was 0.57 (range 0.51-0.63). Two estimates were biased because parents and offspring were grown in the same year in different locations, the average of which was 0.38 (range 0.29–0.46). Two estimates were biased because parents and offspring were grown in the same year at similar locations. These averaged 0.41 (range 0.40-0.42). Considered together, the moderate estimates of heritability suggest that it should be possible to continue to improve this population for specific gravity under high-temperature growing conditions. There was an apparent upward bias in the heritability estimates when the parents and offspring were not grown in different years and different locations. Contribution from the Dep. of Horticultural Science, North Carolina State Univ. Paper no. 11239 of the Journal Series of the North Carolina Agric. Res. Service, Raleigh, NC 27695-7601. Research was partially funded by the Int. Potato Ctr., Lima, Peru.