Crude Protein Content in Diploid Hybrid Potato Clones of Solanum phureja-S. stenotomum

Breeding potato (Solanum tuberosum L.) with high protein content is important for food value and for the processing sector to extract protein from potatoes. Due to the narrow genetic base of the common potato, a new germplasm has to be explored for breeding high-protein potatoes. The objectives of this research were to quantify the crude protein content of diploid hybrid Solanum phureja-Solanum stenotomum (PHU-STN) genotypes, determine the correlation of crude protein content with dry matter and other important agronomic traits, and estimate broad sense heritability for crude protein content. In 2008 and 2009, 70 diploid clones were grown in replicated field plots in Jiagedaqi, Heilongjiang. Also, two tetraploid potato cultivars, Kexin 2 (table potato) and Atlantic (high dry matter), were included in this experiment as controls. The crude protein content on a fresh weight basis (FW) over replications and years for PHU-STN clones ranged from 2.85% to 5.01% with a grand mean of 3.72%, and most of these clones were significantly or highly significantly higher in crude protein content than the two tetraploid controls. Correlations between crude protein content and agronomic traits were all negative, but the magnitudes were generally weak or moderate. Therefore it should be possible to select diploid clones with high crude protein content and acceptable agronomic traits. The estimate of broad sense heritability for crude protein content (FW) on a clonal mean basis was 0.66 with a 95% confidence interval of 0.46 to 0.79, whereas for crude protein content on a dry weight basis the estimate of broad sense heritability was 0.65 with a 95% confidence interval of 0.43 to 0.78. These results suggest that these diploid hybrid PHU-STN clones would be a good germplasm source for a high-protein-breeding effort, and identification of tetraploid progenies with high protein content and acceptable agronomic traits from 4x-2x cross should be possible.