Genetic Analysis For Main Traits In A Diploid Potato Hybrid Population

As Potato industry develops rapidly in China, processing and special-purpose cultivars are needed more and more. The current cultivars can not meet these demands and new cultivars need to be released in China. But because the genetic base of common tetraploid potato is narrow and inbreeding is obvious, new cultivars with interested traits are difficult to be developed. So, expanding the genetic base of common tetraploid potato is urgent. In this research, a diploid hybrid population, Solarium phurejaS. stenotomum (PHU-STN), was investigated for some main traits and frequency of 2n pollen. The purposes were to see whether large genetic variation exists in this population and whether this population can be continually improved by the recurrent selection, and to screen some diploid clones with interested traits, which may be used in 4x-2x crosses in a potato breeding effort. The final goal of diploid breeding is to transfer the target gene(s) from diploid to tetraploid level and broaden the genetic base of commercial tetraploid potatoes. The main results were as following.(1) The results of analysis of variance indicated that plant vigor, plant height, main stem number, tuber number per plant, tuber yield per plant, specific gravity, and crude protein content were highly significantly different among diploid clones, suggesting that large genetic variation exists in the PHU-STN hybrid population.(2) Broad-sense heritability for tuber number per plant, yield per plant, specific gravity, crude protein content on the basis of dry weight (DW) and crude protein content on the basis of fresh weight (FW) were estimated as 0.7508, 0.7782, 0.6938, 0.5140 and 0.5996, respectively, all of which are more than 0.50, indicating that these traits were controlled mainly by genetic factors, and additional cycle of selection on this population is feasible.(3) The specific gravity was positively correlated to plant vigor, main stem number per plant, plant height, tuber number per plant, and more importantly yield per plant. This result was opposite to the situation that has been observed in advanced selections from tetraploid breeding programs, where a negative correlation between yield and specific gravity has been reported. The content of crude protein (both DW and FW) was negatively correlated to other traits including plant vigor, plant height, tuber number per plant, tuber yield per plant, and specific gravity except that the protein content (FW) had no correlation with specific gravity.(4) Some clones with interested traits were selected out of 216 clones. For example, clones with high specific gravity and high crude protein content, clones with some 2n pollen production, clones with shallow or very shallow eye, and clones with various skin colors, flesh colors, tuber shapes, and tuber set.In short, large genetic variation exists in the PHU-STN hybrid population based on the performance of tuber traits, tuber number per plant, yield per plant, specific gravity, and crude protein content. The estimates of road-sense heritability for tuber number per plant, yield per plant, specific gravity, crude protein content (DW) and crude protein content (FW) suggested that additional cycle of selection on this population is feasible. Also, some clones with interested traits were selected in this population.