Analysis Of Agronomic And Quality Traits Of Advanced Clones From Progenies Of 4X-2X Crosses In Potato

Potato breeding have not been breaking through the extent of Solanum tuberosum germplasm in China, limiting the progress in breeding. Therefore, the introduction of new germplasm is urgent and important for the potato breeding. The purpose of this research is to introduce the desirable gene(s) present in diploid potatoes into common tetraploid potato through unilateral sexual polyploidization (diploid potato as male and tetraploid potato as female parent), and broaden the genetic base of the common potato. Twenty-eight 4x-2x advanced clones, plus two varieties, Kexin 18 (table potato) and Atlantic (Chipper) as controls, were grown in Jiagedaqi in 2009 and 2010 in a Randomized Complete Block with 3 replicates to study the plant traits (plant height and main stem number), yield traits (total tuber yield and marketable tuber yield), tuber traits (tuber shape, eye depth, skin color and flesh color), and quality traits (specific gravity, reducing sugar content, crude protein content and chip grade). The results are as follows:(1) Highly significant difference was found between the two years for all traits, except for main stem number in a combined analysis of variance. Also, highly significant difference was found in the 4x-2x advanced progenies (the two control varieties included) for all traits tested.(2) Clone (variety)×year interactions were highly significant for plant height, main stem number, total tuber yield, marketable tuber yield and specific gravity, indicating that these traits were prone to be influenced by the environment and unstable.. However, clone (variety)×year interactions were not detected for reducing sugar content, crude protein content (FW) and chip quality, indicating that they were stable.(3) The progenies derived from a cross where local variety (Dongnong 303) was used as female had good performance. This is mainly due to the fact that the variety Dongnong 303 is a very early maturing variety, and the experimentation was set in Jiagadaqi where it is located at high latitude and has a short growing season.(4) Some promising clones with good integrated traits were selected out: HJ21-69 with highest total and marketable tuber yield, good shape, and shallow eyes; HJ18-17 with highest specific gravity, relatively high total and marketable tuber yield, relative high crude protein content, good shape and shallow eyes.(5) Some clones with one or some promising traits were also identified: HJ18-22 with highest crude protein content (FW), and HJ37-7 with lowest reducing sugar content and highest grade of chip color. These clones could be used as parent in further breeding efforts.(6) In a simple correlation analysis, marketable tuber yield, plant height and main stem number were highly significantly positively correlated to total tuber yield, and plant height and main stem number were also highly significantly positively correlated to marketable tuber yield. Crude protein content (FW) was high significantly negatively correlated to total tuber yield and plant height, and reducing sugar was also highly significantly negatively correlated to chip grade.(7) In the partial correlation analysis, main stem number and marketable tuber yield were highly significantly positively correlated to total tube yield, but no significant correlation was found between plant height and total tuber yield. Chip grade and total tuber yield were highly significantly positively correlated to marketable tuber yield, while chip grade was highly positively negatively correlated to total tuber yield. Chip grade was highly significantly positively correlated to main stem number and marketable tuber yield, while reducing sugar content was highly significantly negatively correlated to chip quality.(8) In the path analysis, marketable tuber yield had the largest positive direct effect on the total tuber yield, whereas reducing sugar content, crude protein content (FW), and chip grade had negative impacts on total tuber yield. Main stem number and specific gravity affected the total tuber yield through the indirect effect of marketable tuber yield.In general, potato yield and quality could be improved via unilateral sexual polyploidization of 4x-2x cross. The progeny with promising integrated traits could be put on the list of Heilongjiang Potato Regional Trial, while the progeny with one or some promising traits be used as parent in further breeding effort.