Evaluation of some Newly Developed Diploid Hybrids and their Breeding Value in 4x-2x Crosses

The narrow genetic base in potato (Solanum tuberosum L.) limits the progress in cultivar development.The rich diploid germplasm in the origin center of potato provide a unique resource for improvement of tetraploid potatoes.Seven newly developed diploid hybrids with 2n pollen production,all of which have S. phureja background,were developed and evaluated for their value in potato breeding.They were crossed as male parnets to six tetraploid Solanum tuberosum cultivars,and seeds in large quantity from eleven crosses were obtained.Main agronomic traits,such as tuber yield,tuber number,mean tuber weight,tuber shape,eye depth,skin smoothness,flesh color,and specific gravity,were measured for 4x 2x tetraploid progenies in seedling generation,and their parents as well.All of the diploid hybrids had some merit for specific traits and the DH39 was more promising;high specific gravity trait in some diploid hybrids was successfully introgressed into tetroploid progenies via 4x 2x crosses.These diploid hybrids have potential value in potato breeding.

马铃薯4x-4x和4x-2x杂种后代高世代选系总产和商品薯产量比较

传统的4x-4x杂交方法很难进一步提高马铃薯(Solanum tuberosum L.)产量,倍性操作育种技术为提高马铃薯产量提供了新途径。试验比较4x-4x和4x-2x杂种后代高世代选系总产、商品薯产量的差异,探讨利用倍性操作育种的可能性。从4x-4x和4x-2x组合根据块茎性状和产量各选出17个高世代无性系,按随机区组设计,3次重复,在黑龙江省加格达奇比较两种组合类型高世代选系总产和商品薯产量的差异。4x-4x和4x-2x组合后代高世代选系在总产量方面无差异,但从4x-2x组合中可以选出更多的高产无性系。4x-2x组合高世代选系商品薯产量显著低于4x-4x组合,这主要是由于4x-2x组合后代选系单株结薯多,但单薯重低。采用4x-2x组合方式育种可有效利用具有丰富遗传变异的二倍体种质资源,但要注意在二倍体水平上选择,重点改良二倍体种或二倍体杂种对长日照的适应性,以及块茎性状,提高大薯率。

4x-4x和4x-2x杂种后代高世代选系比重的比较

马铃薯的比重是加工企业要考虑的一个重要性状。本研究的目的是比较4x-4x和4x-2x杂种后代高世代选系的比重,试图利用单向有性多倍化(Unilateral sexual polyploidization,USP)的方法从二倍体栽培种向四倍体普通栽培种转育高比重基因。四倍体亲本为品种或高世代选系,二倍体亲本是普通马铃薯栽培种(Solanum tuberosum)双单倍体与二倍体栽培种富利亚(S.phureja)杂种的互交后代,或经轮回选择适应长日照的S.phureja-S.stenotomum杂种后代。从4x-4x和4x-2x组合各选出17个高世代无性系,以‘克新18号’(鲜食)和‘夏坡地’(薯条加工)为对照,采用随机区组设计,2011～2012年在黑龙江省的加格达奇评价了4x-4x和4x-2x高世代选系比重的表现。4x-2x和4x-4x后代高世代选系比重平均为1.0727和1.0659,二者差异极显著。但是,4x-2x内和4x-4x内无性系的差异仍达极显著水平。4x-2x四倍体后代HJ04-18-17,HJ04-27-41,HJ04-22-19以及HJ04-15-36比重高于对照品种‘夏坡地’,并和其有显著差异。结果表明,和4x-4x组合相比,4x-2x组合后代含有较高的比重。

马铃薯4x×2x杂种无性一代产量及产量性状的表现

产生２ｎ花粉的Ｎｅｏ－ｔｕｂｅｒｏｓｕｍ双单倍体×Ｓｏｌａｎｕｍｐｈｕｒｅｊａ的二倍体杂种以及其与Ｎｅｏ－ｔｕｂｅｒｏｓｕｍ双单倍体的回交后代与普通马铃薯（Ｓ．ｔｕｂｅｒｏｓｕｍｓｓｐ．ｔｕｂｅｒｏｓｕｍ品种东农３０３进行了杂交。４ｘ杂种在株高方面表现出了很强的杂种优势。商品薯产量与４ｘ亲本无显著差异，但两个杂种群体的最高值分别超４ｘ亲本的２６０ｇ／株和６０ｇ／株。总产量杂种优势明显，但杂种单株结薯数多，平均块茎重小，这些是限制４ｘ×２ｘ杂种利用的不利因素，需要进一步地改善。

4x-2x杂交创制马铃薯新种质

以二倍体马铃薯‘USW4’和Solanum chacoense杂交产生的F1株系‘XD-3’为材料,检测其2n花粉产率和花粉活力。研究结果表明,‘XD-3’能产生2n花粉,2n花粉产率约7.7%,且花粉活力较高,达74.75%。在此基础上,开展了4x-2x杂交,进行了4个不同的杂交组合,平均杂交结实率为36.5%,但平均种子数/浆果仅0.67粒。4个不同的杂交组合共获得19个杂交后代,2对父本特异的SSR引物检测结果表明,有14个株系可以确认为真杂种;杂种植株的倍性检测结果表明,7个为三倍体,7个为四倍体。大量三倍体的产生为n花粉的直接利用提供了一条新思路。

马铃薯4X—2X选系在不同密度下产量及产量性状的表现

本试验采用裂区试验设计。以品种（系）为主区因素、密度为副区因素，研究７个４Ｘ—２Ｘ选系（Ａ１～Ａ７）及其４Ｘ亲本东衣３０３（Ａ８）以及密度（Ｂ１～Ｂ３）对产量和产量性状的影响。品种（系）间在小区总量、小区块茎数、小区商品薯重、小区商品薯数方面差异极显著。Ａ６品系小区块茎数极显著的低于东农３０３，但小区总产、小区商品薯重、小区商品薯数和东农３０３差异没有达到极显著水平．不同密度对小区总产和小区块茎数的影响分别达到了显著和极显著的水平，但对小区商品薯重和小区商品薯数没有显著的影响。较高密度下（Ｂ１，株距３０ｃｍ）小区总产和小区块茎数极显著高于Ｂ２（株距３５ｃｍ）和Ｂ３（株距４０ｃｍ）。在小区块茎数方面，品种（系）×密度互作显著。

The Potential Breeding Value of Two Newly Developed 2N Pollen Producing Diploid Hybrids in Potato

Diploid hybrid derived from dihaploid Neo-tuberosum × Solanum phurejaand progeny of the diploid hybrid backcrossed to dihaploid Neo-tuberosum,which could produce 2n pollen, were crossed as male to S.tuberosumssp. tubersumc.v. NEA303. The performance of the 4x hybrids obtained from 4x × 2x cross was investigated for yield and yield components in the first year clonal generation. The 4x hybrids shown a drastic heterosis in plant height. Marketable yield/plant for the 4x hybrid was no better than that for the 4x cultivar, but the best hybrid individual of the two hybrid populations exceeded the best individual of the cultivar by 260 g/plant and 60 g/plant, respectively. Total yield/plant for the 4x hybrids performed drastic heterosis, however tuber number/plant was high and mean tuber weight low. These limit the use of 4x × 2x hybrids in potato breeding programs and need to be improved in near future.