甘薯与近缘野生种I.trifida种间杂交结实率和结薯性

SeedSettingRateofInterspecificHybridofSweetPotatoandRelativeWildSpeciesI.trifidaandItsTuberSettingProperty

甘薯品种与不同倍性（２ｘ，３ｘ，４ｘ）野生种Ｉ．ｔｒｉｆｉｄａ杂交，获得Ｆ１代种子７０３粒，平均结实率为５．９％；甘薯品种与不同倍性种间杂种回交，结实率平均为１５．４％。结果显示：野生种及多数种间杂种表现父本花粉育性障碍；种间杂交父母本染色体倍性愈趋近平衡，其结实率及种子可育率越高。通过双列杂交试验，筛选出甘薯品种“徐薯１８”和“美国红”，种间杂种７Ｋ－１和７Ｋ－２为杂交亲和性较好的亲本；对１７７个野生种及其种间杂种后代材料进行了田间结薯性鉴定，种间杂交Ｆ１品系结薯率为１１．４％，结薯品系间块根重性状呈广泛变异，单株薯块鲜重３００ｇ以上的占１．７％。从甘薯与二倍体野生种杂交后代中筛选出两个块根重较突出的四倍体杂种，对于甘薯育种资源的创新将具有重要意义。

Atotalof703trueseedswereharvestedwithameanseedsettingrateof59%whenI.trifidagermplasm(2x,3x,4x),therelativewildspecieswerecrossedwithsweetpotatocultivatedvarieties.Backcrosseswereconductedamonginterspecifichybridsandsweetpotatowithameanseedsettingrateof154%.Wildspeciesandmostoftheinterspecifichybridsshowedhighercrossabilityasfemaleparentsthanasmaleparentswhencrossedorbackcrossedwithsweetpotato.Whenthechromosomeploidyoffemaleparentandmaleparenttendedtowardbalance,theseedsettingrateandfertilitywerehigh.SweetpotatovarietiesXushu18andMeiguohongwereselectedbydiallelcrossaswellasinterspecifichybrids7K1and7K2whichhadbettercrosscompatibility.Tubersettingpropertyofprogeniesofinterspecifichybridwereinvestigated.ResultsshowedthattubersettingrateofF1hybridswere114%,buttuberweightofdifferentlinesweregreatlydifferent,and17%tubershadfreshweightbeyond300g.Twotetraploidhybridswithbettercharacterofbuberweightwhichwereselectedfromtheprogeniesofsweetpotatoanddiaploidwildspecieswereveryimportantforthecreationofsweetpota