近年育成されたイチゴ品種の近親交配の程度および近交係数と収量の関係(育種・遺伝資源)  [in Japanese] The Inbreeding Coefficients of Recently Developed Cultivars and the Relationship between Inbreeding Coefficiets and Yield in Strawberry(Breeding & Germplasm Resources)  [in Japanese]

栄養繁殖作物のイチゴでは,限られた育種材料間での交配を繰り返すため近親交配が問題となる.そこで,近年育成されたイチゴ品種の近交係数を計算した.また,近交係数と収量との関係を調べた.近交係数の計算は推論型言語Prologとパーソナルコンピューターを利用した手軽な処理系で計算プログラムを作成した.交雑実生の近交係数と実生の選抜率との間に相関関係は認められなかった.栃木県農業試験場栃木分場の育成系統(3次選抜系統)の近交係数と収量の関係を調べたところ,-0.37(危険率1%)の有意な負の相関が認められた.また,イチゴでは近交係数が0.3程度までであれば,近交弱勢による収量の低下は見られないことが明らかになった.近年育成されたイチゴ品種の近交係数は,一季成り性品種では0.2を超えるものが多く,'とちおとめ','章姫','さがほのか','あまおう','さつまおとめ','ひのしずく','やよいひめ'はそれぞれ0.261, 0.222, 0.257, 0.213, 0.257, 0.247, 0.346であった.一方,四季成り性品種では'サマープリンセス'と'きみのひとみ'の2品種がが0.183と0.195でやや高い値であったが,それ以外はいずれも0.1以下であった.代表的な一季成り性品種15品種の総当たり交配による雑種の近交係数を計算した結果,自殖を除いた近交係数の値は0.067〜0.440で平均は0.210となり,近親交配の程度が高くなることが明らかになった.

Inbreeding is a great concern for strawberry plant breeders because of the repeated crossings among a limited number of breeding materials. Coefficients of inbreeding (CI) in recently developed cultivars of strawberry were calculated using a personal computer and a programming language, Prolog. The relation between CI and yield was also investigated in the strawberry. There was no correlation between the selection rate of F1 seedling plants and CI of those plants. In the strawberry breeding lines from Tochigi Branch, Tochigi Prefectural Agricultural Experiment Station, the correlation coefficient between CI and yield was -0.37, which was significant at the 1% level. The figure showed that strawberry plants with a CI less than 0.3 did not show any inbreeding depression. The CIs of several recently bred strawberry cultivars of the June-bearing type were approximately 0.2. CIs of 'Tochiotome', 'Akihime', 'Sagahonoka', 'Amaou', 'Satumaotome', 'Hinosizuku' and 'Yayoihime' were 0.261, 0.222, 0.257, 0.213, 0.257, 0.247 and 0.346, respectively. Those of CIs of ever-bearing type cultivars were approximately 0.1, except 'Summer Princess' and 'Kiminohitomi'. Hypothetical diallel crossing among 15 representative June-bearing type cultivars resulted in CIs of their offsprings ranging from 0.067 to 0.440 with an average CI of 0.210.