甘藷品種間雜交組合力研究

Abstract

本研究所用材料係由甘藷品種中，逢機選出5個甘藷親本，作為一逢機樣品，進行各親本間完全組合互交，共得20種雜交組合後裔之兩年試驗三性狀所得之資料，以探討甘藷品種間雜交一般和特定組合力，互交差異及其與年份交感作用變方之相對衡量與各親本之一般和特定組合力效果大小及各種互交組合間差異情形等，俾供甘藷雜交育種上選定交配親本時之參考，藉使甘藷雜交育種工作，得有更明確之目標，以增進甘藷雜交育種工作之效率。 由兩年綜合分析所得結果，知塊根產量之特定組合力均方極顯著，莖葉產量之特定組合力均方為顯著，而塊根及莖葉產量之一般組合力均方皆為不顯著，製簽率之一般組合力均方為極顯著，各性狀之互交差異均不顯著，莖葉產量之一般組合力×年份及塊根產量之特定組合力×年份之交感作用均方皆為顯著。 由一般和特定組合力兩變方成分大小比較來說，甘藷莖葉產量之特定組合力變方比一般組合力變方成分為稍大，其特定組合力變方成分之穩定性(Relative stabilitv)亦比一般組合力為較大。塊根產量之特定組合力變方成分極明顯地大於一般組合力變方成分，而製簽率之一般組合力變方成分比特定組合力變方成分約大34.9倍。由此可知，甘藷塊根及莖葉產量之遺傳變方，係以非累加性變方為較重要，而製簽率之主要遺傳變方成分，以累加性效果為重要。 估算各個親本及雜交組合三項性狀之一般和特定組合力效果以及互交效果所得之結果，可知塊根產量之特定組合力效果，以沖繩100號×紅心尾之雜交組合為顯著之正值，其所表現效果為最優，而紅心尾×臺農45號及七十日早×沖繩100號所表現之特定組合力效果為最低。莖葉產量之特定組合力效果，以沖繩100號×臺農27號、紅心尾×臺農45號及七十日早×臺農45號等三個雜交組合所表現之效果為最大，而沖繩100號×臺農45號、紅心尾×臺農27號、七十日早×臺農27號及臺農27號×臺農45號等雜交組合所表現之效果為最低。製簽率之一般組合力效果，以沖繩100號及臺農27號兩親本所表現之一般組合力效果為優異，而紅心尾及七十日早兩親本所表現之一般組合力效果為較差。互交差異效果均不大且無顯著差別，可知各種互交組合間無特殊之優異效果表現。 All possible crosses among 5 parents selected at random from a population of the sweet potato varieties (Ipomea batatas Lam.), including their reciprocals, were tested for a period of 2 consecutive years to ascertain the relative importance of the effects of general and specific combining abilities and reciprocal crosses and of their interaction with year for three agronomic characters in sweet potato. Agronomic characters measured were tuber yield, vine yield and the chip percentage. The data obtained for each character were analysed on a plot-mean basis. The analysis of variance for single year's experiment and for two-year's combined data were made for each of the characters. In the combined analysis, the mean square for specific combining ability was highly significant for tuber yield and at the 5% level for vine yield but the general combining ability mean square for tuber yield and vine yield were not significant. The general combining ability mean square for the chip percentage was significant at the 1% level. Reciprocal differences were not significant for all characters. The general conbining abilily × year (gy) mean square for vine yield and specific combining ability × year (gy) mean square for tuber yield were significant at the 5% level. In comparing the relative magnitude of the components of general vs. specific combining ability, the esimated variance component for specific combining ability was slightly larger than that for general combining ability and more stable over years for vine yield. Estimates of variance component for specific combining ability was significantly greater than that for general combining ability for tuber yield. The estimated component of variance of general combining ability for the chip percentage was 34.9 times as large as that for specific combining ability. Based on the results of this investigation, it is suggested that the nonadditive genetic variance is relatively more important than additive genetic variance in determining tuber and vine yield. For the chip percentage, the main component of genetic variance is of the additive type. Estimates of the effects of general and specific combining abilities and reciprocal crosses of the varieties and their crosses for 3 agronomic characters are presented in Table 8. The Cross, Okinawa 100 × Red-tuber-tail showed the highest positive value, indicating the best specific combining ability for tuber yield. The two crosses showing the lowest specific combining ability effects for tuber yield were Red-tuber-tail × Tainung No. 45 and 70-day early × Okinawa 100. Corsses showing the largest specific combining ability effects for vine yield were Okinawa 100 × Tainung No. 27, Red-tuber-tail × Tainung No. 45, and 70-day early × Tainung No. 45, whereas the combinations Okinawa 100 × Tainung No. 45, Red-tuber-tail × Tainung No. 27, 70-day early × Tainung No. 27, and Tainung No. 27× Tainung No. 45 had the lowest in specific combining ability effects. Estimates of general combining ability effect for the chip percentage indicated parents Okinawa 100 and Tainung No. 27 were high in general combining ability, but parents Red-tuber-tail and 70-day early were low. The values for the reciprocal effects were all relatively low and nonsignificant.