甘藷收穫指數之遺傳及其與塊根收量等有關性狀之關係

Abstract

本試驗利用甘藷逢機交配集團第6世代中，用逢機方法，選取32個植株作為親本。及由每親本逢機交配所得後裔之兩個地點一年的親子試驗資料，以供研究甘藷收穫指數之遺傳及其與塊根收量及收量有關性狀等之關係。 由合併分析結果得知，甘藷收穫指數之表行變方中，其遺傳變方成分為72%，佔有較大之比率，而收穫指數之遺傳變方中，其累加性變方所佔比率為52%，非累加性部份所佔比率為48%，以累加性變方比非累加性部份為稍大。收穫指數之狹義遺傳率為37%。此表示由遺傳上改進收穫指數，藉以提高塊根收量，乃為可能的事。 估算4種性狀之表型，遺傳及環境相關所得結果得知，甘藷塊根乾重與收穫指數及總乾物重之淨遺傳相關係數均為極顯著之正值。當減除塊根乾物重之影響後，收穫指數與總乾物重之遺傳相關為極顯著之負值；當減除莖葉乾物重之影響後，收穫指數與總乾物重之遺傳相關為極顯著之正值，由此相關分析所得結果可知，欲獲得高塊根收量之品種，應選育具有塊根與莖葉之比率高的株型，才可達成提高塊根收量之效果。 據路徑係數分析結果顯示，甘藷收穫指數及總乾物重對塊根乾物重之影響，兩者均表現有相同的重要性。 Thirty-two plants selected at random from the sixth generation of a randomly intermating sweet potato population and their respective open-pollinated progenies were grown at two locations in one year to investigate the inheritance of harvest index and its correlation with root yield and yield related traits in sweet potatoes. The results of combined analysis indicated that the genetic variance component accounted for a large portion (72%) of the phenotypic variance. The additive component of genetic variance was slightly larger than non-additive part for the harvest index and the estimated narrow sense heritability was 37%. The presence of considerable genetic variability in the harvest index suggests the possibility of improving the harvest index genetically and thereby increasing the root yield. A highly significant partial genotypic correlations were found between root dry weight and harvest index and between root dry weight and total dry weight. Genotypic correlation between harvest index and total dry weight was negative and highly significant when the root dry weigh was held constant, and was positive and highly significant when the top dry weight was held constant. This indicanted that yield increasing might be achieved by selecting plants with high root-to-top ratio. The partitioning of genotypic correlation coefficients into direct and indirect effects by path-coefficient analysis revealed that both total dry weight and harvest index were equally important in determining root dry weight of sweet potatoes.