(42(3):280-291)Genetic and Agronomic Variation among Yam Genotypes

由本所1991年山藥品系產量比較試驗中，篩選七種高產質優而性狀互異之山藥品系，進行初步品系間變異性研究，其中四種白肉山藥為山藥臺農1號、70W02、70W04與81W06，三種紅肉山藥為80R04、70R09及70R01。此七品系除了塊莖顏色分成紅白兩類外，在植物特徵及電泳分析上分別具有不少之差異性。 依據田間植物特徵之調查結果可知，山藥臺農1號具有典型田薯（Dioscorea alata L.）之特性，而70R01及70R09則具備典型紫田薯（D. alata L. var. purpurea（Roxb.）M. Pouch.）之特性。另外三種白肉山藥之特性較接近於田薯，而另一紅肉品系80R04則近似紫田薯。 根據同功異構酶電泳分析結果可知，就過氧化酶（PRX）而言，屬於D. alata及D. alata var. purpurea之山藥品系在Rf＝0.2處具有相同條帶，而D. esculenta（Lour.）Burk.在Rf＝0.2及Rf＝0.28處各具一條帶。就草醯乙酸轉胺酶（GOT）而言，同屬於D.alata之70W04較山藥臺農1號在Rf＝0.45處多一條帶。此二品系共同在Rf＝0.2及0.6有條帶，而同屬於D. alata var. purpurea之70R01及80R04則在Rf＝0.17及0.63處有條帶，前後互異。 七品系之田間成熟度似與塊莖顏色有關，屬於D. alata var. purpurea之紅肉三品系較具早熟趨勢，而D. alata四品系則趨向晚熟。此外，屬於D. alata之白肉四品系具有較高單株塊莖收量、田間成活率及塊莖公頃產量之特點，其塊莖粘度較大，且顏色不易褐變。而D. alata var. purpurea之三品系則具較高蛋白質與澱粉含量之傾向。 A total of seven yam genotypes selected from yield trials by Taiwan Agricultural Research Institute were used to compare their genetic variability by taxonomical and electrophoretic investigation. The seven entries included four white-flesh genotypes, i. e., Tainung No. 1, 70W02, 70W04, and 81W06, and three red-flesh genotypes, i. e., 80R04, 70R09, and 70R01. Taxonomically, Tainung No. 1 is a typical Dioscorea alata L., and 70R01 and 70R09 are typical D. alata var. purpurea. The other three white-flesh genotypes are suggested to be under D. alata, whereas the red-flesh 80R04 is similar to D. alata var. purpurea in many of the botanical characteristics studied. Results from electrophoretic analysis indicated that both D. alata and D. alata var. purpurea had the same leaf peroxidase (PRX) isozyme banding at Rf＝0.2, while D. esculenta had two bands at Rf＝0.2 and 0.28. For sprout glutamate oxaloacetate transaminase (GOT), although both 70W04 and Tainung No. 1 are classified as D. alata and possessed four same bands at Rf＝0.2, 0.5, 0.6, and 0.73, the former had an additional GOT band at Rf＝0.45. On the other hand, genotypes 70R01 and 80R04, both are D. alata var. purpurea, had GOT bands at Rf＝0.17, 0.5, 0.63, and 0.73. There was a close relationship between tuber flesh color and maturity grouping. Yam genotypes with red flesh (D. alata var. purpurea) were more early maturing than those with white flesh (D. alata). Furthermore, genotypes of D. alata performed better in the field in terms of tuber yield per plant, field survival rate and yield. Their tubers were high in viscosity and showed less browning upon storage as compared to tubers of D. alata var. purpurea. However, genotypes of D. alata var. purpurea had high protein and starch contents in the tubers