Varietal Improvement of Yam (Dioscorea spp.)

Abstract

山藥為最重要根莖類作物之一，具高產及富含營養之特色。由於分佈極廣，遍及全部熱帶、副熱帶及其他地區，品種十分繁雜“其種原能否加強蒐集，實為本省山藥品種改良與生產利用之首要工作。在眾多山藥種原中最具生產力的為D. alala L.、D. esculenta (Lour.) Burk. D. rotunda/a (L.) Poir.、D. cayenensis Lam.及D. bulbilera L.；而就本省而言，D. alala L.、B alala L var. purpurea (Roxb.)M. Pouch. D. japonica Thunb. var. pseudojponica (Hay.) Yamam.及D. doiyophora Hance亦深具發展潛力。多年來，台灣省農業試驗所即針對上述重要山藥種原積極進行引種工作，至今已有卯品系，除了先行繁殖、觀察及進行農藝性狀與產量之調查外，同時另進行開花習性、細胞遺傳及同功異構酣電泳之探討與分析，並繼續進行早熟性、抗病或抗蟲性、成分分析及其他性狀之篩檢工作，以配合山藥選種或育種工作之進行。由於大多數山藥種原不易開花，若有開花亦因其雄株或雌株具不孕性，不易生成種子，故傳統雜交育種工作極為困難，一般以選擇育種法為主。本所利用選擇育種法育成山藥台農1 號及篩選得到優良品系70W04，此二優良品種（系）共同具備高產、質優、適應性大、耐貯性佳及適合多元化加工及利用之價值，值得促銷推廣。70W04之另一特色為其葉與蔓產量甚高、營養豐富、且質地細緻可口，有可能成為本省夏季蔬菜之另一良好供源。 Yam is one of the most important root crops due to its high yield potential and nutritional value. It is distributed in almost every part of the tropics and subtropics and possesses a wide diversity in its genetic background. The collection of yam germplasm resources is particularly imperative to the successful varietal improvement of yam in Taiwan. A total of 90 genotypes belonging to five most productive yam species in the world, i.e., D. alala L., D. esczilenla (Lour.) Burk., D. roLundala (L.) Poir., D. cayeneasis Lam., and D. bulbifera L., and four promising species in Taiwan, i.e., D. alala L., D. alala L. var. prnpurea (Roxb.) M. Pouch., D. Japonica Thunb. var. pseudojponia (Hay.) Yamam., and D. doryophora Hance has been collectedpoodgated by Taiwan Agricultural Research Institute. A number of traits including agronomic and cytological characters, yield performance, flowering habit, isozyme patterns, disease and insect resistances, and chemical composition have been investigated on all or part of those genotypes. With the exception of a few species, e. g., D. rotundata varietal improvement by conventional method is difficult because of the low frequencies of flowering and seed-setting. Therefore, introduction and subsequent selection of the introduced germplasm have been adopted in the breeding programs. A new yam variety, Tainung No. 1 and a superior line, 70W04 have been selected for their high yield potential, quality, wide adaptability, long shelf life, and processing feasibility. The leaves and vines of line 70W04 are very productive and are thus recommended as good sources of summer vegetable due also to their high nutritional value and fine texture