波斯核桃與長山核桃品種改良之評論

An Appraisal of Cultivar Improvement for Persian Walnut and Pecan

首先比較長山核桃[pecan, Carya illinoensis （Wang） K. Koch]與波斯核桃（或稱核桃）Persian walnut, walnut, Juglans regiaL.）兩種作物間生長習性、強制演化與產業發展的差異。其次探討核桃18個性狀中，遺傳率與其外表型間的相關性，以尋求直接影響產量的主要性狀。從遺傳率的研究中，發現篩選側枝的結實性（fruitfulness of lateral shoots）與側枝的生長勢，是提升核桃產量潛能中的遺傳獲得量（genetic gain）最經濟、有效的方法。相反的長山核桃品種改良只著重於產量、品質與抗病育種，而未曾建立一套有效的選拔策略，以致育種成效不彰，此一情形與目前台灣果樹育種的遭遇大致相同。波斯核桃育種成功的例子或許可為本省果樹育種研究方向的參考模式。

Different growth habits, evolutionary constraints and industry constraints of pecan and walnut were comparatively studied. Then heritabilities and phenotypic correlations among 18 traits of walnut (Juglans regia L.) were discussed in order to find the main characteristics which directly related to the yield potential. It was found that the most effective and efficient means of improving the rate of genetic gain for yield potential in walnut has been performed by selecting for fruitfulness and vigor of lateral shoots. On the other hand, pecan breeding mainly emphasized on yield, quality and disease resistance so that did not have a powerful selection strategy. Methods in fruit breeding of Taiwan encountered the same problem as pecan. The successful walnut breeding may provide a model for the fruit breeding program in Taiwan.