應用嫁接技術促進甘藍開花及根瘤病抗性

Abstract

嫁接技術(grafting technique)廣泛用於葫蘆科及茄科果菜類蔬菜商業生產，目的為促進土壤傳播性病害、非生物性逆境的抗性、提高生長勢、增加產量及誘導或促進開花。在台灣，甘藍2016年 (cabbage; Brassica oleracea L. var capitata) 的產量位居所有蔬菜種類中的第一名 (399,174.53 tons) ，但因台灣位於亞熱帶缺乏低溫，採種目的需求之甘藍常因低溫不足而導致無法順利開花，此外，於台灣根瘤病 （Plasmodiophora brassicae Woronin.）為影響甘藍生產最嚴重之土壤傳播性病害之一，但於台灣防治效果仍相當有限，相反地，日本具有較完整的抗病品種，已可有效地防治日本根瘤病的發生，因此本研究目的利用甘藍嫁接技術研究不同品種根砧促進甘藍開花及抗根瘤病之效果。‘初秋’甘藍作為接穗，本研究使用十字花科植物作為根砧希冀可降低嫁接不親和性 （Grafting incompatibility） 之發生。於促進甘藍開花試驗，使用芥蘭、油菜、芥菜、結球白菜、青花菜、花椰菜及甘藍作為根砧，於低地試驗中所有嫁接組合之開花率均為零，於高地試驗中，有些嫁接組和之開花率可高於對照組(未嫁接)之50%，最高達57.14%，此外，於不同品種作為根砧之到花天數並未有顯著差異，結果指出本試驗選用之根砧對於促進開花之效果有限。於抗病試驗中，結果顯示，春陽農場及梅峰農場採集之根瘤病皆為Hatakeyama group 4，與日本根瘤病‘HG-02’之Hatakeyama group 1並不相同；因台灣並無報告指出芥蘭根瘤病疫情，因此選用三種台灣常見之品種試驗，結果顯示皆無抗病力；於濃度試驗中，選用五種抗病品種並以日本小種‘HG-02’及台灣小種‘CY’感染，結果顯示於各種濃度中五種抗病品種之疾病指數皆低於50%；於抗病嫁接試驗中，結果顯示抗病品種作為根砧可對台灣小種‘CY’具有抵抗力。基於以上結果，使用日本抗病品種作為根砧有望解決台灣根瘤病之問題

Grafting is widely used in commercial production of vegetables in Cucurbitaceae and Solanaceae so as to, e.g., improve resistance to soil-borne diseases and tolerance to abiotic stresses, promote plant vigor, increase yield, and induce or promote flowering. In Taiwan, the production of cabbage (Brassica oleracea L. var. capitata) ranked the first (399,174.53 tons) among all kinds of vegetables in 2016. Due to the lack of low temperature in tropical or subtropical countries, the flowering of cabbage often faces many difficulties, which is essential for breeding and seed production. In addition, one of the most serious diseases on cultivated and wild crucifers in Taiwan is clubroot disease which caused by a soil-borne plant pathogen, Plasmodiophora brassicae Woronin. In contrast, Japan has a long history in breeding of resistant varieties against clubroot disease, which highly contributes to reduce and control of this disease in Japan. This research aims to identify the best rootstocks for promoting cabbage flowering and clubroot disease resistance, respectively. With ‘K-Y cross’ cabbage used as scion, the identification was conducted among the rootstocks chosen from the genus of Brassica, so that the occurrence of grafting incompatibility may be reduced. For promoting cabbage flowering, the chosen rootstocks were Chinese kale, rape, leaf mustard, Chinese cabbage, broccoli, cauliflower, and cabbage. The flowering rate of each of grafting combinations in the lowland is 0%. In the highland, the flowering rates of some of the grafting combinations were slightly higher than the ungrafted control (50%), but the highest one was only 57.14%. In addition, no significant difference in days to flowering was found between the grafting combinations and the control. The results indicated that only limited plants chosen for rootstock were able to promote the flowering of ‘K-Y cross’ cabbage. For promoting clubroot disease resistance, the result showed that isolate ‘CY’ and ‘MF’ were classified into group 4 while isolate ‘HG-02’ was in group 1 in Hatakeyama method. Three cultivars of Chinese kale were tested for clubroot disease resistance ability because there is no epidemic revealed in Taiwan. However, the result showed severe symptom in Chinese kale. Then, five clubroot resistant cultivars were chosen to test resistance in different pathogen concentration in Taiwan and Japan. The result showed five cultivars were resistant to isolate ‘CY’ and ‘HG-02’ no matter which concentration were used. In grafting experiments, the results showed resistant cultivars being as rootstock were resistant against isolate ‘CY’ while the susceptible cultivar being as rootstock was not. Based on the results, grafting can solve the clubroot disease problem when resistant cultivars were used as rootstocks.