Genetic Diversity Analysis And Breeding Of Pumpkins Special For Rootstocks

Pumpkin is one of commonly grafted rootstock species for watermelon, melon, cucumber, bitter gourd and other cucurbits. Pumpkin rootstocks including China pumpkin (Cucurbita moschata. Duch, commonly known as Wogua, Fangua), Indian pumpkin (C. maxima. Duch, commonly known as Sungua) and black seed pumpkin (C. ficifolia) three cultivars. Now in the domestic market, commercial pumpkin rootstocks varieties in India and China pumpkin squash interspecific hybrids and Chinese pumpkin intraspecific hybrids. The study on genetic diversity of pumpkin rootstocks offers theoretical foundation for identifying of genetic relationship and parent selection, then benefits pumpkin rootstocks germplasm collection, characterization, conservation and utilization. The study analyzed genetic diversity of20pumpkin rootstocks by the morphological markers, identified the genetic relationship of35commercial varieties and rootstock materials use by SSR markers, then selected seven rootstocks which were excellent overall performance to form hybrid combinations. On this basis this study compared different combinations of watermelon melon grafted rootstock affinity growth and quality of yield. The main results obtained are as follows:1. In36botanical traits (14quantitative traits and22qualitative traits) survey of20pumpkin rootstocks, the results showed that the average coefficient of variation was42.42%, the coefficient of variation was between7.53%～112.96%Old pumpkin face brindle had the largest coefficient of variation for112.96%, and cotyledons aspect smallest coefficient of variation, was7.53%. Cluster analysis and principal component analysis showed that four Indian pumpkin inbred lines (C12-213, C12-193, C12-245and C12-195) was classified as a group and the other16pumpkin inbred line were classified as the second group. The four Indian pumpkin in the first group was divided into two sub-group,that C12-195was a single subgroup.In the second largest group,each of C12-192and C12-212was divided into a subgroup. In the research, the material was more dispersed, indicating pumpkin rootstocks germplasm resources were abundant. Resistance and disease resistance evaluation results showed C12-198, C12-197, C12-199, C12-193, C12-213, C12-195and C12-210performed much better, screening out seven pumpkin rootstocks as the parent materials to breed hybrid combinations.2. SSR molecular marker technology,53pairs of primers effectively detected129polymorphic bands, the results of cluster analysis. In similarity coefficient0.55,35 pumpkin rootstocks could be divided into three groups, C12-192, C12-193and C12-198separately classified as a group,21pumpkin rootstocks such as C12-203, Xinshijiquanwang Xiaoquanwang, etc. were classified as second group, the third group were12pumpkin material which included C12-197, C12-206, Osaka Taro, etc.3. Making22different combinations parent and2commercial pumpkin varieties as rootstocks,’Elizabem’ melon and ’Zaochunhongyu’ watermelon as scion, comparing scion graft compatibility, the symbiotic affinity, plant growth, fruit quality and yield selected suitable rootstock combinations. In grafted watermelon trials, C12-196×C12-197, C12-196x C12-198, C12-197x C12-198rootstock grafting combinations optimaled overall performance. In grafted melon trials, C12-197×C12-198, C12-213×C12-197, C12-194x C12-196rootstock grafting combination had best performance.