RAPD analysis showed that all the OTUs of 'Sandolbae' were the same species because amplified band patterns of all samples generated by each of 5 random primers were identical. Even though there were different environmental conditions, all the "Chuiangne" trees from three different places were the same species, and also all the "Cheongshilli" trees were the same species too. No genetic variations were detected between native Korean pears grown in the habitats and in the research field. Because 212 polymorphic bands were generated by 9 primers selected through primer screening, they were possible to analyze genetic relationship among naturally growing three native Korean pears and nine cultivars of Pyrus pyrifolia and P. communis. Based on the RAPD analysis, three main groups were formed. The first group represented the Six P. pyrifoia cultivars, the second group was the three native Korean pears, and the last group was the three P. communis cultivars. Genetic distance between 'Wonwhang' and 'Chojuro' was closer than other cultivars in group 1 since dissimilarity index value between these two cultivars was 50.82. However, genetic distance between 'Niitaka' and 'Chojuro' was the most distant compared to the others in group 1. In group 2, 'Sandlobae' was genetically closer to 'Chuiangne' than 'Cheongshilli' because dissimilarity index value between 'Sandlobae' and 'Chuiangne' was smaller, 50.82, than the value between 'Sandlobae' and 'Cheongshilli', 63.636. In group 3, 'Old Home' was genetically closer to 'Bartlett' than 'Kaiser Alexander(or Bosc)'. Group 3 composed of P. communis cultivars was genetically further than other two groups, P. pyrifolia cultivars and native Korean pears.

An effective grafting method for jujube nursery trees was developed to shorten the operation time, improve the percentage of "takes" and shoot emergence, and form the better graft union. Out of 7 grafting methods, the splice, modified scion Ono graft and the bark graft showed relatively short operation time during the grafting operation comparing to the modified rootstock Ono graft or the chip budding. Among these methods, the bark graft demonstrated 100% "takes", but the modified scion Ono graft or the standard Ono graft showed 58.3% of "takes". The percentages of the vegetative shoot emergence were 100% for the bark graft, 70% for the modified scion Ono graft and lower emergence percent for the rest grafting methods. The union tissue formation for the modified scion Ono graft, the bark graft, or the whip-and-tongue graft was significantly larger than the standard Ono graft or the splice graft. In a close examination of the cross sectional areas of the graft union formation through the microscope, the bark graft was superior, the standard Ono graft was inferior and rest of the grafting methods were intermediate.