在茎尖嫁接和热处理技术发展以前,培育珠心苗是从病毒或其它嫁接传播病原感染的无性系,繁殖无病柑桔栽培种的唯一方法。然珠心胚芽系的最主要缺点是表现童期现象,幼树多刺,生长健旺和直立性,结果迟,早期隔年结果,果实外观不美影响市场销售。这些特征可持续多年,且在许多芽接后代中遗传。珠心芽系丰产较亲本长8～10年或更长。其原因是否由于脱去其亲本芽系的病毒和类病毒尚来确定。除了童期现象以外,柑桔珠心芽系间的变异,和亲本系的差异,已有大量报导,指出珠心系的繁殖,其 Prior to the development of shoot tip grafting and heat treatment techniques, nucellus growth was the only method of propagating disease-free citrus cultivars from viruses or other clonal-infecting clones propagating pathogens. However, the most important drawbacks of pearl bud germ line is the manifestation of childhood phenomenon, young prickly, vigorous growth and erection, the result is late, the results of early next year, the appearance of the fruit is not the United States affect the market. These features can persist for many years and are inherited in many budding progeny. Zhu Xin heart buds than the parents of 8 to 10 years or longer. Whether the reason is due to take off their parent germ-line viruses and viruses is still to be determined. In addition to the phenomenon of childhood, citrus bead bud mutation between strains, and the differences in the parental line, there have been a large number of reports, pointed out that the growth of the Pearl heart, its