ABSTRACT
Most of the Citrus species are perennial trees initially found in forest habitats that were later domesticated and improved for commercial uses. Many of these trees can survive for more than 100 years but with age, production gradually becomes uneconomical. Juvenility of these domesticated species is high and they start fruiting after six years. Their specific productivity usually appears after ten years. To remove juvenility and to achieve early uniform fruiting, grafting/budding was introduced in citriculture during the nineteenth century. Historically, Sour orange was the standard rootstock in citrus-growing regions because of its tolerance to Phytophthora foot rot. Gradually rootstock became an important component in advanced citriculture to resolve field problems and to improve commercial qualities. Japan had the problem of cold hardiness for seedless Satsuma oranges but eventually found the use of Trifoliate orange (Poncirus trifoliata) resolved this problem. Similarly, Rough lemon was introduced in the USA as rootstock for growing citrus in sandy soil and remained predominant till the blight disease started to take a heavy toll of the crop. Standard rootstock sour orange also got a setback because of its susceptibility in combination with sweet orange to the Citrus tristeza virus. Thus rootstock research began to gather momentum and has been primary focus in citriculture since the 1980s.
