Citrus Rootstocks for Improving the Horticultural Performance and Physiological Responses Under Constraining Environments

Due to fruit nutritional value and economical importance, citrus species are grown and cultivated around the World, with large plantations being found under subtropical, tropical, and Mediterranean climates. In such areas, citrus trees are subjected to constraining environmental conditions that impair plant development and crop yield, reducing fruit yield and causing economical losses. Such scenario is more severe in developing countries, where the environmental risk to crop production is larger as the technological packages are not always available. As field-grown citrus tree is commonly a scion-rootstock combination, the choice of citrus rootstock is a strategy for increasing scion resistance to unfavorable conditions and then reducing crop losses. Among environmental constraints, citrus trees are severely affected by water deficit, flooding, salinity, chilling, and heat stress when considering the various citrus-growing regions worldwide. This chapter has as aim to reveal the horticultural benefits due to the use of citrus rootstocks for alleviating the deleterious consequences of abiotic stresses. In addition, the physiological bases of such increased resistance are discussed as well as the future perspectives and research needs are presented.