Rootstocks may have unique properties that strongly influence shoot growth, fruit yield and tolerance to various pathogens and abiotic environmental stresses. Although, there is considerable information of the effects of different rootstocks on tree performance, there is little mechanistic information on how specific anatomical, morphological and physiological aspects of the roots affect the tree. They usually live less than a year and may only live a few days. Some species construct roots to live a long time, others build roots that can be shed quickly when soil conditions become unfavorable. The specific life-history strategies in roots and how they are linked to root form and function are being examined for a wide range of woody species, including apple and citrus.
Plants generally allocate more carbon below- than aboveground on an annual basis.
Thus, there is an enormous expense in growing and maintaining a root system. Many factors can influence belowground carbon allocation and these are generally poorly understood. Using root video and gas exchange techniques, we have taken a rigorous approach to understanding allocation patterns of woody plants in both greenhouse and field situations. The effects of certain horticultural practices such as pruning, fertilization and irrigation on tree carbon allocation, nutrient uptake, root and shoot growth, and fruit production are being examined. Recent attention has focused on the effect of different apple rootstocks and different soil properties on root and shoot behavior.