Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 31, 2002
Publication Date: May 31, 2003
Citation: Swietlik, Dariusz. Plant Nutrition. Baugher, T.A., Singha, S., editors. The Haworth Reference Press, BInghamton, NY. Concise Encyclopedia of Temperate Tree Fruit. 2003. p.251-257. Technical Abstract: The essential nutrients utilized by fruit trees consist of carbon (C),hydrogen (H), oxygen (O), nitrogen (N), phosphorous (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), boron (B), and chlorine (Cl). Soil clay particles carry a negative charge that allows them to adsorb positively charged nutrients (ions) and thus minimize their leaching losse to the groundwater. Negative charged ions, however, such as NO3-, BO3-, and Cl- are easily leached. Most of the nutrients reach the roots surface by mass flow or diffusion. The first step in nutrient uptake by roots involves crossing the cell wall of epidermis followed by radial movement across the root cortex in the apoplast or symplast. In order to bypass the impermeable Casparian strip and enter the vascular cylinder, however, nutrients must enter the symplast. Long distance transport of mineral nutrients involves upward movement in the xylem and downward or upward movement in the phloem. Some of the nutrients act as building blocks for amino acids, proteins (including many enzymes), lipids, and nucleic acids. Some other nutrients are involved in activating enzymatic reactions or in maintaining the integrity of the plasma membrane and various enzymatic systems. Modern nutrient management practices in fruit tree orchards rely on fine-tuning the application of nutrients to satisfy needs of different tree organs at times most beneficial from the standpoint of tree productivity and fruit quality. A better understanding of the genetic control of plant nutrient uptake and translocation on a molecular level will open new frontiers for further improving the efficiency of mineral nutrients acquisition and utilization with the use of less fertilizer.