Leaf N and P in different growth habits of peach: Effects of root system morphology and transpiration

Abstract: Adequate mineral nutrition is critical for high fruit quality and sustained yield of fruit trees. In this experiment, peach [Prunus persica L. (Batch)] trees with different shoot and root growth habits were evaluated for leaf nitrogen (N) and phosphorus (P) concentrations after fertilizer applications in the greenhouse and field. In the field during 2008, Compact trees had higher root length density than Pillar and Standard trees (6.2, 3.8, and 3.7 mm cm^-3, respectively). Compact trees also had higher foliar P (0.21%) but the same N (1.3%) as Standard and Pillar trees (P concentrations of 0.14 and 0.11%, respectively) when fertilizer was applied once in the greenhouse. Following multiple applications of fertilizer, Compact tree leaves had the same P (approximately 0.21 and 0.29% in the greenhouse and field, respectively) as the other growth habits. After multiple fertilizer applications, Pillar trees had the greatest increase in foliar N and P, which was associated with high transpiration rates. Pillar, Compact, and Standard had transpiration rates of 3.0, 2.1, and 2.3 mmol H₂O m^-2 s^-1, respectively. The data indicate that peach trees with fibrous roots systems may have an advantage to absorb nutrients such as P that move primarily by diffusion, when the nutrient is present in low concentrations in the soil. However, under conditions of high soil fertility, fibrous root systems did not improve nutrient uptake and trees with greater transpiration rates absorbed greater levels of nutrients. Different growth habits of peach have diverse root systems and transpiration rates that affect nutrient uptake and, consequently, the selection of tree growth habit should be considered in orchard soil management plans. Growth habits with more fibrous root systems may require reduced inputs of nutrients with low diffusion coefficients.