Submitted to: Annual Cumberland Shenandoah Fruit Workers Conference
Publication Type: Proceedings
Publication Acceptance Date: February 6, 2009
Publication Date: March 27, 2009
Citation: Tworkoski, T., Scorza, R., Glenn, D.M. 2009. Effects of peach tree root system morphology and transpiration on leaf nitrogen and phosphorus. Annual Cumberland Shenandoah Fruit Workers Conference. Pg 175. Technical Abstract: Adequate mineral nutrition is critical for high fruit quality and sustained yield of fruit trees. It is likely that nutritional competence of a fruit tree depends on several physiological and morphological traits that affect nutrient uptake. Fruit trees with improved root systems (own-rooted or as rootstocks) may be beneficial on infertile soils and for efficient use of fertilizer. Experiments were conducted in the greenhouse and field with the objectives to (1) determine root system morphology of selected growth habits of peach trees [Prunus persica L. (Batch)] in the field and (2) determine if root and shoot growth habit traits affected leaf concentrations of nitrogen (N) and phosphorus (P). Peach trees with different shoot and root growth habits were evaluated for leaf N & P concentrations after fertilizer applications in the greenhouse and field. In the greenhouse, one-year-old Compact, Pillar, and Standard peach trees were fertilized once or ten times and photosynthesis, transpiration, N and P concentrations were measured in leaves. The same growth habits of peach were planted in the field and grown for 10 years when fertilizer was applied in two consecutive years and roots and leaf N and P concentrations were measured. In the greenhouse and field, Compact trees had higher leaf P but the same N as Standard and Pillar trees when fertilizer was applied once. Field measurements of peach root number and length showed that Compact trees had a more fibrous root system than the other growth habits. The Compact tree root system morphology could support exploitation of the soil volume to enable uptake of nutrients, such as P, that move from soil to root surfaces primarily by diffusion. After more than one fertilizer application in the greenhouse and field, Pillar trees had the greatest increase in leaf N and P. Higher transpiration rates in Pillar trees may have increased movement of nutrients to Pillar roots by mass flow. The data indicate that peach trees with fibrous root 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 had greater absorptive capacity 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 included in soil management plans. Growth habits with more fibrous root systems may require reduced inputs of nutrients with low diffusion coefficients.