Nitrogen absorbtion and respiration in white and brown peach roots

The relation between root age and root physiology is poorly understood, despite its importance for nutrient absorption. In peach, roots are white when first appear and then they become brown with age, which corresponds to a number of physiological changes. We related root browning to nitrogen absorption and respiration in order to provide a better understanding of how color changes as typically observed using minirhizotrons relate to changes in root physiology. The experiment was conducted on peach seedlings (Prunus persica cv. Guardian) grown in 30-L pots in a greenhouse. Brown roots showed lower respiration rates than white roots. White roots showed a higher 15N uptake than brown roots and higher concentration of nitrogen (N), potassium (K), magnesium (Mg), manganese (Mn), iron (Fe) and copper (Cu), no significant differences were observed regarding calcium (Ca) and zinc (Zn) concentration.