Elevated O3 decreased N rhizodeposition of spring wheat and its availability to subsequent buckwheat

• A split-root 15N labeling method was used to investigate NdfR and its availability to a subsequent crop under O3 elevated conditions.
• Spring wheat N rhizodeposition represents a significant pool in plant-soil N dynamics.
• Elevated O3 decreased the quantity of spring wheat 15N rhizodeposition by 24–48%.
• Elevated O3 reduced about one half of spring wheat rhizodeposited 15N available to buckwheat.

Nitrogen derived from rhizodeposition (NdfR) is an important N source both for the current and subsequent crops in soil-plant system. However, few studies have focused on the effects of elevated O3 concentration on NdfR and its availability to subsequent crops. A pot experiment was conducted to investigate the effects of elevated O3 on spring wheat NdfR and its availability to buckwheat in open-top chambers (OTCs), where spring wheat was labeled with 15N urea by using a split-root method under ambient (Control; CK) and two O3 concentration-elevated conditions (60 ± 5 and 110 ± 5 nmol mol−1, respectively), and buckwheat was cultivated in the soil contained rhizodeposited 15N compounds after spring wheat harvest. The results showed that O3 stress significantly decreased the quantity of spring wheat 15N rhizodeposition (15NdfR) by 24–48% compared to CK. Spring wheat 15NdfR accounted for on average 8–15% of the total plant 15N (15N assimilation in plant material +15NdfR; T15N), and 78–95% of the total belowground parts of plant 15N (root 15N +15NdfR; BGP-15N) during plant growth. N recovery of buckwheat plant accounted for 12–25% of spring wheat 15N deposited into soil, and was significantly decreased by approximately one half under the two O3 level-elevated conditions. These results indicate that N rhizodeposition represents a significant pool in N dynamics of soil-plant system, and the projected future O3 concentration might induce adverse effects on NdfR and its availability to subsequent crops to influence N transformation and cycling in soil-plant system.