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The root nitrogen uptake response to partial nitrogen stress is related to previous nutritional status
- Niu, Xiaoli, Hu, Tiantian, Zhang, Fucang, Duan, Aiwang, Zhang, Jiyang
- Plant growth regulation 2019 v.87 no.1 pp. 55-67
- containers, corn, nitrogen, nutrient solutions, nutrient use efficiency, nutritional status, root systems, seedlings
- We investigated the dynamics and factors influencing the N uptake capacity in two sub-root systems of maize seedlings under partial N stress. Maize seedlings were grown in split-root containers containing nutrient solutions. Two N application conditions prior to partial N stress (full-strength N (4.0 mM): CP; N stress: SP) were considered. Thus, two experiments were conducted: (A) four treatments: CPNc, CPN₂, CPN₁ and CPN₀, in which half of the root system was exposed to 4.0 mM, 2 mM, 1 mM and 0 mM N (CPNc–c, CPN₂–₂, CPN₁–₁ and CPN₀–₀), respectively, and the other half received full-strength N (CPNc–c, CPN₂–c, CPN₁–c and CPN₀–c); (B) four treatments: SPNc, SPN₂, SPN₁ and SPN₀, in which both sub-root systems received 4.0 mM, 2 mM, 1 mM and 0 mM N for 6 days, respectively, after which half of the root system was maintained at original N level (SPNc–c, SPN₂–₂, SPN₁–₁ and SPN₀–₀) and the other half received full-strength N (SPNc–c, SPN₂–c, SPN₁–c and SPN₀–c). At 0.25 days after treatment (DAT), CPN₂–c and CPN₁–c enhanced N inflow rates (Iᵣₒₒₜ), whereas CPN₀–c decreased it by 27.3% compared with CPNc–c, Iᵣₒₒₜ in CPN₂–c, CPN₁–c and CPN₀–c was uniformly enhanced at 1 DAT, but were only enhanced in CPN₀–c at 5 DAT compared with CPNc–c. In contrast, SPN₁–c had a significantly increased Iᵣₒₒₜ by 10.52% compared with SPNc–c, although other treatments showed a negative effect on Iᵣₒₒₜ at 0.25 DAT. At 1 and 5 DAT, Iᵣₒₒₜ in SPN₂–c, SPN₂–₂, SPN₁–c, SPN₁–₁ and SPN₀–c were significantly lower than that in SPNc–c. Furthermore, CP significantly enhanced Iᵣₒₒₜ in non-stressed sub-roots compared with SP. Additionally, CPN₂ improved shoot dry mass and N use efficiency even under SPN₂. Thus, N uptake capacity in each sub-root zone varied not only depending on the severity and duration of the N stress, but was also related to the N status prior to partial N stress. Moreover, the occurrence and disappearance of the root compensatory effect were delayed with increasing N stress severity. A higher compensatory effect developed following CP, even under CPN₀.