|
| Response of photosynthetic nitrogen use efficiency and nitrogen partitioning to water conditions in soybean leaves |
| Received:November 20, 2024 |
| View Full Text View/Add Comment Download reader |
| KeyWord:photosynthetic nitrogen use efficiency;nitrogen partition ratio;CO2 diffusive conductance;moisture |
| Author Name | Affiliation | E-mail | | MA Xiaofang | Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | BAI Yifei | Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | LIU Qian | Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | | | ZHANG Fangmin | Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China | fmin.zhang@nuist.edu.cn |
|
| Hits: 832 |
| Download times: 565 |
| Abstract: |
| Photosynthetic nitrogen use efficiency（PNUE）, a key parameter in leaf economic spectrum theory, is a critical indicator for understanding the trade-off strategies between nutrient utilization and stress adaptation in crops under resource-limited environments. To investigate the mechanistic links between PNUE and nitrogen allocation in soybean leaves under progressive water deficit, we implemented a field experiment with five water regimes：full irrigation throughout growth cycle（CK）; mild drought during entire growth period（W1T1）; moderate drought during entire growth period（W2T1）; adequate irrigation at seedling stage + moderate drought from flowering to maturity （W2T2）; adequate irrigation at seedling and flowering stages + moderate drought at maturity（W2T3）. Key photosynthetic parameters including light-saturated net photosynthetic rate（Amax′）, nitrogen content per unit leaf area（Narea）, CO2 diffusion conductance（stomatal conductance, gs; mesophyll conductance, gm）, and nitrogen allocation proportions（Rubisco-associated nitrogen proportion, PR; bioenergetics components nitrogen allocation proportion, PB; light-harvesting complex nitrogen proportion, PL） were systematically quantified. Significantly, the W2T1 treatment showed reductions of 32.2% in PNUE, 42.6% in Amax′, and 11.9% in Narea compared to CK（P<0.05）. Water deficit significantly impaired stomatal functionality, with gs in W2T1 and W2T3 decreasing to 56.0% and 52.0% of CK values, respectively. Concurrent reductions in gm were observed（60.9% and 78.3% of CK for W2T1 and W2T3）, while a robust positive correlation emerged between gs and PNUE（P<0.01）. Chlorophyll content（cchl）demonstrated progressive depletion under water stress, peaking at 25.6% reduction in W2T1（P<0.05）. Nitrogen allocation to photosynthetic machinery showed systematic declines, with PR and PB significantly decreasing across drought treatments（P<0.05）; all moisture treatments（W1T1, W2T1, W2T2, W2T3）exhibited significantly reduced PL compared to CK（P<0.05）, though no significant inter-treatment differences in PL were observed. PR and PB showed significant positive correlations with PNUE（P<0.05）, indicating their crucial roles in mediating moisture-induced variations in soybean PNUE. The investigation revealed that water stress significantly decreased Amax′, Narea, and PNUE in soybean leaves. Furthermore, water deficit not only impaired leaf CO2 transport capacity but also reduced chlorophyll content, while simultaneously altering nitrogen allocation patterns between photosynthetic and non-photosynthetic systems-particularly manifesting as decreased PR and PB. These findings collectively demonstrate that the observed PNUE reduction under water-limited conditions primarily stems from three interrelated factors：diminished nitrogen allocation to photosynthetic components, compromised leaf CO2 diffusion capacity, and reductions in both PR and PB. |
|
|
|
