Feng Yanru, Alam Muhammad Shahedul, Yan Feng, Frei Michael
Department of Agronomy and Crop Physiology, Institute of Agronomy and Plant Breeding, Justus Liebig University Giessen, 35390 Giessen, Germany; Institute of Crop Science and Resource Conservation (INRES), Crop Science, University of Bonn, 53115 Bonn, Germany.
Department of Agronomy and Crop Physiology, Institute of Agronomy and Plant Breeding, Justus Liebig University Giessen, 35390 Giessen, Germany.
Plant Sci. 2024 Jan;338:111924. doi: 10.1016/j.plantsci.2023.111924. Epub 2023 Nov 20.
Tropospheric ozone accelerates senescence and shortens grain filling, consequently affecting the remobilization and allocation efficiency of aboveground biomass and nutrients into grains in cereal crops. This study investigated carbon (C) and nitrogen (N) concentrations repeatedly in shoot biomass during the growth period and in grain after the harvest in eighteen wheat genotypes under control and ozone treatments in open-top chambers. Season-long ozone fumigation was conducted at an average ozone concentration of 70 ppb with three additional acute ozone episodes of around 150 ppb. Although there were no significant differences in straw C and N concentrations between the two treatments, the straw C:N ratio was significantly increased after long-term ozone fumigation, and the grain C:N ratio decreased under elevated ozone without significance. Grain N concentrations increased significantly under ozone stress, whereas N yield declined significantly due to grain yield losses induced by ozone. Moreover, different indicators of N use efficiency were significantly reduced with the exception of N utilization efficiency (NUtE), indicating that elevated ozone exposure reduced the N absorption from soil and allocation from vegetative to reproductive organs. The linear regression between straw C:N ratio and productivity indicated that straw C:N was not a suitable trait for predicting wheat productivity due to the low coefficient of determination (R). Nitrogen harvest index (NHI) was not significantly affected by ozone stress among all genotypes. However, elevated ozone concentration changed the relationship between harvest index (HI) and NHI, and the reduced regression slope between them indicated that ozone exposure significantly affected the relationship of N and biomass allocation into wheat grains. The cultivar "Jenga" showed optimal ozone tolerance due to less yield reduction and higher NUE after ozone exposure. The genotypes with higher nutrient use efficiencies are promising to cope with ozone-induced changes in nitrogen partitioning.
对流层臭氧会加速衰老并缩短灌浆期，从而影响谷类作物地上生物量和养分向籽粒的转运及分配效率。本研究在开放式气室中，对18个小麦基因型在对照和臭氧处理条件下，在生育期反复测定地上部生物量中的碳（C）和氮（N）浓度，并在收获后测定籽粒中的C和N浓度。整个生长季以平均70 ppb的臭氧浓度进行熏蒸处理，并额外进行三次约150 ppb的急性臭氧暴露处理。虽然两种处理间秸秆C和N浓度无显著差异，但长期臭氧熏蒸后秸秆C:N比显著增加，而在臭氧浓度升高时籽粒C:N比虽有下降但不显著。在臭氧胁迫下籽粒N浓度显著增加，而由于臭氧导致籽粒产量损失，N产量显著下降。此外，除了氮利用效率（NUtE）外，氮利用效率的不同指标均显著降低，这表明臭氧暴露增加降低了土壤氮吸收以及从营养器官向生殖器官的分配。秸秆C:N比与生产力之间的线性回归表明，由于决定系数（R）较低，秸秆C:N不是预测小麦生产力的合适性状。在所有基因型中，氮收获指数（NHI）受臭氧胁迫影响不显著。然而，臭氧浓度升高改变了收获指数（HI）与NHI之间的关系，二者之间回归斜率降低表明臭氧暴露显著影响了氮和生物量向小麦籽粒中的分配关系。品种“Jenga”表现出最佳的臭氧耐受性，因为臭氧暴露后产量降低较少且氮利用效率较高。养分利用效率较高的基因型有望应对臭氧诱导的氮分配变化。
