Laboratory of Air Pollution and Global Climate Change, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
Laboratory of Air Pollution and Global Climate Change, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
Ecotoxicol Environ Saf. 2018 Aug 30;158:59-68. doi: 10.1016/j.ecoenv.2018.04.014. Epub 2018 Apr 24.
Tropospheric ozone (O) is a phytotoxic air pollutant causing a substantial damage to plants and agriculture worldwide. Plant productivity is affected by several environmental factors, which interact with each other. Studies related to interactions involving O and different levels of nitrogen (N) are still rare and elusive. In the present study we grew two wheat cultivars (HD2967 and Sonalika) in open top chambers (OTC) under ambient (AO) and elevated O (EO) (ambient + 20 ppb O) and provided two levels of N fertilization; (a) recommended nitrogen (RN), (b) 1.5 times the recommended N (HN). Growth (root/shoot ratio, leaf number and leaf area), biomass, gas-exchange (stomatal conductance (g), photosynthesis (A), transpiration (E), chlorophyll fluorescence (F/F), physiological (chlorophyll and carotenoids), biochemical [antioxidant activity, lipid peroxidation (MDA)] parameters and leaf N content were measured at the vegetative and reproductive phases. Yield attributes (spike weight plant, grain weight plant, grain numbers plant, husk weight plant, straw weight plant, 1000 grain weight, harvest index) and seed N content were analyzed at the final harvest stage. Grain yield plant was decreased in Sonalika under EO irrespective of different levels of N fertilization. Seed N content decreased by 3.9% and 5.6% in HD2967 and Sonalika, respectively, under EO at RN treatment. Antioxidant defense played an important role in protecting the plants against O stress which was enhanced under HN treatment. Response of antioxidants varied between the cultivar, growth phase (at the vegetative or reproductive phase) and the N levels (RN or HN). Cultivar HD2967 was characterized by higher biomass, g and stronger antioxidant protection system, while, Sonalika showed early senescence response (decreased leaf number plant, g) and greater resources allocation towards eco-physiological parameters (increased A and F/F) at the vegetative phase, resulting in the significant decrease in the yield attributes. Further study warrants the need to screen a large number of cultivars in relation to their response to various levels of N fertilization to minimize the yield losses under highly O polluted areas.
对流层臭氧（O）是一种对植物具有植物毒性的空气污染物，对全球的植物和农业造成了重大损害。植物生产力受到多种环境因素的影响，这些因素相互作用。涉及 O 和不同氮（N）水平相互作用的研究仍然很少且难以捉摸。在本研究中，我们在开放顶室（OTC）中用两种小麦品种（HD2967 和 Sonalika）进行生长，在环境（AO）和升高的 O（EO）（环境+20 ppb O）下，并提供两种氮施肥水平；（a）推荐氮（RN），（b）推荐氮的 1.5 倍（HN）。在营养和生殖阶段测量生长（根/茎比、叶片数和叶面积）、生物量、气体交换（气孔导度（g）、光合作用（A）、蒸腾作用（E）、叶绿素荧光（F/F）、生理（叶绿素和类胡萝卜素）、生化[抗氧化活性、脂质过氧化（MDA）]参数和叶片 N 含量。在最终收获阶段分析产量属性（穗重植物、粒重植物、粒数植物、壳重植物、茎重植物、千粒重、收获指数）和种子 N 含量。在 EO 下，无论氮施肥水平如何，Sonalika 的植株产量都降低了。在 RN 处理下，EO 下 HD2967 和 Sonalika 的种子 N 含量分别降低了 3.9%和 5.6%。抗氧化防御在保护植物免受 O 胁迫方面发挥了重要作用，在 HN 处理下，抗氧化防御得到了增强。抗氧化剂的反应在品种之间、生长阶段（在营养或生殖阶段）和氮水平（RN 或 HN）之间有所不同。品种 HD2967 的特点是生物量较高、g 较高且抗氧化保护系统较强，而 Sonalika 在营养阶段表现出较早的衰老响应（叶片数减少）植物，g）和对生态生理参数的更大资源分配（增加 A 和 F/F），导致产量属性显著下降。进一步的研究需要筛选大量品种，以了解它们对不同氮施肥水平的反应，以最大限度地减少在高 O 污染地区的产量损失。
