Agronomy Department, Federal University of Sergipe, São Cristóvão, SE, 49100-000, Brazil.
Agronomy Department, Federal University of Sergipe, São Cristóvão, SE, 49100-000, Brazil; Ecophysiology and Post-Harvest Laboratory - ECOPOC, Postgraduate Program in Agriculture and Biodiversity, Department of Agronomic Engineering, Federal University of Sergipe (UFS), Av. Marechal Rondon, s/n - Jd. Rosa Elze, CEP: 49100000, São Cristóvão, SE, Brazil.
Ecotoxicol Environ Saf. 2019 Nov 15;183:109557. doi: 10.1016/j.ecoenv.2019.109557. Epub 2019 Aug 10.
Biochar has been recently used as an alternative strategy to improve soil quality and plant growth in metal contaminated soils. However, the effects of biochar on gas exchange parameters such photosynthetic rate (A), water use efficiency (WUE) and instantaneous carboxylation efficiency (ICE) in metal tolerant plant species in contaminated soils is still unknown. Such information is important to understand how different biochar types can influence plant biomass production and metal uptake. Hence, a greenhouse experiment was set up as a completely randomized design combining two types of crop residue biochar (coconut husk (CB) and orange shell (OB) and two rates of application (30 t ha and 60 t ha)). A control treatment (no biochar) was also included. The aim of the study was to investigate the influence of biochar on the physiological performance, growth and concentration of copper (Cu) in the shoot of B. juncea plants in a Cu-contaminated soil. Besides reduced growth on the control soil, all other treatments increased plant growth. No toxicity symptom was observed in the plant, confirming its Cu tolerance. Biochar increased plant biomass by approximately 170% and reduced Cu concentration up to 51%. Application of 30 t ha biochar significantly increased net photosynthesis in 59% (CB) and in 34% (OB) while reducing stomatal conductance in 40% and transpiration rate in 14% (CB) and 19% (OB). Application of 60 t ha of biochar reduced stomatal conductance and transpiration rate in 51% and 60% (CB) and 26% and 7% (OB), respectively. All biochars improved the water use efficiency (WUE) in the plants (52-182%) for the instantaneous WUE and 80-162% for the intrinsic (IWUE). Therefore, biochar, especially CB, caused an improved regulation of the stomata aperture so that plant could maintain a high photosynthetic rate while efficiently controlling the use of water. This could be an important mechanism to reduce the excessive uptake of Cu by the plant.
生物炭最近被用作一种改善重金属污染土壤中土壤质量和植物生长的替代策略。然而，在重金属耐受植物物种中，生物炭对气体交换参数（如光合速率（A）、水分利用效率（WUE）和瞬时羧化效率（ICE））的影响在受污染土壤中仍然未知。这些信息对于了解不同类型的生物炭如何影响植物生物量的产生和金属的吸收非常重要。因此，进行了一项温室实验，该实验采用完全随机设计，结合了两种作物残余生物炭（椰子壳（CB）和橙壳（OB））和两种应用率（30 t ha 和 60 t ha）。还包括一个对照处理（无生物炭）。本研究的目的是调查生物炭对在 Cu 污染土壤中 B. juncea 植物叶片生理性能、生长和 Cu 浓度的影响。除对照土壤上的生长减少外，所有其他处理均增加了植物生长。植物没有观察到毒性症状，证实其具有 Cu 耐受性。生物炭使植物生物量增加了约 170%，并将 Cu 浓度降低了 51%。施用 30 t ha 生物炭使 CB 的净光合速率增加了 59%，OB 增加了 34%，同时使 CB 的气孔导度降低了 40%，蒸腾速率降低了 14%，OB 降低了 19%。施用 60 t ha 生物炭使 CB 的气孔导度和蒸腾速率分别降低了 51%和 60%，OB 降低了 26%和 7%。所有生物炭都提高了植物的水分利用效率（WUE）（瞬时 WUE 提高了 52-182%，IWUE 提高了 80-162%）。因此，生物炭，特别是 CB，导致气孔开度的调节改善，使植物能够在有效控制水分利用的同时保持较高的光合速率。这可能是减少植物过度吸收 Cu 的一个重要机制。
