Laboratory of Soil Biological Chemistry, Department of Soils, Federal Rural University of Rio de Janeiro, Seropédica, RJ, Brazil.
Laboratory of Soil Biological Chemistry, Department of Soils, Federal Rural University of Rio de Janeiro, Seropédica, RJ, Brazil.
Plant Physiol Biochem. 2021 May;162:171-184. doi: 10.1016/j.plaphy.2021.02.043. Epub 2021 Mar 2.
Chemical eustressors induce a eustress state "positive stress" increasing the resistance and improve the plant growth. The potentiality of humic acids (HA) to act as a eustressor has been scarcely explored. The present study aims to evaluate how HA with different structural characteristics induce differently, a eustress state in rice plants through the regulation of photosynthesis. The photosynthetic performance index showed an initial eustress state in plant by HA application characterized by reduction in photosynthesis followed by an increase in photosynthetic efficiency. The HA as a chemical eustressor triggering changes in plant metabolism indicate that the interaction of HA with root system induces a roots growth stimulus preceded by an initial positive stress. The eustress caused by HA is differentiated and is related to its chemical-physics characteristics. The HAVC, with a predominance of C-(O,N), C-di-O, C-O structures and greater polarity, stimulated the accumulation of N-NO and of soluble sugars in the sheath, increase carbohydrates content in the root and the root emission, resulting in higher total biomass production. The HASOIL, with a predominance of C-(H,R), C-O, C-H,R structures and greater hydrophobicity caused a decrease in N-NH and N-amine. The HARN, with a predominance of C-O, C-H,R, and CO, characterized by average polarity, caused an increase in photosynthetic pigment and N-NH content. These results are keys to understand that quality of soil organic matter is related to plant development and that HA are efficient proxies for elucidate its function in natural environments.
化学环境胁迫诱导剂会引起“正胁迫”状态，增加植物的抗性并改善其生长。腐植酸（HA）作为环境胁迫诱导剂的潜力尚未得到充分探索。本研究旨在评估具有不同结构特征的腐植酸如何通过调节光合作用，以不同的方式诱导水稻植株进入正胁迫状态。光合作用性能指标显示，HA 处理后，植物会表现出初始正胁迫状态，表现为光合作用降低，随后光合作用效率增加。腐植酸作为一种化学环境胁迫诱导剂，引发植物代谢变化，表明腐植酸与根系的相互作用会诱导根系生长刺激，随后出现初始正胁迫。腐植酸引起的正胁迫是有区别的，与它的物理化学特性有关。以 C-(O,N)、C-二-O 和 C-O 结构为主，极性较大的 HAVC 刺激鞘中 N-NO 和可溶性糖的积累，增加根中的碳水化合物含量和根排放，从而导致更高的总生物量生产。以 C-(H,R)、C-O 和 C-H,R 结构为主，疏水性较大的 HASOIL 会导致 N-NH 和 N-胺减少。以 C-O、C-H,R 和 CO 为主，具有平均极性的 HARN 会导致光合色素和 N-NH 含量增加。这些结果是理解土壤有机质质量与植物发育的关系的关键，并且腐植酸是阐明其在自然环境中功能的有效替代物。
