Todorova Dessislava, Anev Svetoslav, Iliev Martin, Petrakova Margarita, Sergiev Iskren
Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Street, Bldg. 21, 1113 Sofia, Bulgaria.
Department Dendrology, Faculty of Forestry, University of Forestry, 10 Sveti Kliment Ohridski Blvd, 1756 Sofia, Bulgaria.
Plants (Basel). 2024 Dec 5;13(23):3414. doi: 10.3390/plants13233414.
Drought stress affects many aspects of plant biochemistry, with photosynthesis being one the most significantly impaired physiological processes. Melatonin is a natural antioxidant with growth-regulating properties in plants. Its diverse physiological functions have been extensively studied in recent decades. Changes in leaf gas exchange and chlorophyll fluorescence parameters were investigated in young wheat plants ( L.) cv. Fermer and cv. Gines which were characterized to differ in their responses to drought, with cv. Gines being more tolerant than cv. Fermer. The plants were subjected to drought for five days by withholding their water supply. Melatonin was applied as a root supplement to the irrigation water before or after the drought period. Analyses were performed before and at the end of the stress period, as well as during the recovery phase. Changes in leaf pigment content, photosynthetic rate, stomatal conductance, and transpiration, as well as some chlorophyll fluorescence parameters, were recorded. Melatonin alone did not cause considerable changes in the measured traits. We found a significant decrease in leaf gas exchange parameters, F/F and F/F values, and leaf pigments due to drought, especially in cv. Fermer. The data show that the application of melatonin favorably influenced the efficiency of the photosynthetic apparatus under water deprivation and during plant recovery. The pre-treatment with melatonin maintained the photosynthesis-related parameters closer to the control levels during the stress period. Both melatonin treatments supported the recovery of photosynthesis when the water supply was restored and the post-drought treatment showed a similar but weaker effect than pre-drought treatment.
干旱胁迫影响植物生物化学的许多方面，光合作用是其中受影响最显著的生理过程之一。褪黑素是一种天然抗氧化剂，对植物具有生长调节特性。近几十年来，对其多样的生理功能进行了广泛研究。在小麦（L.）品种Fermer和Gines的幼苗中研究了叶片气体交换和叶绿素荧光参数的变化，这两个品种对干旱的反应不同，Gines品种比Fermer品种更耐旱。通过停止供水使植株遭受五天干旱处理。在干旱处理之前或之后，将褪黑素作为根系补充剂施用于灌溉水中。在胁迫期开始和结束时以及恢复阶段进行分析。记录叶片色素含量、光合速率、气孔导度、蒸腾作用以及一些叶绿素荧光参数的变化。单独施用褪黑素并未引起所测性状的显著变化。我们发现，干旱导致叶片气体交换参数、F/F和F/F值以及叶片色素显著下降，尤其是在Fermer品种中。数据表明，施用褪黑素有利于在水分亏缺和植物恢复期间提高光合器官的效率。在胁迫期，褪黑素预处理使与光合作用相关的参数更接近对照水平。当恢复供水时，两种褪黑素处理均有助于光合作用的恢复，且干旱后处理的效果与干旱前处理相似，但较弱。
