Amooaghaie Rayhaneh, Rajaie Nafiseh
Plant Science Department, Faculty of Science, Shahrekord University, Shahrekord, Iran.
Biotechnology Research Institute, Shahrekord University, Shahrekord, Iran.
BMC Plant Biol. 2025 Jul 2;25(1):799. doi: 10.1186/s12870-025-06887-y.
The beneficial effects of chitosan on stress tolerance and secondary metabolism have been documented in a few medicinal plants. However, the impact of chitosan on water deficit tolerance in St John's Wort (Hypericum perforatum L) remains largely unknown. Therefore, a field experiment was executed to assess the effect of foliar spraying various chitosan concentrations (0, 100, 200, and 400 mg L) under irrigation intervals 7 (normal), 10 (mild water stress), and 13 (severe water stress) days. When irrigation intervals increased, biomass substantially decreased in both harvests. However, hypericin content increased at mild water stress, whereas it decreased under severe water stress. Foliar application of chitosan increased biomass, total phenol content )TPC( and hypericin content under all irrigation intervals. The highest hypericin content and TPC were verified by spraying 200 mg L chitosan under the mild water stress that corresponded with the most 2,2-diphenylpicrylhydrazyl (DPPH) scavenging activity in the leaves. The foliar application of chitosan improved relative water content, chlorophyll a, b contents and decreased the content of HO and malondialdehyde in plants grown under irrigation intervals of 10 and 13 days. The compensatory effect of chitosan was due to enhancing the activities of catalase and peroxidase and increasing proline content in leaves. However, 400 mg L of chitosan negatively affected most of the aforementioned attributes in St John's Wort. Collectively, the results indicate that foliar spraying with an appropriate concentration of chitosan may be a promising solution for improving the productivity and pharmaceutical value of medicinal plants under water deficit.
壳聚糖对一些药用植物的胁迫耐受性和次生代谢的有益作用已有文献记载。然而，壳聚糖对贯叶连翘（Hypericum perforatum L）水分亏缺耐受性的影响仍 largely unknown。因此，进行了一项田间试验，以评估在灌溉间隔为7天（正常）、10天（轻度水分胁迫）和13天（重度水分胁迫）时，叶面喷施不同浓度壳聚糖（0、100、200和400 mg/L）的效果。当灌溉间隔增加时，两次收获时的生物量均大幅下降。然而，金丝桃素含量在轻度水分胁迫下增加，而在重度水分胁迫下降低。在所有灌溉间隔下，叶面喷施壳聚糖均增加了生物量、总酚含量（TPC）和金丝桃素含量。在轻度水分胁迫下喷施200 mg/L壳聚糖时，金丝桃素含量和TPC最高，且与叶片中最强的2,2-二苯基苦味酰基自由基（DPPH）清除活性相对应。在灌溉间隔为10天和13天的条件下生长的植物中，叶面喷施壳聚糖提高了相对含水量、叶绿素a和b含量，并降低了过氧化氢和丙二醛的含量。壳聚糖的补偿作用归因于提高了过氧化氢酶和过氧化物酶的活性以及增加了叶片中的脯氨酸含量。然而，400 mg/L的壳聚糖对贯叶连翘的上述大多数属性产生了负面影响。总体而言，结果表明，叶面喷施适当浓度的壳聚糖可能是提高药用植物在水分亏缺条件下的生产力和药用价值的一种有前景的解决方案。
