Natural algaecides are more likely to be specific and biodegradable, and may offer an environmentally friendly method for control of cyanobacterial blooms. We explored, for the first time, the potential for watermelon peel aqueous extract (WMPAE) to control the growth of the harmful blue-green alga Aphanizomenon flos-aquae. The growth inhibition and several physiological parameters of A. flos-aquae, in response to WMPAE, were analyzed. Results showed that WMPAE significantly inhibited the growth of A. flos-aquae in a concentration-dependent way. The highest inhibition reached 94 % after 3 days’ treatment with 6 g L⁻¹ of WMPAE and a significant effect was obtained with lower doses and shorter times as well. The cell viability decreased quickly, cell shape changed, and intracellular structural damage occurred. At the same time, the antioxidant enzymes (superoxide dismutase SOD, catalase CAT and peroxidase POD) and malondialdehyde (MDA) levels all increased significantly, indicating that WMPAE between 2–6 g L⁻¹ induced severe oxidative stress and damage to A. flos-aquae. Moreover, production of the four pigments chlorophyll a (Chl a), carotenoids, phycocyanin (PC), and allophycocyanin (APC) were all stimulated, though photosynthesis of A. flos-aquae was clearly inhibited. The maximum quantum yield of photosystem II ($F_v/F_m)$ and the effective quantum yield of photosystem II ($F_v^{\text{'}}/F_m^{\text{'}}$) declined sharply, suggesting the decreased photosystem capacity of A. flos-aquae to convert light energy into chemical energy. In addition, non-photochemical quenching ($NPQ$) of A. flos-aquae increased after a very short time exposure to WMPAE, and decreased significantly with prolonged exposure time, which indicated the failure of photo protection mechanisms. These results suggest that the loss of cell viability, and increases in oxidative stress, and damage to intracellular structure and photosynthetic systems might be the mechanisms for the inhibitory effects. Our results suggested that WMPAE could be a novel and effective approach for controlling the growth of A. flos-aquae in aquatic environments.

天然除藻剂更可能具有特异性且可生物降解，并且可以为控制蓝藻水华提供一种环境友好的方法。我们首次探索了西瓜皮水性提取物（WMPAE）控制有害蓝绿藻Aphanizomenon flos-aqua的生长的潜力。生长抑制和若干生理参数甲。FLOS藻，响应于WMPAE，进行了分析。结果表明，WMPAE显著抑制的生长甲。浮游藻以浓度依赖性的方式。用6 g L ^-1处理3天后，最高抑制率达到94％降低WMPAE的使用率，并以更低的剂量和更短的时间获得了显着效果。细胞活力迅速下降，细胞形状改变，并发生细胞内结构损伤。与此同时，抗氧化酶（超氧化物歧化酶SOD，过氧化氢酶（CAT）和过氧化物酶POD）和丙二醛（MDA）级别的所有显著升高，表明WMPAE 2-6之间克L- ^-1诱导严重的氧化应激和损伤甲。浮萍。此外，尽管通过光合作用A，也刺激了四种色素叶绿素a（Chla），类胡萝卜素，藻蓝蛋白（PC）和别藻蓝蛋白（APC）的产生。浮萍显然被抑制了。光系统II（$F_v/F_{米}）$ 和光系统II的有效量子产率（$F_v^{\text{'}}/F_{米}^{\text{'}}$）急剧下降，表明A的光系统容量下降。浮游生物将光能转换为化学能。另外，非光化学淬灭（$ñP问$）的甲。暴露于WMPAE的时间很短后，flos-aquas增加，并且随着暴露时间的延长，flos-aquas显着下降，这表明光保护机制失效。这些结果表明，细胞活力的丧失，氧化应激的增加以及对细胞内结构和光合系统的损害可能是抑制作用的机制。我们的结果表明，WMPAE可能是一种控制A增长的新颖有效的方法。在水生环境中的浮游生物。