纳米银和纳米氧化铁对甜瓜白粉病防治研究

为探究不同浓度纳米银和纳米氧化铁溶液对甜瓜抗白粉病的影响及其作用机理，于4叶1心期对甜瓜植株喷施纳米银（T1处理）、纳米氧化铁（T2处理）溶液及清水（CK），对薄皮甜瓜幼苗叶片病情指数及过氧化物酶（peroxidase，POD）、超氧化物歧化酶（superoxide dismutase，SOD）、过氧化氢酶（hydrogen peroxidase，CAT）活性和丙二醛（malondialdehyde，MDA）含量进行测定。结果表明，与对照相比，喷施纳米银和纳米氧化铁可显著提高薄皮甜瓜抗白粉病的能力，显著降低叶片病情指数，其中，T1-4和T2-4处理（10.00 μmol·mL^-1）病情指数比对照分别减少32.52%和34.96%。T1和T2处理均提高了叶片中POD和SOD活性，在病原菌接种后不同处理时间，T1和T2处理中POD活性呈现先升高后降低的趋势，最高值均出现在接种后72 h，其中，接种72 h后T1-3处理（5.00 μmol·mL^-1）POD活性较对照高56.6%，T2-4处理（10.00 μmol·mL^-1）比对照高61.1%。T1处理中SOD活性先升高，在72 h达到峰值后降低，T1-3处理（5.00 μmol·mL^-1）接种72 h后出现最大值，为376.0 U·g^-1 FW；T2处理中SOD活性呈现逐渐升高的特点，T2-4处理（10.00 μmol·mL^-1）接种96 h后较对照高85.6%。与对照相比，T1和T2处理叶片CAT活性呈现不一致的变化趋势。与对照相比，T1处理MDA含量较低，整体呈现先升高后降低的趋势，T1-3处理（5.00 μmol·mL^-1）48 h MDA含量较对照降低15.8%；T2处理中MDA含量除处理72 h低于对照组，其余均显著高于对照组，T2-1（1.25 μmol·mL^-1）处理24 h后MDA含量较对照组升高41.5%。综上所述，纳米银和纳米氧化铁处理对甜瓜白粉病具有一定的防治效果，研究结果为纳米银和纳米氧化铁对甜瓜白粉病防治提供了理论依据。

Effect Trials of Nano-silver and Nano-iron Oxide Against Melon Powdery Mildew

In order to explore the effects and mechanisms of different concentrations of Nano-silver and Nano-iron oxide solutions on powdery mildew resistance in melon， the melon seedlings were sprayed with Nano-silver （T1）， Nano-iron oxide （T2） solutions and water （CK） in four leaves and one heart stage， and the disease index， activities of peroxidase （POD）， superoxide dismutase （SOD）， catalase （CAT） and content of malondialdehyde （MDA） in leaves were determined. The results showed that the spraying of Nano-silver and Nano-iron oxide significantly improved the resistance of thin-skinned melon to powdery mildew compared with the control， and significantly reduced the leaves condition index with the T1-4 and T2-4 treatments （10.00 μmol·mL^-1） decreasing 32.52% and 34.96%， respectively. Both T1 and T2 treatments increased POD and SOD activities in leaves， and POD activities in T1 and T2 treatments showed an increase followed by a decrease at different treatment times after inoculation， with the highest values occurring at 72 h after inoculation， and after 72 h of inoculation T1-3 treatment （5.00 μmol·mL^-1） was 56.6% higher and T2-4 treatment （10.00 μmol·mL^-1） was 61.1% higher than the control. The SOD activity in T1 treatment increased first， peaked at 72 h and then decreased， with a maximum value of 376.0 U·g^-1 FW at 72 h after inoculation in the T1-3 treatment （5.00 μmol·mL^-1） and a gradual increase in SOD activity in the T2 treatment， which was 85.6% higher than the control after 96 h of inoculation in the T2-4 treatment （10.00 μmol·mL^-1）. Compared with the control， the CAT activity of T1 and T2 treated leaves showed inconsistent trends. The MDA content of T1 treatment was lower than that of the control， showing an overall trend of first increasing and then decreasing， and the 48 h MDA content of T1-3 treatment （5.00 μmol·mL^-1） was 15.8% lower than that of the control. The MDA content in the T2 treatment was significantly higher than the control group except for the treatment at 72 h， which gradually increased before 48 h and then decreased， and the MDA content increased by 41.5% after 24 h in the T2-1 treatment（1.25 μmol·mL^-1） compared with the control group. In conclusion， Nano-silver and Nano-iron oxide treatments were effective against melon powdery mildew， which provided a theoretical basis for the control of melon powdery mildew by Nano-silver and Nano-iron oxide.