مطالعه تأثیر نقاط کوانتومی گرافن سنتز‏شده با روش سبز مبتنی بر عصاره‌ی آبی گیاه خوشاریزه (Echinophora cinerea) علیه نماتد Meloidogyne javanica در شرایط گلخانه

Root-knot nematodes (Meloidogyne spp.) are one of the most important pathogens in tomato. Graphene has various beneficial properties such as anti-fungal and anti-bacterial abilities, promoting plant growth, and being used in fertilizers, nano-encapsulation and smart release systems, pollutant removal, quantitative measurement of pesticides and insecticides, as well as in diagnostic and precision agriculture systems. Graphene quantum dots (GQD) possess unique characteristics including high light stability, biocompatibility, and low toxicity. In the present study, the effect of green GQD, which was synthesized using the aqueous extract of Echinophora cinerea, as well as the aqueous extract of E. cinerea alone, on M. javanica was examined in greenhouse conditions. In an initial investigation, it was found that the concentration of the as-synthesized GQD and the aqueous extract of E. cinerea resulting in 50% mortality of the second-stage juveniles (LC50) was 0.06% and 0.062% respectively, when tested in vitro. In the present study, tomato seeds cv. Early-Urbana were planted in one-kilogram pots filled with a mixture of field soil, sand and cow manure and kept in greenhouse conditions (27±4 °C and 16 hours of light and 8 hours of darkness). After 21 days, the pots were treated with 50 ml of 0.06 and 0.12% of as-synthesized GQD, and 0.062 and 0.124% of aqueous extract of E. cinerea and simultaneously inoculated with 5000 eggs of M. javanica. After 60 days, the plants were harvested and the plant growth and nematode population indices were investigated. The results showed, as-synthesized GQD at the rate of 0.12% as the best treatment, reduced the number of galls, egg masses, eggs and nematode reproduction factor by 16, 61, 55, and 54%, respectively, and increased the shoot length, fresh and dry weight, and the root fresh weight of plants by 7, 21, 14 and 33%, respectively, compared to the control plants. It was also found that the aqueous extract of E. cinerea at the rate of 0.124 reduced the number of galls, egg masses, eggs and nematode reproduction factor by 18, 30, 55 and 50%, respectively, and increased the shoot length, shoot fresh and dry weight, and the root fresh weight of plants by 12, 21, 24 and 31%, respectively, compared to the control plants. This study highlights the effectiveness of the aqueous extract of E. cinerea and as-synthesized GQD in managing M. javanica in tomato plants.