Compound repair effect of carbon dots and Fe2+ on iron deficiency in Cucumis melon L.

Iron-deficiency is one of the most widespread micronutrient deficiency faced by plants, and proper iron supplementation is essential for the growth of crops and for people to obtain iron from food. In order to explore new methods of iron supplementation, we studied the repair effect of CDs on iron-deficient (Cucumis melo L.) muskmelon. Iron-deficient muskmelons were treated with different concentrations of Fe2+, CDs and their complexes. The results showed that CDs significantly increased the iron transport rate and it is noteworthy that 75 mg/L CDs increased the iron transport rate of 0.7 mg/L Fe2+ by 134%. The compound treatment reduced the oxidative stress caused by iron deficiency, such as the CAT activity in the leaves of the compound treatment group was 10%-50% lower than that of the iron supplementation alone. Fluorescent imaging results of melon proved that CDs entered into the muskmelon seedlings. In combination with the above results and the adsorption of CDs, we speculated that the way CDs promoted iron absorption and transport was most likely to combine with Fe2+ and co-transport in melon, which changed the content of reactive oxygen species and other free radicals, thus causing changes of physiological state of melon. This study confirmed that CDs had a positive effect on the iron deficiency of muskmelon, and improved the growth of muskmelon under the condition of iron deficiency, which has a certain reference value for further optimization of iron supplementation solution.