Preliminary Study On The Application Of Perylene Diimide Photosensitizers And Their Compounding With Foliar Fertilizers

The energy crisis and population growth are forcing continuous improvements in photosynthetic efficiency and yield of crops,consuming fewer resources to produce more food is a global challenge.Therefore,it makes sense to find new efficient and environmentally sustainable ways to increase crop yields to meet the growing global demand for food,feed,and energy.The development of efficient solar energy conversion artificial systems is one important way to achieve sustainable agricultural development.Artificial photosynthesis is not only free from the constraints of external environmental conditions but can also break through the limits of natural photosynthesis itself.Inspired by the natural photosynthesis process,various artificial light-harvesting systems(ALHS)have been fabricated using different materials,such as organic fluorescent dyes,carbon quantum dots,organogels,and other materials.Among them,the organic fluorescent dye perylene diimide(PDI)has gained much attention due to its excellent photophysical/photochemical stability,high fluorescence quantum yield,easy adjustment,and other properties.At present,there are few studies on the practical applications of perylene diimide and its derivatives for promoting crop growth.Therefore,in this paper,a PDI-based photosensitizer was prepared to study its effect on the growth of rapeseed and other crops as well as its synergistic effect in combination with foliar fertilizer,and the results were as follows:(1)N,N’-dicyclohexyl-1,7-dicyclohexylamino-3,4,9,10-perylenediimide(PDI-4CHA)was prepared using 1,7-dibromo-3,4,9,10-perylene tetracarboxylic dianhydride as the acceptor and cyclohexylamine as the donor.Subsequently,PDI-4CHA composite nanocapsules were obtained by wrapping silica nanoshells on the surface of PDI-4CHA.The experimental results show that PDI-4CHA has a strong absorption at 400-750 nm and has the potential to promote photosynthesis;PDI-4CHA composite nanocapsules were obtained after encapsulation of silica shells,which extended the absorption spectrum to 800 nm and were well soluble and stable in the aqueous phase,laying the foundation for subsequent compounding and spraying with watersoluble foliar fertilizers.(2)To investigate the synergistic effects of foliar sprays of photosensitizer(PS,PDI-4CHA composite nanocapsules),the photosensitizer in combination with inorganic nitrogen,phosphorus,and potassium foliar fertilizer W(PS&W)on the leafy vegetable rapeseed,and photosensitizer in combination with organic matter-rich humic acid foliar fertilizer F(PS&F)on the leafy vegetable cabbage.The experimental results showed that the photosensitizer spraying concentration in the range of 0-3% could increase the SPAD value(Relative chlorophyll content)and dry fresh weight of rapeseed,and did not reduce the quality of rapeseed.Among them,2% PS treatment had the best effect on the growth of rapeseed,and the SPAD value,dry weight,and fresh weight of rapeseed increased by 21.93%,60.72%,and44.93%,respectively,in the last sampling compared with water spraying.The experiment on the effect of PS&W treatment on the growth of rapeseed showed that rapeseed grew best under1.2% PS&W treatment.Compared with CK,W,and PS treatments,the fresh weight of 1.2%PS&W treated rapeseed increased by 161.43%,173.90%,and 105.46%,and the dry weight increased by 163.98%,173.92%,and 107.64%,respectively,in the last sampling,and the quality of the compound treated rapeseed was not lower than that of the control treatment,which proved that photosensitizers compounded with inorganic nitrogen,phosphorus and potassium foliar fertilizers had a certain synergistic effect on rapeseed.The same conclusion was obtained in the experiment of the effect of PS&F treatment on cabbage,and the synergistic effect of 1.2%PS&F concentration on rapeseed was the most obvious,which proved that photosensitizer and organic matter-rich humic acid foliar fertilizer F also had a promoting effect on cabbage.(3)To investigate the effect of photosensitizer compounded with inorganic nitrogen,phosphorus,and potassium foliar fertilizer W(PS&W)on yield and quality improvement of peanuts in the field.The experimental results showed that compared with CK,the yield of peanut increased by 20.75%,crude protein increased by 5.83%,and linoleic acid increased by10.32% in 2% PS&W treatment,which proved that the spraying of perylene diimide photosensitizer in combination with inorganic nitrogen,phosphorus,and potassium foliar fertilizer in actual production had a promoting effect on peanut yield increase.