Synthesis Of Nano-ferrihydrite And Application Of Bio-nano-complex Foliar Fertilizers

Iron is not only an essential micro-nutrient for plant and human,but also is an important component for many nano-materials.It has little been known that plant uptakes nano-ferrihydrite,which has huge specific surface area and can be used as a carrier for additives and nutrients,for the alleviation of plant iron deficiency.This paper was aimed to explore the potentials of the synthetic and microbial transformed ferrihydrite nano-particles to be used as a carrier of foliar nutrients and to be used as a nutrient for uptake by plant.Main results of this research are listed as follows.(1)Analysis by XRD,SEM and TEM showed that the laboratorial synthetic ferrihydrite is a nano-sized iron oxide with weak crystallization.(2)Anaerobic culture experiments with ferrihydrite as electron receptor and lactic acid as electron donor showed that Shewanella xiamenensis strain NA4-4 had the highest efficiency in reduction of ferric iron from ferrihydrite among Shewanella xiamenensis strain NA4-4,Shewanella oneidensis strain MR-1 and Lysinibacillus macrolides strain D2.Strain D2 had low reduction rate in the first 48h of culture and the reduced ferrous iron was re-oxidized after 72h of culture.The SEM analysis showed ferrihydrite after culture was flaky particle,which indicated that the bacteria had modified the shape of ferrihydrite.(3)Pot with sand greenhouse experiments showed that ferrihydrite fed by foliar could be absorbed and used by peanut,that either ferrihydrite or ferrihydrite with urea as foliar fertilizers had significant positive effects in correcting symptoms caused by iron deficiency and promoting plant growth,and that these effects were dose-dependent.As compared with spraying water,spraying ferrihydrite increased the leaf active iron concentrations by 75.1%to 436.4%.As compared with spraying urea,spraying ferrihydrite with urea increased leaf active iron concentration by 106.5%-526.5%.(4)Pot with soil greenhouse experiments showed that ferrihydrite with surfactant Tween 20 and urea as a foliar fertilizer had significant positive effects in promoting plant growth.As compared with spraying water,spraying the foliar fertilizer increased content of leaf chlorophyll,shoot height,above-ground dry weight and fresh weight by 20.1%,5.8%,123.6%and 70.2%,respectively.As compared with spraying urea,spraying the foliar fertilizer increased these index by 2.7%,13.4%,74.4%and 60.7%,respectively.(5)Three fermented products(NA,MR and D),which were obtained from anaerobic fermentation of Shewanella xiamenensis strain NA4-4,Shewanella oneidensis strain MR-1 and Lysinibacillus macrolides strain D2,respectively,with ferrihydrite and lactic acid,were used with addition of an amino acid liquid(A)for preparation of 3 bio-nano-complex foliar fertilizers(NA-A,MR-A and D-A).Pot with sand greenhouse experiments showed that the 3 fermented products and the 3 bio-nano-complex foliar fertilizers had significant positive effects in correcting symptoms caused by iron deficiency and promoting plant growth.As compared with spraying water,spraying NA,MR,D,A,NA-A,MR-A,and D-A increased the leaf active iron concentrations by 45.1%,24.9%,5.9%,9.6%,66.2%,81.3%and 121.6%,respectively,while increased above-ground dry weight by 30.5%,10.9%,32.5%,12.5%20.0%,21.8%,21.8%.