| It is conclusively proven for about one century that external surfaces(including cuticle,stomata,trichomes or lenticels,etc.)of plant above-ground(stems,leaves and fruits and other organs)can absorb foliar nutrient feedings,enhance cellular nutrient untake and utilization,and promote nutrient thranslocation in plant body.However,the characteristcs of the external.surfaces are highly different among plants,so it is necessary to study the composition of foliar fertilizers for upgrading the efficiecy of foliar nutrition.Nanoparticles due to their huge specific surface area and particular properties have high potential to be used as assistant components in formulation of foliar fertilizers.In this paper,we presented results of our studies on the adsorption and binding characteristics of nano-goethite and kaolinite with phosphate ions,urea,glucose and alanine,and the effects of nano-goethite and kaolinite addition on enhancement of an amino acid foliar fertilizer by pot experiment.Bach adsorption method was used to study adsorption of glucose,urea and potassium dihydrogen phosphate by nano-goethite and kaolinite.The results indicate that the phosphate adsorption data of two minerals can be fitted well by one-sit Langmuir mold.The qmax of nano-goethite is 7 times the amount of kaolinite.The glucose and urea adsorption data of two minerals can be fitted by Freundlich mold.This indicate that adsorption belong to multilayer adsorption of heterogeneity surface.The quantity of urea adsorped to nano-goethite is 4 times that of kaolinite,and the quantity of glucose adsorped to nano-goethie is 3 times that of kaolinite.Two dimentional Fourier transform infrared spectroscopy(FTIR)correlation analysis of urea adsorpted to goethite indicated that urea molecules were adsorpted by forming hydrogen bond with oxygen sites and hydroxyl of surface of nano-goethie.In adsorption process,Fe-O and Fe-OH functional groups of goethite take effect,while C=O and NH2 functional group of urea take effect.Fe-O could possibly form hydrogen bond with NH2 and Fe-OH could possibly form hydrogen bond with C=O.According to Nada's rule,we could arrange the correlation functional groups bongding sequence follow this sequential order:the hydrogen bond formed between Fe-O and NH2>intermolecular forces between urea moleculars>the hydrogen bond formed between Fe-OH and C=O.Morever,it also indicated that urea moleculars adsorped by goethite can adsorp other urea molexulars through intermolecular forces,leading to adsorption of urea by goethite as multilayer adsorption and the accuracy fitting Freundlich mold.As a comparison,two dimentional FTIR correlation analysis on alamine also demonstrated that NH2 and C=O function group of the amino acid could form hydrogen bond with oxygen site and hydroxyl of surface of goethite.Fe-O with NH2 was prior to Fe-OH with C=O in hydrogen bonds formation.However,no evidence suggested that intermolecular forces existed between alamine molecules.The results from seed germination experiments showed that the treatment of amonio acid foliar fertilizer can improve germination potential and germination index significantly as compared to with control,in which only water was added,but had no effect on germination rates,which was not influenced by addition of nano-goethite or kaolinite.The results from pot experiments demonstrated that spraying amino acid foliar fertilizer treatment and spraying amino acid foliar fertilizer added kaolinite and nano-goethite treatments significant increased the plant hight,stem diameter,above ground dry and fresh weight and under ground dry and fresh weight of tomato plant.The enhancement effect of nano-goethite or kaolinite was depended on amounts of addition rate.As compared with no addition,the treatment added 1g/L of nano-goethite or kaolinite significantly increased the stem diameter and fresh weight of above ground,whereas the treatment added 0.1 or 0.5g/L nano-goethite had no difference in plant growth from amino acid foliar fertilizer treatment.From above results,we concluded that nano-goethite and kaolinite could be used as auxiliary agents in amino acid foliar fertilizer to enhance the spraying effect of amino acid foliar fertilizer in promotion of plant growth. |
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