Byusingnutritionaldiagnosisofcitrusleavesanddeterminingsoilmicronutrients,therelationshipbetweensoilmicronutrientsandcitrusgrowthinsouthernChinahasbeenstudied.Studiesshowedthattherewasasignificantpositivecorrelationbetweenavailablemicronutrients(suchasZn,Mo,Cu)inthesoilandthecorrespondingnutrientsincitrusleaves.Thus,onecanroughlylearnofthesufficiencyordeficiencyofcertainnutrientsinsoilsbyanalyzingcitrusleaves.RationalsprayofZnBorMofertilizernotonlyimprovedcitrusyieldsbutalsoincreasedthetotalsugarofSatsumamandarinandofXinhuiorangeby2.9and17.2%respectivelycomparedwiththecontrol.SprayingMofertilizerincreasedthevitaminCcontentofSatsumamandarinjuiceby4.7%-8.4%,maturatedfruits7-10daysearlierandgavethepeelabrightercolor.TheultramicroscopiccharacteristicsofZn-deficientcitrusleaveswereinvestigatedunderanelectronmicroscope.ResultsshowedthattheZn-deficientleafcellwascharacterizedmainlybypoorcytoplasm,endoplasmicreticulaandribosomesandbybigstarchgrainsinthechloroplast.AsaresultofsprayingZnfertilizerthestructureofthecellreturnedtonormal,thecytoplasmbecamerichandtheamountofchloroplastincreased.Therealsoappearedagreatdealofmultiformendoplasmicreticula,thuspromotingthephotosynthesisofZn-deficientplants.Thisprovidesacytologico-theoreticalbasisforfertilizationofhigh-yieldingcitrustrees.
