Effects Of Calcium And Zinc On Growth And Fruit Quality Of Tomato

Zinc(Zn)and Calcium(Ca)are essential mineral elements for plant growth and development.Zinc plays an important role in regulating nitrogen metabolism,amino acid metabolism,protein synthesis,carbohydrate metabolism,growth hormone regulation,enzyme activation,photosynthesis and reproductive development.Calcium is not only a signal substance for regulating plant growth and development,photosynthesis and enzyme activity,and also is a structural substance involved in cell building.In recent years,with the improvement of consumption level,the market has put forward higher requirements for the quality and function of tomato.In this experiment,tomato ’Zheyingfen No1’ was used as material to apply zinc fertilizer(0,0.1 g/L)to coconut bran before tomato seedling planting.Then different concentrations of calcium chloride(0,0.25%,0.5% and 1.0%)were sprayed on the leaves at first flowering and first fruiting stage.To explore the effects of spraying exogenous calcium under zinc fertilizer application on tomato growth characteristics,photosynthetic characteristics and fruit quality,and to provide a theoretical basis for synergistic regulation of tomato growth and fruit quality based on Zn and Ca.The test results are as follows:1.The plant height,stem diameter,internode spacing and fruit number per spike of tomato plants were significantly increased by 26.84%,11.33%,40.93% and 32.26%respectively under the application of zinc fertilizer.Low,medium and high concentrations(0.25%,0.5% and 1.0%)of calcium chloride foliar spraying significantly promoted the physiological characteristics of tomato.The treatment of 0.5% calcium chloride spraying had the most significant effect.Compared with blank control,the plant height,node spacing and fruit number per spike were significantly increased by 28.62%,31.22% and 25.81%,respectively.There was no further increase in plant height,stem diameter,node spacing and fruit number per spike under the treatment of different concentrations of calcium and zinc combined application.2.Zinc fertilizering can promote the Pn,Gs and Tr of tomato leaves were significantly increased by 0.40,1.14 and 1.19 times,respectively.Foliar spraying with the different concentration of calcium chloride increased chlorophyll content and photosynthesis in different degrees;the 0.5% calcium chloride treatment had the best effect,compared with CK,chlorophyll a,chlorophyll b and carotenoid content increased by 54.28%,45.89% and 50.73%,Pn,Gs and Tr increased by 0.49,3.31 and 2.87 times,respectively.The treatment of Zn fertilizering combined with 0.5% Ca spraying could further promote the photosynthesis of tomato,compared with the CK,the Pn,Gs and Tr under the treatment increased by 0.93,7.03 and 5.43 times,respectively.3.Treat of the zinc fertilizering or spraying calcium chloride increased the fruit biomass,promoted the accumulation of soluble solids,lycopene,free amino acids and soluble sugar,and effectively inhibited the increase of organic acids and nitrate nitrogen.The accumulation of lycopene,vitamin C,soluble protein and soluble sugar in fruit could be further promoted by the appropriate concentration of calcium combined with zinc.Zinc treatment did not increase the contents of Ca,Mg,K,Na and Zn in fruits;low and medium concentrations of calcium could effectively promote the accumulation of Ca and Zn in fruits;and the Ca and Zn contents of fruits were further increased under the combined application of appropriate concentration of Ca with Zn.At the same time,both Zn and Ca treatments could inhibit the accumulation of phytic acid and increase the contents of available Zn and Ca in fruits.4.Zinc fertilizering can promote the activities of SOD,POD and CAT significantly increased by 0.59,0.40 and 6.27 times.The activities of antioxidant enzymes were increased by spraying different concentrations of calcium chloride;the best treatment was 1.0%concentration of calcium chloride,and the activities of SOD and CAT were increased by 0.35 and 4.78 times respectively compared with the CK.At the same time,the activities of some antioxidant enzymes and the content of antioxidant substances(vitamin C)were further increased after the application of appropriate concentration of calcium combined with zinc.5.Zinc fertilizering could significantly increased the contents of sugar and sucrose,and the activities of acid invertase and neutral invertase.Different concentrations of calcium chloride foliar spraying increased reducing sugar content and acid invertase activity,inhibited sucrose synthase activity.Low and medium concentrations of calcium combined with zinc could further promote sucrose accumulation and increase the activities of acid invertase,neutral invertase and sucrose phosphate synthase.6.Zinc fertilizer could significantly increase the contents of amino acids in tomato fruit,including essential amino acids for human body,essential amino acids for children,sweet amino acids and aromatic amino acids.The low and medium concentration calcium spray promoted the increase of amino acids and the contents of multi amino acids,but the contents of amino acids decreased significantly under high concentration calcium treatment.Combined application of different concentrations of calcium with zinc did not further promote the increase of amino acid content,but effectively regulated the ratio of various amino acids to the total amount.7.Zinc fertilizering could significantly increased the contents of aldehydes,esters,ketones,alcohols,hydrocarbons and other volatile flavor compounds in fruits.The main flavor compounds of Hexanal,trans-2-vinylaldehyde,trans-2-pentenol and linalool were significantly increased by 1.05,2.05,2.12 and 2.09 times,respectively.Different concentrations of calcium chloride foliar spraying also promoted the content of volatile flavor compounds in fruits;However,the increasing trend of the contents of various flavor compounds decreased significantly under the combined application of different concentrations of calcium with zinc.8.Through the correlation analysis of 23 indexes such as single fruit weight,soluble solids,lycopene and amino acid components,the comprehensive score of fruit under each treatment was calculated,and the ranking was as follows: 0.5Ca+Zn > 0.25Ca+Zn > Zn >0.5Ca > 0.25 Ca > 1.0Ca+Zn > CK > 1.0Ca.