Effects Of Reciprocal Grafting On The Growth And Cadmium Accumulation In Post-Grafting Generation Of Two Cherry Tomatoes

Tomato(Solanum lycopersicum L.)is a representative of solanaceous vegetables,which is the second largest vegetable for commercial consumption second only to potato,and is widely grown around the world.Tomato has a special flavor and contains varieties of important nutrients,especially carotenoids and lycopene,which play a role in human health.Studies have shown that tomato have a certain ability to accumulate cadmium(Cd).With the increase of Cd pollution in soil,tomatoes are planted in moderate to light polluted soil,and increase risk of tomato Cd accumulation.In the experiment,the Cd accumulation characteristics of yellow(RTY-3-2),purple(purple coffee),pink(pink cherry 14-1),green(Y6-1)and red(red cherry 5-5-1-1)cherry tomato were studied,and the red and yellow cherry tomatoes with different capacity of Cd accumulation and translocation were screened out.Then,they were grafted to each other,the leaves and buds of rootstocks were kept.When the fruit mature,the seeds of rootstock and scion were collected respectively.Getting post-grafting generations of yellow rootstock(yellow cherry tomatoes as rootstock YR),yellow scion(yellow cherry tomatoes as scion YS),red rootstock(red cherry tomatoes as rootstock RR)and red scion(red cherry tomatoes as scion RS),the yellow CK(ungrafted yellow cherry tomatoes YC)and red CK(ungrafted red cherry tomatoes SC)were as control.The growth,physiological ecology,fruit quality and Cd accumulation characteristics of post-grafting generations of two cherry tomatoes were studied.The aim of the study was to screen a tomato post-grafting generation with low Cd accumulation,and to provide a reference for the safe production of vegetables under moderate and light Cd pollution.The main research is as follows:(1)There were significantly differences in the Cd accumulation of five cherry tomato.The stem,leave and shoot biomass of yellow cherry tomatoes were significantly higher than that of others under the Cd pollution.The biomass in roots of red cherry tomato is the largest,and the biomass of leaves and shoots were just behind the yellow cherry tomato.The root Cd content of yellow cherry tomatoes was significantly higher than that of other four tomato.The Cd content in shoots of red cherry tomatoes was significantly higher than that of others.The Cd translocation factor of yellow cherry tomatoes was the lowest,and the Cd translocation factor of red cherry tomatoes was the highest.Therefore,the difference of Cd accumulation between yellow cherry tomatoes and red cherry tomatoes is large,and biomass is close.(2)The plant height,root length and biomass of roots,stems and leaves in RR were significantly higher than red CK under Cd pollution conditions.There were no significant differences on photosynthesis pigments of post-grafting generations of yellow cherry tomato under Cd stress,the chlorophyll and carotenoid content were no significantly difference among YR,YS and YC.However,the contents of chlorophyll a,chlorophyll b and total chlorophyll of RR were significantly increased by grafting.Grafting significantly increased the POD and CAT activities of YS and RR.For osmotic adjustment substances,grafting significantly increased the contents of proline and soluble sugar in post-grafting generations(YR,YS,RR and RS)of tomatoes.Grafting increased the Cd content in the roots and leaves of post-grafting generations(YR and YS)of the yellow cherry tomato,and reduced the Cd content in the stems.There were different effects by grafting on the post-grafting generations of red cherry tomato.Grafting increased the Cd content in the roots of RR and reduced the Cd content in stems,leaves and shoots.Grafting increased the Cd content in roots,leaves and shoots of RS,and reduced Cd content in stems.Howerer,grafting significantly reduced the Cd translocation factor(TF)of the post-grafting generations of red and yellow cherry tomatoes.(3)Grafting affected the fruit traits of the post-grafting generations of tomato and increased the fruit shape index.At the same time,grafting increased the single fruit weight.Grafting had little effect on the color of the post-grafting generations of YR and YS,and there was no significant difference compared with the YC.But grafting significantly improved the a value and b value of the color of RR.Grafting significantly reduced the fruit firmness of YR and RR.Except for vitamin C of YR,grafting increased the content of soluble protein,soluble sugar,vitamin C,carotenoids and lycopene of the post-grafting generations of YR and YS.The effect of grafting on the post-grafting generations of red cherry tomatoes was inconsistent.Grafting increased the contents of soluble sugar,vitamin C,carotenoid and lycopene of RR,and increased the contents of soluble protein,vitamin C and lycopene of RS.Except for the YR,grafting increased the root,stem and leaf Cd content of the post-grafting generations of tomatoes.However,the Cd contents in fruit of the YR and RR significantly decreased compared with the respective controls.In conclusion,in the post-grafting generations of two cherry tomatoes,grafting increased the growth,photosynthesis,antioxidant enzyme activity and osmotic adjustment substance content of RR seedlings,and reduced the Cd content in the shoots of tomatoes.After the fruits mature,grafting improved the fruit quality of RR and reduced the cd content.Therefore,planting RR in Cd pollution soil can increase tomato resistance and fruit quality,and which can reduce the absorption of cadmium and promote tomato growth.