| Cyphomandra betacea,the tree tomato of Peruvian origin is making an impact as commercially attractive fruit.In this experiment,straw with different Cadmium(Cd)accumulate characteristics(tolerate,accumulate,hyperaccumulate)were mulched on soil surface in order to study the effects of straw mulching on growth and Cd accumulation of C.betacea seedlings.In this experiment,pot soil was mulched with different straw and then planted with C.betacea seedlings,the growth and Cd accumulate indexes were determined to select the proper straw to regulate Cd accumulation in situ in C.betacea seedlings and provide reference for the prevention and control of Cd pollution in C.betacea planting area and other orchards.The main results were as follows:1.Effects of mulching with Cd tolerant plant species(Digitaria sanguinalis,Plantago asiatica,Clinopodium confine and Ranunculus sieboldii)straw at soil surface on the growth and Cd accumulation of C.betacea under Cd contamination showed that:(1)Mulching with four tolerant plant species straw increased the biomass of root,stem,leave,shoot and the whole plant compared with control,and also improved the photosynthetic pigment content and antioxidant enzyme(SOD,POD,CAT)activity.(2)Mulching with straw of D.sanguinalis,C.confine and R.sieboldii increased Cd content in shoot of C.betacea,respectively,by 80.74%,58.09%and 28.31%compared with the non-mulching control.Only mulching with straw of P.asiatica decreased Cd content in shoot of C.betacea by 12.25%compared with the control.(3)Mulching with straw of D.sanguinalis,C.confine and R.sieboldii improved Cd translocation factor(TF)of C.betacea,and mulching with straw of P,asiatica reduced that compared with the control.(4)Therefore,mulching with straw of P.asiatica could promote the growth of C.betacea seedlings,and decreased Cd content in shoot of C.betacea seedlings,which would be benefit to growth and safe production of C.betacea in Cd-contaminated orchards.2.Mulching with Cd accumulate plant(Trifolium repens,Eclipta prostrata,Conyza Canadensis,Stellaria media)straw showed that:(1)The straw of T.repens,C.canadensis and S.media increased the root,stem,leaf,shoot and whole plant biomasses of C.betacea seedlings under Cd stress compared with the non-mulching control,increased the chlorophyll a,chlorophyll b,total chlorophyll and carotinoid contents,and improved SOD,POD,and CAT activities at the same time.However,the straw of E.prostrata decreased the biomass,photosynthetic pigment content and antioxidant enzyme activity of C.betacea seedlings under Cd stress compared with the control:(2)Mulching with the straw of T.repens,E.prostrate,and S.media increased the Cd contents in roots,stems,leaves,and shoots of C.betacea seedlings compared with the non-muching control,while the straw of C.canadensis decreased the Cd content in C.betacea seedlings.(3)Therefore,mulching C.canadensis straw can promote the growth of C.betacea seedlings,and decrease their Cd accumulation,which benefits the safe production of C.betacea.3.Results of mulching Cd hyperaccumulator(Solanum photeinocarpum,Tagetes erecta,Galinsoga parviflora,Bidens pilosa)straw showed that:(1)The straw of S.photeinocarpum and T.erecta significantly increased the biomass,photosynthetic pigment content,antioxidant enzyme activity of C.betacea seedlings compared with the control,but the straw of G.parviflora and B.pilosa decreased or had no significant effects on that.(2)The straw of S.photeinocarpum and T.erecta decreased the Cd contents in shoots of C.betacea seedlings,while the straw of G.parviflora and B.pilosa increased that.(3)Straw of T.erecta reduced the TF in C.betacea seedlings compared to the non-muching control,while other mulching treatments:increased the TF.(4)Therefore,mulching S.photeinocarpum straw or T.erecta straw can both reduce the Cd uptake of C.betacea,while mulching T.erecta straw reduced the Cd translation to shoot of C.betacea seedlings,which is more benefit for the growth and safe production of C.betacea. |
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