Effects Of Biodegradable Films On The Growth And Cd Uptake Of Three Vegetables

Biodegradable mulches have become the focus of attention,as pollution caused by plastic residue materials becomes increasingly severe.Heavy metal pollution,especially cadmium is still a major problem for agricultural production.BDMs have been made by different polymers and compositions and elected to be degraded in situ,into the agricultural soils.These plastic mulches in soil,with their large surface area may absorb other soil pollutants like heavy metal pollutions,especially cadmium(Cd).However,how BDMs affect the growth and Cd uptake by plants still not known.A pot experiment was carried out to investigate the effects of three biodegradable film fragments on the growth and Cd uptake of three vegetable grown in a Cd polluted soil(Lactuca sativa,Brassica campestris and Brassica chinensis).The experiment treatments included four mulching film fragments(commercial biodegradable films bought from three factories,i.e.BS,HB,SH and a no degradable film,PE)at the application rates of 2 and 10g/kg.No mulching film fragments was used as control CK.The results obtained are listed as follows:(1)PE incorporation decreased the p H values for soil planted three vegetables,all BDMs decreased the p H values of B.chinensis planted soil,SH increased p H values of L.sativa and B.campestris planted soils,BS at high rate can increase p H of L.sativa planted soil while had no influence on p H values of B.campestris.On the contrary,HB did not change the p H values of L.sativa planted soil but increased the p H of B.campestris planted soil.No obvious trends of p H changes when the fragment rates increased with same plant.(2)The influence of plant types on SOM was more extensive than the types of BDMs and the changes of SOM after incorporating BDMs varied with plants grown on it.PE had no obvious effect on SOM for L.sativa and B.chinensis planted soil but increased SOM for B.campestris planted soil,BS increased SOM for L.sativa and B.chinensis planted soil,but decreased SOM for B.chinensis planted soil.HB and SH resulted in no significant difference for SOM grown on three vegetables.(3)Addition of PE and BS fragments significantly increased the content of available Cd in B.chinensis planted soil,had no obvious influence on these values in L.sativa and B.campestris planted soil.Addition of HB and SH decreased available Cd in all soils.(4)BDMs and PE have no significant influence on the height of three vegetables.However,BDMs can improve the SPAD values of B.chinensis and L.sativa but have no influence on the SPAD values of B.campestris.Therefore,the influences follow the order of B.chinensis > L.sativa > B.campestris.(5)PE at low application rate had no obvious influence on the growth of L.sativa and B.chinensis but inhibited the growth of these two vegetables.It inhibited the growth of B.campestris at all application rates.BDMs at a higher rate promoted the growth of L.sativa and B.chinensis,but inhibited the growth of B campestris except SH.(6)When BDMs was incorporated into soil,the treatments BS and HB could decrease the Cd accumulation the root and shoot of L.sativa and B.chinensis,and in the shoot of B.campestris.SH incorporation increased the Cd content in the L.sativa and B.campestris but decreased Cd contents in the root of B.chinensis and the shoot of the three vegetables.PE fragments at the 10 g/kg increased Cd contents in the root and shoot of the three vegetables.Therefore,we can conclude that BDMs results in a decrease in Cd accumulation in vegetables.These are crucial in assessing BDMs’ impact on soil health and the long-term viability of agroecosystems.Therefore,we concluded that the effects of plastic fragments on the plant biomass and Cd contents depended also to the plastic types,the rates of treatments and crop species.However,BDMs showed a high did not decreased the biomass of vegetables.