Preliminary Research On Cadmium Accumulation Rule And Its Control In Lentinula Edodes

Lentinula edodes is a highly nutritive edible mushroom with characteristic fragrance and important medical value. Recently issues on heavy metal accumulation in macro basidiomycete have been widely noticed. Rules and control methods about heavy metal accumulation in L. edodes have been important task that edible mushroom scientific workers have to face to.As、Hg、Cd and Pb content of L. edodes of different cultivation model in main production area of L. edodes in Hubei province are investigated in this article. Sawdust, wheat bran, gypsum, water and layer soil samples used in cultivation are gathered for preliminarily analysis of the possible source of Cd. Experiment about adding Cd artificially to substrate used L. edodes cultivation is carried for analysis of relevance between Cd content in substrate and Cd content in L. edodes fruit body. Cd content of fruit body of different L. edodes strains and different development stage and different part of fruit body is measured for research on Cd accumulation rules. Gypsum, calcium superphosphate and pectin are added into fluid medium that contains Cd to figure out whether they can inhibit the accumulation of Cd by mycelia. Meanwhile, these three exogenous additives are added into substrate used in autumn shelf-cultivation to research the effect of these three exogenous additives to L, edodes yield, quality and control of Cd accumulation. The main results of this research are as follows.1. As、Hg、Cd and Pb content of55L. edodes fruit body samples from different cultivation model are0.216mg/kg,0.010mg/kg,1.284mg/kg and0.136mg/kg, respectively, among which the Cd content of40%samples exceed the Chinese standard "NY5095-2006pollution-free food mushrooms".2. Experiment of artificially adding Cd into substrate used in autumn shelf-cultivation suggest that Cd content in substrate highly significantly positive relevant to Cd content in L. edodes fruit body and the Cd accumulation factor of fruit body to substrate is2.7-3.8. Cd accumulation ability of different L. edodes strains is different; accumulation ability of Huaxiang8is weakest while accumulation ability of Biyang6is strongest. Cd content of different development stage of L. edodes fruit body is different, blastema> fruit body bud> young fruit body> grown fruit body> old fruit body. Cd content of different part of L. edodes fruit body is different, gill> gap> stipe.3. In fluid medium, exogenous additives gypsum, calcium superphosphate and pectin do not inhibit mycelia growth and decrease Cd content in mycelia to some degree, which demonstrate their role in inhibiting Cd accumulation in mycelia. In autumn shelf-cultivation, gypsum, calcium superphosphate and pectin do not inhibit mycelia growth either. Gypsum has an obvious effect in control Cd accumulation in fruit body: addition of1.5%,2%,2.5%and3%gypsum can decrease32.2%,34.0%,45.3%and45.4%Cd content of fruit body, but yield will decrease when gypsum concentration exceed2.5%. Gypsum can also increase Ca content and decrease Zn and Mg content, the largest decrease span of which are almost10%.0.1%calcium superphosphate can also significantly decrease19.1%Cd content of fruit body, but as the increase of calcium superphosphate concentration, L. edodes yield will be severely affected and Cd content will also increase. Calcium superphosphate can decrease Ca and Mg content and increase Zn content. Pectin can increase Ca content of fruit body, but has no effect on yield and Cd accumulation of L. edodes fruit body. Therefore, the gypsum concentration used in cultivation is suggested increasing to2%-2.5%, which benefits to inhibition of Cd accumulation and has a good effect on control of Cd accumulation in L. edodes.