Soil microorganisms alleviate the allelopathic effect of Eucalyptus grandis × E. urophylla leachates on Brassica chinensis

Soil microbes may be critical players in determining the allelopathic potential of some plants. Low levels of plant community biodiversity in Eucalyptus plantations have been attributed to the allelopathic potential of these tree species. The role of soil microbes in the allelopathic effect of leaf leachates of the hybrid tree Eucalyptus grandis x E. urophylla, was tested in Petri dish assays with Brassica chinensis as a receiver plant. Soils were collected from either a local garden (soil A) or a Eucalyptus plantation (soil B) and half of each soil was sterilized to remove microbes. These soils were then treated with E. grandis x E. urophylla leachates for 0-72 h. Seed germination of B. chinensis was significantly inhibited in soils treated with leaf leachates relative to untreated soils. The inhibitory effect of the leaf leachates was more pronounced in sterilized soils. Total phenolic content was obvious lower in nonsterile leachate-treated soils than in sterile soils. Biomass of B. chinensis was negatively correlated with the total phenolic content in soils. Our findings suggest that soil microbes can alleviate the allelopathic potential of Eucalyptus and thereby its negative impact on plant growth.

Overview of Ecological Toxicity of Potassium Chlorate Pollution

Potassium chlorate( KClO_3),as regulation medicament for longan production period,has been widely used in industrial application and enters the global ecological and environmental system. Its strong oxidation leads to certain pollution to ecological environment. In recent years,researches about ecological toxicity of KClO_3 have realized considerable progress,so it is necessary to make proper summarization. This paper makes an overview of researches about ecological toxicity of KClO_3 to land plants,longan,aquatic organism,animals,and human beings. Finally,it comes up with recommendations and prospects including further studying precise detection and degradation technologies for strong oxidation ClO_3^-and its residue,strengthening biological monitoring and recovery technology of KClO_3,and implementing wide science popularization.

Salinity elevates Cd bioaccumulation of sea rice cultured under co-exposure of cadmium and salt

Salt-tolerant rice (sea rice) is a key cultivar for increasing rice yields in salinity soil.The co-existence of salinity and cadmium (Cd) toxicities in the plant-soil system has become a great challenge for sustainable agriculture,especially in some estuaries and coastal areas.However,little information is available on the Cd accumulating features of sea rice under the co-stress of Cd and salinity.In this work,a hydroponic experiment with combined Cd(0,0.2,0.8 mg/L Cd^(2+)) and saline (0,0.6%,and 1.2%NaCl,W/V) levels and a pot experiment were set to evaluate the Cd toxic risks of sea rice.The hydroponic results showed that more Cd accumulated in sea rice than that in the reported high-Cd-accumulating rice,Chang Xianggu.It indicated an interesting synergistic effect between Cd and Na levels in sea rice,and the Cd level rose significantly with a concomitant increase in Na level in both shoot(r=0.54,p<0.01) and root (r=0.66,p<0.01) of sea rice.Lower MDA content was found in sea rice,implying that the salt addition probably triggered the defensive ability against oxidative stress.The pot experiment indicated that the coexistent Cd and salinity stress further inhibited the rice growth and rice yield,and the Cd concentration in rice grain was below 0.2 mg/kg.Collectively,this work provides a general understanding of the co-stress of Cd and salinity on the growth and Cd accumulation of sea rice.Additional work is required to precisely identify the phytoremediation potential of sea rice in Cd-polluted saline soil.