Tolerance of Grasses to Heavy Metals and Microbial Functional Diversity in Soils Contaminated with Copper Mine Tailings

Copper （Cu） mine tailings, because of their high content of heavy metals, are usually hostile to plant colonization. A pot experiment was conducted to determine the tolerance of four forage grasses to heavy metals in Cu mine tailings and to examine the variation in the microbial functional diversity of soils from the tailing sites in southern China. All the four grass species survived on Cu mine tailings and Cu mine tailing-soil mixture. However, on pure mine tailings, the growth was minimal, whereas the growth was maximum for the control without mine tailings. The tolerance of grasses to heavy metals followed the sequence： Paspalum notatum 〉 Festuea arundinaeea 〉 Lolium perenne 〉 Cynodon daetylon. The planting of forage grasses enhanced the soil microbial biomass. The Biolog data indicated that the soil microbial metabolic profile values （average well color development, community richness, and Shannon index） of the four forage grasses also followed the sequence： P. notatum 〉 F. arundinaeea 〉 L. perenne 〉 C. daetylon. Thus, P. notatum, under the experimental conditions of this study, may be considered as the preferred plant species for revegetation of Cu mine tailing areas.

Planting Performance of Several Elephant Grass Species in Northern Guangxi Zhuang Autonomous Region

This study aimed to screen suitable species of Pennisetum purpureum for planting in northern Guangxi Zhuang Autonomous Region. During 2012-2014, a comparative field trial was carried out in Lingyun County of Baise City in northern Guangxi to compare plant height, yield, stem-leaf ratio and nutrient composition am-ong Pennisetum purpureum Schumab cv. Purple, P. purpureum Schum cv. Guimin and P. purpureum Rich ＆#215; P. americana King grass cv. Reyan No.4. The results in-dicated that average annual fresh yield of P. purpureum Schumab cv. Purple reached 141.4 t/hm2, which was 2.3 t/hm^2 higher than that of P. purpureum_Rich×P. americana_King grass cv. Reyan No.4; both average annual fresh yield of these two species was lower than that of P. purpureum Schum cv. Guimin. Stem-leaf ratio of P. purpureum Schumab cv. Purple was the lowest （1.17）, which was 17.8% lower compared with P. purpureum Schum cv. Guimin, with significant differences （P〈0.05）, indicating that P. purpureum Schumab cv. Purple had more leaves. Crude protein content of P. purpureum_Schumab cv. Purple was slightly lower than that of P. purpureum Rich×P. americana_King grass cv. Reyan No.4, while P. purpureum Schumab cv. Purple was superior to P. purpureum Schum cv. Guimin and P. pur-pureum Rich ×P. americana_King grass cv. Reyan No.4 in other indicators. Specifi-cal y, P. purpureum Schumab cv. Purple contained 26.6% of dry matter, 39.1% of nitrogen-free extract and 2.9% of crude fat.

A ^(15)N-Labeling Study of the Capture of Deep Soil Nitrate from Different Plant Systems

The objective of this study was to determine the efficiency of different plant systems in capturing deep soil nitrate （NO3-） to reduce NO3- leaching in a field plot experiment using 15N labelling. The study was conducted on a calcareous alluvial soil on the North China Plains and the plant systems evaluated included alfalfa （Medicago sativa）, American black poplar （Populus nigra） and cocksfoot （Dactylis）. ^15N-labelled N fertilizer was injected to 90 cm depth to determine the recovery of ^15N by the plants. With conventional water and nutrient management, the total recovery of ^15N-labeled NO3--N was 23.4% by alfalfa after two consecutive growth years. The recovery was significantly higher than those by American black poplar （12.3%） and cocksfoot （11.4%）. The highest proportion of soil residual ~SN from the labeled fertilizer N （%Ndff） was detected around 90 cm soil depth at the time of the 1st year harvest and at 110-130 cm soil depth at time of the 2nd year harvest. Soil %Ndff in 0-80 cm depth was significantly higher in the alfalfa treatment than those in all the other treatments. The soil %Ndff below 100 cm depth was much lower in the alfalfa than those in all the other treatments. These results indicated that ^15N leaching losses in the alfalfa treatment were significantly lower than by those in the black poplar and cocksfoot treatments, due to the higher root density located in nitrate labeling zone of soil profile. In conclusion, alfalfa may be used as a plant to capture deep soil NO3- left from previous crops to reduce NO3- leaching in high intensity crop cultivation systems of North China Plain.

Application of CRISPR/Cas9 technology in forages

Genome editing is an advanced genetic modification tool that facilitates the removal,insertion,or substitution of nucleotides in the genome of an organism for mutation induction.CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9)is the most widely used genome editing tool that can precisely modify the specific sequence of a genome.Significant progress has been made in the use of CRISPR/Cas9 for the genetic improvement of food crops.However,in forage crops,the use of CRISPR/Cas9 is still in the infant stage with limited understanding and application.This article reviews current advances in the establishment and application of the CRISPR/Cas9 system in alfalfa,summarizes the application of CRISPR/Cas9 in several other forage legume and grass species,and discusses the prospects of CRISPR/Cas9 in the genetic improvement of forage crops.

Bioaccumulation of metals in human blood in industrially contaminated area

Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from different age group subjects such as children （1–12 years）, adolescent （12–18 years）, adults （18–45 years） and old age （above 45 and 55 years for males and females, respectively） from polluted and relatively less polluted areas. The results revealed that the consumption of contaminated food crops, meat and milk have significantly increased the concentrations of selected metals in the human blood. Cu, Zn and Mn concentrations were significantly higher （p 0.05） in the blood samples collected from the polluted area as compared to control area. Old people had accumulated high concentrations of metals as compared to the younger ones within the same area. Males accumulated higher concentrations of metals as compared to females.