Influences of Cadmium on Grain Mineral Nutrient Contents of Two Rice Genotypes Differing in Grain Cadmium Accumulation

A pot experiment was conducted to study the effects of Cd on grain Cd, K, P, Mg, Zn, Cu, Pb, Fe and Mn accumulation in two rice genotypes （Xiushui 63 and Xiushui 217） differing in grain Cd accumulation under four Cd levels, i.e. 0, 0.5, 2.5 and 12.5 mg/kg. Rice genotype greatly affected the grain K content, but not significantly for P, Mg, Zn, Cu, Pb, Fe and Mn contents. There were remarkable effects of additional Cd on the contents of P, Mg and Zn in grains, while not significant for K, Cu, Pb, Fe and Mn contents. No significant differences were found in the interaction of genotype by additional Cd on these nine element contents. The low grain Cd accumulation genotype Xiushui 217 had significantly higher grain K, Mg, Cu and Mn contents than the high grain Cd accumulation genotype Xiushui 63, but the case was opposite for Zn, Pb and Fe contents. It also showed that Cd addition levels significantly influenced the K, P, Mg, Zn, Cu, Pb, Fe and Mn contents in rice grains. Grain K, P, Mg, Zn, Fe and Mn contents reduced with the increasing rate of Cd addition.

Growth and mineral nutrient analysis of teak (Tectona grandis) grown on acidic soils in south China

Teak （Tectona grandis L.f.） is widely planted in the world due to its high market demand, economic, ecological and social value. Its plantations have mostly been established and expanded into sites that are acidic to severely acidic in southern China. But, there are no available and specific evidence-based nutrient management techniques. To better recognize and understand the relationship between teak tree growth and nutrient content in the foliage and soil and establish nutrient norms are critical to optimally manage these young plantations. We studied the foliar nutrient and soil chemistry in 19 representative teak plantations aged 5-8 years. Regression analysis indicated that the mean annual increment of teak volume was linearly and positively correlated with foliar N, Ca, Fe and B concentrations, with soil base saturation percentage, available P and Zn concentrations, and negatively correlated with soil Al concentration. Only if the Ca and Mg contents in soil were enhanced, could the increase in soil base saturation percentage benefit teak growth. A revised classification of low-and high-yielding stands was established by using a sorting method of principal components over 6 foliar macro and 8 micro elements in a Diagnosis and Recommendation Integrated System （DRIS）. Specific DRIS norms for teak plantations in acid soils were derived. The nutrient balance of N, P, K Ca, Mg, Zn, B with Fe or A1, Ca with Mg, and Fe with AI provided a key to promote the growth of teak in acid soils. Meanwhile, soil Zn was also found as a primary trace element that affected teak growth in this study.

Genotypic Difference in Plant Growth and Mineral Composition in Barley Under Aluminum Stress

Four barley genotypes (Tiantaiyangdamai, Xiyin2, Mimaill4 and Tai94-Ce6) were exposed to 0, 50, 100, and 150μM of Al-containing solution with pH 4.5, to determine the differences in growth inhibition , Al concentration and accumulation and mineral composition among genotypes. The results showed that Mimaill4 and Tai94-Ce6 had significantly higher Al concentration and accumulation than Tiantaiyangdami and Xiyin2, especially in roots, and the growth traits including root and shoot dry weights, shoot height, root length and tillers per plant were more inhibited in the former two genotypes. Al treatments caused a significant reduction of N, P, K, Ca, Mg and Mn content in both roots and shoots, of Cu in shoots; and a significant increase in Fe and Zn content in both roots and shoots, of Cu in roots. The changed rates of mineral content caused by Al treatments, in terms of the content in 150μM Al divided by the content in the control, differed significantly among four genotypes. Two Al-sensitive genotypes, Mimaill4 and Tai94-Ce6 had much greater changes in mineral content than other two Al-tolerant genotypes Tiantaiyangdamai and Xiyin2 when subjected to Al stress in comparison with the control. It is indicated that the Al-tolerant genotype is characterized by less uptake and accumulation of Al in roots and smaller disorders in mineral metabolism and ion homeostasis.

Key minerals influencing apple quality in Chinese orchard identified by nutritional diagnosis of leaf and soil analysis

We investigated the correlation between leaf/soil minerals and fruit quality in apple trees grown in orchards,with the ultimate goal of improving the latter.Leaf mineral nutrients;soil nutrients in the 0-20,20-40,and 40-60 cm layers;and fruit quality traits in 32 apple orchards in China were monitored for 2 years.Significant factors associated with fruit quality were identified via correlation analysis.An analysis of leaf data revealed that leaf nitrogen（N） and leaf magnesium（Mg） levels were extremely high in 75 and 89%of the orchards,respectively.In the Bohai Gulf region,94%of the orchards showed significantly higher values than the standard.The soil pH values of the orchards in eastern China like eastern Shandong or Liaoning were lower than 7.0,while the pH values in the Loess Plateau of northwestern China like Shaanxi were much higher than 7.Soil alkali-hydrolyzable N levels in 47%of the orchards were lower than the optimal level of 70 mg kg^-1.Generally,the soil alkali-hydrolyzable N levels of orchards in the Bohai Gulf region were significantly higher than those in the Loess Plateau region.The available P levels in the orchards of the Bohai Gulf region were up to three times higher than those of the Loess Plateau region.However,although the available potassium（K） in most orchards was sufficient（51.39-309.94 mg kg^-1）,leaf K content in 73%of the orchards was low,possibly due to fruit bagging or fruit overload.Approximately 63%of the orchards in Shandong and 29%of the orchards in Shannxi showed leaf Fe deficiencies.In the Loess Plateau,most orchards showed high leaf Ca levels,a strong correlation was observed between leaf and soil phosphorus/potassium（P/K）content and fruit organic acid content.The amounts of fruit soluble sugar or fructose were positively correlated with soil calcium/potassium（Ca/K） levels and leaf calcium/boron（Ca/B） levels in most orchards.The excessive leaf N levels caused by the extensive application of N fertilizers had a negative effect on fruit quality in most apple orchards in China.P,K,Ca,and B were key minerals associated with fruit quality.

Carbon Dioxide Concentrations and Light Levels on Growth and Mineral Nutrition of Juvenile Cacao Genotypes

In many countries cacao (Theobroma cacao L.) is invariably grown as an understory crop in agroforestry types of cropping systems and subjected to low levels photosynthetic photon flux density (PPFD) due to presence of large number of upper story shade trees with poorly managed canopy structure. In recent years carbon dioxide concentration in the atmosphere is steadily increasing and it is unclear what impact this will have on performance of cacao grown under shade of upper story shade trees. A climatically controlled greenhouse experiment was undertaken to evaluate the effects of ambient and elevated carbon dioxide (400 and 700 μmol·mol-1) and three levels of PPFD (100, 200, and 400 μmol·m-2·s-1) on growth, and macro- and micronutrient use efficiency of three genetically contrasting cacao genotypes (CCN 51, VB 1117 and NO 81). Intraspecific variations were observed in cacao genotypes for growth parameters at ambient to elevated carbon dioxide and low to adequate levels of PPFD. With the exceptions of total root length and leaf area, irrespective of carbon dioxide and PPFD levels, all three genotypes showed significant differences in all the growth parameters. For all the cacao genotypes, increasing PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased overall growth parameters such as leaf, shoot and root biomass accumulation, stem height, leaf area, relative growth rate and net assimilation rate. Irrespective of carbon dioxide and PPFD, invariably genotypes differed significantly in macro-micronutrient uptake parameters such as concentration, uptake, influx, transport and use efficiency. With few exceptions, raising PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased nutrient use efficiency for all the cacao genotypes. Elevated carbon dioxide and adequate PPFD are beneficial in improving cacao growth and mineral nutrient uptake and use efficiency.

The Physiological and Molecular Responses of Exogenous Selenium to Selenium Content and Fruit Quality in Walnut

To study the effect of exogenous selenium on fruit quality in walnut(Juglans regia L.),8-year-old walnut(Qingxiang)was taken as the research object.In the fruit expansion stage,300 mg/L of sodium selenate,yeast selenium and sodium selenite solutions were applied on the leaf of walnut,and the selenium levels in leaves,pericarp and kernel were determined at the ripening stage.The fruit quality,mineral nutrient content,antioxidant enzyme activity,and related genes’expression were analyzed.The results showed that the three exogenous selenium increased the selenium levels in leaves,pericarp and kernel of walnut.They also significantly increased fruit and kernel weights,and kernel linoleic acid,but markedly decreased kernel crude fat and saturated fatty acid.Selenium spraying promoted the absorption of mineral nutrients such as potassium and zinc,but inhibited the absorption of calcium,and had no significant effect on iron and magnesium in the kernel.Three exogenous selenium increased the activities of superoxide dismutase(SOD),peroxidase(POD),ascorbate peroxidase(APX),and catalase(CAT)significantly in the kernel.Except for sodium selenate treatment significantly reduced malondialdehyde(MDA)content in the kernel,the other two selenium sources treatments had no significant effect on MDA and hydrogen peroxide(H2O2)levels.They also increased the expression of JrCu/Zn-SOD,Jr2-Cys POD,JrCyt-APX and JrCAT in kernel,to different extents.These implies that,in the walnut fruit enlargement period,the foliar spraying selenium could increase the selenium content of walnut,affect the mineral nutrient absorption,improve the antioxidant capacity and related genes’expression,and reduce the degree of peroxide,and then improve the quality of fruit.Furthermore,yeast selenium showed the comprehensive effect of the best.

Relationship Between pH Value and Physical and Chemical Properties of Tobacco-growing Soil

[Objectives]This study was conducted to understand the relationship between soil pH and soil physical and chemical properties during tobacco planting.[Methods]Through a field experiment,the pH value of tobacco-growing soil,the contents of mineral nutrients(ammonium nitrogen,alkali-hydrolyzable nitrogen,available potassium,available phosphorus),soil bulk density and porosity were investigated.[Results]The pH value of the soil after tobacco planting increased,and the contents of ammonium nitrogen,alkali-hydrolyzable nitrogen,and available potassium were closely related to the change of pH value.The bulk density of the tobacco-planting soil decreased and the porosity increased.Planting flue-cured tobacco had certain impacts on soil pH,soil bulk density and other physical and chemical properties.[Conclusions]This study provides a theoretical basis for the investigation of the fertilization laws in the process of tobacco planting and the selection of subsequent crops.

Effects of Auxin at Different Concentrations on the Growth,Root Morphology and Cadmium Uptake of Maize(Zea mays L.)

Indoleacetic acid(IAA)is an important regulator that plays a crucial role in plant growth and responses to abiotic stresses.In the present study,a sand cultivation experiment was carried out to investigate the effects of IAA at different concentrations(0,0.01,0.1,0.5,1,and 2.5 mmol/L)on maize growth,root morphology,mineral elements(Ca,Mg)and Cd uptake under 20 mg/kg Cd stress.The results showed that 0.01 mmol/L is the optimal IAA concentration for enhancing the Cd tolerance of maize.Compared with the control treatment,0.01 mmol/L IAA promoted maize growth,with significant increases in the height,shoot and root biomass by 34.6%,25.0%and 16.3%;altered the root morphology,with increases in root length,root tip number,and root tip density by 8.9%,31.4%and 20.7%,respectively;and enhanced the mineral element uptake of maize,resulting in signifi-cant increases in the Ca content in shoots and roots by 640.6%and 1036.4%and in the Mg content in shoots by 205.8%,respectively.In addition,0.01 mmol/L IAA decreased the Cd content and uptake in the shoots by 51.9%and 39.6%,respectively.Furthermore,the Cd content and uptake exhibited a significant negative correlation with Ca content in roots and a significantly positive correlation with root morphology,and the Cd content in shoots was significantly and negatively correlated with root tip number.Thus,0.01 mmol/L IAA was effective in enhancing the Cd tolerance and plant growth of maize.

Ecological significance and risks of mineral licks to mammals in a nature reserve on the Eastern Qinghai-Tibet Plateau

Mineral licks are important components of terrestrial ecosystems that have special value to the maintenance of fluid balance of mammals,by providing them with essential mineral nutrients such as sodium,calcium,and magnesium.In the Anzihe Nature Reserve,southwest China,seven species of ungulates and one species of primates were frequently observed visiting the mineral licks in high densities.As a consequence,mineral licks have attracted illegal hunters and facilitated the spread of parasites and diseases,leading to a depletion of local populations.Therefore,we suggest that regions with abundant mineral licks should be designated as key protected areas in the Anzihe Nature Reserve and relevant zones for animal health surveillance.

Mineral nutrient imbalance,DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L.seedlings exposed to lanthanum ions

Effects of mineral nutrient imbalance,DNA lesion and DNA-protein crosslink on growth of Vicia faba L.seedlings hydroponically cultivated in concentrations of extraneous lanthanum（La） for 20 days were investigated in the present experiment.The results showed that contents of La,Cu or K elements in roots generally changed synchronously with those in leaves,while Ca,Fe,Zn,Mg,Mn or P in the roots altered inversely to those in the leaves.Thus,the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves.DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis（SCGE） and sodium dodecyl sulfate/potassium（SDS/K＋） precipitation methods,respectively.The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks（DPCs） in the seedlings.These results suggested that mineral nutrient imbalance,DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings,which may help to understand the mechanisms of rare earth elements（REEs） on plant growth.

Response mechanism of Chlamydomonas reinhardtii to nanoscale bismuth oxyiodide(nano-BiOI):Integrating analysis of mineral nutrient metabolism and metabolomics

Nanoscale bismuth oxyiodide(nano-BiOI) is widely studied and applied in environmental applications and biomedical fields, with the consequence that it may be deposited into aquatic environments. However, the impact of nano-Bi OI on aquatic ecosystems, especially freshwater microalga, remains limited. Herein, the nano-Bi OI was synthesized and its response mechanism towards microalga Chlamydomonas reinhardtii was evaluated. Results showed that a low concentration of nano-Bi OI(5 mg/L) could stimulate algal growth at the early stage of stress. With the increase in concentration, the growth rate of algal cells was inhibited and showed a dose effect. Intracellular reactive oxygen species(ROS) were significantly induced and accompanied by enhanced lipid peroxidation, decreased nonspecific esterase activity, and significantly upregulated glutathione S-transferase activity(GST) activity. Mineral nutrient metabolism analysis showed that nano-Bi OI significantly interfered with the mineral nutrients of the algae. Non-targeted metabolomics identified 35 different metabolites(DEMs, 22 upregulated, and 13 downregulated) under 100 mg/L Bi OI stress.Metabolic pathway analysis demonstrated that a high concentration of nano-Bi OI significantly induced metabolic pathways related to amino acid biosynthesis, lipid biosynthesis,and glutathione biosynthesis, and significantly inhibited the sterol biosynthesis pathway.This finding will contribute to understanding the toxicological mechanisms of nano-Bi OI on C. reinhardtii.

Plant mineral nutrient sensing and signaling

As terrestrial plants are sessile organisms and therefore must directly deal with an often complex and changing environment, they have had to develop complex and elegant strategies to survive and thrive in the face of environmental stress. This is particularly true for plant adaptation to the soil environment, where essential mineral nutrients often are found at sub- optimal levels and their concentrations can vary significantly, both spatially and temporally. Furthermore, plants also at times have to respond to excessively high and potentially toxic levels of essential nutrients, as well as toxic levels of non- essential metals and metalloids in the soil. Although plant mineral nutrition as a bona ~ide research discipline has a history of over 15o years, beginning with the pioneering work of Justus Von Liebieg and others in the mid-1800＇s, it is only very recently that researchers have begun to truly appreciate how sophisticated plants are with regards to the sensing of their mineral status and the maintaining of mineral homeostasis in the plant.

Biochar increases soil microbial biomass with changes in extra-and intracellular enzyme activities:a global meta-analysis

Biochar application to soil has been proposed as a potential management strategy to enhance soil carbon(C)sequestration,reduce greenhouse gas emission,improve soil quality,and increase crop productivity.The effects of biochar on soil microbial and enzyme activities are integrally linked to the potential of biochar in achieving these benefits.We conducted a global meta-analysis to assess the effects of biochar on soil microbial biomass C and nitrogen(N)and the activities of 12 enzymes,and identify key factors affecting those soil microbial properties using 964 data points from 72 papers.We found that biochar effects on enzyme activities vary widely with soil type,biochar property and the type of enzyme studied.Biochar significantly increased microbial biomass C(MBC)and urease,alkaline phosphatase and dehydrogenase activities by 21.7%,23.1%,25.4%and 19.8%,respectively,with no significant negative effects on any of the enzymes analyzed in this study.Biochar application was more effective in increasing MBC and enzyme activities in soils with low pH(<6.5),TC(<20 g kg^(−1)),TN(<2 g kg^(−1)),and a fine texture(including clay,clay loam and silt clay).Biochars produced at pyrolysis temperature of 350-550℃ with a high pH(>10)and low C/N ratio(<50)increased MBC and urease and dehydrogenase activities.Biochar increased MBC and N-acquisition enzyme activities in the field but not in lab incubation experiments.Urease was increased in short-term studies(within 100 days of biochar application)while alkaline phosphatase was increased in long-term studies that span more than 1 year.The increase in MBC and activities of some soil enzymes in response to biochar application with no negative effects on any hydrolytic and oxidative enzymes illustrate its potential to enhance soil quality particularly in the degraded soils with low nutrient availability and fertility due to limited soil microbial and enzymatic activities.This study also shows that biochars can be designed to achieve specific properties for enhancing microbial and enzymatic activities for specific soils.

Assessment of potential soybean cadmium excluder cultivars at different concentrations of Cd in soils

The selection of cadmium-excluding cultivars has been used to minimize the transfer of cadmium into the human food chain. In this experiment, five Chinese soybean plants were grown in three soils with different concentrations of Cd（0.15, 0.75 and 1.12 mg/kg）.Variations in uptake, enrichment, and translocation of Cd among these soybean cultivars were studied. The results indicated that the concentration of Cd in seeds that grew at1.12 mg/kg Cd in soils exceeded the permitted maximum levels in soybeans. Therefore, our results indicated that even some soybean cultivars grown on soils with permitted levels of Cd might accumulate higher concentrations of Cd in seeds that are hazardous to human health. The seeds of these five cultivars were further assessed for interactions between Cd and other mineral nutrient elements such as Ca, Cu, Fe, Mg, Mn and Zn. High Cd concentration in soil was found to inhibit the uptake of Mn. Furthermore, Fe and Zn accumulations were found to be enhanced in the seeds of all of the five soybean cultivars in response to high Cd concentration. Cultivar Tiefeng 31 was found to fit the criteria for a Cd-excluding cultivar under different concentrations of Cd in soils.