Improved pig behavior analysis by optimizing window sizes for individual behaviors on acceleration and angular velocity data.

This paper presents the application of machine learning algorithms to identify pigs' behaviors from data collected using the wireless sensor nodes mounted on pigs. The sensor node attached to a pig's back senses the acceleration and angular velocity in three axes, and the sensed data are transmitted to a host computer wirelessly. Two video cameras, one attached to the ceiling of the pigpen and the other one to a fence, provided ground truth for data annotations. The data were collected from pigs for 131 h over 2 mo. As the typical behavior period depends on the behavior type, we segmented the acceleration data with different window sizes (WS) and step sizes (SS), and tested how the classification performance of different activities varied with different WS and SS. After exploring the possible combinations, we selected the optimum WS and SS. To compare performance, we used five machine learning algorithms, specifically support vector machine, k-nearest neighbors, decision trees, naive Bayes, and random forest (RF). Among the five algorithms, RF achieved the highest F1 score for four major behaviors consisting of 92.36% in total. The F1 scores of the algorithm were 0.98 for "eating," 0.99 for "lying," 0.93 for "walking," and 0.91 for "standing" behaviors. The optimal WS was 7 s for "eating" and "lying," and 3 s for "walking" and "standing." The proposed work demonstrates that, based on the length of behavior, the adaptive window and step sizes increase the classification performance.

Analyzing the behavior of pigs provides great insights into animal welfare and health. Technologies that enable automatic, continuous, and real-time behavior monitoring have emerged as alternative solutions and have received considerable attention. Using sensor-based animal monitoring technology, we could provide objective and quantitative assessments of the health and continuous care of pigs. We extracted distinct characteristics/features of different activities over given segments of acceleration data to boost classification performance. Pigs have various behavior patterns with different durations; treating behaviors with a small duration the same as a long duration could ignore the minority behaviors in the window frame. Our study showed that by finding the adaptive window sizes customized for individual behaviors, we could reduce the chance of mixing activities and compute the feature for better classification performance.

Rape straw application facilitates Se and Cd mobilization in Cd-contaminated seleniferous soils by enhancing microbial iron reduction.

Many naturally seleniferous soils are faced with Cd contamination problem, which severely limits crop cultivation in these areas. Straw returning has been widely applied in agricultural production due to its various benefits to soil physicochemical properties, soil fertility, and crops yield. However, effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils remain largely unclear. Therefore, the effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils were investigated in this study. The results showed that iron reduction driven by Clostridium and Anaeromyxbacter was responsible for the variations in Se and Cd fates in soil. Straw application respectively increased the gene copy numbers of Clostridium and Anaeromyxbacter by 19.5-56.3% and 33.6-39.8%, thus promoting iron reductive dissolution, eventually resulting in a high release amount of Se and Cd from Fe(III) (oxyhydr) oxides. Under reducing conditions, the released Cd was adsorbed by the newly formed metal sulfides or reacted with sulfides to generate CdS precipitates. Straw application decreased the soil exchangeable Se and soil exchangeable Cd concentration during flooding phase. However, straw application significantly increased Se/Cd in soil solution which had the highest bioavailability during flooding. In addition, straw application increased soil exchangeable Se concentration, but it had no significant effects on soil exchangeable Cd concentration after soil drainage. Taken together, straw application increased Se bioavailability and Cd mobility. Therefore, straw application is an effective method for improving Se bioavailability, but it is not suitable for the application to Cd-contaminated paddy soils. In the actual agricultural production, straw could be applied in seleniferous soils to improve Se bioavailability. At the same time, straw application should be cautious to avoid the release of Cd from Cd-contaminated soil.

Characteristics of Se in water-soil-plant system and threshold of soil Se in seleniferous areas in Enshi, China.

Se-enrichment characteristics in water-soil-plant system and dietary Se status of local residents in seleniferous areas were investigated. Results showed that Se in well water might mainly derived from Se-enriched shales and coals, and Se mobility in seleniferous soils was relatively low with less than 6.7% bioavailable forms in high-Se areas. Soil Se with irrigation, precipitation and fertilization sources contributed more to soil Se than Se-enriched shales and coals in low-Se areas, resulting in slightly higher mobility of Se in low-Se soils. Se concentration in edible parts of main crops ranged from 0.005 mg kg-1 to 4.17 mg kg-1, and cereal plants had a higher Se-enrichment ability than tuber plants. The probable dietary Se intake (PDI) in high-Se areas was decreased to 959.3 µg d-1 in recent years, which might be attributed to tap water as drinking water in recent year rather than well water-dependent and changes in dietary structure, but still far above the permissible value of 400 µg d-1. Reducing cereal-derived dietary Se intake is an important strategy to better Se nutrition status in high-Se areas. After synthesis considerations on soil Se bioavailability and PDI of Se, the soil total Se of 4 mg kg-1 and the soil available Se content of 0.32 mg kg-1 were proposed to be the reference threshold values of soil Se excess in high-Se areas in Enshi, respectively.

Distribution and speciation of selenium in soybean proteins and its effect on protein structure and functionality.

Although the Se concentration and recovery efficiency of soybean seeds treated with selenate were âˆ¼ 1.8 times those of the selenite treatment, the Se was mainly in the organic form of selenomethionine (>90% of total Se) irrespective of the Se source. The Se concentrations of soybean protein isolate (SPI) and glycinin (11S) were 29.1%-38.6% higher than those of soybean protein concentrate (SPC) and ß-conglycinin (7S) in Se-enriched soybeans, with selenomethionine accounting for > 80% of the Se in all proteins. The content of sulfur-containing methionine in SPI and 11S markedly decreased in Se-enriched soybeans compared with the control. No significant effect of Se was observed on protein content, subunit composition, secondary structure, micromorphology, or functionality. Foliar spray of selenate provides an economical and efficient way to produce Se-enriched soybeans without affecting protein structure and functionality, where SPI and 11S display a high ability to enrich Se (mainly selenomethionine).

Microbial induced carbonate precipitation contributes to the fates of Cd and Se in Cd-contaminated seleniferous soils.

Bioremediation based on microbial induced carbonate precipitation (MICP) was conducted in Cd-contaminated seleniferous soils with objective to investigate effects of MICP on the fates of Cd and Se in soils. Results showed that soil indigenous microorganisms could induce MICP process to stabilize Cd and mobilize Se without inputting exogenous urease-producing strain. After remediation, soluble Cd (SOL-Cd) and exchangeable Cd (EXC-Cd) concentrations were decreased respectively by 59.8% and 9.4%, the labile Cd measured by the diffusive gradients in thin-films technique (DGT) was decreased by 14.2%. The MICP stabilized Cd mainly by increasing soil pH and co-precipitating Cd during the formation of calcium carbonate. Compared with chemical extraction method, DGT technique performs better in reflecting Cd bioavailability in soils remediated with MICP since this technique could eliminate the interference of Ca2+. The increase in pH resulted in Se conversion from nonlabile fraction to soluble and exchangeable fractions, thus improving Se bioavailability. And Se in soil solution could adsorb to or co-precipitate with the insoluble calcium carbonate during MICP, which would partly weaken Se bioavailability. Taken together, MICP had positive effects on the migration of Se. In conclusion, MICP could stabilize Cd and improve Se availability simultaneously in Cd-contaminated seleniferous soils.

A sodium salt-assisted roasting approach followed by leaching for recovering spent LiFePO4 batteries.

Mild-temperature (<1000 °C) carbothermic reduction has been proven as an effective way to recover Li and transition metals by converting lithium transition metal oxides to transition metals/alloys and Li2CO3. However, LiFePO4 cannot be reduced by carbon because of its thermodynamically stable olivine structure. Herein, LiFePO4 is converted to Fe and lithium salts by carbon with the assistance of Na2CO3 that acts as an activating agent to break down the chemical bonds of LiFePO4 and thereby enable the carbothermic reduction. Using Na2CO3 as the activating agent, LiFePO4 was reduced to Fe, NaLi2PO4, and LiNa5(PO4)2 which can be separated by magnetic separation with a Li recovery rate of 99.2%. Using NaOH as the activating agent, LiFePO4 was oxidized to Fe3O4, NaLi2PO4 and LiNa5(PO4)2 at 600 °C, and the roasted products can be separated by magnetic separation process with a Li recovery rate of 92.7%. Various sodium salts were tested to screen proper salts for the reduction process, and a 400-g scale roasting-separation process has been demonstrated. Overall, the salt-assisted roasting is a promising way to recycle spent LiFePO4 batteries without using strong mineral acids and shows great potential for the industrial-scale implementation.

Recovery of porous silicon from waste crystalline silicon solar panels for high-performance lithium-ion battery anodes.

A low-cost and easy-available silicon (Si) feedstock is of great significance for developing high-performance lithium-ion battery (LIB) anode materials. Herein, we employ waste crystalline Si solar panels as silicon raw materials, and transform micro-sized Si (m-Si) into porous Si (p-Si) by an alloying/dealloying approach in molten salt where Li+ was first reduced and simultaneously alloyed with m-Si to generate Li-Si alloy at the cathode. Subsequently, the as-prepared Li-Si alloy served as the anode in the same molten salt to release Li+ into the molten salt, resulting in the production of p-Si by taking advantage of the volume expansion/contraction effect. In the whole process, Li+ was shuttled between the electrodes in molten LiCl-KCl, without consuming Li salt. The obtained p-Si was applied as an anode in a half-type LIBs that delivered a capacity of 2427.7 mAh g-1 at 1 A g-1 after 200 cycles with a capacity retention rate of 91.5% (1383.3 mAh g-1 after 500 cycles). Overall, this work offers a straightforward way to convent waste Si panels to high-performance Si anodes for LIBs, giving retired Si a second life and alleviating greenhouse gas emissions caused by Si production.

Control of Streptomyces alfalfae XY25 T Over Clubroot Disease and Its Effect on Rhizosphere Microbial Community in Chinese Cabbage Field Trials.

Clubroot caused by Plasmodiophora brassicae is one of the most destructive diseases in cruciferous crops. Streptomyces alfalfae XY25 T , a biological control agent, exhibited great ability to relieve clubroot disease, regulate rhizosphere bacterial and fungal communities in Chinese cabbage, and promote its growth in greenhouse. Therefore, field experiments were carried out to investigate the effects of S. alfalfae XY25 T on clubroot and rhizosphere microbial community in Chinese cabbage. Results showed that the control efficiency of clubroot by S. alfalfae XY25 T was 69.4%. Applying the agent can alleviate soil acidification; increase the contents of soil organic matter, available nitrogen, available phosphorus, and available potassium; and enhance activities of invertase, urease, catalase, and alkaline phosphatase. During Chinese cabbage growth, bacterial diversity decreased first and then increased, and fungal diversity decreased gradually after inoculation with S. alfalfae XY25 T . High-throughput sequencing analysis showed that the main bacterial phyla were Proteobacteria, Bacteroidetes, Acidobacteria, and Planctomycetes, and the major fungal phyla were Ascomycota and Basidiomycota in rhizosphere soil. The dominant bacterial genera were Flavobacterium, Candidatus, Pseudomonas, Stenotrophomonas, Sphingomonas, Flavisolibacter, and Gemmatimonbacteria with no significant difference in abundance, and the major fungal genera were Monographella, Aspergillus, Hypocreales, Chytridiaceae, Fusarium, Pleosporales, Agaricales, Mortierella, and Pleosporales. The significant differences were observed among Pleosporales, Basidiomycota, Colletotrichum, two strains attributed to Agaricales, and another two unidentified fungi by using S. alfalfae XY25 T . Moreover, quantitative real-time PCR results indicated that P. brassicae content was significantly decreased after the agent inoculation. In conclusion, S. alfalfae XY25 T can affect rhizosphere microbial communities; therefore, applying the agent is an effective approach to reduce the damage caused by clubroot.

Characteristics of selenium enrichment and assessment of selenium bioavailability using the diffusive gradients in thin-films technique in seleniferous soils in Enshi, Central China.

Agricultural products from seleniferous areas commonly face problems associated with substantial variation in selenium (Se) concentration, which is mainly caused by the heterogeneity of Se bioavailability in soil. Many studies have assessed the bioavailability of Se and its influencing factors using soil samples treated with exogenous Se. Given the distinctly different characteristics of Se-spiked soils and naturally seleniferous soils, exploring Se bioavailability in naturally seleniferous soils is crucial to the stable production of Se-enriched agricultural products. In this study, we used the classical sequential extraction method to determine the Se fractionation and then applied the diffusive gradients in thin-films (DGT) technique to assess the Se bioavailability in naturally seleniferous soils. The results indicated that soluble and exchangeable Se fractions with high bioavailability accounted for only 0.7% and 5.1% of total Se, respectively. Both soluble and exchangeable Se concentrations were significantly positively correlated with soil pH (r = 0.329 and 0.262, respectively; P < 0.01). Se mainly exists in Fe-Mn oxide-bound, organic matter-bound, and residual Se fractions with low mobility (94.2% of total Se), among which organic matter-bound Se was the predominant fraction (49.5% of total Se). A significant positive correlation was found between total Se and soil organic matter (r = 0.539; P < 0.01). Multiple regression analysis revealed that the DGT-determined Se was mostly derived from soluble and exchangeable Se. The high correlation between the DGT-determined Se fraction and Se uptake by rice (r = 0.91; P < 0.01) confirmed that DGT can accurately assess Se bioavailability in naturally seleniferous soils in Enshi and other similar environmental settings.

Effects of sulfur application on selenium uptake and seed selenium speciation in soybean (Glycine max L.) grown in different soil types.

AIMS: The objective of the present study was to elucidate the effects of sulfur (S) application on selenium (Se) uptake and seed Se speciation in high-protein soybean (Glycine max L.) grown in different soil types. METHODS: Pot experiments were conducted with soybean plants grown in yellow-brown soil (pH 5.68) and in calcareous alluvial soil (pH 7.87). Sodium selenate (Na2SeO4, 2 mg kg-1) was applied to soil with or without S fertilizer (S, 100 mg kg-1). RESULTS: Soybean grain yield and total biomass in calcareous alluvial soil were both approximately 1.3-fold the levels in yellow-brown soil. Following Se application, seed Se concentration in calcareous alluvial soil was 3.2-fold the concentration in yellow-brown soil, although additional S application reduced the corresponding seed Se concentrations by 55.6% and 38.6%, respectively. Generally, Se application facilitated Se translocation and enrichment in soybean seeds. Organic Se accounted for 92% of seed total Se and Se-methionine (>90%) was always the major Se species. Available Se (soluble and exchangeable fractions) accounted for 50.7% (yellow-brown soil) and 70.1% (calcareous alluvial soil) of soil total Se under Se treatment, while additional S application decreased the corresponding proportion of soluble Se by 12.6% and 14.4%. CONCLUSIONS: The bioavailability of selenate in calcareous alluvial soil was higher than the bioavailability in yellow-brown soil and was more negatively affected by S application. Although S application inhibited Se uptake in soybean plants in both soil types, it did not influence seed Se speciation and Se-methionine was the major Se species.

Effect of excessive nitrogen on levels of amino acids and sugars, and differential response to post-harvest cold storage in potato (Solanum tuberosum L.) tubers.

Nitrogen (N) is an important nutrient for increased potato tuber yield. However, excessive N can decrease tuber quality. Furthermore, the impact of optimal and higher N levels of potato tuber metabolic profile at harvest and cold storage remains unclear. This study aimed to investigate the metabolic profiling of free amino acids and sugars in potato tubers affected by different nitrogen levels (optimal, ON; and excessive, EN) at harvest (AH) and cold storage (CS) (~4 °C, 4 weeks) through untargeted GC-TOF-MS, and targeted UHPLC-QqQ-MS. Carbohydrate content and vacuolar invertase activity (IV) were determined. Principal component analysis of metabolite data indicated a distinct separation between ON and EN treatments at harvest and cold storage. Multivariate data analysis revealed that sucrose, reducing sugars, and free asparagine were the most altered metabolites (VIP > 1 and P < 0.05), which were involved in starch and sucrose metabolism, and alanine, aspartate and glutamate metabolism. At harvest, the absolute contents of various free amino acids including asparagine were higher (by 1.3-1.5 fold) in the EN treatment than ON treatment, and this difference was maintained at 4-week cold storage. Under the EN treatment, tuber maturity was reduced, and sucrose accumulation was increased at harvest, while IV was increased after cold storage, reducing sugar also accumulated. These results highlighted the negative effects of EN on free amino acid and sugars metabolism in the post-harvest tubers and provided useful information for understanding the underpinning physiological mechanisms.

Recovery and regeneration of LiCoO2-based spent lithium-ion batteries by a carbothermic reduction vacuum pyrolysis approach: Controlling the recovery of CoO or Co.

An environmentally benign vacuum pyrolysis (VP) approach is employed to recover Li and Co from spent LiCoO2-based lithium-ion batteries (LIBs). First, the electroactive materials were separated from the current collector by the VP method from 623 to 823 K with an attempt to choose an appropriate temperature. Then, the as-received cathode materials were mixed with different amounts of graphite from the anode to selectively convert LiCoO2 to Co or CoO and Li2CO3 by carbothermic reduction under vacuum and at 873 to 1273 K. After carbothermic reduction, the pyrolyzed powder was leached in water to separate Li2CO3 from Co/CoO. By alternating the C/LiCoO2 mass ratio and the pyrolysis temperature, a recovery rate reaches over 93% for Li and 99% for Co. Finally, the recovered CoO and Li2CO3 were used to regenerated LiCoO2 that delivered a specific capacity of 145 mAh g-1 at 1C and retaining 93% of the initial capacity after 100 cycles. Overall, a multi-vacuum-pyrolysis approach offers a closed-loop route for the management of spent LIBs without using any hazardous chemicals.

Effects of foliar application of selenate and selenite at different growth stages on Selenium accumulation and speciation in potato (Solanum tuberosum L.).

Since the potato is a new staple food in China, the production of selenium (Se)-enriched potato may be an effective approach for Se supplementation in Se-deficient populations. Herein, we biofortified potato via the foliar application of sodium selenate and sodium selenite at three growth stages and investigated the resulting Se contents and speciation. Results showed that selenate was more efficient than selenite in improving total Se, and the highest tuber Se concentration was obtained at the tuber bulking stage. However, the accumulation of inorganic Se was higher in tubers treated with selenate (31.9% of total Se) compared with the selenite treatment (1.5%). The major Se species in tubers treated with both selenite and selenate was selenomethionine, which accounted for ∼80.0% and ∼50.0% of total Se, respectively. The findings suggest that the foliar application of selenite during the tuber bulking stage is appropriate for the production of Se-rich potatoes.

Effects of potassium fertilization on potato starch physicochemical properties.

Potato starch serves as an excellent raw material or food additive in the food industry. With the advancement of the potato staple food strategy in China, improving the potato starch yield and quality has attracted more and more attention. Potassium is an essential nutrient for potato due to its direct effects on the yield and quality of potato tubers. Here, the effects of three different potassium levels on potato starch physicochemical properties were evaluated by field experiments. With increasing potassium fertilization rates, the amylose content, phosphorus content and particle size decreased, thereby resulting in low gelatinization temperature, breakdown and setback viscosity, and high swelling power, relative crystallinity and transparency. Our study indicated that enhanced potassium fertilization improved the resistance to heat and shear stress and decreased the retrogradation of starch, and the 270 kg/ha potassium fertilization rate could obtain the highest tuber and starch production with desirable starch physicochemical properties. The integrated results also provide some novel insights into the management of the fertilization conditions to obtain native starches with special properties.

Effects of a foliar spray of selenite or selenate at different growth stages on selenium distribution and quality of blueberries.

BACKGROUND: Foliar spraying of selenium (Se) has increasingly been applied to improve Se concentrations in grain crops, although little information is available about the properties of Se-enriched fruits. In the present study, selenium distribution in blueberry and Se effect on blueberry quality were investigated by foliar spraying selenite or selenate (200 g ha-1 ) on two blueberry cultivars (Bluecrop and Northland) during the young fruit or coloring stage. RESULTS: Selenium concentration in blueberry was mainly affected by cultivar and spray stage relative to the Se source. Northland was 1.3- to 1.5-fold higher than Bluecrop with respect to Se enrichment. Se treatment at the young fruit stage induced a 1.5- to 2.3-fold increase compared to that at the coloring stage with respect to the Se concentration of blueberry. Additionally, selenium was mainly stored in pomace, with an accumulative distribution ratio of 89.3-94.9%. The proportion of organic Se reached up to 77.0% in blueberry. Furthermore, the foliar application of Se significantly increased the anthocyanin concentration and the intact fruit rate of blueberry. CONCLUSION: Se-enriched blueberry can be used as a 'functional food'. Because Se was mainly accumulated in the pomace, the consumption of blueberries as fresh fruit, dried fruit and jam can improve the efficiency of Se supplement. © 2018 Society of Chemical Industry.

Effect of boron deficiency on anatomical structure and chemical composition of petioles and photosynthesis of leaves in cotton (Gossypium hirsutum L.).

The main symptom of boron (B) deficiency in cotton is the formation of brown rings on leaf petioles. The objective of the present study was to determine the changes in the anatomical structure and chemical composition of petioles and photosynthesis of leaves in cotton under B deficiency. Compared to the control, B deficiency treatment resulted in large increases in the number of petioles with brown rings per plant (160.0%) and the number of rings on the petiole per functional leaf (711.1%) in cotton seedlings. The relative absorbance intensity in the fingerprint region of polysaccharide structure was decreased in petiole rings under B deficiency, while lignin contents were increased. Cotton plants mitigated the impairment of transport function in cotton petioles by increasing the areas of vascular bundles, phloem, xylem, and phloem fiber. Moreover, the stomatal conductance, photosynthetic rate, and transpiration rate in leaves were significantly decreased under B deficiency, thus impeding photosynthesis in cotton plants. Therefore, B deficiency reduces transport function in petioles and photosynthesis in leaves, and leads to the formation of noticeable brown rings on petioles of cotton seedlings.

MAPK-mediated auxin signal transduction pathways regulate the malic acid secretion under aluminum stress in wheat (Triticum aestivum L.).

An isobaric tags for relative and absolute quantitative (iTRAQ)-based quantitative proteomic approach was used to screen the differentially expressed proteins during control treatment (CK), aluminum (Al) and Al+ indole-3-acetic acid (IAA) treatment of wheat lines ET8 (Al-tolerant). Further, the the expression levels of auxin response factor (ARF), Aux/IAA, Mitogen activated protein kinase (MAPK) 2c, and MAPK1a were analyzed. Results showed that 16 proteins were determined to be differentially expressed in response to Al and IAA co-treatment compared with Al alone. Among them, MAPK2c and MAPK1a proteins displayed markedly differential expression during the processes. The expression of ARF2 was upregulated and Aux/IAA was downregulated by Al, while both in concentration- and time-dependent manners. Western-blot detection of MAPK2c and MAPK1a indicated that Al upregulated MAPK2c and downregulated MAPK1a in both concentration- and time-dependent manners. Exogenous IAA could promote the expression of MAPK2c, but inhibit the expression of MAPK1a in the presence/absence of Al. These findings indicated that IAA acted as one of the key signaling molecule controls the response mechanism of wheat malic acid efflux to Al stress through the suppression/activation of Aux/IAA and ARFs, and the activity of MAPK2c and MAPK1a were positively or negatively regulated.

The boron transporter BnaC4.BOR1;1c is critical for inflorescence development and fertility under boron limitation in Brassica napus.

Boron (B) is an essential micronutrient for plants, but the molecular mechanisms underlying the uptake and distribution of B in allotetraploid rapeseed (Brassica napus) are unclear. Here, we identified a B transporter of rapeseed, BnaC4.BOR1;1c, which is expressed in shoot nodes and involved in distributing B to the reproductive organs. Transgenic Arabidopsis plants containing a BnaC4.BOR1;1c promoter-driven GUS reporter gene showed strong GUS activity in roots, nodal regions of the shoots and immature floral buds. Overexpressing BnaC4.BOR1;1c in Arabidopsis wild type or in bor1-1 mutants promoted wild-type growth and rescued the bor1-1 mutant phenotype. Conversely, knockdown of BnaC4.BOR1;1c in a B-efficient rapeseed line reduced B accumulation in flower organs, eventually resulting in severe sterility and seed yield loss. BnaC4.BOR1;1c RNAi plants exhibited large amounts of disintegrated stigma papilla cells with thickened cell walls accompanied by abnormal proliferation of lignification under low-B conditions, indicating that the sterility may be a result of altered cell wall properties in flower organs. Taken together, our results demonstrate that BnaC4.BOR1;1c is a AtBOR1-homologous B transporter gene expressing in both roots and shoot nodes that is essential for the developing inflorescence tissues, which highlights its diverse functions in allotetraploid rapeseed compared with diploid model plant Arabidopsis.

[Effects of selenite addition on selenium absorption, root morphology and physiological characteristics of rape seedlings].

Abstract: The rape (Brassica napus L. cv. Xiangnongyou 571) was chosen as the experimental material to undergo solution cultivation at seedling stage to investigate the effects of selenite addition on the selenium (Se) absorption and distribution, root morphology and physiological characteristics of rape seedlings. The results showed that the bioaccumulation ability of Se decreased significantly with increasing the Se application rate, but the Se distribution coefficient remained around 0.9 with no significant influence. The application of 10 µmol . L-1 selenite stimulated the growth of rape seedlings through improving the root physiological characteristics and root morphology significantly, including significantly increasing the production of superoxide radical (O2∙-) rate and the activities of superoxide dismutase (SOD), peroxidase (POD) and fungal catalase (CAT) in the root system, which resulted in a reduction of the lipids peroxidation (MDA) content as much as 26.0%, consequently increasing the root activity as much as 17.4%. The promoting degrees of selenite on root morphological parameters were from strong to weak in such a tendency: root volume > total surface area > number of root forks > total root length > number of root tips > average diameter. However, such positive effects had no significant difference with those in treatment with 1 µmol . L-1 selenite, indicating that small amounts (≤ 10 Lmol . L-1) of selenite were able to increase the activity of antioxidant enzymes and reduce the content of MDA in root system, which could increase root activity and improve root morphology, hence increased the biomass of rape seedlings.

The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance.

Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.