Phosphorus (P) is a finite natural resource and is increasingly considered to be a challenge for global sustainability. Agriculture in China plays a key role in global sustainable P management. Rhizosphere and soil-based P management are necessary for improving P-use efficiency and crop productivity in intensive agriculture in China. A previous study has shown that the future demand for phosphate fertilizer by China estimated by the LePA model (legacy phosphorus assessment model) can be greatly reduced by soil-based P management (the building-up and maintenance approach). The present study used the LePA model to predict the phosphate demand by China through combined rhizosphere and soil-based P management at county scale under four P fertilizer scenarios: (1) same P application rate as in 2012; (2) rate maintained same as 2012 in low-P counties or no P fertilizer applied in high-P counties until targeted soil Olsen-P (TPOlsen) level is reached, and then rate was the same as P-removed at harvest; (3) rate in each county decreased to 1–7 kg ha^–1 yr^–1 after TPOlsen is reached in low-P counties, then increased by 0.1–9 kg ha^–1 yr^–1 until equal to P-removal; (4) rate maintained same as 2012 in low-P counties until TPOlsen is reached and then equaled to P-removal, while the rate in high-P counties is decreased to 1–7 kg ha^–1 yr^–1 until TPOlsen is reached and then increased by 0.1–9 kg ha^–1 yr^–1 until equal to P-removal. Our predictions showed that the total demand for P fertilizer by whole China was 693 Mt P2O5 and according to scenario 4, P fertilizer could be reduced by 57.5% compared with farmer current practice, during the period 2013–2080. The model showed that rhizosphere P management led to a further 8.0% decrease in P fertilizer use compared with soil-based P management. The average soil Olsen-P level in China only needs to be maintained at 17 mg kg^–1 to achieve high crop yields. Our results provide a firm basis for government to issue-relevant policies for sustainable P management in China.

Caprine arthritis-encephalitis virus (CAEV) is an under-studied virus infecting caprines and ovines worldwide.  Over the last four decades, CAEV has spread in China, obtaining genomic data on CAEV strains circulating in China is of importance for developing diagnostic methods and eradicating associated diseases.  However, there is limited information on the genome, including characterizations, and the probable origin.  This work aimed to characterize Chinese CAEV genomes and population structures.  Five CAEV strains isolated from infected dairy goats between 1989 and 1994 in Gansu, Guizhou, Shaanxi, Shandong and Sichuan provinces were cloned and sequenced.  The Chinese CAEV had a 58–93% genome similarities to strains outside of China, and they belonged to subgenotype B1.  The highest similarity levels (98.3–99.3%) were with two other Chinese strains, and they shared a 91.8–92.3% similarity with the strain Clements (GenBank accession no. NC_001463.1) from outside of China.  The Chinese CAEV strains isolated from different provinces over five years were still highly homologous and contained unique ancestral population components, indicating that these Chinese strains had a common origin that differed from other known strains.  Our results provide genomic data on circulating Chinese CAEV strains and will be useful for future epidemiological investigations and CAEV eradication programs.

In situ mRNA hybridization (ISH) is a powerful tool for examining the spatiotemporal expression of genes in shoot apical meristems and flower buds of cucumber.  The most common ISH protocol uses paraffin wax; however, embedding tissue in paraffin wax can take a long time and might result in RNA degradation and decreased signals.  Here, we developed an optimized protocol to simplify the process and improve RNA sensitivity.  We combined embedding tissue in low melting-point Steedman’s wax with processing tissue sections in solution, as in the whole-mount ISH method in the optimized protocol. Using the optimized protocol, we examined the expression patterns of the CLAVATA3 (CLV3) and WUSCHEL (WUS) genes in shoot apical meristems and floral meristems of Cucumis sativus (cucumber) and Arabidopsis thaliana (Arabidopsis).  The optimized protocol saved 4–5 days of experimental period compared with the standard ISH protocol using paraffin wax.  Moreover, the optimized protocol achieved high signal sensitivity.  The optimized protocol was successful for both cucumber and Arabidopsis, which indicates it might have general applicability to most plants

Sex determination in plants gives rise to unisexual flowers.  A better understanding of the regulatory mechanism underlying the production of unisexual flowers will help to clarify the process of sex determination in plants and allow researchers and farmers to harness heterosis.  Androecious cucumber (Cucumis sativus L.) plants can be used as the male parent when planted alongside a gynoecious line to produce heterozygous seeds, thus reducing the cost of seed production.  The isolation and characterization of additional androecious genotypes in varied backgrounds will increase the pool of available germplasm for breeding.  Here, we discovered an androecious mutant in a previously generated ethyl methanesulfonate (EMS)-mutagenized library of the cucumber inbred line ‘406’.  Genetic analysis, whole-genome resequencing, and molecular marker-assisted verification demonstrated that a nonsynonymous mutation in the ethylene biosynthetic gene 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE 11 (ACS11) conferred androecy.  The mutation caused an amino acid change from serine (Ser) to phenylalanine (Phe) at position 301 (S301F).  In vitro enzyme activity assays revealed that this S301F mutation leads to a complete loss of enzymatic activity.  This study provides a new germplasm for use in cucumber breeding as the androecious male parent, and it offers new insights into the catalytic mechanism of ACS enzymes.

Root-knot nematodes (RKNs) cause huge yield losses to agricultural crops worldwide.  Meanwhile, livestock manure is often improperly managed by farmers, which leads to serious environmental pollution.  To resolve these two problems, this study developed a procedure for the conversion of chicken manure to organic fertilizer by larvae of Hermetia illucens L. and Bacillus subtilis BSF-CL.  Chicken manure organic fertilizer was then mixed thoroughly with Paenibacillus polymyxa KM2501-1 to a final concentration of 1.5×10⁸ CFU g^–1.  The efficacy of KM2501-1 microbial organic fertilizer in controlling root-knot nematodes was evaluated in pot and field experiments.  In pot experiments, applying KM2501-1 microbial organic fertilizer either as a base fertilizer or as a fumigant at the dose of 40 g/pot suppressed root-knot disease by 61.76 and 69.05% compared to the corresponding control treatments, respectively.  When applied as a fumigant at the dose of 1 kg m^–2 in field experiments, KM2501-1 microbial organic fertilizer enhanced the growth of tomato plants, suppressed root-knot disease by 49.97%, and reduced second stage juveniles of RKN in soil by 88.68%.  KM2501-1 microbial organic fertilizer controlled RKNs better than commercial bio-organic fertilizer in both pot and field experiments.  These results demonstrate that this co-conversion process efficiently transforms chicken manure into high value-added larvae biomass and KM2501-1 microbial organic fertilizer with potential application as a novel nematode control agent.

Understanding the characteristics and influences of various factors on phosphorus (P) fractions is of significance for promoting the efficiency of soil P.  Based on long-term experiments on black soil, fluvo-aquic soil, and loess soil, which belong to Phaeozems, Cambisols, and Anthrosols in the World Reference Base for Soil Resources (WRB), respectively, five fertilization practices were selected and divided into three groups: no P fertilizer (CK/NK), balanced fertilizer (NPK/NPKS), and manure plus mineral fertilizer (NPKM).  Soil inorganic P (Pi) fractions and soil properties were analyzed to investigate the characteristics of the Pi fractions and the relationships between Pi fractions and various soil properties.  The results showed that the proportion of Ca₁₀-P in the sum of total Pi fractions was the highest in the three soils, accounting for 33.5% in black soil, 48.8% in fluvo-aquic soil, and 44.8% in loess soil.  Long-term fertilization practices resulted in periodic changes in soil Pi accumulation or depletion.  For black soil and fluvo-aquic soil, the Pi accumulation was higher in the late period (10–20 years) of fertilization than in the early period (0–10 years) under NPK/NPKS and NPKM, whereas the opposite result was found in loess soil.  The Pi accumulation occurred in all Pi fractions in black soil; mainly in Ca₈-P, Fe-P, and Ca₁₀-P in fluvo-aquic soil; and in Ca₂-P, Ca₈-P, and O-P in loess soil.  Under CK/NK, the soil Pi was depleted mainly in the early period in each of the three soils.  In addition to the labile Pi (Ca₂-P) and moderately labile Pi (Ca₈-P, Fe-P, Al-P), the Ca₁₀-P in black soil and fluvo-aquic soil and O-P in loess soil could also be used by crops.  Redundancy analysis showed that soil properties explained more than 90% of the variation in the Pi fractions in each soil, and the explanatory percentages of soil organic matter (SOM) were 43.6% in black soil, 74.6% in fluvo-aquic, and 38.2% in loess soil.  Consequently, decisions regarding the application of P fertilizer should consider the accumulation rate and the variations in Pi fractions driven by soil properties in non-acidic soils.

Cell wall architecture plays a key role in stalk strength and forage digestibility.  Lignin, cellulose, and hemicellulose are the three main components of plant cell walls, and they can impact stalk quality by affecting the structure and strength of the cell wall.  To explore cell wall development during secondary cell wall lignification in maize stalks, conventional and conditional genetic mapping were used to identify the dynamic quantitative trait loci (QTLs) of the cell wall components and digestibility traits during five growth stages after silking.  Acid detergent lignin (ADL), cellulose (CEL), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD) were evaluated in a maize recombinant inbred line (RIL) population.  ADL, CEL, ADF, and NDF gradually increased from 10 to 40 days after silking (DAS), and then they decreased.  IVDMD initially decreased until 40 DAS, and then it increased slightly.  Seventy-two QTLs were identified for the five traits, and each accounted for 3.48–24.04% of the phenotypic variation.  Six QTL hotspots were found, and they were localized in the 1.08, 2.04, 2.07, 7.03, 8.05, and 9.03 bins of the maize genome.  Within the interval of the pleiotropic QTL identified in bin 1.08 of the maize genome, six genes associated with cell wall component biosynthesis were identified as potential candidate genes for stalk strength as well as cell wall-related traits.  In addition, 26 conditional QTLs were detected in the five stages for all of the investigated traits.  Twenty-two of the 26 conditional QTLs were found at 30 DAS conditioned using the values of 20 DAS, and at 50 DAS conditioned using the values of 40 DAS.  These results indicated that cell wall-related traits are regulated by many genes, which are specifically expressed at different stages after silking.  Simultaneous improvements in both forage digestibility and lodging resistance could be achieved by pyramiding multiple beneficial QTL alleles identified in this study.

Genome dynamics of pathogenic organisms are driven by plant host and pathogenic organism co-evolution, in which pathogen genomes are used to overcome stresses imposed by hosts with various genetic backgrounds through generation of a range of field isolates.  This model also applies to the rice host and its fungal pathogen Magnaporthe oryzae.  To better understand genetic variation of M. oryzae in nature, the field isolate V86010 from the Philippines was sequenced and analyzed.  Genome annotation found that the assembled V86010 genome was composed of 1 931 scaffolds with a combined length of 38.9 Mb.  The average GC ratio is 51.3% and repetitive elements constitute 5.1% of the genome.  A total of 11 857 genes including 616 effector protein genes were predicted using a combined analysis pipeline.  All predicted genes and effector protein genes of isolate V86010 distribute on the eight chromosomes when aligned with the assembled genome of isolate 70-15.  Effector protein genes are located disproportionately at several chromosomal ends.  The Pot2 elements are abundant in V86010.  Seven V86010-specific effector proteins were found to suppress programmed cell death induced by BAX in tobacco leaves using an Agrobacterium-mediated transient assay.  Our results may provide useful information for further study of the molecular and genomic dynamics in the evolution of M. oryzae and rice host interactions, and for characterizing novel effectors and AVR genes in the rice blast pathogen.  

This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates (>2, 1–2, 0.5–1, 0.25–0.5, and <0.25 mm) and associated soil organic carbon (SOC) and total nitrogen (TN) content in loess soil. A 21-yr long-term experiment was performed, in which soil management regimes include cropland abandonment (Abandonment), bare fallow (Fallow) and wheat-fallow cropping (Cropping). Under Cropping, the following nutrient treatments were employed: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK, and manure (M) plus NPK (MNPK). Results demonstrated that Abandonment significantly increased the content of soil macro-aggregates (>0.25 mm) and mean weight diameter (MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in >0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in >1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.

The sustainability of the wheat-maize rotation is important to China’s food security. Intensive cropping without recycling crop residues or other organic inputs results in the loss of soil organic matter (SOM) and nutrients, and is assumed to be non- sustainable. We evaluated the effects of nine different treatments on yields, nitrogen use efficiency, P and K balances, and soil fertility in a wheat-maize rotation system (1991-2010) on silt clay loam in Shaanxi, China. The treatments involved the application of recommended dose of nitrogen (N), nitrogen and phosphorus (NP), nitrogen and potassium (NK), phosphorus and potassium (PK), combined NPK, wheat or maize straw (S) with NPK (SNPK), or dairy manure (M) with NPK (M1NPK and M2NPK), along with an un-treated control treatment (CK). The mean yields of wheat and maize ranged from 992 and 2 235 kg ha-1 under CK to 5 962 and 6 894 kg ha-1 under M2NPK treatment, respectively. Treatments in which either N or P was omitted (N, NK and PK) gave significantly lower crop yields than those in which both were applied. The crop yields obtained under NP, NPK and SNPK treatments were statistically identical, as were those obtained under SNPK and MNPK. However, M2NPK gave a significant higher wheat yield than NP, and MNPK gave significant higher maize yield than both NP and NPK. Wheat yields increased significantly (by 86 to 155 kg ha-1 yr-1) in treatments where NP was applied, but maize yields did not. In general, the nitrogen use efficiency of wheat was the highest under the NP and NPK treatments; for maize, it was the highest under MNPK treatment. The P balance was highly positive under MNPK treatment, increasing by 136 to 213 kg ha-1 annually. While the K balance was negative in most treatments, ranging from 31 to 217 kg ha-1 yr-1, levels of soil available K remained unchanged or increased over the 20 yr. SOM levels increased significantly in all treatments. Overall, the results indicated that combinations of organic manure and inorganic nitrogen, or returning straw with NP is likely to improve soil fertility, increasing the yields achievable with wheat-maize system in a way which is environmentally and agronomically beneficial on the tested soil.

The presence of abundant and diverse communities of macro-arthropods is considered an indicator of sustainability in agroecosystems. This study was designed to investigate the effects of different fertilizer treatments on abundance and diversity of insects of arable loess soil on the Loess Plateau of China. These regimes included a control with no fertilizer addition or manure, treatments with application of mineral fertilizers (N, NK, NP, PK, NPK), treatments with NPK in combination with organic materials such as wheat straw or maize stalk, treatments with two rates of organic manure application; and different crop rotations (Rot.1: winter wheat summer maize; Rot.2: winter wheat summer maize soybean intercropping; and Rot.3: winter wheat or rapeseed summer maize soybean intercropping). Soil macro-arthropods were collected from the plough layer (0-20 cm) and sorted by hand after each harvest in June and October 2001 and 2002. A total of 3 132 individuals were collected, from 7 orders and 55 families, dominated by Formicidae (61.72%) and Staphylinidae (14.24%). The results showed that individuals and groups were significantly influenced by sampling dates, while groups were significantly influenced by the fertilization treatments. Soil insect biodiversity, as determined by the Shannon index, was significantly influenced by fertilization and sampling dates. The abundance of soil insects was positively and significantly correlated with soil moisture content in October 2002. Nitrogen, phosphorus and potassium fertilizers and incorporation of organic materials were favorable factors for abundance and diversity in arable loess soil.

Thirty-two Wistar rats were divided randomly into four groups of eight with six females and two males in each group. The rats were exposed to high fluoride drinking water (45 mg F- L-1 from 100 mg NaF L-1), low dietary iodine (0.0855 mg kg-1), or both together in order to assess the effects of these three regimens on the thyroid function of the offspring rats. After the animal model was established, the offspring rats were bred and 10-, 20-, 30-, 60-, and 90-d-old rats were used for the experiment. The treatments for the offspring rats were the same as those of their parents. In comparison with control rats, the relative thyroid glands were changed by three regimens, but the mean values of thyroid weight in the experimental groups saw no marked difference. Serum TT3 levels were increased in all stages in the low iodine (LI) group. In the high fluoride (HiF) group, increase in TT3 levels was observed except in 20-d-old rats. Decrease in TT3 at 20- and 90-d and increase in TT3 at 30- and 60-d were found in HiF+LI group. Serum TT4 levels first saw an increase, and then dropped in the LI and HiF+LI group. However, an increase in TT4 was found in the HiF group. The levels of TSH in serum rocketed at d 20, and then dropped in the next stages in experimental groups. The results suggested that thyroid disorder could be induced by high flroride in drinking water, low iodine diet, or both of them. Exposure time to fluoride or low iodine diet was one of the important factors that fluoride can induce the development of thyroid dyfunction.

Crop models can be useful tools for optimizing fertilizer management for a targeted crop yield while minimizing nutrient losses. In this paper, the parameters of the decision support system for agrotechnology transfer (DSSAT)-CERES-Maize were optimized using a new method to provide a better simulation of maize (Zea mays L.) growth and N uptake in response to different nitrogen application rates. Field data were collected from a 5 yr field experiment (2006-2010) on a Black soil (Typic hapludoll) in Gongzhuling, Jilin Province, Northeast China. After cultivar calibration, the CERES-Maize model was able to simulate aboveground biomass and crop yield of in the evaluation data set (n-RMSE=5.0-14.6%), but the model still over-estimated aboveground N uptake (i.e., with E values from -4.4 to -21.3 kg N ha-1). By analyzing DSSAT equation, N stress coefficient for changes in concentration with growth stage (CTCNP2) is related to N uptake. Further sensitivity analysis of the CTCNP2 showed that the DSSAT model simulated maize nitrogen uptake more precisely after the CTCNP2 coefficient was adjusted to the field site condition. The results indicated that in addition to calibrating 6 coefficients of maize cultivars, radiation use efficiency (RUE), growing degree days for emergence (GDDE), N stress coefficient, CTCNP2, and soil fertility factor (SLPF) also need to be calibrated in order to simulate aboveground biomass, yield and N uptake correctly. Independent validation was conducted using 2008-2010 experiments and the good agreement between the simulated and the measured results indicates that the DSSAT CERES-Maize model could be a useful tool for predicting maize production in Northeast China.