The accurate and rapid estimation of canopy nitrogen content (CNC) in crops is the key to optimizing in-season nitrogen fertilizer application in precision agriculture. However, the determination of CNC from field sampling data for leaf area index (LAI), canopy photosynthetic pigments (CPP; including chlorophyll a, chlorophyll b and carotenoids) and leaf nitrogen concentration (LNC) can be time-consuming and costly. Here we evaluated the use of high-precision unmanned aerial vehicle (UAV) multispectral imagery for estimating the LAI, CPP and CNC of winter wheat over the whole growth period. A total of 23 spectral features (SFs; five original spectrum bands, 17 vegetation indices and the gray scale of the RGB image) and eight texture features (TFs; contrast, entropy, variance, mean, homogeneity, dissimilarity, second moment, and correlation) were selected as inputs for the models. Six machine learning methods, i.e., multiple stepwise regression (MSR), support vector regression (SVR), gradient boosting decision tree (GBDT), Gaussian process regression (GPR), back propagation neural network (BPNN) and radial basis function neural network (RBFNN), were compared for the retrieval of winter wheat LAI, CPP and CNC values, and a double-layer model was proposed for estimating CNC based on LAI and CPP. The results showed that the inversion of winter wheat LAI, CPP and CNC by the combination of SFs+TFs greatly improved the estimation accuracy compared with that by using only the SFs. The RBFNN and BPNN models outperformed the other machine learning models in estimating winter wheat LAI, CPP and CNC. The proposed double-layer models (R²=0.67–0.89, RMSE=13.63–23.71 mg g^–1, MAE=10.75–17.59 mg g^–1) performed better than the direct inversion models (R²=0.61– 0.80, RMSE=18.01–25.12 mg g^–1, MAE=12.96–18.88 mg g^–1) in estimating winter wheat CNC. The best winter wheat CNC accuracy was obtained by the double-layer RBFNN model with SFs+TFs as inputs (R²=0.89, RMSE=13.63 mg g^–1, MAE=10.75 mg g^–1). The results of this study can provide guidance for the accurate and rapid determination of winter wheat canopy nitrogen content in the field.

Maize (Zea mays L.) is one of the three major food crops and an important source of carbohydrates for maintaining food security around the world.  Plant height (H), stem diameter (SD), leaf area index (LAI) and dry matter (DM) are important growth parameters that influence maize production.  However, the combined effect of temperature and light on maize growth is rarely considered in crop growth models.  Ten maize growth models based on the modified logistic growth equation (Mlog) and the Mitscherlich growth equation (Mit) were proposed to simulate the H, SD, LAI and DM of maize under different mulching practices based on experimental data from 2015–2018.  Either the accumulative growing degree-days (AGDD), helio thermal units (HTU), photothermal units (PTU) or photoperiod thermal units (PPTU, first proposed here) was used as a single driving factor in the models; or AGDD was combined with either accumulative actual solar hours (ASS), accumulative photoperiod response (APR, first proposed here) or accumulative maximum possible sunshine hours (ADL) as the dual driving factors in the models.  The model performances were evaluated using seven statistical indicators and a global performance index.  The results showed that the three mulching practices significantly increased the maize growth rates and the maximum values of the growth curves compared with non-mulching.  Among the four single factor-driven models, the overall performance of the Mlog_PTU Model was the best, followed by the Mlog_AGDD Model.  The Mlog_PPTU Model was better than the Mlog_AGDD Model in simulating SD and LAI.  Among the 10 models, the overall performance of the Mlog_AGDD–APR Model was the best, followed by the Mlog_AGDD–ASS Model.  Specifically, the Mlog_AGDD–APR Model performed the best in simulating H and LAI, while the Mlog_AGDD–ADL and Mlog_AGDD–ASS models performed the best in simulating SD and DM, respectively.  In conclusion, the modified logistic growth equations with AGDD and either APR, ASS or ADL as the dual driving factors outperformed the commonly used modified logistic growth model with AGDD as a single driving factor in simulating maize growth.

Photosynthesis occurs mainly in chloroplasts, whose development is regulated by proteins encoded by nuclear genes.  Among them, pentapeptide repeat (PPR) proteins participate in organelle RNA editing.  Although there are more than 450 members of the PPR protein family in rice, only a few affect RNA editing in rice chloroplasts.  Gene editing technology has created new rice germplasm and mutants, which could be used for rice breeding and gene function study.  This study evaluated the functions of OsPPR9 in chloroplast RNA editing in rice.  The osppr9 mutants were obtained by CRISPR/Cas9, which showed yellowing leaves and a lethal phenotype, with suppressed expression of genes associated with chloroplast development and accumulation of photosynthetic-related proteins.  In addition, loss of OsPPR9 protein function reduces the editing efficiency of rps8-C182, rpoC2-C4106, rps14-C80, and ndhB-C611 RNA editing sites, which affects chloroplast growth and development in rice.  Our data showed that OsPPR9 is highly expressed in rice leaves and encodes a DYW-PPR protein localized in chloroplasts.  Besides, the OsPPR9 protein was shown to interact with OsMORF2 and OsMORF9.  Together, our findings provide insights into the role of the PPR protein in regulating chloroplast development in rice. 

Several viroids in the genus Pospiviroid can infect tomato (Solanum lycopersicum) and cause severe diseases, posing a serious threat to tomato production.  For simultaneous detection of six tomato-infecting pospiviroids - columnea latent viroid (CLVd), pepper chat fruit viroid (PCFVd), potato spindle tuber viroid (PSTVd), tomato apical stunt viroid (TASVd), tomato chlorotic dwarf viroid (TCDVd), and tomato planta macho viroid (TPMVd), we developed a universal probe based on a highly conserved 61 nt long sequence shared among them.  Compared with their specific probes, the universal probe has a similar, though slightly reduced, detection sensitivity and has the advantages of simple and cost-effective preparation and simultaneous detection of the six pospiviroids.  In addition, the universal probe was used in dot-blot hybridization assays for a large-scale survey of viroid(s) in tomato plantings in China.  Only PSTVd was detected in a few greenhouse-planted tomato plants.  Sequence analysis revealed that these tomato PSTVd isolates may have been introduced from tomato seeds imported from abroad. 

As intracellular fatty acid (FA) carriers, FA-binding proteins (FABPs) widely participate in the absorption, transport, and metabolism of FAs.  It is a key protein in insect lipid metabolism and plays an important role in various physiological activities of insects.  An FABP gene (HvFABP) was cloned from the transcriptional library of Heortia vitessoides Moore (Lepidoptera: Crambidae), and its expression patterns were determined using reverse transcription quantitative PCR (RT-qPCR).  Stage- and tissue-specific expression profiles indicated that HvFABP highly expressed from prepupal to adult stages and in larval midgut and adult wings.  HvFABP expression may be induced through starvation, mRNA expression was downregulated at 24 and 48 h and upregulated at 72 h after starvation.  Furthermore, 20-hydroxyecdysone can induce the upregulation of its expression.  RNA interference-mediated silencing of HvFABP significantly inhibited HvFABP expression, resulting in delayed development, abnormal molting or lethal phenotypes, and a significantly reduced survival rate.  These results indicate that HvFABP plays a key role in the molting of H. vitessoides

Salinity severely affects plant growth and development. Thus, it is crucial to identify the genes functioning in salt stress response and unravel the mechanism by which plants against salt stress. This study used the phosphoproteomic assay and found that 123 of the 4 000 quantitative analyzed phosphopeptides were induced by salt stress. The functional annotation of the non-redundant protein database (NR) showed 23 differentially expressed transcription factors, including a phosphopeptide covering the Serine 31 in the RAV (related to ABI3/VP1) transcription factor (named SiRAV1). SiRAV1 was located in the nucleus. Phenotypic and physiological analysis showed that overexpressing SiRAV1 in foxtail millet enhanced salt tolerance and alleviated the salt-induced increases of H₂O₂ accumulation, malondialdehyde (MDA) content, and percent of electrolyte leakage. Further analysis showed that SiRAV1 positively regulated SiCAT expression to modulate the catalase (CAT) activity by directly binding to the SiCAT promoter in vivo and in vitro. Moreover, we found that phosphorylation of SiRAV1 at the Ser31 site positively regulated salt tolerance in foxtail millet via enhancing its binding ability to SiCAT promoter but did not affect its subcellular localization. Overall, our results define a mechanism for SiRAV1 function in salt response where salt-triggered phosphorylation of SiRAV1 at Ser31 enhances its binding ability to SiCAT promoter, and the increased SiCAT expression contributes to salt tolerance in foxtail millet.

Cassava is an important tropical cash crop.  Severe drought stresses affect cassava productivity and quality, and cause great economic losses in agricultural production.  Enhancing the drought tolerance of cassava can effectively improve its yield.  Long non-coding RNAs (lncRNAs) are present in a wide variety of eukaryotes.  Recently, increasing evidence has shown that lncRNAs play a critical role in the responses to abiotic stresses.  However, the function of cassava lncRNAs in the drought response remains largely unknown.  In this study, we identified a novel lncRNA, DROUGHT-INDUCED INTERGENIC lncRNA (DIR).  Gene expression analysis showed that DIR was significantly induced by drought stress treatment, but did not respond to abscisic acid (ABA) or jasmonic acid (JA) treatments.  In addition, overexpression of the DIR gene enhanced proline accumulation and drought tolerance in transgenic cassava.  RNA-seq analysis revealed that DIR preferentially affected drought-related genes that were linked to transcription and metabolism.  Moreover, RNA pull-down mass spectrometry analysis showed that DIR interacted with 325 proteins.  A protein–protein interaction (PPI) analysis found a marked enrichment in proteins associated with the mRNA export and protein quality control pathways.  Collectively, these results suggest that DIR and its interacting proteins that regulate mRNA or protein metabolism are involved in mediating the drought stress response.  Thus, regulating DIR expression has potential for improving cassava yield under drought conditions.

Understanding the heterosis in multiple environments between different heterotic groups is of fundamental importance in successful maize breeding.  A total of 737 hybrids derived from 41 maize inbreds were evaluated over two years, with the aim of assessing the genetic diversity and their performance between heterotic groups under drought-stressed (DS) and well-watered (WW) treatments.  A total of 38 737 SNPs were employed to assess the genetic diversity.  The genetic distance (GD) between the parents ranged from 0.05 to 0.74, and the 41 inbreds were classified into five heterotic groups.  According to the hybrid performance (high yield and early maturity between heterotic groups), the heterosis and heterotic patterns of Iowa Stiff Stalk Synthetic (BSSS)×Non-Stiff Stalk (NSS), NSS×Sipingtou (SPT) and BSSS×SPT were identified to be useful options in China’s maize breeding.  The relative importance of general and specific combining abilities (GCA and SCA) suggests the importance of the additive genetic effects for grain yield traits under the WW treatment, but the non-additive effects under the DS treatment.  At least one of the parental lines with drought tolerance and a high GCA effect would be required to achieve the ideal hybrid performance under drought conditions.  GD showed a positive correlation with yield and yield heterosis in within-group hybrids over a certain range of GD.  The present investigation suggests that the heterosis is due to the combined accumulation of superior genes/alleles in parents and the optimal genetic distance between parents, and that yield heterosis under DS treatment was mainly determined by the non-additive effects.

Lipoxygenase (LOXs) is a kind of dioxygenase without heme and iron, which plays an important role in the development and adaptation of many plants to the environment.  However, the study of strawberry LOX gene family has not been reported.  In this study, 14 LOX genes were identified from the diploid woodland strawberry genome.  The phylogenetic tree divides the FvLOX gene into two subfamilies: 9-LOX and 13-LOX.  Gene duplication event analysis showed that whole-genome duplication (WGD)/segmental duplication and dispersed duplication effectively promoted the expansion of strawberry LOX family.  QRT-PCR analysis showed that FvLOX genes were expressed in different tissues.  Expression profile analysis showed that FvLOX1 and FvLOX8 were up-regulated under low temperature stress, FvLOX3 and FvLOX7 were up-regulated under drought stress, FvLOX6 and FvLOX9 were up-regulated under salt stress, FvLOX2, FvLOX3 and FvLOX6 were up-regulated under salicylic acid (SA) treatment, FvLOX3, FvLOX11 and FvLOX14 were up-regulated under methyl jasmonate (MeJA) treatment, FvLOX4 and FvLOX14 were up-regulated under abscisic acid (ABA) treatment.  Promoter analysis showed that FvLOX genes were involved in plant growth and development and stress response.  We analyzed and identified the whole genome of strawberry FvLOX family and characterized a variety of FvLOX candidate genes involved in abiotic stress response.  This study laid a theoretical and empirical foundation for the response mechanism of strawberry to abiotic stress.

A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.  This study was designed to determine whether optimized nitrogen (N) fertilization could fulfill these multiple goals.  In two-year experiments, two high yielding ‘super’ rice cultivars were grown with different N fertilization management regimes, including zero N input, local farmers’ practice (LFP) with heavy N inputs, and optimized N fertilization (ONF).  In ONF, by reducing N input, increasing planting density, and optimizing the ratio of urea application at different stages, N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.  Compared with LFP, yield and partial factor productivity of applied N (PFP) under ONF were increased (on average) by 1.70 and 13.06%, respectively.  ONF increased starch and amylose content, and significantly decreased protein content.  The contents of the short chains of A chain (degree of polymerization (DP) 6–12) and B1 chain (DP 13–25) of amylopectin were significantly increased under ONF, which resulted in a decrease in the stability of rice starch crystals.  ONF increased viscosity values and improved the thermodynamic properties of starch, which resulted in better eating and cooking quality of the rice.  Thus, ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency (NUE) at high yield levels.  These results will be useful for applications of high quality rice production at high yield levels.

Seedlessness in grape (Vitis vinifera) is an important commercial trait for both the fresh and drying markets.  However, despite numerous studies, the mechanisms and key genes regulating grape seedlessness are mostly unknown.  In this study, we sequenced the genomes of the V. vinifera seeded cultivar ‘Red Globe’, the seedless cultivar ‘Centennial Seedless’, and the derived hybrids.  Nonsynonymous single nucleotide polymorphisms (SNPs) were identified by genome sequencing and analyzed using published transcriptome data.  Nonsynonymous SNPs occurred in genes related to seed development, which were identified as protein kinases, transcription factors, and cytochrome P450s and showed differential expression during ovule development in both seeded and seedless grapes.  These nonsynonymous SNP-associated genes were mainly involved in biological processes such as hormone balance, seed coat and endosperm development, reproductive organ development, oxidation and reduction, senescence and cell death.  A potential quantitative trait locus (QTL) region associated with seed size was characterized based on the SNP-index, and expression analysis of candidate genes in the QTL region during ovule development in multiple seeded and seedless grape cultivars were conducted.  Three SNPs were further subjected to SNaPshot analysis and one SNP in G8 showed 67.5% efficiency in the grape progeny validation.  Overall, the data obtained in this study shed light on the differences in seed development between seeded and seedless progeny at the genomic level, which provides valuable resources for future functional studies and grape breeding.

In order to clarify the main pathogens of tomato Fusarium wilt in Shanxi Province, China, morphological identification, elongation factor 1 alpha (EF-1α) sequence analysis, specific primer amplification and pathogenicity tests were applied to study the isolates which were recovered from diseased plants collected from 17 different districts of Shanxi Province.  The results were as follows: 1) Through morphological and molecular identification, the following 7 species of Fusarium were identified: F. oxysporum, F. solani, F. verticillioides, F. subglutinans, F. chlamydosporum, F. sporotrichioides, and F. semitectum; 2) 56 isolates of F. oxysporum were identified using specific primer amplification, among which, 29, 5 and 6 isolates were respectively identified as F. oxysporum f. sp. lycopersici physiological race 1, race 2, and race 3; 3) pathogenicity test indicated the significant pathogenicity of F. oxysporum, F. solani, F. verticillioides, and F. subglutinans to tomato plant.  Therefore, among these 4 species confirmed as pathogenic to tomato in Shanxi, the highest isolation rate (53.3%) corresponded to F. oxysporum.  Three physiological species, race 1, race 2, and race 3 of F. oxysporum f. sp. lycopersici are detected in Shanxi, among which race 1 is the most widespread pathogen and is also considered as the predominant race.

In order to establish grading standards of evaluation indices for sour flavor of apples, 10 indices of samples from 106 apple cultivars were tested, including: malic acid (Mal), oxalic acid (Oxa), citric acid (Cit), lactic acid (Lac), succinic acid (Suc), fumaric acid (Fum), total organic acids (ToA, the sum of the six organic acids tested), titratable acid (TiA), acidity value (AcV), and pH value.  For most of the cultivars studied (85.8%), the order of the organic acid contents in apples was Mal>Oxa>Cit>Lac>Suc>Fum.  Mal was the dominant organic acid, on average, accounting for 94.5% of ToA.  Among the 10 indices, the dispersion of pH value was the smallest with a coefficient of variation of only 8.2%, while the coefficients of variation of the other nine indices were larger, ranging between 31 and 66%.  There were significant linear relationships between Mal and two indices (ToA and AcV) as well as between ToA and AcV.  There were significant logarithmic relationships between pH value and four indices: Mal, TiA, ToA, and AcV.  All the equations had very high fitting accuracy and can be used to accurately predict related indices.  According to this study, Mal, ToA, and AcV of apple were normally distributed, TiA was close to normally distributed, whereas pH value had a skewed distribution.  Using the fitted normal distribution curves, the grading standards of Mal, TiA, ToA, and AcV were established.  The grading node values of pH value were obtained using the logarithmic relationship between pH value and Mal.  The grading standards of these five indices can be used to evaluate the sour flavor of apple.  This study provides a scientific basis for evaluating apple flavor and selecting apple cultivars.

The flower-meristem-identity gene APETALA2 (AP2), one of class-A genes, is involved in the establishment of the floral meristem and the forming of sepals and petals.  Codon usage bias (CUB) identifies differences among species, meanwhile dynamic analysis of base composition can identify the molecular mechanisms and evolutionary relationships of a specific gene.  In this study, eight coding sequences (CDS) of AP2 gene were selected from different plant species using the GenBank database.  Their nucleotide composition (GC content), genetic index, relative synonymous codon usage (RSCU) and relative codon usage bias (RCUB) were calculated with R Software to compare codon bias and base composition dynamics of AP2 gene codon usage patterns in different plant species.  The results showed that the usage of AP2 gene codons from different plant species were influened by GC bias, especially GC3s.  Overall, base composition analysis indicated that the usage frequency of codon AT in the gene coding sequence was higher than GC among AP2 gene CDS from different plant species.  Furthermore, most AP2 gene CDSs ended with AT; AGA, GCU and UGU had relatively high RSCU values as the most dominant codon; the usage characteristic of the AP2 gene codon in Malus domestica was similar to that of Vitis vinifera; Paeonia lactiflora was similar to Paeonia suffruticosa and Solanum lycopersicum was similar to Petunia×hybrida.  There was a moderate preference in the usage of AP2 gene codon among different plant species from relatively low frequency of optimal codon (Fop) values and high effective number of codons (ENC) value.  This study has revealed the usage characteristics of the AP2 gene codon from the comparision of AP2 gene codon preference and base dynamics in different plant species and provide a platform for further study towards transgenic engineering and codon optimization.

We conducted a two-year study of deficit irrigation impact on peach yield and quality in semi-arid northwest China.  Over two years, four-year-old peach trees were irrigated at 100, 75, 50 and 25% of peach evapotranspiration (ET_c), here, ET_c= Coefficient (K_c)×Local reference evapotranspiration (ET_o).  During the April-July fruit production season we measured root zone soil water depletion, sap flow velocity, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), water use efficiency (WUE=P_n/T_r), fruit quality, and yield under a mobile rain-out shelter.  Increased soil water depletion reasonably mirrored decreasing irrigation rates both years, causing progressively greater water stress.  Progressive water stress lowered G_s, which in turn translated into lower T_r as measured by sap flow.  However, mild deficit irrigation (75% ET_c) constricted T_r more than P_n.  P_n was not different between 100 and 75% ET_c treatments in both years, and it decreased only 5–8% in June with higher temperature than that in May with cooler temperature.  Concurrently under 75% ET_c treatment, T_r was reduced, and WUE was up to 13% higher than that under 100% ET_c treatment.  While total fruit yield was not different under the two treatments, because 75% ET_c treatment had fewer but larger fruit than 100% ET_c trees, suggesting mild water stress thinned fruit load.  By contrast, sharply decreased T_r and P_n of the driest treatments (50 and 25% ET_c) increased WUE, but less carbon uptake impacted total fruit yield, resulting 13 and 33% lower yield compared to that of 100% ET_c treatment.  Irrigation rates affected fruit quality, particularly between the 100 and 75% ET_c trees.  Fewer but larger fruit in the mildly water stressed  trees (75% ET_c) resulted in more soluble solids and vitamin C, firmer fruit, and improved sugar:acid ratio and fruit color compared to the 100% ET_c treatment.  Overall, trees deficit irrigated at 75% ET_c maintained yield while improving fruit quality and using less water. 

Rice area has been expanding rapidly during the past 30 years under the influence of global change in northeastern China, which is the northernmost region of rice cultivation in China.  However, the spatio-temporal dynamic changes in rice area are still unclear, although they may have important policy implications for environmental protection and adaptation to climate change.  In this study, we aimed to identify the dynamic changes of the rice area in Heilongjiang Province of northeastern China by extracting data from multiple Landsat images.  The study used ground quadrats selected from Google Earth and the extraction of a confusion matrix to verify the accuracy of extraction.  The overall accuracy of the extracted rice area was higher than 95% as a result of using the artificial neural network (ANN) classification method.  The results showed that the rice area increased by approximately 2.4×10⁶ ha during the past 30 years at an annual rate of 8.0×10⁴ ha, and most of the increase occurred after 2000.  The central latitude of the rice area shifted northwards from 46 to 47°N during the study period, and moved eastwards from 130 to 133°E.  The rice expansion area accounted for 98% of the total change in rice area, and rice loss was notably rare.  The rice expansion was primarily from dryland.  In addition, rice cultivation in marshland and grassland played a minor role in the rice expansion in this region.

To better interpret summer maize stomatal conductance (g_s) variation under conditions of changing water status at different growth stages, three water stress indicators, soil water content (SWC), leaf-air temperature difference (?T) and leaf level water stress index (CWSI_L) were employed in Jarvis model, which were J_S, J_T and J_C models respectively.  Measurements of g_s were conducted in a summer maize field experiment during the year 2012–2013.  In the insufficient irrigation experiment, three levels of irrigation amount were applied at four different growth stages of summer maize.  We constructed three scenarios to evaluate the performance of the three water stress indicators for estimating maize g_s in a modified Jarvis model.  Results showed that J_T and J_C models had better simulation accuracy than the J_S model, especially at the late growth stage (Scenario 1) or considering the plant recovery compensation effects (Scenario 2).  Scenario 3 indicated that the more environmental factors were adopted, the better prediction performance would be for J_S model.  While for J_T model, two environmental factors (photosynthesis active radiation (PAR), and vapor pressure deficit (VPD)) seemed good enough to obtain a reliable simulation.  When there were insufficient environmental data, CWSI_L would be the best option.  This study can be useful to understand the response of plant stomatal to changing water conditions and will further facilitate the application of the Jarvis model in various environments.

To assess levels of contamination and human health risk, we analyzed the concentrations of the heavy metals lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni) in China’s main deciduous fruits - apple, pear, peach, grape, and jujube. The concentration order of the heavy metals was Ni>Cr>Pb>Cd. In 97.5% of the samples, heavy metal concentrations were within the maximum permissible limits. Among the fruits studied, the heavy metal concentrations in jujube and peach proved to be the highest, and those in grape proved to be the lowest. Only 2.2% of the samples were polluted by Ni, only 0.4% of the samples were polluted by Pb, and no samples were polluted by Cd or Cr. Compared with the other fruits, the combined heavy metal pollution was significantly higher (P<0.05) in peach and significantly lower (P<0.05) in grape. For the combined heavy metal pollution, 96.9% of the samples were at safe level, 2.32% at warning level, 0.65% at light level, and 0.13% at moderate level. In the fruits studied, the contribution of heavy metals to the daily intake rates (DIR) followed the order of Ni>Cr>Pb>Cd. The highest DIR came from apple, while the lowest DIR came from grape. For each of the heavy metals, the total DIR from five studied fruits corresponded to no more than 1.1% of the tolerable daily intake, indicating that no significant adverse health effects are expected from the heavy metals and the fruits studied. The target hazard quotients and the total target hazard quotients demonstrated that none of the analyzed heavy metals may pose risk to consumers through the fruits studied. The highest risk was posed by apple, followed in decreasing order by peach and pear, jujube, and grape. We suggest that the main deciduous fruits (apple, pear, peach, grape, and jujube) of China’s main producing areas are safe to eat.

    The aim of this work was to distinguish volatile organic compound (VOC) profiles of royal jelly (RJ) from different nectar plants.  Headspace solid-phase microextraction (HS-SPME) was used to extract VOCs from raw RJ harvested from 10 nectar plants in flowering seasons.  Qualitative and semi-quantitative analysis of VOCs extracts were performed by gas chromatography-mass spectrometry (GC-MS).  Results showed that VOC profiles of RJ from the samples were rich in acid, ester and aldehyde compound classes, however, contents of them were differential, exemplified by the data from acetic acid, benzoic acid methyl ester, hexanoic acid and octanoic acid.  As a conclusion, these four VOCs can be used for distinguishing RJ harvested in the seasons of different nectar plants.

The presence of pesticide residues in pears is a serious health concern. This study presents the results from a 2-year investigation (2013–2014) that used gas chromatography, GS/MS and UPLC/MS-MS to measure the levels of 104 pesticides in 310 pear samples. In 93.2% of the samples, 43 pesticides were detected, of which the maximum residue levels (MRLs) were exceeded in 2.6% of the samples. Multiple residues (two to eight compounds) were present in 69.7% of the samples; one sample contained nine pesticides and one sample contained 10. Only 6.8% of the samples did not contain residues. To assess the health risks, the pesticide residue data have been combined with daily pear consumption data for children and adult populations. A deterministic model was used to assess the chronic and acute exposures based on the Joint Meeting on Pesticide Residues (JMPR) method. A potential acute risk was demonstrated for children in the case of bifenthrin, which was found to be present at 105.36% of the acute reference dose (ARfD) value. The longterm exposure of the Chinese consumer to pesticide residues through the consumption of raw pears was far below the acceptable daily intake (ADI) criterion. Additionally, the matrix ranking scheme was used to classify risk subgroups of pesticides and pear samples. In general, 95.5% of samples were deemed to be safe and nine pesticides were classified as being of a relatively high risk. The findings indicated that the occurrence of pesticide residues in pears should not be considered a serious public health problem. Nevertheless, a more detailed study is required for vulnerable consumer groups, especially children. Continuous monitoring of pesticides in pears and tighter regulation of pesticide residue standards are recommended.

The variation among Chinese genotypes of Brassica napus L. for seed tocopherols content and their analysis using gas chromatography has not been comprehensively reported till to date. In the present study, the tocopherol contents of four Chinese genotypes of Brassica napus L., namely, Gaoyou 605, Zhejiang 619, Zheshuang 758, and Zheshuang 72, were evaluated using three modified sample preparation protocols (P1, P2, and P3) for tocopherol extraction. These methods were distinguished as follows. Protocol one (P1) included the evaporation of solvent after extraction without silylation. Protocol two (P2) followed the direct supernatant collection after overnight extraction without drying and silylation. Protocol three (P3) included trimethylsilylation with N,O-bis(trimethylsilyl) trifluoroacetamide. Genotypic comparison of tocopherol and its isoforms revealed that Gaoyou 605 was dominant over the other genotypes with (140.5±10.5), (316.2± 9.2), and (559.1± 24.3) μg g-1 of seed meal α-, γ-, and total (T-) tocopherol, respectively, and a 0.44±0.04 α- to γ-tocopherol ratio. The comparison of the sample preparation protocols, on the other hand, suggests that P3 is the most suitable method for the tocopherol extraction from Brassica oilseeds and for the analysis of tocopherols using gas chromatography flame ionization detector (GC-FID). Trimethylsilylation is the key step differentiating P3 from P1 and P2. Variations detected in tocopherol contents among the Chinese rapeseed (B. napus) genotypes signify the need to quantify a wide range of rapeseed germplasm for seed tocopherol dynamics in short and crop improvement in long.

How to overcome yield stagnation is a big challenge to rice breeders. An effective method for quickly developing new cultivars is to further improve an outstanding cultivar. In this study, three advanced backcross populations under yield selection that consist of 123 BC2F2:4 introgression lines (ILs) were developed by crossing Minghui 86 (recurrent parent, RP) with three high-yielding varieties (donors), namely, ZDZ057, Fuhui 838, and Teqing, respectively. The progeny testing allowed the identification of 12 promising ILs that had significantly higher mean grain yields than Minghui 86 in two environments. A total of 55 QTLs that affect grain yield and its related traits were identified, which included 50 QTLs that were detected using the likelihood ratio test based on stepwise regression (RSTEP-LRT) method, and eight grain yield per plant (GY) QTLs were detected using chi-squared (c2) test. Among these QTLs, five QTLs were simultaneously detected in different populations and 22 QTLs were detected in both environments. The beneficial donor alleles for increased GY and its related traits were identified in 63.6% (35 out of 55) of the QTLs. These promising ILs and QTLs identified will provide the elite breeding materials and genetic information for further improvement of the grain yield for Minghui 86 through pyramiding breeding.

The spatial-temporal patterns of grain production and consumption have an important influence on the effective national grain supply on condition of tight balance in the total grain amount in China. In this paper, we analyze the spatial-temporal patterns of grain production, consumption and the driving mechanism for their evolution processes in China. The results indicate that both gravity centers of grain production and consumption in China moved toward the northern and eastern regions, almost in the same direction. The coordination of grain production and consumption increased slightly from 1995 to 2007 but decreased from 2000 to 2007. There is a spatial difference between the major districts of output increase and the strong growth potential in grain consumption, which indicates an increasing difficulty in improving the regional coordination of grain production and consumption. The movement of the gravity center of grain production is significantly correlated with regional differences in grain production policy, different economic development models, and spatial disparity of land and water resource use. For grain consumption, the main driving factors include rapid urbanization, the upgrade of food consumption structure, and distribution of food industries.

The soil organic matter and nutrients are fundamental for the sustainability of pear production, but little is known about the spatial distribution of soil organic matter and nutrients in a pear orchard. With the soil of the pear (cv. Dangshansu on P.betulifolia Bunge. rootstock) orchard under clean and sod cultivation models as test materials, the experiment was conducted to evaluate spatial variability of soil organic matter (SOM), total nitrogen (STN), total phosphorus (STP), total potassium (STK), available nitrogen (SAN), and available potassium (SAK) in and between rows at different soil depths (0-60 cm). The SOM, STN, STP, STK, SAN and SAK of the different soil layers under the two tillage models were different in the vertical direction. The SOM, STN, STP and SAN in the 0-20 cm soil layer were higher than those in the 20-40 and 40- 60 cm soil layers. The STK of 40-60 cm soil layer was higher than that in the 0-20 and 20-40 cm soil layers. The STK increased with the depth of soil in the vertical direction in the clean cultivated pear orchard. Variability of the SOM, STN, STP, STK, SAN and SAK of sample sites in between rows of the same soil layer was found in the pear orchard soil in the horizontal direction under clean and sod cultivation management systems, except that STK of all sites did not show the difference in identical soil layers in the pear orchard under clean cultivation. The sod cultivation model improved the SOM, STN, and STK in the 0-20 cm soil layer in the pear orchard, and the three components increased by 12.8, 12.7 and 7.3% compared to clean cultivation, respectively. The results can be applicable to plan collection of orchard soil samples, assess orchard soil quality, and improve orchard soil management practices.