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The crown root system is the most important root component in maize at both the vegetative and reproductive stages. However, the genetic basis of maize crown root traits (CRT) is still unclear, and the relationship between CRT and aboveground agronomic traits in maize is poorly understood. In this study, an association panel including 531 elite maize inbred lines was planted to phenotype the CRT and aboveground agronomic traits in different field environments. We found that root traits were significantly and positively correlated with most aboveground agronomic traits, including flowering time, plant architecture and grain yield. Using a genome-wide association study (GWAS) coupled with resequencing, a total of 115 associated loci and 22 high-confidence candidate genes were identified for CRT. Approximately one-third of the genetic variation in crown root was co-located with 46 QTLs derived from flowering and plant architecture. Furthermore, 103 (89.6%) of 115 crown root loci were located within known domestication- and/or improvement-selective sweeps, suggesting that crown roots might experience indirect selection in maize during domestication and improvement. Furthermore, the expression of Zm00001d036901, a high-confidence candidate gene, may contribute to the phenotypic variation in maize crown roots, and Zm00001d036901 was selected during the domestication and improvement of maize. This study promotes our understanding of the genetic basis of root architecture and provides resources for genomics-enabled improvements in maize root architecture.

The yield and nitrogen use efficiency (NUE) of hybrid rice combinations are closely related to restorer line. Therefore, it is essential to evaluate the agronomic characteristics of restorer lines with high yield and high NUE (HYHN). However, it is unclear which restorer lines are HYHN, and neither have the common agronomic traits of the HYHN restorer lines been identified. Aiming to address this issue, we conducted two filed experiments using three nitrogen applications, which screened five HYHN restorer lines from 15 indica restorer lines. Yield, NUE and nutrient transportation of restorer lines with different yields and NUE types were examined. Yield and total nitrogen absorption in aboveground biomass (TNA) increased, whereas NUE for grain production decreased with increasing nitrogen application levels. The HYHN restorer lines had large spikelets and high weight per panicle that were significantly positively correlated with yield and NUE. Therefore, large sink potential may be beneficial for both yield and NUE. We further studied the differences in nutrient transportation to panicles between the HYHN and low yield and low NUE (LYLN) restorer lines and found that the former had a higher nitrogen absorption level and dry matter weight ratios of panicle in maturity. Moreover, the HYHN lines also had a higher root and neck-panicle node bleeding intensity per stem after heading and more developed vascular bundles of neck-panicle nodes and leaves than the LYLN lines, which could contribute to the transportation of nutrients from root to ground and from stem and leaf to spike. Therefore, the advantages of large sink potential of the HYHN restorer lines include large nutrient accumulation in and distribution to the panicles and smooth flow of nutrients along the transportation channels.

Leaf color has been considered an important agronomic trait in rice (Oryza sativa L.) for a long time. The changes in leaf color affect the yield of rice. In this study, a green-revertible albino (graS) mutant was isolated from a 60Co-gamma-irradiated mutant pool of indica cultivar Guangzhan 63-4S. The fine mapping indicated that graS mutant was mapped to chromosome 1, and was located in a confined region between markers ab134 and InDel 8 with genetic distances of 0.11 and 0.06 cM, respectively. Based on the annotation results, four open reading frames (ORFs) were predicted in this region. Sequence analysis revealed that LOC_Os01g55974 had a 2-bp nucleotide insertion (AA) in the coding region that led to premature termination at the 324th base. Sequence analysis and expression analysis of related genes indicated that LOC_Os01g55974 is the candidate gene of GraS. We studied the genome and protein sequences of LOC_Os01g55974, and the data showed that GraS contains a deoxycytidine deaminase domain, which was expressed ubiquitously in all tissues. Further investigation indicated that GraS plays an essential role in the regulation of chloroplast biosynthesis, photosynthetic capacity and yield. Moreover, leaf color mutant can be used as an effective marker for the purity of breeding and hybridization.

The rice mutant ossac4 (starch accumulating 4) was raised from seeds of the rice (Oryza sativa L.) indica maintainer line Xinong 1B treated with ethyl methanesulfonate. The distal and medial portions of the second leaf displayed premature senescence in the ossac4 mutant at the four-leaf stage. Physiological and biochemical analysis, and cytological examination revealed that the ossac4 mutant exhibited the premature leaf senescence phenotype. At the four-leaf stage, the leaves of the ossac4 mutant exhibited significantly increased contents of starch compared with those of the wild type (WT). Quantitative real-time PCR analysis showed that the expression levels of photosynthesis-associated genes were down-regulated and the expression levels of glucose metabolism-associated genes were abnormal. Genetic analysis indicated that the ossac4 mutation was controlled by a single recessive nuclear gene. The OsSAC4 gene was localized to a 322.7-kb interval between the simple-sequence repeat marker XYH11-90 and the single-nucleotide polymorphism marker SNP5300 on chromosome 11. The target interval contained 20 annotated genes. The present results demonstrated that ossac4 represents a novel starch accumulation and premature leaf senescence mutant, and lays the foundation for cloning and functional analysis of OsSAC4.

Length of grain affects the appearance, quality, and yield of rice. A rice long-grain chromosome segment substitution line Z744, with Nipponbare as the recipient parent and Xihui 18 as the donor parent, was identified. Z744 contains a total of six substitution segments distributed on chromosomes (Chrs.) 1, 2, 6, 7, and 12, with an average substitution length of 2.72 Mb. The grain length, ratio of length to width, and 1 000-grain weight of Z744 were significantly higher than those in Nipponbare. The plant height, panicle number, and seed-set ratio in Z744 were significantly lower than those in Nipponbare, but they were still 78.7 cm, 13.5 per plant, and 86.49%, respectively. Furthermore, eight QTLs of different traits were identified in the secondary F2 population, constructed by Nipponbare and Z744 hybridization. The grain weight of Z744 was controlled by two synergistic QTLs (qGWT1 and qGWT7) and two subtractive QTLs (qGWT2 and qGWT6), respectively. The increase in the grain weight of Z744 was caused mainly by the increase in grain length. Two QTLs were detected, qGL1 and qGL7-3, which accounted for 25.54 and 15.58% of phenotypic variation, respectively. A Chi-square test showed that the long-grain number and the short-grain number were in accordance with the 3:1 separation ratio, which indicates that the long grain is dominant over the short-grain and Z744 was controlled mainly by the principal effect qGL1. These results offered a good basis for further fine mapping of qGL1 and further dissection of other QTLs into single-segment substitution lines.

The spikelet is a unique inflorescence structure in grasses. However, the molecular mechanism that regulates its development remains unclear, and we therefore characterize a spikelet mutant of rice (Oryza sativa L.), aberrant-floral spikelet 1 (afs1), which was derived from treatment of Xinong 1B with ethyl methanesulfonate. In the afs1 mutant, the spikelet developed an additional lemma-like organ alongside the other normally developed floral organs, and the paleae were degenerated to differing degrees with or without normally developed inner floral organs. Genetic analysis revealed that the afs1 phenotype was controlled by a single recessive gene. The AFS1 gene was mapped between the insertion/deletion (InDel) marker Indel19 and the simple sequence repeat marker RM16893, with a physical distance of 128.5 kb on chromosome 4. Using sequence analysis, we identified the deletion of a 5-bp fragment and a transversion from G to A within LOC_Os04g32510/LAX2, which caused early termination of translation in the afs1 mutant. These findings suggest that AFS1 may be a new allele of LAX2, and is involved in the development of floral organs by regulating the expression of genes related to their development. The above results provide a new view on the function of LAX2, which may also regulate the development of spikelets.

Rice (Oryza sativa L.) is one of the most important food crops worldwide and a model monocot plant for gene function analysis, so it is an ideal system for studying flower development. This study reports a mutant, named multi-floret spikelet 3 (mfs3), which is related to the spikelet development in rice and derived from the ethylmethane sulfonate (EMS)-treated rice cultivar XIDA 1B. In mfs3, the main body of palea (bop) was degenerated severely and only glume-like marginal regions of palea (mrp) remained, while other floral organs developed normally, indicating that the palea identity was seriously influenced by the mutation. It was also observed that the number of floral organs was increased in some spikelets, including 2 lemmas, 4 mrp, 4 lodicules, 8–10 stamens, and 2 pistils, which meant that the spikelet determinacy was lost to some degree in mfs3. Furthermore, genetic analysis demonstrated that the mfs3 trait was controlled by a single recessive gene. Using 426 F2 mutants derived from the cross between sterile line 56S and mfs3, the MULTI-FLORET SPIKELET 3 (MFS3) gene was mapped between the molecular markers RM19347 and RM19352 on Chr.6, with a physical distance of 106.3 kb. Sequencing of candidate genes revealed that an 83-bp fragment loss and a base substitution occurred in the LOC_Os06g04540 gene in the mutant, confirming preliminarily that the LOC_Os06g04540 gene was the MFS3 candidate gene. Subsequent qPCR analysis showed that the mutation caused the down-regulation of OsMADS1 and FON1 genes, and the up-regulation of OsIDS1 and SNB genes, which are all involved in the regulation of spikelet development. The MFS3 mutation also significantly reduced the transcription of the REP gene, which is involved in palea development. These results indicated that the MFS3 gene might be involved in the spikelet meristem determinacy and palea identity by regulating the expression of these related genes.

Eukaryotic translation initiation factor 1A (eIF1A) functions as an important regulatory factor of protein synthesis and plays a crucial role in responses to abiotic stresses in plants. However, little is known about the eIF1A gene involved in fruit development and stress response of mango. In this study, the MieIF1A-b gene was isolated from Mangifera indica, and contains a 435-bp open reading frame, which encodes a putative protein of 144 amino acids (GenBank accession number: KP676599). The predicted MieIF1A-b protein had a molecular weight of 16.39 kDa with a pI of 4.6. Sequence homology analysis showed that MieIF1A-b shared high homology with Elaeis guineensis, Manihot esculenta, and Populus trichocarpa, with 96 and 95% identity, respectively. Quantitative reverse transcriptative PCR (qRT-PCR) analyses indicated that MieIF1A-b was expressed in all tested tissues, and had the highest expression level in fruit 80 d after flowering. The expression of MieIF1A-b was obviously regulated by NaCl and H2O2 treatments in leaves. Functional analysis indicated that the overexpression of MieIF1A-b in transgenic Arabidopsis thaliana enhanced the growth, phenotype and salinity tolerance compared with wild-type (WT) plants. The results indicated that MieIF1A-b may be correlated with the control of fruit development and salt adaptation, and it was a candidate gene for abiotic stress in mango.

An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat (SSR) marker-assisted selection (MAS). Z550 carries 13 substitution segments distributed on chromosomes 1, 6, 7, 8, 9, 10, and 12, with an average substitution length of 1.68 Mb. Compared with the Nipponbare parental line, plant height, panicle length, spikelets per panicle, grains per panicle, and grain weight for Z550 were significantly increased. While the grain width of Z550 was significantly narrower, and the seed setting ratio (81.43%) was significantly lower than that of Nipponbare, it is still sufficient for breeding purposes. Quantitative trait loci (QTLs) mapping for important agronomic traits was conducted with the F2 population derived from Nipponbare crossed with Z550 using the restricted maximum likelihood (REML) method. A total of 16, including 12 previously unreported QTLs were detected, with contribution rates ranging from 1.46 to 10.49%. Grains per panicle was controlled by 8 QTLs, 5 of which increased number of grains whereas 3 decreased it. qGPP-1, with the largest contribution (10.49%), was estimated to increase grains per panicle by 30.67, while qGPP-9, with the minimum contribution rate (2.47%), had an effect of increasing grains per panicle by 15.79. These results will be useful for further development of single segment substitution lines with major QTLs, and for research of their molecular functions via QTL cloning.

Allopolyploidy has played an important role in plant evolution and heterosis. Recent studies indicate that the process of wide hybridization and (or) polyploidization may induce rapid and extensive genetic and epigenetic changes in some plant species. To better understand the allopolyploidy evolutionism and the genetic mechanism of Arachis interspecific hybridization, this study was conducted to monitor the gene expression variation by cDNA start codon targeted polymorphism (cDNA-SCoT) and cDNA high-frequency oligonucleotide-targeting active gene (cDNA-HFO-TAG) techniques, from the hybrids (F1) and newly synthesized allopolyploid generations (S0–S3) between tetraploid cultivated peanut Zhongkaihua 4 with diploid wild one Arachis doigoi. Rapid and considerable gene expression variations began as early as in the F1 hybrid or immediately after chromosome doubling. Three types of gene expression changes were observed, including complete silence (gene from progenitors was not expressed in all progenies), incomplete silence (gene expressed only in some progenies) and new genes activation. Those silent genes mainly involved in RNA transcription, metabolism, disease resistance, signal transduction and unknown functions. The activated genes with known function were almost retroelements by cDNA-SCoT technique and all metabolisms by cDNA-HFO-TAG. These findings indicated that interspecific hybridization and ploidy change affected gene expression via genetic and epigenetic alterations immediately upon allopolyploid formation, and some obtained transcripts derived fragments (TDFs) probably could be used in the research of molecular mechanism of Arachis allopolyploidization which contribute to thwe genetic diploidization of newly formed allopolyploids. Our research is valuable for understanding of peanut evolution and improving the utilization of putative and beneficial genes from the wild peanut.

The combined use of chemical and organic fertilizers is considered a good method to sustain high crop yield and enhance soil organic carbon (SOC), but it is still unclear when and to what extent chemical fertilizers could be replaced by organic fertilizers. We selected a long-term soil fertility experiment in Gongzhuling, Northeast China Plain to examine the temporal dynamics of crop yield and SOC in response to chemical nitrogen, phosphorus, and potassium (NPK) fertilizers and manure, applied both individually and in combination, over the course of three decades (1980–2010). We aimed to test 1) which fertilizer application is the best for increasing both maize yield and SOC in this region, and 2) whether chemical fertilizers can be replaced by manure to maintain high maize yield and enhance SOC, and if so, when this replacement should be implemented. We observed that NPK fertilizers induced a considerable increase in maize yield in the first 12 years after the initiation of the experiment, but manure addition did not. In the following years, the addition of both NPK fertilizers and manure led to an increase in maize yield. SOC increased considerably in treatments with manure but remained the same or even declined with NPK treatments. The increase in maize yield induced by NPK fertilizers alone declined greatly with increasing SOC, whereas the combination of NPK and manure resulted in high maize yield and a remarkable improvement in SOC stock. Based on these results we suggested that NPK fertilizers could be at least partially replaced by manure to sustain high maize yield after SOC stock has reached 41.96 Mg C ha−1 in the Northeast China Plain and highly recommend the combined application of chemical fertilizers and manure (i.e., 60 Mg ha−1).

Leaves play a key role in photosynthesis in rice plants. The premature senescence of such plants directly reduces the accumulation of photosynthetic products and also affects yield and grain quality significantly and negatively. A novel premature senescence mutant, mps1 (mid-late stage premature senescence 1), was identified from a mutant library consisting of ethyl methane sulfonate (EMS) induced descendants of Jinhui 10, an elite indica restorer line of rice. The mutant allele, mps1, caused no phenotypic differences from the wild type (WT), Jinhui 10, but drove the leaves to turn yellow when mutant plants grew to the tillering stage, and accelerated leaf senescence from the filling stage to final maturation. We characterized the agronomic traits, content of photosynthetic pigments and photosynthetic efficiency of mps1 and WT, and fine-mapped MPS1. The results showed that the MPS1-drove premature phenotype appeared initially on the leaf tips at the late tillering stage and extended to the middle of leaves during the maturing stage. Compared to the WT, significant differences were observed among traits of the number of grains per panicle (–31.7%) and effective number of grains per panicle (–38.5%) of mps1 individuals. Chlorophyll contents among the first leaf from the top (Top 1st), the second leaf from the top (Top 2nd) and the third leaf from the top (Top 3rd) of mps1 were significantly lower than those of WT (P

The nuclear-encoded light-harvesting chlorophyll a/b-binding proteins (LHCPs) are specifically translocated from the stroma into the thylakoid membrane through the chloroplast signal recognition particle (cpSRP) pathway. The cpSRP is composed of a cpSRP43 protein and a cpSRP54 protein, and it forms a soluble transit complex with LHCP in the chloroplast stroma. Here, we identified the YGL9 gene that is predicted to encode the probable rice cpSRP43 protein from a rice yellow-green leaf mutant. A phylogenetic tree showed that an important conserved protein family, cpSRP43, is present in almost all green photosynthetic organisms such as higher plants and green algae. Sequence analysis showed that YGL9 comprises a chloroplast transit peptide, three chromodomains and four ankyrin repeats, and the chromodomains and ankyrin repeats are probably involved in protein-protein interactions. Subcellular localization showed that YGL9 is localized in the chloroplast. Expression pattern analysis indicated that YGL9 is mainly expressed in green leaf sheaths and leaves. Quantitative real-time PCR analysis showed that the expression levels of genes associated with pigment metabolism, chloroplast development and photosynthesis were distinctly affected in the ygl9 mutant. These results indicated that YGL9 is possibly involved in pigment metabolism, chloroplast development and photosynthesis in rice.

Deoxynivalenol (DON) is a type B trichothecenes mycotoxin produced by several Fusarium species, often found in foodstuffs for humans and animals. DON is in great demand for the toxicological researches both in vivo and in vitro. In this work, wheat culture was inoculated with a Fusarium graminearum PH-1 strain for DON production. The solvent system for crude extraction was acetonitrile-water (84:16, v/v). A simple two-step silica gel column chromatography was employed to separate the DON mycotoxin from wheat culture, combined with preparative high performance liquid chromatography (preparative HPLC) to purify the compound. The solvent system for the second silica gel column chromatography was methylene chloride-methanol (17:1, v/v), which provided a good elution effect selected on thin layer chromatography (TLC). The target compound was identified by HPLC, and the chemical structure was confirmed by mass spectrometry (MS) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. A total of 433 mg of purified DON was obtained from 1 kg of wheat culture, with a purity of 99.01%. The study had provided an easy-operating and cost-effective method to isolate an expensive compound in a simple way.

In order to generate an antibody against a small hapten molecule, the hapten is cross-linked with carrier protein to make it immunogenic. In this study, the hapten (ochratoxin A, OTA) was coupled to ovalbumin (OVA) by an active ester reaction. To develop a technique for detecting the conjugation, the hapten-protein conjugate (OTA-OVA) was characterized thoroughly by immunoarray technology, ultraviolet (UV) spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), respectively. The molecular weight of OTA-OVA was 50 350.141 Da, and the molecular weight of OVA was 44 887.506 Da, which were determined by MALDI-TOF-MS, respectively. In OTA-OVA, the molecular coupling ratio was 13:1 by MALDI-TOF-MS while the molecular coupling ratio was 10:1 by UV. In this experiment, UV and MALDI-TOF-MS were selected as the efficient methods to evaluate the cross-linking effect and calculate the molecular coupling ratio.

Improving nitrogen use efficiency (NUE) and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency (NAE) and N loss in long-term (16- or 24-yr) experiments carried out at three rice-wheat rotation sites (Chongqing, Suining and Wuchang) in subtropical China. Three treatments were examined: sole chemical N, N+phosphorus (NP), and NP+potassium (NPK) fertilizations. Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone, 1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%) and Wuchang (11.8%), but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N ha−1 would increase 40 kg rice and 30 kg wheat ha−1. Nitrogen loss/input ratios were ∼60, ∼40 or ∼30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25–55 kg ha−1 yr−1 under NPK at three sites, whereas by 35 kg ha−1 yr−1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.

Whether the biochar amendment could affect soil organic matter (SOM) turnover and hence soil carbon (C) stock remains poorly understood. Effects of the addition of 13C-labelled rice straw or its pyrolysed biochar at 250 or 350°C to a sugarcane soil (Ferrosol) on soil labile C (dissolved organic C, DOC; microbial biomass C, MBC; and mineralizable C, MC) and soil organic C (SOC) were investigated after 112 d of laboratory incubation at 25°C. Four treatments were examined as (1) the control soil without amendment (Soil); (2) soil plus 13C-labelled rice straw (Soil+Straw); (3) soil plus 250°C biochar (Soil+B250) and (4) soil plus 350°C biochar (Soil+B350). Compared to un-pyrolysed straw, biochars generally had an increased aryl C, carboxyl C, C and nitrogen concentrations, a decreased O-alkyl C and C:N ratio, but similar alkyl C and δ13C (1 742–1 877 ‰). Among treatments, significant higher DOC, MBC and MC derived from the new C (straw or biochar) ranked as Soil+Straw>Soil+B250>Soil+B350, whilst significant higher SOC from the new C as Soil+B250>Soil+Straw≈Soil+B350. Compared to Soil, DOC and MBC derived from the native soil were decreased under straw or biochar addition, whilst MC from the native soil was increased under straw addition but decreased under biochar addition. Meanwhile, native SOC was similar among the treatments, irrespective of the straw or biochar addition. Compared to Soil, significant higher total DOC and total MBC were under Soil+Straw, but not under Soil+B250 and Soil+B350, whilst significant higher total MC and total SOC were under straw or biochar addition, except for MC under Soil+B350. Our results demonstrated that the application of biochar to soil may be an appropriate management practice for increasing soil C storage.

Increasing basic farmland soil productivity has significance in reducing fertilizer application and maintaining high yield of crops. In this study, we defined that the basic soil productivity (BSP) is the production capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local environment and field management. Based on 22-yr (1990–2011) long-term experimental data on black soil (Typic hapludoll) in Gongzhuling, Jilin Province, Northeast China, the decision support system for an agro-technology transfer (DSSAT)-CERES-Maize model was applied to simulate the yield by BSP of spring maize (Zea mays L.) to examine the effects of long-term fertilization on changes of BSP and explore the mechanisms of BSP increasing. Five treatments were examined: (1) no-fertilization control (control); (2) chemical nitrogen, phosphorus, and potassium (NPK); (3) NPK plus farmyard manure (NPKM); (4) 1.5 time of NPKM (1.5NPKM) and (5) NPK plus straw (NPKS). Results showed that after 22-yr fertilization, the yield by BSP of spring maize significantly increased 78.0, 101.2, and 69.4% under the NPKM, 1.5NPKM and NPKS, respectively, compared to the initial value (in 1992), but not significant under NPK (26.9% increase) and the control (8.9% decrease). The contribution percentage of BSP showed a significant rising trend (PNPKM>NPK≈NPKS, indicating that organic manure combined with chemical fertilizers (1.5NPKM and NPKM) could more effectively increase BSP compared with the inorganic fertilizer application alone (NPK) in the black soil. This study showed that soil organic matter (SOM) was the key factor among various fertility factors that could affect BSP in the black soil, and total N, total P and/or available P also played important role in BSP increasing. Compared with the chemical fertilization, a balanced chemical plus manure or straw fertilization (NPKM or NPKS) not only increased the concentrations of soil nutrient, but also improved the soil physical properties, and structure and diversity of soil microbial population, resulting in an iincrease of BSP. We recommend that a balanced chemical plus manure or straw fertilization (NPKM or NPKS) should be the fertilization practices to enhance spring maize yield and improve BSP in the black soil of Northeast China.

Soil organic carbon (SOC) and soil Olsen-P are key soil fertility indexes but information on their relationships is limited particularly under long-term fertilization. We investigated the relationships between SOC and the percentage of soil Olsen-P to total P (PSOPTP) under six different 15-yr (1990–2004) long-term fertilizations at two cropping systems in northern China. These fertilization treatments were (1) unfertilized control (control); (2) chemical nitrogen (N); (3) N plus chemical P (NP); (4) NP plus chemical potassium (NPK); (5) NPK plus animal manure (NPKM) and (6) high NPKM (hNPKM). Compared with their initial values in 1989 at both sites, during the 11th to 15th fertilization years annual mean SOC contents were significantly increased by 39.4–47.0% and 58.9–93.9% at Gongzhuling, Jilin Province, and Urumqi, Xinjiang, China, under the two NPKM fertilizations, respectively, while no significant changes under the no-P or chemical P fertilization. During the 11th to 15th fertilization years, annual mean PSOPTP was respectively increased by 2.6–4.2 and 5.8–14.1 times over the initial values under the two chemical P fertilizations and the two NPKM fertilizations, but was unchanged in their initial levels under the two no-P fertilizations at both sites. Over the 15-yr long-term fertilization SOC significantly positively correlated with PSOPTP (r2=0.55–0.79, P

Long-term fertilization experiment provides the platform for understanding the proton budgets in nitrogen transformations of agricultural ecosystems. We analyzed the historical (1990–2005) observations on four agricultural long-term experiments in China (Changping, Chongqing, Gongzhuling and Qiyang) under four different fertilizations, i.e., no-fertilizer (control), sole chemical nitrogen fertilizer (FN), sole chemical phosphorous and potassium fertilizers (FPK) and chemical nitrogen, phosphorous and potassium fertilizers (FNPK). The significant decline in topsoil pH was caused not only by chemical N fertilization (0.29 and 0.89 ΔpH at Gongzhuling and Qiyang, respectively) but also by chemical PK fertilization (0.59 ΔpH at Gongzhuling). The enhancement of available nutrients in the topsoil due to long-term direct nutrients supply with chemical fertilizers was in the descending order of available P (168–599%)>available K (16–189%)>available N (9–33%). The relative rate of soil pH decline was lower under long-term judicious chemical fertilization (−0.036–0.034 ΔpH yr−1) than that under long-term sole N or PK fertilization (0.016–0.086 ΔpH yr−1). Long-term judicious chemical fertilization with N, P and K elements decreases the nutritional limitation to normal crop growth, under which more N output was distributed in biomass removal rather than the loss via nitrate leaching. We concluded that the N distribution percentage of nitrate leaching to biomass removal might be a suitable indicator to the sensitivity of agricultural ecosystems to acid inputs.

In this study, a rice spikelet mutant, multi-floret spikelet 1 (mfs1), which was derived from ethylmethane sulfonate (EMS)-treated Jinhui 10 (Oryza sativa L. ssp. indica) exhibited pleiotropic defects in spikelet development. The mfs1 spikelet displayed degenerated the empty glume, elongated the rachilla, the extra lemma-like organ and degraded the palea. Additionally, mfs1 flowers produced varied numbers of inner floral organs. The genetic analysis revealed that the mutational trait was controlled by a single recessive gene. With 401 recessive individuals from the F2 segregation population, the MFS1 gene was finally mapped on chromosome 5, an approximate 350 kb region. The present study will be useful for cloning and functional analysis of MFS1, which would facilitate understanding of the molecular mechanism involved in spikelet development in rice.