Remote sensing of quality traits in cereal and arable production systems:A review

Cereal is an essential source of calories and protein for the global population.Accurately predicting cereal quality before harvest is highly desirable in order to optimise management for farmers,grading harvest and categorised storage for enterprises,future trading prices,and policy planning.The use of remote sensing data with extensive spatial coverage demonstrates some potential in predicting crop quality traits.Many studies have also proposed models and methods for predicting such traits based on multiplatform remote sensing data.In this paper,the key quality traits that are of interest to producers and consumers are introduced.The literature related to grain quality prediction was analyzed in detail,and a review was conducted on remote sensing platforms,commonly used methods,potential gaps,and future trends in crop quality prediction.This review recommends new research directions that go beyond the traditional methods and discusses grain quality retrieval and the associated challenges from the perspective of remote sensing data.

Effects of fresh-cut and storage on glucosinolates profile using broccoli as a case study

Glucosinolates(GLS) contribute to the unique flavour, nutrition, and plant defence of the Cruciferous vegetables. Understanding the GLS changes through postharvest processing is essential for defined preservation. In this study, four different fresh-cut types, whole flower(W),floret(F), quarterly cut floret(QF) and shredded floret(FS) of broccoli, were stored for 0, 1, 2 and 3 day(s) to explore GLS responses to postharvest treatments. As a result, seven GLS were identified, mainly including glucoraphanin(RAA), neoglucobrassicin(NEO), and glucobrassicin(GBC)and accounting for 52.69%, 20.12% and 14.99% of the total GLS(21.92 ± 0.48) μmol · g ^(-1 )DW, respectively. FS had the sharpest decrease in GLS after three days of storage(6.55 ± 0.37) μmol · g-1DW, while QF had the least(10.16 ± 0.33) μmol · g ^(-1 )DW. All GLS components decreased over storage, except for 4-methoxyglucobrassicin(4 ME) in FS and QF, suggesting its key role in serious wound defence. The results suggested certain postharvest approaches influenced the flavour and nutrition of broccoli.

Transcriptomics and metabolomics analyses provide insights into postharvest ripening and senescence of tomato fruit under low temperature

Tomato is one of the most important vegetable crops in the world and is a model plant used to study the ripening of climacteric fleshy fruit.During the ripening process of tomato fruit,flavor and aroma metabolites,color,texture and plant hormones undergo significant changes.However,low temperatures delayed the ripening process of tomato fruit,inhibiting flavor compounds and ethylene production.Metabolomics and transcriptomics analyses of tomato fruit stored under low temperature(LT,5°C)and room temperature(RT,25°C)were carried out to investigate the effects of storage temperature on the physiological changes in tomato fruit after harvest.The results of transcriptomics changes revealed that the differentially expressed genes(DEGs)involved in tomato fruit ripening,including several kinds of transcription factors(TFs)(TCP,WRKY,MYB and bZIP),enzymes involved in cell wall metabolism[beta-galactosidase(β-GAL),pectinesterase(PE)and pectate lyase(PL),cellulose and cellulose synthase(CESA)],enzymes associated with fruit flavor and aroma[acetyltransferase(AT),malic enzyme(ME),lipoxygenase(LOX),aldehyde dehydrogenase(ALDH),alcohol dehydrogenase(ADH)and hexokinase(HK)],genes associated with heat stress protein 70 and genes involved in the production of plant hormones such as Ethylene responsive factor 1(ERF1),Auxin/indoleacetic acids protein(AUX/IAA),gibberellin regulated protein.Based on the above results,we constructed a regulatory network model of the effects of different temperatures during the fruit ripening process.According to the analysis of the metabolomics results,it was found that the contents of many metabolites in tomato fruit were greatly affected by storage temperature,including,organic acids(L-tartaric acid,a-hydroxyisobutyric acid and 4-acetamidobutyric acid),sugars(melezitose,beta-Dlactose,D-sedoheptulose 7-phosphate,2-deoxyribose 1-phosphate and raffinose)and phenols(coniferin,curcumin and feruloylputrescine).This study revealed the effects of storage temperature on postharvest tomato fruit and provided a basis for further understanding of the molecular biology and biochemistry of fruit ripening.

Comparative transcriptome analysis of Ts(Resistant genotype)and Ma(Susceptible genotype)marigold(Tagetes erecta L.)leaves in response to Alternaria tagetica

Marigold black spot caused by Alternaria tagetica is a major disease that can decrease marigold production by 40%,resulting in serious economic losses.In this study,we identified many genes responsive to A.tagetica in the resistant and susceptible marigold genotypes.Analyses of differentially expressed genes,expression trends,and a weighted gene co-expression network revealed a series of hub genes with key roles in different A.tagetica infection stages.Additionally,1216 unigenes encoding transcription factors from eight families were differentially expressed between Ts and Ma.Moreover,R genes fromvarious families(e.g.,N,NL,RLP,and TNL)were differentially expressed in the twomarigold genotypes before and after the inoculation with A.tagetica.Pathway diagrams were used to visualize the leaf transcriptional changes in the two marigold genotypes infected by A.tagetica to clarify the effects of A.tagetica on the expression patterns of genes involved in phosphatidylinositol signaling,plant–pathogen interactions,and plant hormone signal transduction.We identified candidate genes related to disease resistance and generated valuable resources for analyzing the candidate gene functions related to black spot resistance in marigold.The study data may be useful for the molecular marker-assisted screening and breeding of marigold lines with increased disease resistance.

Mulching broad ridges with a woven polypropylene fabric increases the growth and yield of young pear trees ‘Yuluxiang' in the North China Plain

Unlike traditional ridging, mulching broad ridges with a woven polypropylene fabric (WPF) can reduce soil evaporation during the drought season and avoid long saturation time in the root zone of pear trees during the rainy season. In this study, field experiments were conducted from 2017 to 2020 in a pear orchard in the North China Plain to investigate the effects of mulching broad ridges (0.3 m in height and 2 m in width) with WPF on soil temperature and moisture, nitrogen leaching, vegetative and reproductive growth of young pear trees(Pyrus bretschneideri Rehd.‘Yuluxiang’). The experiments involved two treatments, namely, control (traditional no-ridge planting without mulching) and mulching broad ridges with WPF (RM treatment). The results showed that the RM treatment increased soil moisture and temperature and decreased nitrogen leaching, resulting in vigorous growth of the young pear trees. Moreover, the RM treatment increased the tree trunk cross-sectional area and height of the young pear trees by 37%and 8%in 2020, respectively. The nitrate nitrogen content at the soil layer depth of 0-30 cm was significantly higher in the RM than that in control. Furthermore, the RM treatment significantly increased the fruit yield due to larger tree size. In addition, compared with control, significantly higher fruit soluble solid content of RM treatment was detected in 2020. High precipitation (423 mm) occurred during fruit enlargement stage in 2020, RM treatment decreased the rainfall infiltration in the ridge and the soil moisture in root region, resulting in the improvement of fruit quality, compared with control.Therefore, mulching broad ridges with WPF can be implemented to increase soil moisture during drought season, soil temperature, and nitrate nitrogen content, thereby improving the growth and fruit yield of young pear trees. Additionally, it can reduce soil moisture in the root zone during the rainy season and improve the fruit quality of the trees. Finally, it can reduce nitrate nitrogen leaching, thereby reducing environmental pollution.

Spatiotemporal miRNA and transcriptomic network dynamically regulate the developmental and senescence processes of poplar leaves

Poplar is an important afforestation and urban greening species.Poplar leaf development occurs in stages,from young to mature and then from mature to senescent;these are accompanied by various phenotypic and physiological changes.However,the associated transcriptional regulatory network is relatively unexplored.We first used principal component analysis to classify poplar leaves at different leaf positions into two stages:developmental maturity(the stage of maximum photosynthetic capacity);and the stage when photosynthetic capacity started to decline and gradually changed to senescence.The two stages were then further subdivided into five intervals by gene expression clustering analysis:young leaves,the period of cell genesis and functional differentiation(L1);young leaves,the period of development and initial formation of photosynthetic capacity(L3-L7);the period of maximum photosynthetic capacity of functional leaves(L9-L13);the period of decreasing photosynthetic capacity of functional leaves(L15-L27);and the period of senescent leaves(L29).Using a weighted co-expression gene network analysis of regulatory genes,high-resolution spatiotemporal transcriptional regulatory networks were constructed to reveal the core regulators that regulate leaf development.Spatiotemporal transcriptome data of poplar leaves revealed dynamic changes in genes and miRNAs during leaf development and identified several core regulators of leaf development,such as GRF5 and MYB5.This in-depth analysis of transcriptional regulation during leaf development provides a theoretical basis for exploring the biological basis of the transcriptional regulation of leaf development and the molecular design of breeding for delaying leaf senescence.

Genetic diversity, population structure, and genome-wide association analysis of ginkgo cultivars

Ginkgo biloba is an economically valuable tree worldwide.The species has nearly become extinct during the Quaternary,which has likely resulted in reduction of its genetic variability.The genetic variability is now conserved in few natural populations in China and a number of cultivars that are,however,derived from a few ancient trees,helping the species survive in China through medieval times.Despite the recent interest in ginkgo,however,detailed knowledge of its genetic diversity,conserved in cultivated trees and cultivars,has remained poor.This limits efficient conservation of its diversity as well as efficient use of the existing germplasm resources.Here we performed genotyping-by-sequencing(GBS)on 102 cultivated germplasms of ginkgo collected to explore their genetic structure,kinship,and inbreeding prediction.For the first time in ginkgo,a genome-wide association analysis study(GWAS)was used to attempt gene mapping of seed traits.The results showed that most of the germplasms did not show any obvious genetic relationship.The size of the ginkgo germplasm population expanded significantly around 1500 years ago during the Sui and Tang dynasties.Classification of seed cultivars based on a phylogenetic perspective does not support the current classification criteria based on phenotype.Twenty-four candidate genes were localized after performing GWAS on the seed traits.Overall,this study reveals the genetic basis of ginkgo seed traits and provides insights into its cultivation history.These findings will facilitate the conservation and utilization of the domesticated germplasms of this living fossil plant.

Tissue Culture of Calla Lily (Zantedeschia spreng.): An Updated Review on the Present Scenario and Future Prospects

The calla lily(Zantedeschia spreng.)is a bulbousflower native to the tropical regions of Africa.Calla lily has gained significant popularity in the international market owing to its intricate morphology and prolonged flowering duration.Despite such advantages,for two sub-groups of calla lily,known as group Zantedeschia and group Aestivae,there are challenges in terms of hybrid production due to the‘plastome-genome incompatibility’there-between.Tissue culture is a fundamental biotechnological tool used in gene editing research,with a focus on disease resistance andflower color in calla lily breeding programs.The present review provides a brief background on the history and development of the calla lily,as well as a comprehensive and critical summary of calla lily tissue culture research.The regeneration pathways for both group Zantedeschia and group Aestivae can be divided into de novo organogenesis and somatic embryogenesis.Both groups are capable of obtaining replants through such means.However,only some species in group Aestivae have been reported to be successful in the somatic embryogenesis pathway.In the present review,special attention was paid to the influence of explant types,plant growth regulators,and culture conditions on both de novo organogenesis and somatic embryogenesis in calla lily tissue culture.Ultimately,future research prospects were determined based on integrated analysis of recent progress in calla lily tissue culture research.

Development Status, Problems and Countermeasures of Large- and Intermediate-Scale Biogas Projects in Beijing’s Mountainous Counties

Developing large- and intermediate-scale biogas project is an important gripper ofBeijingrural energy construction and “Green Beijing” construction. The existing projects have made obvious energy and environment benefits, but the overall effects have not been fully exerted. There is still a large gap betweenBeijing’s ecological civilization goal and the operation effect. This paper takes biogas projects ofBeijingseven mountainous counties as examples, the development status, ecological environment construction and existing problems of operating are explained respectively. Finally, some countermeasures and suggestions are proposed for promoting the sustainable development of biogas project inBeijing, such as strengthening technical innovation and setting standards, innovating development patterns and planning reasonable layout, improve the maintenance mechanism and intensify policy support.

Insights into the mechanism of L-malic acid on drip loss of chicken meat under commercial conditions

Background A deterioration in the meat quality of broilers has attracted much more attention in recent years.L-malic acid(MA)is evidenced to decrease meat drip loss in broilers,but the underlying molecular mechanisms are still unclear.It’s also not sure whether the outputs obtained under experimental conditions can be obtained in a com-mercial condition.Here,we investigated the effects and mechanisms of dietary MA supplementation on chicken meat drip loss at large-scale rearing.Results Results showed that the growth performance and drip loss were improved by MA supplementation.Meat metabolome revealed that L-2-aminoadipic acid,β-aminoisobutyric acid,eicosapentaenoic acid,and nicotinamide,as well as amino acid metabolism pathways connected to the improvements of meat quality by MA addition.The transcriptome analysis further indicated that the effect of MA on drip loss was also related to the proper immune response,evidenced by the enhanced B cell receptor signaling pathway,NF-κB signaling pathway,TNF signaling pathway,and IL-17 signaling pathway.Conclusions We provided evidence that MA decreased chicken meat drip loss under commercial conditions.Metabolome and transcriptome revealed a comprehensive understanding of the underlying mechanisms.Together,MA could be used as a promising dietary supplement for enhancing the water-holding capacity of chicken meat.

Transcriptomic and metabolomic analysis provides insights into lignin biosynthesis and accumulation and differences in lodging resistance in hybrid wheat

The use of hybrid wheat is one way to improve the yield in the future.However,greater plant heights increase lodging risk to some extent.In this study,two hybrid combinations with differences in lodging resistance were used to analyze the stem-related traits during the filling stage,and to investigate the mechanism of the difference in lodging resistance by analyzing lignin synthesis of the basal second internode(BSI).The stem-related traits such as the breaking strength,stem pole substantial degree(SPSD),and rind penetration strength(RPS),as well as the lignin content of the lodging-resistant combination(LRC),were significantly higher than those of the lodgingsensitive combination(LSC).The phenylpropanoid biosynthesis pathway was significantly and simultaneously enriched according to the transcriptomics and metabolomics analysis at the later filling stage.A total of 35 critical regulatory genes involved in the phenylpropanoid pathway were identified.Moreover,42%of the identified genes were significantly and differentially expressed at the later grain-filling stage between the two combinations,among which more than 80%were strongly up-regulated at that stage in the LRC compared with LSC.On the contrary,the LRC displayed lower contents of lignin intermediate metabolites than the LSC.These results suggested that the key to the lodging resistance formation of LRC is largely the higher lignin synthesis at the later grain-filling stage.Finally,breeding strategies for synergistically improving plant height and lodging resistance of hybrid wheat were put forward by comparing the LRC with the conventional wheat applied in large areas.

Transcriptomics integrated with metabolomics reveals the mechanism of CaCl_(2)-HCl electrolyzed water-induced glucosinolate biosynthesis in broccoli sprouts

Glucosinolates are important phytochemicals in Brassicaceae.We investigated the effect of CaCl_(2)-HCl electrolyzed water(CHEW)on glucosinolates biosynthesis in broccoli sprouts.The results showed that CHEW treatment significantly decreased reactive oxygen species(ROS)and malondialdeh yde(MDA)contents in broccoli sprouts.On the the 8^(th)day,compared to tap water treatment,the the total glucosinolate content of broccoli sprouts with CHEW treatment increased by 10.6%and calcium content was dramatically enhanced from 14.4 mg/g DW to 22.7 mg/g DW.Comparative transcriptome and metabolome analyses revealed that CHEW treatment activated ROS and calcium signaling transduction pathways in broccoli sprouts and they interacted through MAPK cascades.Besides,CHEW treatment not only promoted the biosynthesis of amino acids,but also enhanced the expression of structural genes in glucosinolate synthesis through transcription factors(MYBs,bHLHs,WRKYs,etc.).The results of this study provided new insights into the regulatory network of glucosinolates biosynthesis in broccoli sprouts under CHEW treatment.

Isomerization and bioaccessibility of cypermethrin and fenpropathrin in Pacific oyster during simulated digestion as influenced by domestic cooking methods

Pyrethroids can be ingested by humans through eating contaminated oysters,which is potentially harmful to health.This study aimed to investigate the effects of raw,steaming,and roasting on cypermethrin(CP)and fenpropathrin(FP)in oysters during simulated digestion.Results showed that the amount of released CP and FP was different from raw(CP:0.617μg·g−1,FP:0.266μg·g−1),steaming(CP:0.498μg·g−1,FP:0.660μg·g−1),and roasting(CP:1.186μg·g−1,FP:0.588μg·g−1)at the end of simulated digestion.The share of cis-CP and low-efficiency CP increased significantly(p<0.05),and the share of high-efficiency trans-CP did not maintain a high level for a long time during simulated digestion.The fluorimetric titration and isothermal titration calorimetry confirmed that CP and FP could spontaneously interact with oyster actin,and CP could bind with oyster actin more tightly than FP.This study reveals that cooking methods affect the binding capacity of CP and FP to oyster tissues and influence the changes of CP and FP in oysters during digestion.Furthermore,the current study provides a reference for assessing the potential harm of pyrethroids in oysters to consumers.

Development of a RBFNN prediction model for carrot quality based on meteorological temperatures at vegetable stations

To evaluate and predict the quality of carrots during logistics process in North China under extreme temperature conditions,quality indicator changes of carrots were investigated,and temperature-coupled quality prediction models were developed.Seven temperatures were selected from meteorological temperature data by cluster analysis to simulate the changes in extreme temperatures during the short-term transportation of carrots.No carrots rotted during the 48h storage period.Under both isothermal and nonisothermal conditions,weight loss andΔE increased while the firmness and sensory evaluation(SE)decreased.The RBFNN performed better than the Arrhenius model in predicting weight loss andΔE,with R^(2)>0.97,MSE<0.009 and relative errors within±18%.The results of the predictive confidence level and standardized residual indicated the good performance of the RBFNN model.The temperature-coupled prediction models of RBFNN were promising candidates for predicting the quality of vegetable products and therefore reducing economic loss of vegetable industry.

Genome-wide identification, characterization, and expression analysis of the SWEET gene family in cucumber

SWEETs （sugars will eventually be exported transporters） are a novel class of recently identified sugar transporters that play important roles in diverse physiological processes. However, only a few species of the plant SWEETgene family have been functionally identified. Up till now, there has been no systematic analysis of the SWEETgene family in Cucurbitaceae crops. Here, a genome-wide characterization of this family was conducted in cucumber（Cucumis sativus L.）. A total of 17 CsSWEETgenes were identified, which are not evenly distributed over the seven cucumber chromosomes. Cucumber SWEET protein sequences possess seven conserved domains and two putative serine phosphorylation sites. The phylo- genetic tree of the SWEET genes in cucumber, Arabidopsis thaliana, and Oryza sativa was constructed, and all the SWEET genes were divided into four clades. In addition, a number of putative cis-elements were identified in the promoter regions of these CsSWEET genes： nine types involved in phytohormone responses and eight types involved in stress responses. Moreover, the transcript levels of CsSWEETgenes were analyzed in various tissues using quantitative real-time polymerase chain reaction. A majority （70.58%） of the CsSWEET genes were confined to reproductive tissue development. Finally, 18 putative watermelon ClaSWEETgenes and 18 melon CmSWEETgenes were identified that showed a high degree of similarity with CsSWEETgenes. The results from this study provided a basic understanding of the CsSWEETgenes and may also facilitate future research to elucidate the function of SWEET genes in cucumber and other Cucurbitaceae crops.

Diversity and Genetic Differentiation of the Whitefly Bemisia tabaci Species Complex in China Based on mtCOI and cDNA-AFLP Analysis

The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（MED）.In an extensive field survey of the B.tabaci complex present throughout part of China from 2004 to 2007,we obtained 93 samples of B.tabaci from 22 provinces.We determined that these Chinese haplotypes included 2 invasive species（MEAM1 and MED）,and 4 indigenous cryptic species（Asia II 1,Asia II 3,China 3 and Asia II 7）by sequencing mitochondrial cytochrome oxidose one gene（mtCOI）.The diversity and genetic differentiation of a subset of 19 populations of B.tabaci were studied using cDNA amplified fragment length polymorphism（AFLP）.Prior to 2007,MEAM1 was a dominant species in many provinces in China.By 2007,MED was dominant in 11 provinces.Both invasive and indigenous species were simultaneously found in some regions.Indigenous species of B.tabaci were found in six provinces in southern China.MED and MEAM1 have broad ranges of host plants,and indigenous species appeared to have much narrower host ranges.All Asia II 3 samples were found on cotton except one on aubergine.China 3 has more host plants than Asia II 3.Twelve samples of China 3 were collected from sweet potato,Japanese hop,squash and cotton.A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained.The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%.Unweighted pair-group method analysis indicated that the clustering was independent of the different species.MED showed the lowest degree of similarity than the other species.The data indicate that both MEAM1and MED were rapidly established in China.

Molecular cloning,identification,and chromosomal localization of two MADS box genes in peach(Prunus persica)

MADS box proteins play an important role in floral development. To find genes involved in the floral transition of Prunus species, cDNAs for two MADS box genes, PpMADS1 and PpMADSIO, were cloned using degenerate primers and 5＇- and T-RACE based on the sequence database of P. persiea and P. duleis. The full length of PpMADS1 cDNA is 1,071 bp containing an open reading frame （ORF） of 717 bp and coding for a polypeptide of 238 amino acid residues. The full length of PpMADSIO cDNA is 937 bp containing an ORF of 633 bp and coding for a polypeptide of 210 amino acid residues. Sequence comparison revealed that PpMADS1 and PpMADSIO were highly homologous to genes API and PI in Arabidopsis, respectively. Phylogenetic analysis indicated that PpMADS1 belongs to the euAP1 clade of class A, and PpMADSIO is a member of GLO/PI clade of class B. RT-PCR analysis showed that PpMADS1 was expressed in sepal, petal, carpel, and fruit, which was slightly different from the expression pattern ofAPl; PpMADS10 was expressed in petal and stamen, which shared the same expression pattern as PI. Using selective mapping strategy, PpMADSI was assigned onto the Binl：50 on the G1 linkage group between the markers MCO44 and TSA2, and PpMADSIO onto the Bin1：73 on the same linkage group between the markers Lap- 1 and FGA8. Our results provided the basis for further dissection of the two MADS box gene function.

Global sensitivity analysis of wheat grain yield and quality and the related process variables from the DSSAT-CERES model based on the extended Fourier Amplitude Sensitivity Test method

A crop growth model,integrating genotype,environment,and management factor,was developed to serve as an analytical tool to study the influence of these factors on crop growth,production,and agricultural planning.A major challenge of model application is the optimization and calibration of a considerable number of parameters.Sensitivity analysis(SA) has become an effective method to identify the importance of various parameters.In this study,the extended Fourier Amplitude Sensitivity Test(EFAST) approach was used to evaluate the sensitivity of the DSSAT-CERES model output responses of interest to 39 crop genotype parameters and six soil parameters.The outputs for the SA included grain yield and quality(take grain protein content(GPC) as an indicator) at maturity stage,as well as leaf area index,aboveground biomass,and aboveground nitrogen accumulation at the critical process variables.The key results showed that:(1) the influence of parameter bounds on the sensitivity results was slight and less than the impacts from the significance of the parameters themselves;(2) the sensitivity parameters of grain yield and GPC were different,and the sensitivity of the interactions between parameters to GPC was greater than those between the parameters to grain yield;and(3) the sensitivity analyses of some process variables,including leaf area index,aboveground biomass,and aboveground nitrogen accumulation,should be performed differently.Finally,some parameters,which improve the model’s structure and the accuracy of the process simulation,should not be ignored when maturity output as an objective variable is studied.

Characteristics of Steep Cultivated Land and the Impact of the Grain-for-Green Policy in China

The Grain-for-Green Policy in China could not only improve China's ecological quality, but also influence grain supplies for a short term. Based on data from the detailed nationwide land use survey in 1996 and the steep cultivated land survey update in 2000, a regression model for the driving forces affecting steep cultivated lands was developed, and cluster analysis was used to identify seven steep cultivated land types in order to analyze the grain availability impact of the project with land usage estimates for 2010 and 2030. The results suggested that consecutive days with minimum daily temperature over 10℃ and the dominant slope in a county constrained the spatial distribution of steep cultivated lands. In terms of socioeconomic factors, steep cultivated land was a complex interaction of population size, gross domestic production level, and the richness and quality of cultivated lands having slopes less than 15°. The trends for steep cultivated land in 2010 and 2030 were forecast using a driving forces model and China's grain security criteria and showed that the Grain-for-Green Policy at the national level would not cause a grain shortage or threaten food security criteria. However, if steep sloped lands were to be retired from production, some regions would need grain supplements as early as 2010. Also, assuming that only 60% of the cultivated land at the national level was needed, population and economic development pressures in 2030 would require some steep cultivated lands to be used for grain production.

Cytological Evaluation and Karyotype Analysis in Plant Germplasms of Elytrigia Desv.

Elytrigia Desv. is widely distributed throughout the world and is represented with species of various levels of ploidy including diploids, tetraploids, hexaploids, octaploids, and decaploids. The distribution pattern of these ploidy levels, however, is not well-defined. In this study, the levels of ploidy for 64 accessions of Elytrigia from 25 countries were determined with microscopic procedures. The results showed that accessions of E. intermedia and E. repens were grouped into three distinct levels of ploidy including diploids, tetraploids and hexaploids. For E. elongata, E. pontica, and E. caespitosa, it was found that two ploidy levels presented, and only one ploidy level was in those of E. hybrid, E. pycnantha, E. pungens, E. juncea, and E. alatavica. Karyotype analysis indicated that the karyotype formula of diploid, tetraploid and hexaploid of E. intermedia was 2n = 2x = 14 = 6m ＋ 6sm ＋ 2st, 2n = 4x = 28 = 2M ＋ 10m ＋ 16sm and 2n = 6x = 42 = 4M ＋ 18m ＋ 20sin, respectively. Furthermore, the karyotype formula of three germplasms in tetraploid of E. intermedia was 2n=4x=28 =2M＋ 10m＋ 16sm, 2n=4x=28=4M＋22m （sat）＋2sm and 2n=4x=28 =4M＋ 12m＋ 12sm （sat）, which were not completely uniform. Therefore, it could be suggested that the studies about chromosome constitution would be helpful for the detail understanding of the diversity of germplasm resource in Elytrigia and promoting the utilization in the crop molecular breeding.