Breeding wheat for resistance to Fusarium head blight in the Global North: China, USA, and Canada

The objective of this paper is to review progress made in wheat breeding for Fusarium head blight(FHB) resistance in China, the United States of America(USA), and Canada. In China,numerous Chinese landraces possessing high levels of FHB resistance were grown before the 1950 s. Later, pyramiding multiple sources of FHB resistance from introduced germplasm such as Mentana and Funo and locally adapted cultivars played a key role in combining satisfactory FHB resistance and high yield potential in commercial cultivars.Sumai 3, a Chinese spring wheat cultivar, became a major source of FHB resistance in the USA and Canada, and contributed to the release of more than 20 modern cultivars used for wheat production, including the leading hard spring wheat cultivars Alsen, Glenn, Barlow and SY Ingmar from North Dakota, Faller and Prosper from Minnesota, and AAC Brandon from Canada. Brazilian wheat cultivar Frontana, T. dicoccoides and other local germplasm provided additional sources of resistance. The FHB resistant cultivars mostly relied on stepwise accumulation of favorable alleles of both genes for FHB resistance and high yield,with marker-assisted selection being a valuable complement to phenotypic selection. With the Chinese Spring reference genome decoded and resistance gene Fhb1 now cloned, new genomic tools such as genomic selection and gene editing will be available to breeders, thus opening new possibilities for development of FHB resistant cultivars.

Marker-assisted selection to pyramid Fusarium head blight resistance loci Fhb1 and Fhb2 in the high-quality soft wheat cultivar Yangmai 15

Fusarium head blight(FHB)is one of the most detrimental wheat diseases which greatly decreases the yield and grain quality,especially in the middle and lower reaches of the Yangtze River of China.Fhb1 and Fhb2 are two major resistance loci against Fusarium graminearum.Yangmai 15(YM15)is one of the most popular varieties in the middle and lower reaches of the Yangtze River,and it has good weak gluten characters but poor resistance to FHB.Here we used Fhb1 and Fhb2 to improve the FHB resistance of YM15 by a molecular marker-assisted selection(MAS)backcrossing strategy.The selection of agronomic traits was performed for each generation.We successfully selected seven introgressed lines which carry homozygous Fhb1 and Fhb2 with significantly higher FHB resistance than the recurrent parent YM15.Three of the introgressed lines had agronomic and quality characters that were similar to YM15.This study demonstrates that the pyramiding of Fhb1 and Fhb2 could significantly improve the FHB resistance in wheat using the MAS approach.

Can effectoromics and loss-of-susceptibility be exploited for improving Fusarium head blight resistance in wheat?

Bread wheat(Triticum aestiuum L.),which provides about 20%of daily calorie intake,is the most widely cultivated crop in the world,in terms of total area devoted to its cultivation.Therefore,even small increases in wheat yield can translate into large gains.Reducing the gap between actual and potential grain yield in wheat is a crucial task to feed the increasing world population.Fusarium head blight(FHB)caused by the pathogenic fungus Fusaium graminearum and related Fusarium species is one of the most devastating wheat diseases throughout the world.This disease reduces not only the yield but also the quality by contaminating the grain with mycotoxins harmful for humans,animals and the environment.In recent years,remarkable achievements attained in omics"technologies have not only provided new insights into understanding of processes involved in pathogenesis but also helped develop effective new tools for practical plant breeding.Sequencing of the genomes of various wheat patho gens,including F.graminearum,as well as those of bread and durum wheat and their wild relatives,together with advances made in transcriptomics and bioinformatics,has allowed the identification of candidate pathogen effectors and corresponding host resistance(R)and susceptibility(S)genes.However,so far,FHB effectors and wheat susceptibility genes/factors have been poorly studied.In this paper,we first briefly highlighted recent examples of improving resistance against pathogens via new techniques in different host species.We then propose effective strategies towards developing wheat cultivars with improved resistance to FHB.We hope that the article will spur discussions and interest among researchers about novel approaches with great potential for improving wheat against FHB.

Relation of Leaf Stomatal Traits to Yield and Drought Resistance of Wheat

[ Objective] The study aimed to discuss the relation of leaf stomatal traits to yield and drought resistance of wheat. [ Method] Using the DH population of wheat cultivar Hanxuanl0/Lumai14 as the test object, the relation of leaf stomatal density （SD）, length （SL） and width （ SW）, stomatal conductance （g,）, photosynthetic rate （ Pn ）, transpiration rate （ Tr） to grain yield per plant and index of drought resistance （IDR） on the 10th and 20t＂ day after anthesis under the conditions of drought stress and normal irrigation were discussed by the methods of correlation analysis and path analysis. [ Result] Under the two water conditions, the correlations of these stomatal traits with yield components and IDR were mostly not significant on the 10t＂ day after anthesis, but there were significantly positive correlations between thousand kernel weight （TKW） and these traits on the 20^th day after anthesis. Path analysis showed that g,, Pn and Tt, were main factors affecting yield per plant （YPP） and IDR, and they had stron- ger direct effects on YPP and IDR, while their indirect interaction was also strong. The direct effects of SD, SL and SW on YPP and IDR were small, as well as their indirect action among SD, SL and SW. On the other hand, the correlations between SD and SL were significant, and the correlations of SL with SW, gn, P, and Tt, were extremely significant on the 10th and 20th day after anthesis under the two water conditions. However, the correlations of SD and SL with g,, P,, and Tr changed with water conditions or growth stages, showing that water conditions or growth stages had great effects on the correlations between two traits. Therefore, it is not always a good means to improve stomatal conductance, photosynthetic rate and transpiration rate and hence promote wheat yield by selecting stomatal density and size. [ Conclusion] The research could provide scientific references for revealing the roles of leaf stomatal traits in wheat breeding for drought resistance.

Genetic architecture of quantitative trait loci(QTL)for FHB resistance and agronomic traits in a hard winter wheat population

Wheat resistance to Fusarium head blight(FHB)has often been associated with some undesirable agronomic traits.To study the relationship between wheat FHB resistance and agronomic traits,we constructed a linkage map of single nucleotide polymorphisms(SNPs)using an F6:8 population from G97252WG97380A.The two hard winter wheat parents showed contrasts in FHB resistance,plant height(HT),heading date(HD),spike length(SL),spike compactness(SC),kernel number per spike(KNS),spikelet number per spike(SNS),thousand-grain weight(TGW)and grain size(length and width).Quantitative trait locus(QTL)mapping identified one major QTL(QFhb.hwwg-2DS)on chromosome arm 2DS for the percentage of symptomatic spikelets(PSS)in the spike,deoxynivalenol(DON)content and Fusarium damaged kernel(FDK).This QTL explained up to 71.8%of the phenotypic variation for the three FHB-related traits and overlapped with the major QTL for HT,HD,SL,KNS,SNS,TGW,and grain size.QTL on chromosome arms 2AL,2DS,3AL and 4BS were significant for the spike and grain traits measured.G97252W contributed FHB resistance and high SNS alleles at QFhb.hwwg-2DS,high KNS alleles at the QTL on 2AL and 2DS,and high TGW and grain size alleles at QTL on 3AL;whereas G97380A contributed high TGW and grain size alleles at the QTL on 2AL and 2DS,respectively,and the high KNS allele at the 4BS QTL.Combining QFhb.hwwg-2DS with positive alleles for spike and grain traits from other chromosomes may simultaneously improve FHB resistance and grain yield in new cultivars.

小麦新品系赤霉病抗性鉴定及基因效应分析

为创制黄淮麦区小麦新品系、提高小麦抗赤霉病育种效率,2022年在小麦扬花期利用喷洒孢子液的方法对81份抗赤霉病高代品系和4份对照品种在濉溪柳湖试验基地开展了赤霉病抗性鉴定,并利用与4个抗赤霉病主效基因Fhb1、Fhb2、Fhb4和Fhb5紧密连锁的6个标记对供试小麦材料进行了基因型检测。结果表明,供试81份材料的赤霉病抗性整体较好,平均病小穗率为27.95%,其中13份自育品系平均病小穗率低于扬麦20;携带单个或多个赤霉病抗性基因的品系共有60份,Fhb1、Fhb2、Fhb4、Fhb5检出频率分别为64.20%、12.35%、20.99%、34.57%;携带单个抗病基因Fhb1、Fhb4、Fhb5的小麦品系分别为18份、3份、2份;有45.68%品系同时携带2~3个赤霉病抗性基因。携带抗性基因的品系平均病小穗率低于不含抗性基因的品系;聚合多个抗赤霉病基因可以有效提高小麦品种的抗赤霉病水平。

Genome-wide identification and characterization of thaumatin-like protein family genes in wheat and analysis of their responses to Fusarium head blight infection

Thaumatin-like proteins (TLPs) play potential roles in plant resistance to various diseases. Identifying TLPs is neces-sary to determine their function and apply them to plant disease resistance. However, limited information is available about TLP-family genes in wheat, especially regarding their responses to Fusarium species, which cause Fusarium head blight in wheat. In this study, we conducted a comprehensive genome-wide survey of TLP genes in wheat and identified 129 TLP genes in the wheat genome, which were unevenly distributed on 21 wheat chromosomes, with 5A containing the highest number. Phylogenetic analysis showed that these 129 wheat TLP genes together with 24 Arabidopsis TLPs were classified into 7 groups based on the protein sequences. We systematically analyzed the genes in terms of their sequence characterization, chromosomal locations, exon-intron distribution, duplication (tandem and segmental) events and expression profiles in response to Fusarium infection. Furthermore, we analyzed differen-tially expressed TLP genes based on publicly available RNA-seq data obtained from a resistant near isogenic wheat line at different time points after Fusarium graminearum inoculation. Then, the expression of 9 differentially expressed TLP genes was confirmed by real-time PCR, and these 9 genes were all upregulated in the resistant Sumai 3 variety, which was generally consistent with the RNA-seq data. Our results provide a basis for selecting candidate wheat TLP genes for further studies to determine the biological functions of the TLP genes in wheat.

我国小麦赤霉病流行与化学防控现状及控病降毒关键技术理论创新与应用

概述了我国小麦赤霉病发生危害现状,深入剖析了该病流行危害的原因,回顾了近年来我国小麦赤霉病化学防控历程,综述了化学防控及其抗药性发生的现状,并总结了小麦赤霉病菌抗药性检测技术的发展过程。此外,对小麦赤霉病控病降毒关键技术理论创新与应用成果进行了分析和总结,展望了小麦赤霉病精准防控的科学用药技术方案,并对其可行性和有效性进行了阐释。旨在为小麦赤霉病的精准选药、科学用药提供重要的参考数据,保障我国的粮食生产安全和食品安全,进而推动我国农业实现可持续、高质量发展。

55个小麦主栽及后备品种抗赤霉病评价与籽粒DON毒素含量分析

为发掘赤霉病的抗性种质资源,评估小麦品种籽粒DON毒素含量与赤霉病抗性内在联系,本研究分别以‘华麦1169’‘小偃22’‘郑9023’和‘苏麦3号’为高感、中感、中抗和高抗赤霉病对照品种,于2021年春季对生产上种植面积超过10万hm2的16个主栽品种和湖北的39个主栽和后备品种,采用双花滴注接种法开展田间赤霉病抗性鉴定,同时对供试材料用与Fhb1、Fhb2、Fhb4、Fhb5和Fhb7和QFhs.crc-2DL连锁的分子标记进行检测,并对55个小麦品种测定其收获后籽粒DON毒素含量。结果表明,55个供试小麦品种中有21个表现为中抗赤霉病。结合分子检测结果发现,抗性鉴定为中抗的21个小麦品种中,16个品种未检测出目标抗赤霉病基因,推测其可能含有其他未知或未检测的抗赤霉病基因;55个小麦中仅‘华麦169’携带Fhb1,平均病小穗率22.34%;‘新麦18’‘扬麦11’和‘西农979’等5个品种携带Fhb2,平均病小穗率为28.34%~45.92%;‘偃展4110’‘衡观35’和‘烟农19’等5个品种携带Fhb4,平均病小穗率为26.73%~65.59%;‘良星99’‘华麦1123’和‘襄麦35’等13个品种携带QFhs.crc-2DL,平均病小穗率为32.96%~70.81%;未检测到携带Fhb5的品种。籽粒DON毒素测定结果表明,田间鉴定为中抗赤霉病的21个品种中,其籽粒DON毒素含量最高的品种超过最低的8倍,有8个品种籽粒DON毒素含量超过3500μg/kg,田间鉴定为中感赤霉病的13个品种中,DON毒素含量最高的品种超过最低的4倍,除‘扬麦13’‘鄂麦352’和‘荆麦66’这3个品种DON毒素含量低于3500μg/kg,其余10个均高于3500μg/kg。这些检测结果充分说明对小麦抗赤霉病遗传改良的种质资源筛选来说,田间抗病鉴定取得的信息量远远不够,即使田间鉴定为中抗,也有必要对品种的籽粒DON毒素进行测定,更客观全面地反映品种的综合抗赤霉病潜力。

小麦抗赤霉病遗传育种研究进展

小麦赤霉病是世界性病害,严重危害小麦生产,已成为我国粮食安全的重大威胁。国内外在小麦赤霉病抗源筛选、抗病基因发掘与克隆、抗赤霉病育种等方面取得重大进展。在综述小麦赤霉病危害、小麦赤霉病抗性鉴定技术及评价指标、抗赤霉病QTL与基因定位、抗赤霉病育种技术、育种成果等方面研究进展的基础上,提出了相关展望,包括对全世界的抗赤霉病小麦品种及与其亲缘关系较近的小麦种属和一些野生资源材料进行征集和鉴定,通过物理和化学诱变创造新抗源,加强已有抗赤霉病材料的应用。

小麦赤霉病抗性改良研究进展

小麦赤霉病是一种全球性的毁灭性病害,培育抗病品种是减轻小麦赤霉病危害最经济环保的有效途径。本文介绍了赤霉病抗性种质资源的发掘及其在常规育种中的应用、抗赤霉病分子标记辅助育种和抗赤霉病转基因育种等方面的最新研究进展,提出在加强小麦赤霉病抗性机理研究的同时,结合分子育种技术与常规育种手段,加快小麦赤霉病抗性改良研究进程。

小麦赤霉病抗性机理研究进展

赤霉病(Fusarium head blight,FHB)是小麦最主要的病害之一,严重影响小麦生产安全和食品安全,研究小麦赤霉病抗性机理对于解决小麦赤霉病这一世界性难题具有重要意义。根据对赤霉病的抗性表现形式,将小麦赤霉病抗性分为五个大类,分别为抗侵入(Type I)、抗扩展(Type II)、籽粒抗感染(Type III)、耐病性(TypeⅣ)和抗毒素积累(Type V)。小麦赤霉病的抗性机理可以分为形态机制和生理机制,形态抗性机制是被动的,株高、抽穗期、花期长短、花药挤出程度、有芒无芒、穗长、穗密度、颖壳张开程度和穗部蜡质程度等形态特征均可能与赤霉病抗侵染特性有关。细胞学研究表明,病原菌侵染后抗病品种可迅速从细胞结构和生理生化方面产生防卫反应,通过乳突、胞壁沉积物的形成以及木质素、硫堇、富含羟脯氨酸糖蛋白和水解酶类等的增长来协同抵御病菌在体内的扩展。在植物复杂的信号途径中,水杨酸(SA)、茉莉酸(JA)和乙烯(ET)3种信号途径在植物抵御病原菌入侵中的作用最为重要,SA和ET信号途径对小麦赤霉病抗性方面的作用目前还存在一定争议,而JA信号途径在小麦赤霉病抗性中积极作用已经被多数研究者所证实。迄今为止,人类定位了200个以上不同类型的抗赤霉病QTL位点,这些位点分布于所有的小麦染色体,其中的22个QTL位点被不同的作图群体所定位,包括2个定位在3BS和6BS染色体上稳定的抗扩展位点Fhb1和Fhb2,以及2个定位在4B和5A染色体上的抗侵染位点Fhb4和Fhb5。在受到病原菌侵染后,植物会产生一系列复杂的信号途径激活应答反应,诱导抗病相关基因的表达,进而引起蛋白以及代谢水平的变化,抵御病原菌的侵袭,研究表明,病程相关蛋白基因、抗菌肽基因、转录因子基因、脱毒相关蛋白基因以及其他赤霉病抗性相关基因均参与了小麦赤霉病抗性提高的过程。随着生物工程技术和生物信息技术的迅猛发展,将来可利用图位克隆技术分离抗赤霉病主效基因,并在全基因组关联分析和各种组学技术的基础上,从全基因组和基因调控网络水平上研究小麦赤霉病抗性机理,以期在更深层次上理解小麦赤霉病的抗性机理。

湖北省小麦品种(系)的赤霉病抗性分析

为评价湖北省小麦品种(系)的赤霉病抗性水平,对湖北省2008年以来选育的183份小麦新品系和2000年以来审定的30个小麦品种的赤霉病抗性进行了田间接种鉴定,并通过系谱分析对审定的30个小麦品种的赤霉病抗性来源进行了推测。结果显示,在183个参试品系中,对赤霉病抗性达到中感及以上水平的品系占27.32%,其中2010-2011年度和2011-2012年度中感赤霉病品系所占比例分别为42.31%和30.00%,比前两年有明显的提高。2000年以来湖北省审定的30个小麦品种的赤霉病抗性以中感为主,占56.7%,只有2个品种的赤霉病抗性达到中抗。对审定品种的系谱分析表明,湖北省小麦品种赤霉病抗性主要来源于南大2419及其衍生系、阿夫及其衍生系、太谷核不育抗病材料,部分品种的赤霉病抗性可能有多个来源,如鄂麦24、鄂麦25、鄂麦26和荆麦103等。推测湖北省当前主导品种鄂麦596、鄂麦352、襄麦25和襄麦55抗性来源都为南大2419,赤霉病抗性来源单一的问题仍较为突出。

小麦赤霉病的抗性遗传分析

为给小麦抗赤霉病遗传改良提供参考,利用苏麦3号及5个当地推广小麦品种为亲本,按Griff-ing双列杂交法Ⅱ配制15个杂交组合,以赤霉病病小穗率为抗性指标,研究了小麦赤霉病抗性的遗传。结果表明,在6个小麦品种中,苏麦3号和扬麦9号赤霉病抗性的一般配合力最好,能极显著地提高杂种后代的赤霉病抗性。小麦赤霉病抗性的遗传符合加性-显性模型,同时受加性和显性效应的作用,且加性效应更重要,显性程度为部分显性。控制赤霉病遗传的增效等位基因为显性,增减效等位基因频率在亲本中的分配存在显著差异。苏麦3号具有最多的控制赤霉病抗性遗传的显性基因,而宁麦8号则具有控制赤霉病抗性遗传最多的隐性基因。小麦赤霉病抗性可能受2～3对主效基因的控制,狭义遗传力较高,早代选择有效。论文最后还就小麦抗赤霉病育种进行了探讨。

长江中下游小麦抗赤霉病品种的筛选与部分农艺性状分析

【目的】赤霉病严重危害中国乃至世界小麦的产量和品质,培育和种植抗病品种是控制赤霉病最经济、有效和安全的方法。Fhb1是国内外公认的抗赤霉病主效基因,通过筛选综合农艺性状优良的抗赤霉病品种,探明Fhb1在不同遗传背景下对小麦赤霉病抗性的影响,为小麦抗赤霉病育种提供理论依据和材料来源。【方法】选取历年来长江中下游广泛种植的75份小麦改良品种和18份地方品种,2016—2018年连续3年采用单花滴注结合弥雾保湿进行供试品种的赤霉病抗扩展鉴定,根据3年平均病小穗率和严重度分级,将供试品种分成抗病(R级)、中抗(MR级)、中感(MS级)和感病(S级),并利用Fhb1的KASP标记检测;2019年调查筛选出的平均赤霉病抗性水平达到中感及以上小麦品种的株高、穗粒数、小穗数、穗长和千粒重。【结果】3年赤霉病鉴定结果表明,供试品种中有2个品种平均赤霉病抗性达到R级,平均病小穗率范围为7.8%—9.7%,65个品种达到中抗至中感,平均病小穗率范围为13.2%—49.5%,26个品种达到S级,平均病小穗率范围为53.6%—78.5%。22个小麦品种在Fhb1位点呈抗病基因型(简称Fhb1+),71个品种在该位点呈感病基因型(简称Fhb1-),Fhb1+品种平均病小穗率显著低于Fhb1-品种(P<0.05)。赤霉病鉴定筛选得到67个抗性达到中感及以上水平的品种,考察这些品种的农艺性状发现宁麦19、扬麦29、扬麦16、扬麦23、扬糯麦1号、扬麦20、宁麦12和扬辐麦4号的株高、穗粒数和千粒重等综合农艺性状优良,可作为小麦抗赤霉病育种的亲本选用。【结论】除苏麦3号和望水白外,供试材料中未发现其他高抗赤霉病的种质资源。筛选得到的赤霉病抗性与综合农艺性状结合较好的小麦品种以扬麦品种为主,其中只有扬辐麦4号携带Fhb1抗病基因。利用Fhb1抗病基因并不是解决小麦赤霉病危害的唯一途径。

扬麦品种(系)赤霉病抗扩展性基因分子检测及其抗性评价

为明确扬麦品种(系)赤霉病抗扩展性基因组成,利用3个抗扩展QTL(Fhb1、Fhb2、QFhb-2DL)的7个分子标记对202份扬麦品种(系)进行分子检测,并在田间接种对其抗病性进行鉴定和评价。结果表明,供试的202份扬麦品种(系)中,抗病品种(系)有68份,占33.6%;有37份携有Fhb1,其中31份对赤霉病表现抗病,抗性表现稳定;携有Fhb2和QFhb-2DL基因的分别有30份和39份,但标记阳性的品种(系)抗病性表现复杂,可能跟载体品种的遗传背景有关;另有30份材料抗性稳定,但未检测出Fhb1和Fhb2。基因检测和系谱分析表明,扬麦品种(系)所含抗扩展性基因至少有两个来源,其一为含有Fhb1基因的品种,以扬麦18号、扬麦21号等为代表,其抗源主要来自宁麦9号或其衍生品种;其二为不含Fhb1品种,以扬麦14号、扬麦16号、扬麦17号和扬麦23号等为代表,推测这类品种所含抗性基因来自扬麦158。

黄淮南部麦区小麦赤霉病抗性鉴定及基因型分析

为丰富抗赤霉病育种亲本材料,连续2年采用土表接种法对762个黄淮南部麦区小麦品种(系)的赤霉病抗性进行鉴定,发现15个小麦品种(系)表现为中抗赤霉病,133个小麦品种(系)表现为中感赤霉病。采用单小花滴注接种法对15个经土表接种鉴定为中抗小麦品种(系)以及2个多抗性基因聚合的种质材料和4个小麦-长穗偃麦草易位系的赤霉病抗性进行鉴定,发现10个小麦品种(系)表现为中抗赤霉病,10个小麦品种(系)表现为中感赤霉病。采用与抗赤霉病基因Fhb1、Fhb2、Fhb4、Fhb5和Fhb7相关的分子标记对15个经土表接种法鉴定为中抗赤霉病的小麦品种(系)、部分(120个)中感赤霉病小麦品种(系)、2个多抗性基因聚合种质材料和4个小麦-长穗偃麦草易位系进行检测,发现135个经土表接种鉴定为中抗或中感赤霉病的小麦品种(系)中,有11个小麦品种(系)含有Fhb1基因,但未检测到含有Fhb2、Fhb4、Fhb5和Fhb7基因的品种(系);2个多抗性基因聚合的种质材料分别含有Fhb1、Fhb2、Fhb4基因和Fhb1、Fhb2、Fhb5基因;4个小麦-长穗偃麦草易位系均含有Fhb7基因,且其中2个易位系还含有Fhb1基因。

湖北小麦品种赤霉病抗性及其在生产中的应用

为了解湖北省小麦主栽品种的赤霉病抗性现状,对湖北省不同时期审定的14个主栽小麦品种的赤霉病抗性进行了多年田间接种鉴定。结果发现,湖北省主要小麦品种赤霉病病情指数介于18.67%~47.24%之间,变异幅度较大。其中,6个小麦品种的赤霉病抗性达到中抗水平,8个品种的赤霉病抗性为中感。8个2008年后审定的小麦新品种平均赤霉病病情指数为28.15%,其中有6个品种达到中抗水平;6个2008年前审定的品种均为中感,平均赤霉病病情指数为42.35%。湖北省新育成小麦品种赤霉病抗性明显提高;在生产中,湖北省小麦品种布局仍存在种植品种赤霉病抗性水平不高、品种多样性差、新品种推广应用速度过慢等问题。

四川省小麦条锈病、白粉病、赤霉病抗性鉴定及抗原筛选

从1981～2003年,通过在小麦条锈病、白粉病、赤霉病若干个重病区设点,多点异地,自然发病与人工接种相结合,并以反应型与严重度相结合,评价品种的抗病性,提高了鉴定的准确性和可靠性。本文对抗源多样化、品种的合理布局、持久抗性等方面总结了经验与教训。

高光谱数据处理算法的小麦赤霉病籽粒识别

赤霉病是小麦的一种主要病害,它会导致小麦减产甚至绝收,严重影响小麦种子质量,此外小麦受侵染分泌的真菌毒素危害人类身体健康。因此,小麦赤霉病籽粒的识别具有非常重要的意义。起初普遍采用色谱法和酶联免疫法进行赤霉病检测,这些方法设备昂贵、检测速度慢、准确性低。近年来,高光谱成像技术被广泛应用于农作物的识别与检测中,但是在小麦赤霉病检测的应用研究中,大多采用抽样检测的方法,图像采集完成后需要通过ENVI软件手动选取感兴趣区域。前期准备工作冗杂,而且容易发生漏检,漏检的小麦籽粒在存储运输过程中向周边籽粒快速侵染,难以保障小麦安全健康。鉴于此,利用高光谱成像系统结合机器学习提出了一种用于对大量小麦赤霉病籽粒样本快速可视化识别的算法,以降低漏检率并提升检测效率。实验分别采集健康小麦和染病小麦469~1 082nm波段的高光谱图像,通过直方图线性拉伸结合图像分割的方法获取小麦样本的掩膜图像信息。利用Savitzky-Golay平滑去噪法与标准正态变量变换法(SNV)进行数据预处理,通过主成分分析法(PCA)和连续投影法(SPA)进行特征变量提取,筛选特征变量个数分别为4个和8个。在掩膜图像位置采集健康小麦样本与染病小麦样本各400份,其中75%用于建模集,25%用于测试集。采用十折交叉验证法结合线性判别分析法(LDA)、K-近邻算法(KNN)、支持向量机(SVM)分别建立分类模型,测试集准确率都达到90%以上。随后比较了网格法(GRID)、粒子群算法(PSO)、遗传算法(GA)三种核参数寻优方法对SVM模型的影响,其中,SG-SPA-SVM(PSO)模型分类效果最优,建模集准确率为95.5%,均方根误差为0.212 1,测试集准确率为98%,均方根误差为0.141 4。基于样本点预测的基础之上,对掩膜获得所有小麦样本的光谱曲线进行预测并将识别结果反馈回掩膜中再进行伪彩色显示,实现染病籽粒可视化识别。结果表明,高光谱成像结合SG-SPA-SVM(PSO)算法建立的分类模型可以高效快速、准确无损、可视化的实现小麦赤霉病籽粒识别,为研制小麦赤霉病自动识别设备提供了算法基础。