小麦春季倒伏的防治措施

<正>倒伏是影响小麦高产、稳产、优质的重要因素之一。小麦倒伏主要发生在肥水充足、小麦旺长、群体过大、田间郁蔽的高产麦田。早春是预防小麦倒伏的关键时期。小麦抽穗前倒伏可减产30%~40%,灌浆期倒伏减产20%~30%,乳熟期倒伏减产10%左右,倒伏严重时减产可达50%以上。一、发生症状分茎倒伏和根倒伏两类。     

预防小麦倒伏的关键技术措施

针对陕西关中地区小麦生产上出现的严重倒伏问题,总结分析了发生倒伏的一般特点、主要影响和形成倒伏的主要原因,提出了提高小麦抗倒伏性的关键技术措施,同时,穿插分析了实施这些技术措施的科学依据。     

小麦倒伏的原因和综合防控措施

<正>小麦倒伏年年都有发生,给生产带来了不小的损失。笔者对此作了大量的调查后发现,除自然灾害外,栽培管理不当也是小麦倒伏的重要因素。只有了解小麦倒伏的原因,采取综合防控措施,才能正确地预防小麦倒伏现象的发生。一、倒伏的原因小麦倒伏可分为茎倒和根倒两种。茎倒是由小麦播种量过大、肥水施用过多造成基部节间过长、茎秆细弱、韧性差引起的;根倒是小麦根系浅和后期浇水后遇大风引起的。     

小麦春季冻害和后期倒伏与品种的关系及防灾减灾技术

2006～2007年度小麦生育中、后期,济宁市及周边地区麦田发生了较大面积春季冻害和后期倒伏,给小麦生产造成了巨大损失。由于冻害造成有效穗数减少,倒伏造成千粒重下降。为正确认识和解决因小麦冻害和倒伏发生的种子纠纷,现根据小麦冻害和倒伏原因的调查分析,谈一谈小麦春季冻冷害和后期倒伏与品种的关系及防灾减灾措施。     

小麦倒伏原因与预防措施

小麦倒伏主要发生在肥水充足、小麦旺长、群体过大、田间郁蔽的高产麦田。预防小麦倒伏是夺得小麦高产不可忽视的一项管理措施。试验结果表明,小麦在抽穗前后倒伏会减产50％以上．灌浆期倒伏减产20％～30％。因为小麦倒伏后叶片重叠,光合作用受到了影响,植株体内输导组织不畅通,养分和水分的运输受到阻碍,对产量影响很大。     

小麦品种抗倒伏能力定性定量研究

为有效评价小麦品种抗倒伏能力,以2015-2016年河南省小麦区域试验水地组参试品种为研究对象,采用倒伏指数、聚类分析和主成分分析等方法,利用多试点倒伏鉴定结果,对84个河南省小麦新品种的抗倒伏能力进行了初步定性和定量分析。结果表明,84个小麦品种平均倒伏指数为7. 06,倒伏指数≤3. 50的品种有40个,占参试品种的47. 6%,倒伏指数≥20的品种有8个,占参试品种的9. 5%,河南省区域试验参试小麦新品种抗倒伏能力总体上处于较好水平。相关性分析表明,倒伏指数与倒伏面积、倒伏级别、严重倒伏点率相关系数分别达到0. 977**,0. 912**,0. 906**,说明倒伏指数能较好地评价小麦品种的抗倒伏能力。主成分分析表明,倒伏指数、倒伏面积、倒伏级别和严重倒伏点率(2017版标准)是本研究中衡量品种抗倒性最好的指标。综合倒伏指数和倒伏参数(包含严重倒伏点率、倒伏点率、倒伏面积和倒伏级别)对品种进行抗倒性表型聚类分析,比单独应用倒伏指数或倒伏参数效果更好。上述方法在单点或多点试验中均可有效地定性和定量小麦品种抗倒伏能力大小,同时可推广到其他禾谷类作物抗倒伏能力鉴定研究,可有效估测小麦品种抗倒伏能力大小及准确地进行品种分类。     

小麦纹枯病的发生与防治

纹枯病是小麦生产上的主要病害之一，在高水肥、地势低洼、密植、高产地块尤为严重。后期危害严重时可造成白穗、整株倒伏，导致麦田减产，严重影响小麦的产量和品质。     

小麦冻害及倒伏预防措施

近年来，随着全球气候变暖，我国小麦主产区基本处于暖冬的气候条件，小麦冬前旺长，冬季和早春冻害及后期倒伏现象时有发生。面对小麦生产的严峻形势，我们根据田间调查分析，总结出小麦冻害及倒伏预防措施。     

周口小麦安全生产关键技术

正周口市位于黄淮平原西部,地处黄泛区腹地,常年小麦播种面积60万hm~2,年产小麦40亿kg,是河南省乃至全国的小麦主产区。该区属暖温带向亚热带的过渡性季风气候,小麦生产面临干旱、倒伏、阴雨寡照、干热风、病虫害流行等多种制约因素,因此,周口市的小麦管理要根据当时的墒情、苗青及天气情况采取适当措施,扬长避短,发挥优势,把不利因素的影响降到最低,才能取得好的收获。选用优良品种其目的是选择适合当地生态条件的优良小麦品种,     

陇东冬小麦高产春季机械沟施化肥技术

冬小麦是陇东地区主要的粮食作物,种植面积和总产均居粮食作物之首,既是当地人民的主食,也是食品工业的主要原料,因此,大力发展小麦生产,不断探索小麦丰产新途径,对确保粮食安全.     

Russian wheat aphid-induced protein alterations in spring wheat

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a perennial, serious pest of wheat (Triticum aestivum L.) in the western United States. Current methodologies used to enhance RWA resistance in wheat germplasm could benefit from an understanding of the biochemical mechanisms underlying resistance to RWA. This study was initiated to identify specific polypeptides induced by RWA feeding that may be associated with RWA resistance. The effects of RWA feeding on PI 140207 (a RWA-resistant spring wheat) and Pavon (a RWA-susceptible spring wheat) were examined by visualizing, silver-stained denatured leaf proteins separated by two-dimensional polyacrylamide gel electrophoresis. Comparisons of protein profiles of noninfested and RWA-infested Pavon and PI 140207 revealed a 24-kilodalton-protein complex selectively inhibited in Pavon that persisted in PI 140207during RWA attack. No other significant qualitative or quantitative differences were detected in RWA-induced alterations of protein profiles. These results suggest that RWA feeding selectively inhibit synthesis and accumulation of proteins necessary for normal metabolic functions in susceptible plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of Russian wheat aphid resistance from tetraploid wheat accessions during transfer to hexaploid wheat

Identification of new sources of resistance to Russian wheat aphid (RWA) (Diuraphis noxia (Kurdjumov) in wheat (Triticum aestivum L.) has become very important with the identification of several new biotypes since 2003. Our objective was to characterize inheritance and expression of resistance to RWA biotype 2 from three tetraploid wheat landraces (Triticum turgidum L. subsp. dicoccon) during transfer to hexaploid wheat. Resistant tetraploid accessions PI 624903, PI 624904, and PI 624908 were crossed to the susceptible hexaploid cultivars ‘Len’ and ‘Coteau’. Resistant F1 progeny were advanced to the F2:3 by self-pollination and to the BC1F2 and BC2F1 by backcrossing. Leaf rolling and chlorosis were recorded in standard seedling screening tests on F1 and F2:3 individuals while the F2, BC1F1, BC1F2, and BC2F1 were scored as resistant or susceptible. Segregation in the BC1F1 and BC2F1 fit a 1:1 resistant:susceptible ratio, indicative of control by a single dominant gene. Segregation for resistance in the F2 did not fit 3:1, 13:3, or 15:1 ratios for any of the resistant accessions. Expression of resistance in homogeneous resistant F2:3 lines was greater than susceptible checks, similar to the resistant tetraploid accessions, and less than a line carrying the Dn7 resistance gene. Resistance derived from these tetraploid accessions will be useful to broaden the base of RWA resistance available for use in wheat breeding.     

Agronomic evaluation of AABB wheat tetraploids extracted from wheat neo-allohexaploids

In order to understand if the mechanisms leading to stabilization of hexaploid wheats occurred in early generations after hybridization or accumulated slowly over the evolutionary course, we extracted tetraploids from newly synthesized allohexaploid wheats and characterized the effects of changes in polyploidy levels. Extracted wheat tetraploids (ETW) were developed from two neo-allohexaploids and their five phenotypic traits were compared to the parents. The ETWs displayed few small amplitude differences relative to the tetraploid parent of the synthetics. This suggest that genomic changes that might have occurred during the first three generations of the newly-synthesized wheat allopolyploids had very weak effects on the phenotypes.     

Genetic diversity of wheat storage proteins and bread wheat quality

To understand the genetic and biochemical basis of the bread makingquality of wheat varieties, a large experiment was carried out with a set of162 hexaploid bread wheat varieties registered in the French or EuropeanWheat Catalogue. This material was used to analyse their allelic compositionat the twelve main storage protein loci. A large genetic and biochemicaldiversity of the gluten proteins was found. Several gliadin encoding lociexhibited the highest allelic diversity whereas the lowest diversity was foundfor Glu-A1 and Glu-D3 loci encoding some high molecularweight glutenin subunits (HMW-GS) and LMW-GS respectively. Thevarieties were grown in three experimental locations in France. Qualityevaluation was carried out from material harvested in each location usingseven technological tests: grain protein content (Prot), grain hardness(GH), Zeleny sedimentation test (Zel), Pelshenke test (Pel), water solublepentosans (relative viscosity: Vr ), mixograph test (giving 11 parameters)and the alveograph test (dough strength W, tenacity P , extensibility L,swelling G, ratio P/L and the elasticity index Ie). Genetic and locationeffects as well as broad-sense heritability of each of the 22 technologicalparameters were calculated. GH, corresponding to the major Ha gene, Pel,and MtxW (mixograph parameter) had the highest heritability coefficients,alveograph parameters like W, P, the relative viscosity Vr and severalmixograph parameters had medium heritability coefficients whereas Protand L had the lowest. Variance analysis (using GLM procedure) allowed theeffect of the allelic diversity of the storage proteins, on the geneticvariations of each quality parameters, to be estimated. Glu-1 and Glu-3 loci had significant additive effects in the genetic variations of manyparameters. Gliadin alleles encoded at Gli-1 and Gli-2 were alsofound to play significant effect on several quality parameters. The majorpart of the phenotypic variation of the different quality parameters like Zel,Pel, W or mixograph peak time MPT was explained with the GH and allelesencoded at Glu-1 and Glu-3. Allelic variants encoded at Glu3and Gli-2 had similar contribution to the phenotypic variations ofquality parameters and accounted for 4% up to 21% each.     

Partial resistance to wheat leaf rust in 18 spring wheat cultivars

Summary Eighteen spring wheat cultivars were tested in microfields and race nurseries for their partial resistance PR to wheat leaf rust under low and high disease pressure respectively. Large differences existed between the 18 cultivars, Skalavatis 56 being the most susceptible and Ponta Grossa 1 being the most resistant cultivar. Of the three epidemic parameters, disease severity (DS) at the time that the susceptible check was severely diseased and area under the transformed disease severity curve (AUTC) and the logistic growth rate (r), AUTC and DS were highly correlated. Both seemed to be reliable estimators of PR but DS should be preferred for economical reasons. The logistic growth rate seemed to be unsuitable as an estimator of partial resistance.High and low disease pressure gave similar cultivar ranking. PR can be screened and selected equally well in race nurseries with low space, low time and low cost input as in microfields with high space, time and cost input.Cultivar differences in development rate had a large impact on the cultivar differences for amount of disease and can therefore greatly bias the estimation of cultivar resistance. The resistance of early cultivars tended to be underestimated whereas the resistance of late cultivars tended to be overestimated. The effect of differences in developmental rate was most pronounced in the flag leaf. It is advisable to avoid the assessment of disease levels on the flag leaf only and to incorporate in the tests several susceptible and resistant checks that cover the range of development rates in the material to be selected, because otherwise selection for resistance will tend to select also for lateness.Regression of the epidemiological parameters on three components of partial resistance revealed that latency period (LP) is an important factor in determining the resistance observed in the field explaining on average 67% of the observed variation. Adding infection frequency (IF) and urediosorus size (US) to the linear model increased the proportion of the observed variation in the field explained by the components to 80%. This result supports the idea that the components of PR inherit independently, at least, in part.     

Adaptation of wheat rusts to the wheat cultivars in former Czechoslovakia

Summary In former Czechoslovakia virulence of rusts attacking wheat was studied since the sixties. Since the same time genes for resistance in the registered cultivars were identified. The role of Berberis and Thalictrum as alternate hosts for stem rust and leaf rust, respectively, was investigated as well. Determined changes of virulence in rust populations could only partially be ascribed to changes of resistance genes in the grown cultivars. Unnecessary genes for virulence had no negative effect on the fitness of the pathogen. All tested samples of aeciospores from barberries attacked rye, not wheat. None of Thalictrum species occurring in the Czech and Slovak Republics was found to host wheat leaf rust. However, the sexual stage of wheat stem rust and wheat leaf rust could be induced on Berberis vulgaris and Thalictrum speciosissimum, respectively. General epidemiological conclusions are drawn from the results and experience of the last 35 years.     

Genetic relationships and diversity among Tibetan wheat, common wheat and European spelt wheat revealed by RAPD markers

An endemic hexaploid wheat found in Tibet, China was taxonomically classified as a subspecies in common wheat, i.e. Triticum aestivum ssp. tibetanum. Seven accessions of the Tibetan wheat, 22 cultivars of common wheat and 17 lines of spelt wheat were used for RAPD analysis to study the genetic relationships of the Tibetan wheat with common wheat and spelt wheat, and to assess the genetic diversity (GD) among and within the taxa. RAPD polymorphism was found to be much higher within spelt wheat and the Tibetan wheat than within common wheat. The GD value between the Tibetan wheat and common wheat is lower than that between the Tibetan wheat and spelt wheat. The result of cluster analysis showed that the 46 genotypes were distinctly classified into two groups. Group 1 included all European spelt wheat lines, while group 2 includes all Chinese common wheat and the Tibetan wheat accessions. However, the Tibetan wheat was substantially differentiated from Chinese common wheat at a lower hierarchy. Our results support an earlier classification of the Tibetan wheat as a subspecies in common wheat. European spelt wheat and the Tibetan wheat showed much higher genetic diversity than Chinese common wheat, which could be used to diversify the genetic basis for common wheat breeding. This revised version was published online in July 2006 with corrections to the Cover Date.     

AFLP genetic diversity analysis in Russian wheat aphid resistant wheat accessions

Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is an important insect pest which causes severe economic losses in wheat (Triticum spp.). Among the various U.S. RWA biotypes, biotype 1 (RWA1) and biotype 2 (RWA2) are the most prevalent and most virulent on cultivated genotypes. Although many sources of resistance to these biotypes are available among landraces, their relatedness should be characterized to permit their more efficient use in breeding programs. In this study, 38 hexaploid accessions resistant to biotype 1 and/or biotype 2 were evaluated for genetic diversity based on amplified fragment length polymorphisms (AFLP). Fifteen AFLP selective primer combinations were used to genotype these accessions, resulting in 893 amplicons. Of these, 274 (30.6%) informative polymorphic bands were used for genetic diversity analysis. Genetic similarity coefficients ranged from 0.47 to 0.87 among the resistant accessions, indicating high genetic diversity among them. Cluster analysis grouped the 38 accessions into two major clusters, I and II, including resistant lines for RWA1 and RWA2. The study indicated that accessions in the National Small Grains Collection conferring RWA1 or RWA2 resistance comprise a diversified population which should support introgression efforts and provide genetic diversity for future breeding for RWA resistance.     

Inheritance of Russian wheat aphid resistance in PI 140207 spring wheat

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a serious, perennial pest of wheat (Triticum aestivum L.) in many areas of the world. This study was initiated to determine the inheritance of RWA resistance in PI 140207 (a RWA-resistant spring wheat) and to determine its allelic relationship with a previously reported RWA resistance gene. Crosses were made between PI 140207 and ‘Pavon’ (a RWA-susceptible spring wheat). Genetic analysis was performed on the parents, F₁, F₂, backcross (BC) population and F₂-derived F₃ families. Analyses of segregation patterns of plants in the F₁, F₂, and BC populations, and F₂-derived F₃ families indicated single dominant gene control of RWA resistance in PI 140207. Results of the allelism test indicated that the resistance gene in PI 140207, while conferring distinctly different seedling reactions to RWA feeding, is the same as Dn 1, the resistance gene in PI 137739.     

Environmental stability of partial resistance in spring wheat to wheat leaf rust

Summary Five spring wheat cultivars differing in partial resistance (PR) to wheat leaf rust were tested at Wageningen (the Netherlands) on a sandy and a clay site, El Batan (CIMMYT, Mexico) and Ponta Grossa (Brazil) over two years. The cultivars were Skalavatis 56, Little Club (both very susceptible), Westphal 12A, Akabozu and BH 1146 (all three with high levels of PR). The results showed that PR was expressed at all four locations in both years. The level of expression was influenced by the environment but the cultivar ranking was hardly affected. Selection for PR in the field can therefore be carried out over a wide range of environments.