Breeding for yield and quality in durum wheat

Three populations of an intervarietal durum wheat cross IWP5308/PDW208, F₅, F₅BIP₁ (population derived after intermating in F₂) and F₅BIP₂ (population derived after intermating in BIPF₁), were evaluated under three different agronomic environments for mean performance and stability of genotypes for grain yield, yield components and protein content. Though the biparental progenies indicated a higher mean performance, they did not differ significantly from progenies of the pedigree method for almost all characters. The biparental progenies, however, produced a higher number of stable genotypes for grain yield per plant, grains per ear and protein content. The F₅ population had a higher number of stable genotypes for 1000 grain weight and number of tillers per plant. The BIP progenies also had a higher number of genotypes with above average mean performance, and many were significantly higher than the checks WH896 and WH542, compared with F₅ progenies. Hence, in spite of high G x E interactions, the use of cycles of biparental mating and selection of top yielding lines on the basis of yield components can enable selection of stable genotypes with high protein content. Number of tillers per plant and 1000 grain weight were the yield component characters which made maximum contribution to phenotypic stability of the genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Combining frost tolerance,high grain yield and good pasta quality in durum wheat

Growing in Central Europe winter instead of spring durum wheat would substantially increase yield potential but is currently hampered by the lack of knowledge of frost tolerance present in elite material. The objectives of our survey were to (i) study the genetic variability and heritability of frost tolerance and its association with other important agronomic and quality traits in durum wheat, (ii) examine the potential to combine frost tolerance with high quality and high grain yield and (iii) investigate the consequences of the heritabilities and associations among traits on the optimum design of a multistage selection programme for winter durum wheat. We investigated 101 elite winter durum wheat lines and four commercial checks in field trials at four locations. Four agronomic as well as nine quality traits were recorded. In addition, frost tolerance was evaluated using a semi‐controlled test resulting in high‐quality phenotypic data. Genotypic variances (σ²_G) were significantly larger than zero for all traits, and heritabilities were moderate to high. Several elite durum wheat lines exhibited a frost tolerance comparable to that of two frost‐tolerant Triticum aestivum varieties. Frost tolerance was not negatively associated with other important agronomic and quality traits. The high quality of the phenotypic data for frost tolerance evaluated in a semi‐controlled test suggests that this is a cost‐efficient approach to consider frost tolerance at early stages of a multistage durum wheat breeding programme.     

Yielding ability, yield stability, and quality of exotic durum wheat germplasm in Sicily

A set of 20 accessions of durum wheat (Triticum turgidum L., durum group), which mostly included exotic landraces from various Mediterranean countries, and four Italian improved varieties were evaluated for grain yield in five environments and for quality traits in two environments of Sicily. Glutenin composition was also assessed electro-phoretically on six seeds per entry. The cultivars differed (P ≤ 0.01) for yield, protein content and sodium dodecyl sulphate (SDS-sed) sedimentation volume, in the presence of significant (P ≥ 0.001) genotype-environment interaction effects. These effects were large for yield and moderately large for protein content relative to genotype main effects following estimation of variance components. Most exotic cultivars yielded comparably with, and some of them showed greater stability than, the best yielding Italian variety 'Simeto. Some exotic cultivars combined outstanding yield, protein content and SDS-sedimentation values and represent therefore extremely valuable germplasm sources to broaden the local genetic base. The glutenin composition LMW-2 and HMW 7 + 8 was positively associated with gluten quality. Six entries showed heterogeneous electrophoretic patterns, suggesting the presence of different genotypes within the cultivar.     

Nitrogen uptake and remobilization in tetraploid 'Langdon' durum wheat and a recombinant substitution line with the high grain protein gene Gpc-B1

Tetraploid wheat (Triticum turgidum L. var. durum) cv. ‘Langdon’ (LDN) and its near‐isogenic recombinant substitution line no. 68 (RSL no. 68) carrying the high grain protein gene Gpc‐B1 from emmer wheat, were compared in three greenhouse experiments to establish in which way Gpc‐B1 increases grain protein concentration (GPC). At anthesis, RSL no. 68 had higher soluble protein and amino acids concentrations in the flag leaf than LDN. At maturity, both lines presented a similar above ground biomass and grain yield. However, RSL no. 68 showed a higher total N content in ears, grain and chaff than LDN; N harvest index (NHI) was also higher because of a lower straw N concentration and higher grain N concentration. When both lines were grown with a low N supply, and when N supply was interrupted before anthesis, similar trends were observed but the differences in GPC were smaller. It is concluded that RSL no. 68 accumulates a higher GPC than LDN mainly because of a more efficient N remobilization from the leaves to the ears during grain filling.     

Environmental and genetic determination of protein content and grain yield in durum wheat under Mediterranean conditions

The unpredictability of the Mediterranean climate causes fluctuations in wheat yield and quality, but offers the opportunity for obtaining high‐quality durum wheat in terms of grain protein content. Twenty‐five durum wheat genotypes were grown under irrigated and rainfed conditions at each of two latitudes in Spain during 1998 and 1999. Differences between latitudes in grain protein content and chlorophyll content in the flag leaf were attributable to nitrogen fertilization management. Cycle length until anthesis was less affected by the environment than grain‐filling duration, and was longer under irrigated conditions than in the rainfed sites. A negative asymptotic curve was the best equation to fit the relationship between yield and protein content, suggesting that yield improvements in fertile environments may be attained with negligible reductions in protein content. ‘Jabato’, ‘Waha’, ‘Lagost‐3’, ‘Massara‐1’ and ‘Vit?on’ showed medium to high yield, yield stability and high protein content. Chlorophyll content in the flag leaf, measured at anthesis with the soil‐plant analysis development (SPAD) portable field unit, may be useful for the fast and cheap detection of durum wheat genotypes with high grain protein content in drought‐stressed Mediterranean environments.     

氮素形态对小麦花后干物质积累与分配的影响

采用随机区组试验,研究了铵态氮、硝态氮和酰胺态氮3种氮素形态对小麦花后干物质积累与分配的影响,结果表明：（1）小麦花后籽粒干重及地上部总干重随生育进程不断增加,而旗叶、穗下节、穗下鞘、颖壳的干重均随着生育进程呈下降趋势;（2）氮素形态对小麦花后干物质积累与分配有显著影响。硝态氮处理下小麦花后地上部总干物质量最高,并且随着生育进程,干物质在旗叶、穗下节、穗下鞘、颖壳中分配比例降低,在籽粒中的分配比例高于其它2个处理。（3）铵态氮、硝态氮和酰胺态氮3种氮素形态处理下小麦产量分别为7250.5kg/hm2、7575.3kg/hm2和7156.2 kg/hm2。在本试验条件下,硝态氮处理增产效果最佳,较酰胺态氮处理增产5.8%。     

Grain quality and yield characteristics of D-genome disomic substitution lines in 'Langdon' (Triticum turgidum var. durum)

Sets of D-genome disomic substitution lines of ‘Langdon’ (Triticum turgidum var. durum) were used to study the effect of chromosome substitutions on grain yield and flour technological properties. In general, the substitution of any D-genome chromosome had a detrimental effect on grain yield and growth vigour (some lines were sterile). SDS-sedimentation, SE-HPLC and two-gram mixograph procedures were used to measure dough strength of the lines studied. Significant correlations were observed between protein concentration and grain yield and other quality parameters such as SDS-sedimentation value, the proportion of glutenin, dough mix time and peak resistance. Most of the quality characters were highly correlated with each other. Substitution of chromosomes 1D, 5D, 2D and 7D resulted in positive responses to SDS-sedimentation values, but only chromosome 1D had positive effects on the proportion of peak 1 (P₁%), measured by SE-HPLC. Besides the major influence of chromosome 1D on three major mixograph parameters (mixing time, peak resistance and resistance breakdown), chromosome 5D also exhibited significant effects on these mixing parameters. Principal-component analysis showed that the predominant effect on durum-wheat rheological properties was from chromosome 1D, whereas chromosome 5D had a major effect on grain hardness (50%) and increased the whiteness of the flour.     

Identification of bread wheat,durum wheat and barley cultivars adapted to dry areas of Southern Italy

Summary Among the cultivars of bread wheat, durum wheat and barley grown in the South of Italy, genetic variation for adaptation to the high temperature and drought stress conditions typical of the Mediterranean environment has been found.The basic data have been extrapolated from 5 years of Italian national network cultivar trials, where 20–30 cultivars were grown in replicated plot trials in 30–50 locations per year, including some where stress strongly affected grain yield.After careful identification of the most representative years and testing sites it was possible to characterise the cultivars on the basis of the grain yield in stress conditions and the Fischer & Maurer (1978) susceptibility index and to find genotypic differences sufficiently repeatable in years.The cultivars giving the best yield under stress associated with low susceptibility indices were in bread wheat: Etruria, Spada, Pandas, Centauro, Oderzo, Costantino and Gladio, in durum wheat: Aldura, Arcangelo, Adamello, Vespro and Capeiti, in barley: Fleuret, Barberousse, Jaidor, Express, Trebbia, Georgie, Dahlia, Criter and Magie.     

增密减氮对棉花干物质和氮素积累分配及产量的影响

为了探讨种植密度和施氮量对棉花干物质与氮素积累分配及产量的影响。本研究以聊棉6号为试验材料,设置5.25、6.75和8.25万株hm^-2 (D_5.25、D_6.75、D_8.25) 3个种植密度, 0、105、210、315和420 kg hm^-2 (N₀、N₁₀₅、N₂₁₀、N₃₁₅、N₄₂₀) 5个施氮量,研究增密减氮对棉花干物质积累与分配、氮素积累与分配、产量及其构成因素的影响。结果表明,与D_5.25相比, D_6.75、D_8.25条件下棉花干物质积累量显著升高, 2016年提高了17.6%、28.7%, 2017年提高了12.6%、20.9%。与N₀相比,施氮肥后干物质积累量随施氮量的增加显著升高, 2016年各施氮处理分别提高了4.5%、11.1%、13.7%、16.3%, 20...     

Production of haploids in bread wheat, durum wheat and hexaploid triticale crossed with pearl millet

Pearl millet is an efficient alternative to maize as a pollen source for haploid production in bread wheat. To compare haploid production frequencies in other Triticeae species, the crossabilities of two genotypes each of bread wheat, durum wheat and hexaploid triticale with four pearl millet genotypes and a maize control were examined. Embryos were obtained from crosses of all three species with both pearl millet and maize. However, significant differences in crossability were found among the three species (10.5–79.8% seed development and 1.4–15.8% embryo formation), as well as among genotypes of durum wheat (7.2–23.7% and 2.1–6.4%) and hexaploid triticale (0.3–20.6% and 0.1–2.7%). Crossability of bread wheat with pearl millet was relatively high. Haploid plants were regenerated from crosses of all three species with pearl millet. As in the case of maize crosses, low crossabilities of durum wheat and hexaploid triticale with pearl millet can be attributed to the absence of D-genome chromosomes.     

Nitrogen uptake and nitrogen harvest index in durum wheat cultivars varying in their grain protein concentration

Summary In a field experiment, plant (excluding roots) and grain nitrogen at harvest were estimated in 15 durum wheat cultivars varying in their grain protein concentration. They showed significant variation in grain yield, grain protein concentration, biological yield, total plant nitrogen at harvest and residual nitrogen in straw. Harvest index and nitrogen harvest index were calculated from this primary data. Nitrogen harvest index varied from 57 to 83%. Plant nitrogen showed significant positive correlation with biological yield, grain yield and grain protein yield, but the correlations with grain protein concentration, harvest index and nitrogen harvest index were not significant. Nitrogen harvest index was positively correlated with harvest index indicating that the distribution of N between straw and grain to a large extent, but not entirely, depends upon the partitioning of dry matter between the two. Grain protein concentration was neither correlated significantly to plant nitrogen nor to nitrogen harvest index.     

种植密度与施氮量对玉米顺单 6 号 干物质积累量及产量的影响

为探究玉米品种顺单6号的适宜种植密度及施氮量,设置3个种植密度和4个施氮水平,采用随机区组设计,研究不同密度及施氮量对顺单6号叶面积、干物质积累、穗部性状及产量的影响。结果表明,当种植密度与施氮量分别为60000株/hm^2与210kg/hm^2时,玉米干物质积累量最大,叶面积及叶面积指数大小适宜,千粒重较大,产量最高,为10547.06kg/hm^2。综合分析认为玉米品种顺单6号在贵州安顺地区适宜种植密度和施氮量分别为60000株/hm^2与210kg/hm^2。     

Grain yield and other traits of tall and dwarf isolines of modern bread and durum wheats

Near-isogenic Rht lines of ten modern bread wheat (Triticumaestivum L.) and six durum wheat (T. turgidum L.) cultivars weredeveloped and evaluated in replicated trials under three soil moisturetreatments for two years in northwestern Mexico. The three soil moisturetreatments were created by providing one, two or six irrigations during eachcrop season. Grain yield and other traits were measured for each line ineach trial. Mean grain yields of short and tall T. aestivum or T.turgidum isolines were similar in the lowest yielding environment whenmean grain yields (0% grain moisture) of T. aestivum and T.turgidum were 2,232 and 1,870 kg ha^-1, respectively. Mean grainyield of dwarf T. aestivum was significantly higher than that of tallgenotypes in another five trials with moderate to high yields. Theperformance of dwarf and tall T. turgidum isolines was unpredictablein moderate yielding trials, and the dwarf isolines yielded significantly morein trials that received six irrigations. Given that the tall isolines producedsignificantly more straw than their shorter counterparts, cultivation of tallwheats may be beneficial in semiarid environments where farmers' yields areclose to 2.5 t ha^-1 or lower, and straw has value.     

Relationships among adaptation patterns, morphophysiological traits and molecular markers in durum wheat

Breeding for specific or wide adaptation would be more cost-efficient if preliminary indications on genotype adaptive responses could be provided by easily-detectable morphophysiological or molecular characteristics. We investigated the consistency among adaptation parameters, morphophysiological traits and SSR markers in estimating and structuring the genetic diversity among 24 durum wheat genotypes. Additive main effects and multiplicative interaction adaptation parameters were estimated across 14 Algerian locations belonging to a low- or a high-elevation subregion. Eight morphophysiological traits were assessed in two locations per subregion. Genotype Euclidean distances based on adaptation parameters were closely related to those based on morphophysiological traits ( r  = 0.75, P = 0.01). Marker-based distances exhibited low correlation with those based on adaptation parameters ( r  = 0.26, P = 0.01) or morphophysiological traits ( r  = 0.32). The consistency between adaptation parameters and morphophysiological traits for genotype ordination and classification was greater than that between either information layer and SSR markers. Optima of phenology and plant height differed between subregions, whereas many kernels per spike and fertile tillers were associated with adaptation to both subregions.     

限水减氮对豫北冬小麦产量和植株不同层次器官干物质运转的影响

采用节水栽培并减少氮肥用量是实现豫北冬小麦生产的高产、高效和环境友好发展的必然选择,探明限水减氮对冬小麦产量和植株各层次器官干物质运转的影响,可为该地区冬小麦节水栽培和合理施用氮肥提供科学依据。2009—2010和2010—2011年连续2年在河南浚县钜桥进行小麦田间裂区试验,主区设置2个灌溉水平[拔节水(W1)和拔节水+开花水(W2)],副区设置5个氮肥水平[330 kg hm~(–2) (N4,豫北地区小麦生产中常规施氮量)、270 kg hm~(–2) (N3)、210 kg hm~(–2) (N2)、120 kg hm~(–2) (N1)、0 kg hm~(–2) (N0)],测定了籽粒产量和植株各层次器官干物质运转量、运转率和对籽粒贡献率。减量施氮与N4相比,各营养器官向籽粒运转的干物质量均有增加,其中,穗轴+颖壳的干物质运转量增加了323.2%,增幅远高于茎节的24.5%和叶片的4.6%,且穗轴+颖壳的干物质运转率和对籽粒贡献率增幅也远高于茎节和叶片。减量施氮处理的叶片干物质运转量的增加主要源于倒三叶和倒四叶,分别增加28.7%和201.1%,而茎节干物质运转量的增加主要源于除穗位节外的其他茎节,分别增加21.7%(倒二节)、71.8%(倒三节)、44.5%(倒四节)和31.1%(余节)。与W2相比, W1干物质运转量无显著差异,但干物质运转率略高(24.6%vs. 23.8%),对籽粒贡献率较高(35.1%vs. 30.0%),籽粒产量降低11.2%,水分供应量减少750 m3 hm~(–2)。可见,减量施氮促进了营养器官,尤其是穗轴+颖壳和下层器官(倒三叶、倒四叶、倒三节、倒四节和余节)的干物质向籽粒的运转,提高了对籽粒贡献率,有利于提高籽粒产量。     

Inheritance of glume color and gluten strength in durum wheat

Summary The correlation between glume color and gluten strength and the heritability of each trait was estimated in two durum wheat crosses. Brown glume color appeared to be dominant to white in both crosses. In one cross, glume color was clearly controlled by one gene while in the other cross it appeared to be controlled by one or two genes with modifiers. The heritability of gluten strength was moderately high. The correlation of F₂ glume color and F₃ gluten strength was high (r=0.66 and 0.78) indicating that F₂ glume color was a good predictor of gluten strength in the F₃ generation. Selection for glume color appears to be an effective breeding strategy for improving gluten strength in those environments where glume color differences are easily detected.     

Sources of resistance to Indian pathotypes of Puccinia graminis tritici and P. triticina in durum wheat

Stem rust and leaf rust are important diseases affecting durum wheat production in India. Inheritance and extent of diversity in resistance were studied in five durum genotypes, viz. ?B 662', ?ED 2398‐A', ?HG 110', ?IWP 5019' and ?Line 1172? using Pgt pathotypes 40A and 117‐6, and Pt pathotypes 12‐2 and 104‐2. F₂ and F₃ analyses showed that resistance was conferred by one or two genes in each line. In all, four genes for resistance to 40A, and eight each for pathotypes 117‐6 and 12‐2 were identified among the five genotypes, and three for resistance to 104‐2 among B 662, ED 2398‐A and IWP 5019 were indicated by tests of allelism. Although the gene identities are not known, at least some of them should be different from Sr2, Sr7b, Sr8a, Sr8b, Sr9e, Sr9g, Sr11, Sr12, Sr13, Sr14, Sr17, Sr23 and Sr28; and from Lr3, Lr14a, Lr23 and Lr27 + Lr31. These genotypes enrich the diversity of resistance to stem rust and leaf rust for durum wheat improvement.     

Ontogenetic analysis of yield components and yield stability of durum wheat in water-limited environments

Summary One main reason for the slow improvement of durum wheat in water-limited environments is the lack of clear understanding of the interrelationships among yield components and their compensatory changes under low and erratic moisture availability. Five cultivars, varying in many physiological attributes, were tested under different drought-stress conditions in field and greenhouse experiments. The cause-effect relationships of duration of vegetative period, duration of grain-filling period, number of spikes per m², kernels per spike, kernel weight and grain yield per m² were assessed. Furthermore, yield stability was evaluated. Yield reduction was largest under mid-season stress (58%), followed by terminal stress (30%) and early stress (22%). Cultivar Po was very sensitive to terminal stress.Path-coefficient analysis revealed a complex pattern of relationships among the six variables. An increase in vegetative period reduced the grain-filling period under all conditions. It increased number of kernels per spike under non-stress conditions. The direct effect of spikes per m² on grain yield was significantly positive. However, more spikes per m² resulted in fewer kernels per spike and a low kernel weight and, as a result, a negative relationship with grain yield under early stress. Grain-filling period had a strong influence on grain yield via kernel weight. Kernels per spike had the largest direct effect on grain yield. However, it was negatively correlated with kernel weight, especially under terminal stress. Grain yield heavily depended on kernels per spike under early stress and grain-filling period and kernels per spike under terminal stress.Variation in drought susceptibility index among cultivars was significant under early and terminal stress conditions, but not under mid-stress conditions. Yield potential and stability were not correlated for the different drought-stress conditions.Longer grain-filling period, increased number of kernels per spike and limited spike number per m² can be used as selection criteria for sustainable yield in water-limited environments.     

Analysis of Wheat Cultivar Differences in Grain Yield, Grain Nitrogen Yield and Nitrogen Utilization Efficiency.

More detailed information on the causes of yield variability among wheat cultivars is needed to further increase wheat yield. Field studies were conducted in Northern Greece over the two cropping seasons of 1985—1986 and 1986—1987 to assess the effects of nitrogen fertilizer and application timing of the various component traits that determine grain yield, grain nitrogen yield and nitrogen utilization efficiency of two bread ( Triticum aestivum L.) and two durum ( Triticum durum Desf.) wheat cultivars, using yield and yield component analysis. Nitrogen at a rate of 150 kg ha^-1 was applied before planting or 100 N kg ha^-1 before planting and then 50 N kg ha^-1 top dressed at early boot stage. Nitrogen and cultivars affected all traits examined, while split nitrogen application affected only some of the traits. Grain yields in the most cases were correlated with number of grains per unit area and grain weight and grain nitrogen yields in all cases with grain number per unit area. The contribution of the number of grains per spike to total variation in grain yield among cultivars was almost consistent (37 to 55 %), while the contribution of grain weight was more significant (up to 55 %) in high yields (>6.500kg ha^-1) and number of spikes per unit area (>500). The number of grains per spike contributed from 60 to 83 % to the total variation in grain nitrogen per spike. Increased grain nitrogen concentration resulted in a reduction of its contribution in grain nitrogen yield variation. Nitrogen utilization efficiency was higher during grain filling than during vegetative biomass accumulation. The contribution of nitrogen harvest index to the variation of utilization efficiency for grain yield was higher in plants receiving nitrogen application.