Effect of the grain protein content locus Gpc-B1 on bread and pasta quality

Grain protein concentration (GPC) affects wheat nutritional value and several critical parameters for bread and pasta quality. A gene designated Gpc-B1, which is not functional in common and durum wheat cultivars, was recently identified in Triticum turgidum ssp. dicoccoides. The functional allele of Gpc-B1 improves nitrogen remobilization from the straw increasing GPC, but also shortens the grain filling period resulting in reduced grain weight in some genetic backgrounds. We developed isogenic lines for the Gpc-B1 introgression in six hexaploid and two tetraploid wheat genotypes to evaluate its effects on bread-making and pasta quality. In common wheat, the functional Gpc-B1 introgression was associated with significantly higher GPC, water absorption, mixing time and loaf volume, whereas in durum wheat, the introgression resulted in significant increases in GPC, wet gluten, mixing time, and spaghetti firmness, as well as a decrease in cooking loss. On the negative side, the functional Gpc-B1 introgression was associated in some varieties with a significant reduction in grain weight, test weight, and flour yield and significant increases in ash concentration. Significant gene × environment and gene × genotype interactions for most traits stress the need for evaluating the effect of this introgression in particular genotypes and environments.     

Path analysis of genotype × environment interactions in rainfed durum wheat

This study was investigated to analyze genotype × environment (GE) interactions for grain yield and its components and to investigate the mechanism by which the stability of grain yield is achieved in rainfed durum wheat. Twenty-four durum wheat genotypes (breeding lines, old, and new varieties) along with one old bread wheat cultivar were tested in 21 diversified rainfed environments during 2010–2013 cropping seasons. The data were analyzed by path analysis model which is composed of a main effect and four multiplicative effects. The flowering time (X1), maturity time (X2), plant height (X3), and 1000-kernel weight (X4) were assumed to be sequential characters for the development of grain yield productivity (Y) in rainfed durum wheat. A high relationship (p < .01) between observed and expected yields of genotypes in different environments confirmed the validity of the causal scheme adopted in the analysis. Comparison the estimates of components provided information on the degree of response of each genotype to the environmental stresses. The results indicated that higher grain yields are associated with higher kernel weight (v₄), which resulted from early flowering (v₁), and so more emphasis should be given to these traits for the improvement of yield potential in durum wheat under highland rainfed conditions of Iran. Positive correlation of stability variance (σ²) with v₄ component indicated that the kernel weight is the main contributor towards GE interaction for grain yield in rainfed durum wheat.     

Grain quality traits of commercial durum wheat varieties and their relationships with drought stress and glutenins composition

Durum wheat is an important crop widely distributed which grain is used in the elaboration of diverse food products. Most notably, durum wheat is used for the production of high quality pasta all around the world, but also for bread, couscous or bulgur, among other products. The end-use quality of these products is heavily determined by the grain quality characteristics, which depend on the wheat variety cultivated, the environmental effects and GxE interactions. The present study was conducted using a collection of 46 commercial durum wheat varieties to describe the phenotypic variation of the main target traits determining wheat quality, ascertain the effects of drought stress (very common in durum areas) on grain quality traits, and to assess the relationship between allelic variations of glutenins composition and gluten properties. Overall the varieties from Australia, USA and Italy showed the best performance in terms of grain quality. Additionally, the effects of drought stress on grain quality traits were analyzed: some traits were favored due to a higher protein concentration but others, such as flour yellowness were not affected by drought stress. The analysis of the varieties' glutenins composition showed the positive or negative effect of some alleles on different quality traits.     

Metabolite profiling of the response to high-nitrogen fertilizer during grain development of bread wheat (Triticum aestivum L.)

Wheat yield and quality are dependent largely on nitrogen (N) availability. In this study, we performed the first metabolomic analysis of the response to high-N fertilizer during wheat grain development using non-targeted gas chromatography-mass spectrometry (GC–MS). Quality parameter analyses demonstrated that high-N fertilizer application led to a significant increase in grain protein content and improvement in starch and bread-making quality. Comparative metabolomic profiling of six grain developmental stages resulted in identification of 74 metabolites, including amino acids, carbohydrates, organic acids and lipids/alcohol, which are primarily involved in carbon and N metabolism. Under high-N fertilizer treatment, numerous metabolites accumulated significantly during grain development. Principal component analysis revealed two principal components as being responsible for the variances resulting from N-fertilizer treatments. Metabolite–metabolite correlation analysis demonstrated that the high-N treatment group had a greater number of positive correlations among metabolites, suggesting that high-N fertilizer treatment induced a concerted metabolic change that resulted in improved grain development. Particularly, the high-N treatment-mediated significant accumulation of metabolites involved in the TCA cycle, starch and storage protein synthesis could be responsible for the improvement of grain yield and quality. Our results provide new insight into the molecular mechanisms of wheat grain development and yield and quality.     

Effect of Genotype,Environment and Their Interaction on Quality Parameters of Wheat Breeding Lines of Diverse Grain Hardness

Abstract

Understanding the contribution of genotype, environment and genotype-by-environment interaction to wheat grain quality facilitates the selection for quality in breeding programs. Stability of grain quality characteristics is an important requirement in the baking industry. We assessed 24 winter wheat genotypes with different grain hardness in multienvironment trials at four locations and two levels of fertilization in each location. Grain samples were analyzed for hardness, protein and starch content, and wet gluten content, Zeleny sedimentation value, alveograph parameter (W) and hectoliter weight. All parameters were evaluated on whole grains using the near infrared transmittance technique. Differences between hard and soft genotypes appeared to be significant, apart from grain hardness, for protein content, Zeleny test and alveograph parameter. Genotype was found to have a major influence only on grain hardness; for protein content, wet gluten and Zeleny sedimentation value environment prevailed the influence of genotype, and for starch content, alveograph W parameter and hectoliter weight both sources of variation had similar importance. Genotype-by-environment interaction was of smaller size relative to genotype and environment in terms of all the studied quality parameters. Stable genotypes predominate the breeding lines studied. Response of unstable genotypes to environmental conditions was nonlinear in most cases.     

Vitreosity,its stability and relationship to protein content in durum wheat

High quality requirements are set on durum wheat (Triticum durum) from semolina mills and pasta producers. For the production of semolina and pasta with good cooking quality, high grain protein content and vitreosity is required. The dependency of vitreosity on protein content as well as its stability under the influence of humidity was not well investigated up to now. We (1) compared two methods to determine vitreosity, (2) investigated the relationship between vitreosity and protein content, (3) developed a method to analyze vitreosity under humidity, and (4) examined the relationship between protein content and agronomical as well as quality traits in durum wheat. The results showed that the formation of vitreous kernels greatly depends on the protein content. To evaluate the stability of vitreosity under the influence of humidity a new method was elaborated and employed to assess the durum germplasm under study. This revealed that vitreosity of a durum wheat variety depends on the potential to form vitreous kernels but also to maintain this vitreosity under the influence of humidity. Our results further show that protein content is a central trait in durum wheat that strongly influences important traits like grain yield, vitreosity, and b-value.     

Using CERES-Wheat to simulate durum wheat production and phenology in Southern Sardinia,Italy

Durum wheat is a crop of great economic relevance for Mediterranean regions, especially in developing countries. A decreasing trend in durum production is expected in the near future because of several factors, in particular environmental constraints due to climate change and variability. The aim of this work was to test the predictive performance of CERES-Wheat model, implemented in DSSAT software systems, under Mediterranean climate condition and soil types of Southern Sardinia, Italy. CERES-Wheat model was calibrated for three durum wheat Italian varieties (Creso, Duilio, and Simeto) using a 30-year data set (1974–2004) and a trial and error iterative procedure. Then, the model was validated and evaluated using several statistics. The model showed a quite good performance in predicting grain yield and anthesis date, with errors comparable with those reported by other studies conducted on bread and durum wheat. Predictions of grain weight and grain number did not match very well observations, confirming the difficulties of CERES-Wheat in estimating grain yield components. The results of this study suggest the need of specific field experiments and further model evaluations and improvements to better understand model simulation results of grain yield components of durum wheat.     

Wheat stem sawfly (Cephus pygmaeus L.) damage; impacts on grain yield, quality and marketing prices in Anatolia

This study aimed to draw the attention of the all stake holders attention to an underestimated insect pest of wheat in Southeastern Anatolia. The field studies were carried out in the experimental field of GAP Training, Extension and Research Center in Koruklu in 2003–2004 cropping season.

It was found that the number of sawfly damaged spikes varied between 6 and 12% in durum wheat and 8 and 12% in bread wheat. Comparing healthy grains, grain weight spike⁻¹ decreased significantly, giving 0.430 g less kernel weight in durum wheat and 0.385 g in bread wheat. Some of the grain quality characteristics of both sawfly damaged and healthy spikes were tested and it was found that protein content (%) in durum wheat, and 1000 kernel weight in bread wheat were reduced significantly, whilst, the SDS sedimentation value in bread wheat increased significantly for sawfly damaged grains. Grain yield losses by sawfly infestation were found to be 2.23% in durum wheat and 3.32% in bread wheat. Marketing price studies showed that sawfly damage reduced it significantly, resulting in $ 0.016 kg⁻¹ less price in bread wheat. But this was not serious for durum wheat.

It was concluded that income loss, depending on grain yield loss, un-harvestable broken spikes and lower marketing price of sawfly damaged grains, could be no less than $ 68.8 ha⁻¹ in durum wheat and $ 68.6 ha⁻¹ for bread wheat. Therefore, some control methods are required for sawfly infestation, where damage is already over the economic threshold (10–15% stem cut by pest) especially in bread wheat.     

Analysis of Genotype-by-Environment Interaction for Agronomic Traits of Durum Wheat in Iran

Abstract

Grain yield of durum wheat (Triticum turgidum L. var. durum) under Mediterranean conditions is frequently limited by both high temperature and drought during grain filling. Genotype-by-environment (GE) interaction and genotype-by-trait (GT) data were analyzed for agronomic performance of durum wheat breeding lines. Data were obtained from 18 durum wheat breeding lines and two cultivar checks (Zardak and Sardari) for their agronomic performance under three different climate locations (moderate, warm and cold winters) and two moisture regimes (rainfed and two supplemental irrigations conditions) in two cropping seasons (2006 and 2007) in Iran. Analysis of GE interaction data based on multiple traits showed that the environment (combination of year-location- moisture regimes) effect was always the most important source of trait variation, accounting for 58.6 to 98.4% of the total variation. Biplot analysis of the studied traits revealed that (i) the locations tended to discriminate genotypes in dissimilar fashions, and (ii) the relationships among traits were not consistent over the locations, where they facilitated visual genotype comparisons and selection at each location.     

Study of the microstructure of durum wheat endosperm using X-ray micro-computed tomography

Durum wheat grains are used for producing food, such as pasta or couscous. The grain mechanical properties which are linked to its internal micro-structure (i.e. endosperm porosity) are known to determine its ability to produce semolina during milling. The proportion of grains having porous endosperm in a batch appears therefore as a critical quality factor for the durum wheat value chain. Our objective was to investigate the ability of X-ray micro-tomography (μCT) method to describe the porous or vitreous counterpart structures in the endosperm of durum wheat grains. We selected two different durum wheat samples displaying vitreous or partially porous endosperms. The grains were analyzed using μCT at two pixel sizes (1 μm or 7 μm). The μCT data collected at 7 μm pixel size were used for qualitative classification of grains according to apparent distribution curve of the porosity parameters. Analysis of μCT images at 1 μm pixel size allowed us to propose pore size classification in the vitreous and porous parts of the endosperm in three durum wheat grain. Results are used to better describe the durum-wheat endosperm microstructure, but requires long scanning periods.     

Do barley and wheat (bread and durum) differ in grain weight stability through seasons and water-nitrogen treatments in a Mediterranean location?

Under Mediterranean environments, farmers usually prefer to sow barley rather than wheat as it is generally believed that barley yields more under stressful conditions. As terminal stresses such as high temperature and water are common constraints in Mediterranean regions, higher grain weight stability may confer a clear advantage in order to maintain higher yields. The objective of the present study was to compare the stability in terms of grain weight and its components for barley, bread wheat, and durum wheat, exploring a wide range of nitrogen and water availabilities in experiments conducted in a Mediterranean region. Grain weight ranged from 23.8 to 47.7 mg grain⁻¹, being higher for durum wheat than barley and bread wheat. Durum wheat presented higher variability both in maximum grain filling rate and duration of grain filling period than bread wheat or barley. The three species responded similarly in terms of grain nitrogen content to changes in the environmental conditions explored. It is concluded that in terms of grain weight barley is as stable as bread wheat. However, durum wheat presented a lower stability than barley and bread wheat.     

Effect of foliar treatments to durum wheat on flag leaf senescence, grain yield, quality and deoxynivalenol contamination in North Italy

Since the production of durum wheat in the drier areas of the Mediterranean Basin is characterized by high variability in terms of yield and grain quality, there is also considerable interest in developing durum wheat in the northern regions, where the pedo-climatic conditions can offer the possibility of obtaining grain yields with higher technological quality and stability. However, the climatic conditions in the northern regions make durum wheat more prone to fungal foliar disease, particularly to Septoria Tritici Blotch (Septoria tritici Rob.) and to Fusarium Head Blight (Fusarium graminearum Petch and Fusarium culmorum Sacc.), with the consequent occurrence of DON in grains.Field experiments have been conducted over two growing seasons at four sites in North West Italy to evaluate the effect of fungicides and foliar nitrogen fertilizer application on durum wheat yield and grain quality. Five combinations of foliar application were compared at each site and each year (untreated control, azole fungicide application at heading, strobilurin fungicide at the stem elongation stage and/or at heading, the addition of a foliar N fertilizer to a fungicide programme). The following parameters were analysed: Septoria Tritici Blotch (STB) severity, flag leaf greenness using a chlorophyll meter, grain yield, test weight, grain protein content, ash content, vitreousness, Fusarium Head Blight (FHB) incidence and severity and deoxynivalenol (DON) contamination. The collected data underline that the cultivation of durum wheat at the climatic conditions of North Italy is actually risky and needs a direct control of fungal disease, which would be able to reduce the development of both foliar and head attacks. The double treatment, with a strobilurin application during the stem elongation stage and azole at heading, results to be an essential practice and showed advantages in terms of the delay of flag leaf senescence (+27%), STB control (+31), FHB control (+11%), yield (+32%) and DON contamination (−45%), compared to the untreated control. Other foliar treatments at heading, such as strobilurin or foliar N fertilizer applications, do not seem to provide any further advantage, for either grain yield or quality. No significant effect of fungicide or foliar N fertilizer application was recorded on the protein or ash concentration or vitreousness.     

Carotenoid accumulation during grain development in durum wheat

Yellow pigment (YP) concentration is an important quality trait in durum wheat and is comprised primarily of carotenoids. The main objective of our study was to measure the accumulation of carotenoids during the grain fill period to improve our understanding of the physiological basis for differences among durum wheat cultivars. Thirteen genotypes with large variation in total YP concentration were studied. Spikes were sampled from replicated field plots in 2007 and 2008 at 14, 21, 28 and 35 days after heading (DAH). The remainder of each plot was harvested at grain maturity for analysis. trans-Lutein was the predominant carotenoid at maturity and was detected at 14 DAH in all genotypes. The rate and duration of lutein accumulation was variable among genotypes expressing high, intermediate and low YP. The accumulation of all carotenoids was lowest in genotypes expressing low YP, and suggests rate limitations early in the carotenoid biosynthetic pathway. The ratio of trans-zeaxanthin to trans-lutein was inversely correlated with total YP and suggests that the β,? branch of lycopene cyclization leading to α-carotene and thus lutein, synthesis may also be limiting in low-YP genotypes. These results provide insights into the regulation of the carotenoid biosynthetic pathway in durum wheat grain.     

Baking quality of emmer-derived durum wheat breeding lines

Durum wheat (Triticum turgidum L. var. durum) is used predominantly for pasta products, but there is increasing interest in using durum for bread-making. The goal of this study was to assess the bread-making potential of 97Emmer19, an Emmer wheat (Triticum turgidum L. var. dicoccum) and in breeding lines derived from crosses of 97Emmer19 with adapted durum wheat cultivars. 97Emmer19 and its progeny were evaluated in 2005 and 2006 along with five durum wheat cultivars. Three bread wheat (Triticum aestivum L.) cultivars were included as checks to provide a baseline of bread making quality observed in high quality bread wheat cultivars. 97Emmer19 exhibited higher LV than all the durum wheat checks and approached the LV achieved with the bread wheat cultivar ‘AC Superb’. Breeding lines derived from 97Emmer19 had higher LV than those of the durum wheat checks, confirming that this trait was heritable. In general, durum wheat cultivars with elevated gluten strength and/or increased dough extensibility were noted to have higher LV. Dough extensibility appeared to be a more critical factor as gluten strength increased. These results indicate that there is potential to select for genotypes with improved baking quality in durum breeding programs.     

不同施肥条件下的小麦籽粒代谢组学研究

为探究不同肥料对小麦籽粒代谢物的影响,通过非靶向代谢组学结合气相色谱-质谱联用技术(GC-MS)与多元统计学的方法,对不同施肥条件下(常规施肥CK、缓控释肥一次性基施E、有机肥缓控释肥配施A、缓控释肥B、专家系统推荐施肥NE)的中信麦99籽粒代谢物进行分析。结果显示,从小麦籽粒中共检测到代谢物47种,主要为有机酸类、氨基酸类、糖类及其衍生物、酯类和其他有机物。与CK相比,B、E处理对促进小麦籽粒中有机酸类代谢物积累的效果较优,B、A处理对促进小麦籽粒中糖类代谢物积累的效果较优,B、NE处理对促进小麦籽粒中氨基酸类代谢物积累的效果较优;B、NE处理对促进小麦籽粒中总代谢物含量积累的效果最优,E处理效果次之,A处理效果最差。不同施肥处理对小麦籽粒代谢物中糖类和氨基酸类代谢物影响较大,通过富集20种差异代谢物,得到3条显著变化的代谢途径,分别为氨酰基-tRNA的生物合成,苯丙氨酸、酪氨酸和色氨酸的生物合成,异喹啉生物碱的生物合成。     

Bread-making performances of durum wheat semolina,as affected by ageing

The present study addresses the influence of ageing on the bread-making performances of durum wheat semolina by bread image analysis. Bread loaves were produced from semolina samples stored in 4 different packaging materials for up to 150 days. Sampling and bread-making trials were performed every 15 days. Results showed that ageing does affect durum wheat semolina bread-making performances, highlighting that storage time, rather than the type of packaging material, is the main factor determining quality changes in the final bread samples. In particular, a change in the crust colour parameters and a reduction of the bread slice area and height by 20–35% were observed with increasing semolina storage time, along with a slight increase of crust % area. The change in farinographic parameters of dough suggests that the observed reduction of technological quality might be due to increased stiffness and reduced extensibility of gluten occurring in aged semolina. Unlike common wheat flours, which usually improve their technological features during ageing, durum wheat semolina is negatively affected in its quality by storage. The study highlights the importance of considering bread-making performances among the quality parameters to be taken into account for the shelf life evaluation of durum wheat semolina.     

Yield and agronomic traits of Khorasan wheat (Triticum turanicum Jakubz.)

The consumer's interest in natural, unconventional and nutritional foods led to the development of new specialty foods based on grain blends. Components of such foods are often so-called ‘ancient wheats’ which were never the subject of modern plant breeding programmes. Khorasan or Oriental wheat (Triticum turanicum) is a neglected and underutilised tetraploid wheat species, which probably survived over the centuries in subsistence farming systems in the Near East and Central Asia. In the present study the agronomic potential of Khorasan wheat was evaluated under eastern Austrian conditions.Fourteen accessions of Khorasan wheat were investigated together with check durum wheat cultivars over a period of 4 years in the Marchfeld region, north-east of Vienna. The crops were sown both in autumn and spring.The investigated material was inferior to modern durum wheats in most agronomic traits. No accession was found to tolerate soil temperatures below −5 °C. Tolerance to drought and fungal diseases was limited and/or modest, and grain yields were significantly lower. While the best performing turanicum accessions yielded in average 385.8 and 233.8 g m⁻² for autumn and spring sowing, respectively, the check winter durum yielded 466.5 g m⁻² and the check spring durums between 351.5 and 391.8 g m⁻². Several characteristic and interesting features were observed which permit successful marketing of pure Khorasan grain or as a component in grain blends, despite possible flour quality traits. The grain has an impressive kernel size and thousand kernel weight, in most cases greater than 50 g and often even greater than 60 g. The high thousand kernel weight might be a valuable trait to transfer into durum wheat to improve grain yield. Moreover, the grain has an amber colour and high vitreousness.Due to higher plant height, low lodging tolerance and high susceptibility against powdery mildew, Khorasan wheat is more suitable for organic farming systems. Although there is evidence that Khorasan wheat has low adaptation, it is of interest as an alternative cereal to increase diversity both in the field and on the consumer's table. However, further experiments are necessary: on the one hand to study the interactions between sowing rates, sowing dates, weed suppression, thousand kernel weight and kernel plumpness in order to find out optimal production procedures, and on the other hand to find out areas/fields with the best growth conditions for Khorasan wheat.     

Variability in dehydrodiferulic acid composition of durum wheat (Triticum durum Desf.) and distribution in milling fractions

The dehydrodiferulic acid content of different common and durum wheat grains and milling fractions was determined by an HPLC procedure. The 8-O-4′, 5–8′ benzofuran, 5–8′ and 5-5′ dehydrodimers were identified in all samples studied and occurred in decreasing relative amounts, respectively. Durum wheats were twice as concentrated in dimers as common wheats. An important genetic variation for dehydrodiferulic acid content was shown within durum wheat grains, whereas the agronomic conditions had no effect. There was 10 to 20 times more dehydrodiferulic acids in external layers (aleurone, bran) than in the starchy endosperm of durum wheat grains. The content and composition in dimers of the inner endosperm did not vary according to genotypes and cultivation conditions. The ratio of dehydrodimers to monomers of ferulic acid which represented an index of dimerisation, was 1·6 times higher in the external layers of the grain than in the endosperm. No relation was found, however, between the degree of ferulic acid dimerisation and the milling behaviour of durum wheat grains.     

Effects of Fusarium culmorum and water stress on durum wheat in Tunisia

The effects of water stress on Fusarium foot and root rot in durum wheat were investigated in growth chamber, greenhouse and field tests in Tunisia. In the seedling stage, emergence of six durum wheat cultivars in the growth chamber was significantly reduced by inoculation with Fusarium culmorum and water stress (P<0.0001), with more disease under drier conditions. Additionally, the tiller number per mature plant, the 1000 grain weight and disease severity in mature stage were reduced by inoculation in greenhouse studies. In a field test, inoculation with F. culmorum significantly reduced the yield (P<0.001), by more than 17% for Om Rabiaa and 38% for Karim, the two cultivars tested. Yield was also significantly affected by precipitation and irrigation levels. The severity of the disease, estimated by the percentage of white heads, was separately affected by the cultivar (P<0.001) and inoculation (P = 0.0004). Percentage of white heads was 1.5 and 2 × higher in inoculated plants than non-inoculated for Om Rabiaa and Karim cultivars, respectively. Disease severity was highest in treatments with the greatest water stress. This is the first detailed study of water stress and F. culmorum on durum wheat in Tunisia, and indicates that cultivar resistance and irrigation management may be important in the management of Fusarium foot rot.     

Grain yield,zinc efficiency and zinc concentration of wheat cultivars grown in a zinc-deficient calcareous soil in field and greenhouse

Field experiments were carried out to study grain yield, zinc (Zn) efficiency and concentrations of Zn in shoot and grain of 37 bread wheat (Triticum aestivum) and three durum wheat (Triticum durum) cultivars grown in a Zn-deficient calcareous soil with (23 kg Zn ha⁻¹), and without, Zn fertilization in 1993–1994 and 1994–1995. The same Zn-deficient soil was used in greenhouse experiments to study shoot dry weight, Zn efficiency and shoot Zn concentrations of 21 bread and three durum wheat cultivars (same cultivars used in the field experiments). Zinc fertilization of cultivars in the field enhanced grain yield on average by 30% in both years. Increases in grain yield to Zn fertilization varied substantially between cultivars from 8% to 76%. Accordingly, there was large variability in Zn efficiency of cultivars, expressed as the ratio of grain yield or shoot dry-matter yield produced under Zn deficiency compared to that under Zn fertilization. On average, Zn efficiency values ranged from 57% to 92% for grain yield in field experiments and from 47% to 83% for shoot dry weight in greenhouse experiments. Most of the cultivars behaved similarly in their response to Zn deficiency in the field and greenhouse. The cultivars selected from local landraces had both, a high Zn efficiency and high yield under Zn-deficient conditions. The bread wheat cultivars, improved for irrigated conditions, had generally low Zn efficiency and low yield, both in the field and greenhouse. All durum wheat cultivars in this study also showed low levels of Zn efficiency, grain yield and shoot dry weight under Zn deficiency. Overall, there was no relation between Zn efficiency values and Zn concentrations in grain or shoot dry matter. The results presented here demonstrate the existence of substantial variation in Zn efficiency among wheat cultivars, particularly bread wheat cultivars, and suggest that wheat landrace populations are a valuable source of genes to improve high Zn efficiency of wheat for Zn-deficient soils.