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Durum wheat [Triticum turgidumL. ssp. durum(Desf.)] is cultivated on nearly one million hectares in Morocco.About half of the durum‐planted areas are located in unfavorable rainfed areas. The predominant abiotic stresses are drought and heat, and the predominant biotic stresses are Hessian fly, leaf rust, tan spot, Septoria blotch, and root rot. End use grain quality‐related traits are important. ‘Faraj’ (Reg. no. CV‐1190, PI 699898) is a durum cultivar that possesses adaptation to drought and genetic resistance to Hessian fly, leaf rust, tan spot, and Septoria leaf blotch and tolerance to root rot. Faraj possesses good levels of grain yellow pigment and grain protein concentration. Faraj was registered in 2007 and released to seed commercialization in 2014. Faraj could be used by breeders as a good genetic resource with grain yield potential and end use quality as well as resistance or tolerance to multiple diseases and pests.

Durum wheat is one of the most important staple food crops, grown mainly in the Mediterranean region where its productivity is drastically affected by salinity. The objective of this study was to identify markers associated with grain yield and its related traits under saline conditions. A population of 114F8 recombinant inbred lines (RILs) was derived by single-seed descent from a cross between Belikh2 (salinity-tolerant variety) and Omrabi5 (less salinity tolerant) was grown under non-saline and saline conditions in a glasshouse. Phenotypic data of the RILs and parental lines were measured for 15 agronomic traits. Association of 96 simple sequence repeat (SSR) loci covering all 14 chromosomes with 15 agronomic traits was analysed with a mixed linear model. In total, 49 SSR loci were significantly associated with these traits. Under saline conditions, 12 markers were associated with phenological traits and 19 markers were associated with yield and yield components. Marker alleles from Belikh2 were associated with a positive effect for the majority of markers associated with yield and yield components. Under saline condition, five markers (Xwmc182, Xwmc388, Xwmc398, Xbarc61, and Xwmc177) were closely linked with grain yield, located on chromosomes 2A, 3A, 3B, 4B, 5A, 6B, and 7A. These markers could be used for marker-assisted selection in durum wheat breeding under saline conditions.

In rain-fed agricultural regions, limited rainfall and frequent unpredictable droughts have resulted in low and variable wheat yields. Balanced water use between root water-uptake and remaining soil moisture is a key factor for drought adaptation. Thirteen recombinant inbred lines selected from a backcross population of synthetic-derived bread wheat were examined for the association among root water-uptake ability, grain yield and root elongation under limited water conditions using pot and field experiments. The effect of wax coating on grain formation under soil desiccation was also studied in two selected genotypes. There were significant variations in both root water-uptake ability estimated in pot experiments and grain yield obtained in field experiments among wheat genotypes. Infrared thermography indicated that canopy temperature was related to the leaf transpiration due to root water-uptake. A significant negative correlation was found between root water-uptake ability and grain weight, suggesting that lower root water-uptake ability was associated with higher grain weight. Genotype SYN-10 had the lowest water-uptake ability and the highest grain weight, indicating a type of ‘water-saving wheat’. Wax coating significantly reduced root water-uptake in wheat genotypes SYN-8 and SYN-10. Infrared thermography showed an increased leaf temperature due to the transpiration-suppression effect of the wax coating. Reductions in grain yield due to soil desiccation were found in SYN-8, but not in SYN-10. The higher grain yield of SYN-10 was attributed to more grains under soil desiccation. Grain yield of SYN-10 was decreased by the wax coating under soil desiccation. Dehydration tolerance of SYN-10 might be associated with the transpiration process of the leaves.

Vernalization and photoperiod response genes play a significant role in the geographical adaptation, agronomic performance and yield potential of crops. Therefore, understanding the distribution pattern and allelic diversity for vernalization and photoperiod genes are important in any wheat breeding program. In this study, we screened 63 bread wheat cultivars and 7 bread wheat landraces from Turkey for photoperiod (Ppd-D1)and vernalization genes (Vrn-A1, Vrn-B1, Vrn-D1and Vrn-B3) using diagnostic molecular markers. The photoperiod insensitive dominant allele, Ppd-D1a, was present in 60% of wheat cultivars and 42% of landraces, whereas, all other genotypes carried the photoperiod sensitive allele Ppd-D1bas recessive allele. Twenty-four cultivars and two landraces contained recessive alleles for all four VRN loci, whereas 39 wheat cultivars and 6 landraces contained one or more dominant VRN alleles. The highest percentage of Turkish wheat cultivars contained the dominant Vrn-B1allele followed by Vrn-D1and Vrn-A1. Information for vernalization and photoperiod alleles in Turkish germplasm will facilitate the planning and implementation of molecular markers in wheat breeding programs. This information will be helpful to develop elite wheat cultivars carrying suitable vernalization and photoperiod alleles with higher grain yield potential and better quality suitable for different production environments through marker assisted selection.

The drought stress in the rain-fed regions of West Asia and North Africa strongly depends on residual soil water available for the reproductive plant growth. The water uptake ability (i.e. water consumption per unit dry matter per day) of three synthetic-derived bread wheat genotypes, SYN-8, SYN-10 and SYN-15, and their parental variety Cham 6 were examined under controlled conditions. In addition, yield performance was compared under one artificial environment with supplemental irrigation and ten rain-fed environments at two locations over five cropping seasons. Large differences were found in water uptake ability among the four wheat genotypes; SYN-8 had the highest and SYN-10 the lowest ability. These differences were reflected in decrease of soil water content and increase of leaf temperature after irrigation. Under field conditions of supplemental irrigation, there were no significant differences in grain yield among genotypes Cham 6, SYN-8 and SYN-10; however, SYN-15 had lower grain yield due to low harvest index. Significant differences of the grain yield were found between SYN-8 and SYN-10 grown in rain-fed conditions. Lower water uptake ability was associated with higher grain yield; this speculates that intensive extraction of water from soil during vegetative growth might increase biomass production, but leave inadequate available soil moisture for reproductive growth and grain production. The balancing of water consumption by plants with stored soil moisture over the whole growing period is a major attribute of drought adaptation in these synthetic-derived wheat genotypes.

In plant breeding, large numbers of test entries are tested annually and across many environments, making field designs that can reduce costs and time highly advantageous. In the ICARDA durum breeding program the augmented design (AD) is used extensively. In this study, two series of multi‐environment agronomic trials that used an AD for a set of replicated check lines and unreplicated test lines were analyzed using restricted (or residual) maximum likelihood (REML) estimation with mixed models, allowing for spatial correlation in the experimental layout. The characteristics of a subset of the trials were used to simulate the precision of estimates of variance parameters and test line effects when the test lines were fitted as fixed or random, and to establish the performance of Akaike's information criterion (AIC) and the Bayesian information criterion (BIC) for model selection in this context. With test lines fitted as random, estimates of variance parameters were less biased and more precise, the information criteria chose the correct model more often, and use of the information criteria led to a model that gave good estimates of test line means. Estimation and model selection performed less well with the test lines fitted as fixed effects, but a hybrid method improved both estimation and model selection in this case. Statistical models that improve trial accuracy and reduce costs are important tools when testing a large number of breeding lines over multi‐environment trials.

Three synthetic bread wheat genotypes and their parental cultivar Cham 6 were used to examine the effects of a strobilurin-class fungicide pyraclostrobin on leaf temperature, root water uptake and grain yield under increasing water deficit conditions. Wheat plants of Cham 6 treated with the pyraclostrobin at the booting stage showed a rapidly increased leaf temperature as compared with the gradually increased leaf temperature of the untreated plants. The final temperature reached, however, was lower for the pyraclostrobin treated plants than the untreated. Potted soil of the treated wheat plants also showed higher water contents than the untreated potted soil, suggesting delay of plant water uptake by pyraclostrobin treatment. A variation in water uptake by roots was also found between the four wheat genotypes examined. Daily water uptake was depressed after the pyraclostrobin treatment in all four wheat genotypes. Grain yields were slightly increased by the pyraclostrobin treatment in field trials under controlled water supply whereas no significant differences were detected in soil water content between treatments. The increase in grain yield by pyraclostrobin treatment might be dependent on the different water uptake of the wheat genotypes. These results suggest that foliage treatment of pyraclostrobin fungicide on wheat delays root water uptake, resulting in postponement of soil dehydration, which contributes to a slight increase of grain yield in some wheat genotypes in the field under water deficit conditions.

This study aimed to analyze drought tolerance in bread wheat by examining the effect of soil water deficit on yield performance of synthetic bread wheat derivatives. Thirteen genotypes of synthetic bread wheat derivatives selected from a backcross (Cham 6 ///Haurani / Ae. tauschiiICAG400709 //Cham 6) were used for field evaluation in two experimental sites for two consecutive years. In addition, three synthetic wheat genotypes grown under different planting dates were compared for yield performance. Grain yield was highly correlated with harvest index under all of four cropping environments. No significant contribution of biomass to the grain yield was found in these plant materials. Late planting generated plant growth under the drier soil conditions after the heading time than under normal planting conditions, which resulted in considerable grain yield reduction. A synthetic wheat genotype selected from the materials showed significantly higher grain yield under late planting condition than the check variety, Cham 6. These results suggest that higher grain yield in a synthetic bread wheat genotype is associated with rapid translocation of photosynthetic carbohydrates to the grains after heading time.

Lipoxygenases constitute a family of enzymes that catalyze the breakdown of lipids, resulting in products that may have undesirable effects. These enzymes can affect pasta color and cause off‐flavors. The purpose of this study was to map the loci associated with lipoxygenase activity in seeds of a durum wheat (Triticum turgidumssp. durum) population to determine if lipoxygenase activity is associated with flour color. Seed of the parents, Jennah Khetifa and Cham 1, and the recombinant inbred population consisting of 113 progeny lines were used to assay lipoxygenase activity and flour color. A saturated molecular‐marker linkage map for this population was previously constructed. Allele specific primers targeting the wheat homolog to barley LoxAwere designed, and a fragment length polymorphism resulting from a miniature inverted‐repeat transposable element (MITE) insertion in an intron of the durum wheat LoxAhomolog allowed mapping of the locus to chromosome 4BS. To measure lipoxygenase activity, spectrophotometric changes were recorded. Cham 1 had a change in absorbance of 0.284 units of absorbance over 1 min compared with 0.752 units for Jennah Khetifa. Quantitative trait locus analysis of these data indicated that most of the lipoxygenase activity was associated with the wheat lipoxygenase gene (Lpx) on chromosome 4BS. A quantitative trait locus for vitreous appearance of seeds also was associated with this locus. Flour color was not correlated with lipoxygenase activity in this population. With this knowledge, marker‐assisted selection can be used to select genotypes with lower lipoxygenase activity in durum wheat populations.

The objective of this study is to identify QTLs linked to yellow pigment content in durum wheat. A durum-dicoccoides genetic linkage map was constructed using 124 microsatellites, 149 amplified fragment length polymorphism (AFLPs), and six seed storage proteins (SSP) in a population of 114 recombinant inbred lines (F8). The population has been obtained from a cross between a durum cultivar Omrabi5 and Triticum dicoccoides600545 and backcrossed to Omrabi5. The map consists of 14-durum chromosomes plus an unknown group; and shows a good synteny to the previously published wheat maps. Yellow pigment was measured in the population in three different locations during 3 seasons. Analysis of QTLs was based on simple and simplified composite interval mapping (SIM and sCIM). Three QTLs for yellow pigment were detected on the chromosomal group 7 (7AL and 7BL telomeres) explaining 62% of the total variation. On 7BL, a major microsatellite (Xgwm344) explained by itself 53%, whereas on 7AL, the other two QTLs have contributed 13 and 6%. A11 determined QTLs showed a strong genetic effect and a weak QTL × E effect. The QTLs effect was consistent across all environments and showed a large effect. Consequently, promising QTLs will be used in the marker assisted breeding program to enhance the selection efficiency for yellow pigment.

Carbon isotope discrimination (Δ13C) in grain is a potentially useful trait in breeding programs that aim to increase the yield of wheat and other cereals. Near infrared reflectance spectroscopy (NIRS) is used in routine assays to determine grain and flour quality. This study assesses the ability of NIRS to predict Δ13C in mature kernels of durum wheat. Plants were grown in north-west Syria as this location provided 3 distinct Mediterranean trials that covered a wide range for Δ13C values in grains (from about 12.9‰ to 17.6‰). We measured the spectral reflectance signature between 1100 and 2500 nm in samples from the same flour used in the conventional (i.e. mass spectrometry) determinations of Δ13C. By using principal components regression and partial least squares regression (PLSR), a model of the association between conventional laboratory analysis and these spectra was produced. Global regressions, which included samples from all 3 trials, and local models, which used samples from only one trial, were built and then validated with sample sets not included in calibration procedures. In global models, strong significant correlations (P < 0.001) were found between NIRS-predicted Δ13C and measured Δ13C values. PLSR gave r 2 values of 0.86 and 0.82 for calibration and validation sets, respectively. Although less strongly correlated, all local models selected for a subset of samples with significantly higher Δ13C values. Local models also performed well when selecting samples from the other 2 trials. The advantages and possible limitations of NIRS are further discussed. Additional keywords: NIRS, carbon isotope discrimination, PCR, PLSR, multivariate analysis, regression.

Carbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in bread wheat (Triticum aestivumL.) and barley (Hordeum vulgareL.), with potential value for durum wheat (Triticum turgidumconvar. durumDesf. MacKey). We evaluated the genetic variation for Δ, the relationship between Δ and grain yield, and the magnitude of genotype × year (G × Y) interactions in durum wheat. Field experiments were conducted under Mediterranean conditions on 144 durum wheat accessions during three successive years. Grain yield and carbon isotope discrimination of flag leaves (ΔF) and kernels (ΔK) were measured. Large genotypic and year variation was observed for ΔF and ΔK. Flag leaf Δ was correlated with grain yield in 2 yr characterized as having greater water limitation (r= 0.29 − 0.38, P< 0.001). Conversely, ΔK and grain yield were significantly correlated in all 3 yr (r= 0.49 − 0.52, P< 0.001). In addition, G × Y interactions were significant for ΔF, ΔK and grain yield. However, significant correlations (P< 0.001) were noted for ΔK across years. As a result, ΔK may serve as a better predictive criterion for higher grain yield under Mediterranean conditions.

Advanced durum wheat lines obtained from crosses with different Triticumand Aegilopsspecies and some of the wheat parents involved in these crosses were compared for their adaptation to Mediterranean drought conditions. Field studies were undertaken under rainfed conditions during two successive years at Montpellier (South France). Carbon isotope discrimination (?) of flag leaf and grain, specific leaf dry weight, grain yield, total biomass and harvest index were measured. Differences between interspecific lines and durum wheat genotypes occurred mainly under water stressed conditions. Lines derived from crosses between T. durumand each of Ae. columnaris, T. dicoccoidesand T. carthlicumshowed higher ? values and correlatively higher grain yield and harvest index under stress conditions. Our results emphasise the potential interest to use these tetraploid wheat species for drought tolerance improvement in durum wheat.

The yield performance of three hundred and twenty durum wheat genotypes has been evaluated under late-planting conditions at Aleppo, Syria. Chlorophyll fluorometry was used to determine the in vivotolerance of photosynthetic membranes to high temperatures in leaves of a subset of seventeen lines which covered a wide range of yield. An important variation was noted for Tc, the threshold temperature for photosystem-II denaturation and for Tp, the peak temperature corresponding to maximal Fo fluorescence. A strong correlation was noted between the two traits (r = 0.69**). A significant correlation (r = 0.53*) was registered between Tc and yield under late-planting conditions. Earliness was also found to strongly correlate with yield (r = 0.75***). Various durum wheat varieties and several lines derived from a cross between the heat susceptible durum variety Korifla and the heat tolerant accession T. dicoccoides600808 were screened for the tolerance of photosynthetic membranes to high temperatures. The potential interest of the accession T. dicoccoides600808 as source of heat tolerance has been confirmed.

In the Mediterranean region, progress in selection for yield in harsh environments is hampered by large environmental variation between seasons and locations. This study analyzes the genotype‐by‐environment (GE) interaction of 36 two‐rowed genotypes of barley (Hordeum vulgareL.), grown in 14 environments in Syria and North Africa. It assesses the effect of growth type (winter or spring type) and heading date on the GE interaction and determines whether or not high‐yielding (HY) environments are representative of low‐yielding (LY) ones. Average grain yield per environment ranged from 7 to 513 g m−2. Genotypes and environments were classified by a cluster analysis and the interaction was analyzed with an additive main effects and multiplicative interaction model. Genotypes were classified into four clusters, related to their growth type and earliness of heading. Environments were clustered in a HY and LY group; this classification was related to seasonal rainfall and temperature. Medium‐early heading winter types had a positive interaction with LY environments and a negative interaction with HY environments, whereas late heading genotypes (spring and winter types) had the opposite interaction pattern. Early heading spring types had above‐average mean yields; the highest‐yielding among them tended to have a low interaction with environments. High‐yielding environments did not discriminate well between genotypes with high or low yields in LY environments, and may thus have limited value for yield selection for LY environments. For a breeding program aimed at improving yield in environments where favorable conditions are rare, selection for yield should be done in representative less‐favorable environments.

Summary Nineteen durum wheat landraces, cultivars or advanced lines of different origins in West Asia and North Africa (WANA), and three barley and two bread wheat varieties were evaluated for their boron (B) toxicity tolerance. Seedlings were grown at five levels of soluble soil B in a plastic house under controlled temperatures. Significant differences existed between the durum wheat entries in days-to-symptom appearance and foliar symptom score. Under the highest soil B treatment, large differences existed between entries for dry weight per plant (P<0.05) but differences were non-significant for shoot B concentrations. Days-to-symptom appearance was highly correlated with symptom score, which was not correlated with shoot B concentrations. Boron toxicity symptom scores of the durum wheat entries ranged from the sensitive barley check to the moderately sensitive bread wheat check. As expected, days-to-symptom appearance decreased and symptom severity increased as the soil B concentrations increased.

The possibility of using proline accumulation and fluorescence inhibition as predictive tests for drought tolerance in durum wheat has been investigated. The drought susceptibility of 25 genotypes was evaluated by comparing yields and yield components in irrigated and non irrigated conditions in the field. A drought susceptibility index (DSI) was calculated based on yields from irrigated and dry treatments and compared with the results obtained using the two physiological criteria. Proline accumulation and chlorophyll fluorescence inhibition were found to be significantly and negatively correlated with DSI of grain yield, biological yield, and thousand kernel weight, and tiller index. The use of both criteria for breeding durum wheat in Mediterranean dryland is discussed.

The joint durum wheat (Triticum turgidum L var ‘durum’) breeding program of the International Maize and Wheat Improvement Center (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA) for the Mediterranean region employs extensive multilocation testing. Multilocation testing produces significant genotype-environment (GE) interaction that reduces the accuracy for estimating yield and selecting appropriate germ plasm. The sum of squares (SS) of GE interaction was partitioned by linear regression techniques into joint, genotypic, and environmental regressions, and by Additive Main effects and the Multiplicative Interactions (AMMI) model into five significant Interaction Principal Component Axes (IPCA). The AMMI model was more effective in partitioning the interaction SS than the linear regression technique. The SS contained in the AMMI model was 6 times higher than the SS for all three regressions. Postdictive assessment recommended the use of the first five IPCA axes, while predictive assessment AMMI1 (main effects plus IPCA1). After elimination of random variation, AMMI1 estimates for genotypic yields within sites were more precise than unadjusted means. This increased precision was equivalent to increasing the number of replications by a factor of 3.7.

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.

A total of 185 durum wheat (Triticum turgidum var. durum Desf.) landraces was collected from 166 sites in the Syrian Arab Republic. With K-means clustering the collecting sites are grouped based on four climatological variables to create relatively homogeneous regions of origin with respect to agro-ecological characteristics. Stepwise Discriminant Analysis confirmed the minimization of variation within regions.

Hessian fly, Mayetiola destructor (Say), is the major pest of wheat in North Africa. In Morocco, durum wheat (Triticum turgidum L. subsp. durum (Desf). Husn.) losses due to this pest have been estimated at 32%. Genetic resistance is the only economical and practical means of controlling this insect. Field and greenhouse screening of durum wheat genotypes resulted in the identification of one source of resistance to Hessian fly in Morocco. This is the first source of durum wheat Hessian fly-resistance identified in Morocco. This source of resistance expresses a medium level of antibiosis against first-instar Hessian fly larvae; about 25% of the larvae survive on resistant plants. The deployment of varieties that allow for larval survival on resistant plants should reduce selection for biotype development. This source of resistance is being used by CIMMYT/ICARDA and Moroccan breeders to develop resistant durum wheat varieties.

This greenhouse study examined the variation in growth, development, and yield between 9 durum wheat (Triticum turgidum L. var. durum Desf., syn. T. durum) lines in response to high soil boron (B) levels. The lines were selected to represent the range of B-toxicity tolerance in an earlier screening experiment. Three soil B levels (hot-water extractable B concentrations of 0·3, 7·1, and 17·4 mg/kg, designated as B0, B25, and B50, respectively) were set up by mixing different amounts of boric acid with soil. Foliar B-toxicity symptom score, dry weight, and shoot-B concentration were measured at tillering. Agronomic traits and yield were measured. There were differential responses to high soil B levels between the durum lines. The boron×line interaction was significant for B-toxicity symptom score and shoot-B concentration. Based on these 2 characters, and percentage of shoot dry weight and grain yield reduction from B0 to B50, Oued Zenati, Omrabi-5, and Gezira-17 were the most tolerant of the 9 durum lines, yet they were less tolerant to high soil B levels than the tolerant bread-wheat check, Halberd. Nonetheless, until more tolerant materials are developed, these moderately tolerant durum lines could still be useful for areas, like southern Australia, where B toxicity is a problem. boron toxicity, foliar symptom, phenotypic variation, shoot boron concentration, yield components.