Durum Wheat In Tunisia Research Articles

Measuring Technical Efficiency for Closuring Yield Gap and Improving Water Productivity of the Irrigated Durum Wheat in Tunisia

In Tunisia, the development of the irrigated cereal sector plays a key role in the mitigation of the fluctuation of the rainfed production and to ensure a minimum of production. However, the archived yields remain under the expected potential performance, and the water productivity is very low. Hence, this work aims to investigate the performance of the irrigated durum wheat activity and to identify eventual determinants to improve the water productivity. To reach the objective, a field survey was carried out with a sample of 555 farmers. We adopted a data envelopment analysis approach to assess the technical efficiency and water use efficiency. A Tobit model was estimated to identify determinants of the technical performance. The results showed that the technical efficiency reached only 63%, which meant that farmers could increase the durum wheat yield from 3.5 tha−1 to 4.8 tha−1. The water use efficiency reached only 30%, which translates to an unwise use of the water resource. The results also showed an eventual improvement of the water productivity by more importantly saving the irrigation water rather than optimizing the production. To improve the performances, the results revealed some key determinants that could be taken into account by policy makers to implement appropriate strategies.

Effects of tillage and crop rotation on yield and quality parameters of durum wheat in Tunisia

Conservation agriculture has been proposed as an alternative to conventional agriculture to mitigate the climate change impact and ensure food security. This study examined the effect of three tillage systems, ((conventional tillage (CT), chisel tillage (ChT) and no tillage (NT)) and two crop-rotation systems ((two year crop rotation (2-yr) and three year crop rotation (3-yr)) on some yield and quality parameters of two winter durum wheat genotypes. The results showed that biological yield (BY) and thousand kernel weight (TKW) were neither significantly affected by tillage, crop rotation nor genotype. Only the genotype significantly affected grain yield (GY). Grain protein content (GPC %) showed higher values than straw protein content (SPC %) and NT negatively affected GPC%. Some significant differences of mineral elements were observed according to tillage system applied and NT showed the lowest values of grain N, straw K, straw Ca and straw Na. Tillage system, croprotation system and genotype had no effect on total phenolic content (TPC) and total flavonoid content (TFC). Highly significant negative correlation (-0,378**) was recorded between GY and grain N, and accordingly GPC%. The two winter durum wheat genotypes demonstrated that with the two crop-rotation systems, yields and most of quality parameters under NT and ChT were similar to those under CT. This study expands our knowledge on durum wheat chemistry variation in relation to agricultural system adopted and provides a basis for selecting the adequate crop

Screening for resistance of Tunisian, Moroccan and Algerian wheat cultivars to Zymoseptoria tritici in Northern Tunisia

Septoria tritici blotch (STB) disease caused by Zymoseptoria tritici is the most predominant disease on durum wheat in Tunisia, while its occurrence on bread wheat is rare. In this study, we investigated the performance of 89 wheat cultivars from Morocco, Algeria and Tunisia, screened in Tunisia for their relative resistance to STB. Field experiments were carried out in an augmented design, during 2016–17 and 2017–18 cropping seasons at two locations in Northern Tunisia: Beja (Oued Beja station) and Cap Bon regions (Menzel Temim and El Haouaria). All trials were conducted under natural infection. Visual disease assessments were quantified using the percentage of leaf area covered by pycnidia (PC), necrotic area (N), area under disease progress curve of each genotype (AUDPC) and the relative area under disease progress curve (rAUDPC). Results indicated that the majority of Tunisian, Algerian and Moroccan durum wheat populations (TDM, ADW and MDW) were susceptible to STB at both locations in Tunisia ranging from susceptible to highly susceptible, with the rAUDPC, N and PC ranging from 0.5 to 0.8, 30 to 65% and 40 to 75% respectively. On the other hand, the Moroccan bread wheat genotypes (MBW) were susceptible in Cap Bon area and resistant at Beja. Tunisian bread wheat genotypes (TBW) were resistant at both locations; with levels varying from immune to resistant classes where rAUDPC, PC and N did not exceed 0.2 and 10% respectively, with the exception of the local bread wheat variety known as “Farina Arbi” which was susceptible at Cap Bon and resistant at Beja.

Impacts of previous crops on inoculum of Fusarium culmorum in soil, and development of foot and root rot of durum wheat in Tunisia

Fusarium foot and root rot (FFRR) of cereals, caused by Fusarium culmorum and other Fusarium spp., is one of the most important soil- and residue-borne diseases in Tunisia. Management of the disease relies primarily on cultural practices such as crop rotation. Impacts of previous crops on the population of F. culmorum in the soil, and the incidence and severity of FFRR in durum wheat, were evaluated under Tunisian farming systems. A field trial showed that break crops of faba bean and fenugreek reduced the amount of F. culmorum DNA in soil, by 58% (faba bean) and 65% (fenugreek), and decreased numbers of F. culmorum propagules per g of soil by 83% (faba bean) and 85% (fenugreek). Farm demonstration trials also showed that faba bean and vetch used as previous crops reduced F. culmorum inoculum in the soil. Non-cereal crops also reduced the incidence of F. culmorum present in durum wheat roots and stem bases. The greatest grain yields and thousand kernel weights were recorded when faba bean and vetch were used as previous crops, but were less where durum wheat was previously grown. There were strong correlations between inoculum level of F. culmorum in the soil and incidence of FFRR in the following year. Results obtained in the field trial were supported by those collected from three demonstration farm trials during two cropping seasons. This study demonstrated for the first time in Tunisia and the Mediterranean region that break crops are effective for reducing F. culmorum inoculum in the soil and decreasing the pathogen in wheat roots and stem bases. Inoculum levels in soil can predict the expression of the disease in the following year in Tunisian farming conditions. These results are likely to be useful for developing and implementing guidelines for the management of FFRR of durum wheat.

Identification of valuable sources of resistance to Zymoseptoria tritici in the Tunisian durum wheat landraces

Tunisia is one of the main producers of durum wheat, the most consumed cereal in Tunisia and represents a trademark of several local dishes such as couscous and bulgur. Nonetheless and despite its leading stand in the local consumption and commercial share, a scarcity in Tunisian durum wheat production has long been a major problem obstructing the fulfilment of the increasing local demand. Septoria tritici blotch (STB) caused by Zymoseptoria tritici (Z. tritici) is one of the most common and detrimental foliar disease on durum wheat in Tunisia causing considerable yield losses. To-date and despite the damaging effects of STB on durum wheat, limited sources of resistance to Z. tritici have been identified. In this present study, we assessed necrosis and pycnidia development of a collection of 304 Tunisian durum wheat landraces representative of 11 landrace populations and artificially inoculated with Z. tritici at the seedling stage under controlled conditions and at the adult plant stage under field conditions. Based on necrosis and pycnidia scores, a hierarchical classification analysis clustered the durum wheat landraces into three phenotypic classes of response to Z. tritici, namely resistant, intermediate and susceptible genotypes. While resistant plants represented the most frequent class at the seedling stage, susceptible phenotypes were more frequent at the adult plant stage. Nevertheless, a heat map correlation study showed that resistant landraces with low-percentages of necrosis and pycnidia at seedling and adult plant stages represented the dominant group within the tested collection. Moreover, the assessed frequencies per landrace populations of the resistant, the intermediate and the susceptible accessions to Z. tritici infection at the adult plant stage for pycnidia development has shown that the landrace populations Badri, Jneh Khotifa (JK), Mekki and Taganrog were the highest resistant accessions, in contrast to the landrace populations Biskri, Mahmoudi, Azizi and Biada where susceptible genotypes were predominant. Mahmoudi and Azizi represented the most variable landrace populations encompassing the three phenotypic classes. Our results highlight that Tunisian durum wheat landraces may harbour variable and stable sources of resistance to Z. tritici at seedling and adult plant stages, which would represent a good basis for further investigation and deployment in breeding programs to enhance STB resistance.

Sexual reproduction of Zymoseptoria tritici on durum wheat in Tunisia revealed by presence of airborne inoculum, fruiting bodies and high levels of genetic diversity

Septoria tritici blotch (STB) caused by the heterothallic ascomycete Zymoseptoria tritici is currently one of the most devastating diseases of wheat worldwide. The extent of sexual reproduction of this pathogen is well documented on bread wheat, but not on durum wheat. The objective of the present study was to quantify the occurrence of Z. tritici sexual reproduction on durum wheat in the Tunisian environment. The assessment was undertaken using a triple approach combining fruiting body assessment, ascospore trapping and population genetic analyses. The results highlighted the formation of pseudothecia on leaves and stubble from the autumn until the end of the growing season. Likewise, qPCR monitoring highlighted a constant release of Z. tritici airborne inoculum during the wheat-growing season, with a peak of production at the end of the season. Genetic investigations using microsatellites revealed high levels of gene and genotypic diversities, an equal distribution of mating types, and a lack of genetic clustering within and between growing seasons. Taken together, these findings indicate that Z. tritici undergoes sexual reproduction on durum wheat in Tunisia at least to the same extent than on bread wheat in Western Europe, and that the dry and warm climate does not affect the mating process of the fungus. Frequent occurrence of sexual reproduction is a valuable knowledge to take into account in STB control strategies on durum wheat.

Genetic variability, chemotype distribution, and aggressiveness of Fusarium culmorum on durum wheat in Tunisia

Fusarium culmorum is the most commonly reported root rot pathogen in Tunisian durum wheat. Isolates of the pathogen from four durum wheat growing areas in the north of Tunisia were analyzed for their chemotypes. Two chemotypes were detected at unequal abundance (96% of 3-ADON and 4% of NIV). Distribution of a SNP mutation located at the position 34 bp after the first exon of the EF-1α partial sequence was analysed, to verify whether the haplotype was specifically associated to Fusarium root rot. A and T haplotypes were homogeneously distributed in three different Tunisian regions (Mateur, Beja and Bousalem) but not for the region of Bizerte, from which greatest number of A haplotype strains were detected. The isolates were tested for their virulence under glasshouse conditions, and a mean of 91% of crown and root infection was observed. Chemotype influenced virulence, but there was no significant influence of the geographical origin or haplotype on virulence. The distribution of three inter simple sequence repeats (ISSR) was examined, to better understand the structure of F. culmorum populations in Tunisia. A total of 27 fragments were obtained with eight polymorphic bands. Cluster analysis showed a high level of similarity between isolates. Analysis of molecular variance confirmed that there was little genetic differentiation among F. culmorum strains from different locations.

Insights into a century of breeding of durum wheat in Tunisia: The properties of flours and starches isolated from landraces, old and modern genotypes

The present work had a dual objective: to assess if the evolution of durum wheat from landraces to modern genotypes as function of breeding programs impacted proteins and starch fractions, as well as starch properties. Flours and starches isolated from Tunisian durum wheat landraces, old and modern lines were thoroughly characterized for their compositional, morphological, and gel properties. Statistical results showed significant (p ≤ 0.05) differences among the studied set. Protein and starch fractions assessment revealed that modern genotypes had the highest total starch and albumin contents, old genotypes had the highest amylose and glutenin contents, and landraces had the highest protein and gliadin contents. Starch properties screening allowed several findings: no significant (p > 0.05) differences were found among starch granules morphology, significant (p ≤ 0.05) differences were recorded in terms of technological properties, and old genotypes had the highest starch gel hardness. Overall, these results indicated that the influence of genotype on flour and starch properties was more relevant than breeding history.

Efficacy of some rhizospheric and endophytic bacteria in vitro and as seed coating for the control of Fusarium culmorum infecting durum wheat in Tunisia

Sixty two rhizospheric and endophytic bacterial strains were evaluated for their biocontrol effect on two aggressive Fusarium culmorum isolates (Fc2 and Fc3). We observed that 35 % and 23 % of the tested strains inhibited the in vitro growth of Fc2 and Fc3 respectively. The observed antagonism was due to inhibition by contact (13–19 % of the strains) or at distance (10–16 % of the strains) for both fungal isolates. Some of the antagonistic bacteria showed the ability to produce diffuse and/or volatile compounds that inhibit the growth, the sporulation and macroconidia germination of F. culmorum. None of the tested antagonistic bacteria showed chitinase activity on synthetic medium. The sequencing of the 16S rDNA genes of some antagonistic bacteria showed that they belong to the genera Bacillus, Pseudomonas and Microbacterium. The double inoculation of durum wheat seeds by the antagonistic bacterial strains (B13, B18, BSE1, BSE3 and B16E) and the two F. culmorum isolates showed that germination and seedling vigor were generally improved in vitro. The percentage of infected seeds was also reduced. In greenhouse trials, the biocontrol effectiveness of F. culmorum was dependant from the virulence of the fungal strain and the specificity of the antagonistic interaction between bacterial and fungal strains. The bacterial strains B18 and B16E reduced F. culmorum infection on durum wheat plants probably due to their antagonistic and plant growth promoting activities and they may be used in a mixture as seed biopriming inoculum for plant growth bio-promoting and Fusarium wheat diseases biocontrol.

Estimating grain yield losses caused by septoria leaf blotch on durum wheat in Tunisia

Septoria leaf blotch (SLB), caused by Zymoseptoria tritici (Desm.) Quaedvlieg & Crous, 2011 (teleomorph: Mycosphaerella graminicola (Fuckel) J. Schrot.), is an important wheat disease in the Mediterranean region. In Tunisia, SLB has become a major disease of durum wheat (Triticum turgidum L. subsp. durum [Desf.] Husn.) particularly during favorable growing seasons where significant yield losses and increase of fungicides use were recorded over the last three decades. The objectives of this study were to evaluate the effect of SLB severity on grain yield of new elite durum wheat breeding lines and to measure the relative effect of fungicide control on grain yield. Experiments were conducted during 2007-2008 and 2008-2009 cropping seasons. A set of 800 breeding lines were screened for reaction to SLB under natural infection at Beja research station. To estimate the disease effect, correlation between disease severity at early grain filling stage and grain yield was performed. Results showed that susceptible varieties yield was significantly reduced by SLB. Average yield reduction was as high as 384 and 325 kg ha-1 for every increment in disease severity on a 0-9 scale in both seasons, respectively. A negative correlation coefficient varied between -0.61 and -0.66 in both seasons. Treated and untreated trials conducted during 2008-2009 and 2009-2010 showed that yield of treated plots increased by 50% on the commonly cultivated susceptible varieties. The results of this investigation suggested that septoria incidence is related to large grain yield losses particularly on susceptible high yielding cultivars. However, appropriate fungicide application at booting growth stage could be beneficial for farmers. The development and use of more effective fungicide could be sought to alleviate the disease effects and therefore could be considered as a part of the integrated pest management and responsible use strategy on septoria leaf blotch in Tunisia.

Quantitative inheritance of resistance to Septoria tritici blotch in durum wheat in Tunisia

Septoria tritici blotch, causal agent Mycosphaerella graminicola (Fuckel) J. Schrot. (anamorph: Zymoseptoria tritici Desm.), is the major foliar disease of wheat (Triticum aestivum L.) in Tunisia causing frequent epidemics on T. turgidum L. var. durum (Desf.) Bowden, and important yield and grain quality losses. To determine the inheritance of resistance to septoria, a cross was made using resistant ('Salim') and susceptible ('Karim') cultivars. Parents, and the 149 derived recombinant lines, were tested for resistance to septoria under field conditions during the 2009 and 2010 crop seasons. The inheritance of resistance to septoria was quantitative where a continuous and normal distribution (W = 0.93) was shown among segregate progenies. During 2009 and 2010 crop seasons, the mean disease severities of recombinant inbred lines (RILs) ranged from 29.1% to 41.8%, respectively, and 53% of RILs were associated with lower disease severity than the mid-parent value. The severity was significantly affected by Genotype x Year interaction (p < 0.01). Broad sense heritability was 0.55 suggesting a quantitative inheritance of resistance to M. graminicola. These results would imply that genetic resistance to STB could be attributed to additive gene effects. Thus, using identified sources of tolerance to STB in a breeding program would enhance the development of cultivars that are adapted to the prevailing isolates in field conditions.

Remote Sensing Based Yield Estimation in a Stochastic Framework — Case Study of Durum Wheat in Tunisia

Multitemporal optical remote sensing constitutes a useful, cost efficient method for crop status monitoring over large areas. Modelers interested in yield monitoring can rely on past and recent observations of crop reflectance to estimate aboveground biomass and infer the likely yield. Therefore, in a framework constrained by information availability, remote sensing data to yield conversion parameters are to be estimated. Statistical models are suitable for this purpose, given their ability to deal with statistical errors. This paper explores the performance in yield estimation of various remote sensing indicators based on varying degrees of bio-physical insight, in interaction with statistical methods (linear regressions) that rely on different hypotheses. Performances in estimating the temporal and spatial variability of yield, and implications of data scarcity in both dimensions are investigated. Jackknifed results (leave one year out) are presented for the case of wheat yield regional estimation in Tunisia using the SPOT-VEGETATION instrument. Best performances, up to 0.8 of R2, are achieved using the most physiologically sound remote sensing indicator, in conjunction with statistical specifications allowing for parsimonious spatial adjustment of the parameters.

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.

Occurrence of deoxynivalenol in durum wheat in Tunisia

Wheat is frequently contaminated by the deoxynivalenol (DON) which is a member of the trichotecene family, the most important group of mycotoxins produced by the Fusarium moulds. As Tunisian population is a big consumer of cereals mainly durum wheat, human exposure to DON can be, consequently high. This survey was performed to study the occurrence of DON in Tunisian durum wheat area during the crop of 2007. A total of 65 samples of durum wheat from five cultivating locations in the North of Tunisia, the major cropping area, were analysed. To detect and to quantify the mycotoxin DON, an efficient HPLC/UV method was developed, including immunoaffinity step for DON extraction from durum wheat followed by liquid chromatography (LC) for quantification. As DON is a water soluble toxin, the extraction procedure from wheat samples was performed using water. Samples were centrifuged then passed through the immunoaffinity columns. After column’s washing, the toxin was slowly eluted by methanol. Wheat sample extracts were injected to the LC system set at a wavelength of 220 nm. From 65 samples, 83% showed DON contamination with averages ranging from 12.8 ± 5% to 30.5 ± 13.3% μg/g exceeding the maximum permitted limit of 1.75 μg/g set by the European Commission in wheat.

Potential impact of climate change on durum wheat cropping in Tunisia

The potential effect of climate change on durum wheat in Tunisia is assessed using a simple crop simulation model and a climate projection for the 2071–2100 period, obtained from the Meteo-France ARPEGE-Climate atmospheric model run under the IPCC (International Panel on Climate Change) scenario A1B. In the process-oriented crop model, phenology is estimated through thermal time. Water balance is calculated on a daily basis by means of a simple modelling of actual evapotranspiration involving reference evapotranspiration, crop coefficients and some basic soil characteristics. The impact of crop water deficit on yield is accounted for through the linear crop-water production function developed by the FAO (Food and Agriculture Organization of the United Nations). Two stations are chosen to study the climate change effect. They are representative of the main areas where cereals are grown in Tunisia: Jendouba in the northern region and Kairouan in the central region. In the future scenario, temperature systematically increases, whereas precipitation increases or decreases depending on the location and the period of the year. Mean annual precipitation declines in Jendouba and raises in Kairouan. Under climate change, the water conditions needed for sowing occur earlier and cycle lengths are reduced in both locations. Crop water deficit and the corresponding deficit in crop yield happen to be slightly lower in Kairouan; conversely, they become higher in Jendouba.

Adapting PILOTE model for water and yield management under direct seeding system: The case of corn and durum wheat in a Mediterranean context

Crop models are useful tools for integrating knowledge of biophysical processes governing the plant–soil–atmosphere system. But few of them are easily usable for water and yield management especially under specific cropping systems such as direct seeding. Direct seeding into mulch (DSM) is an alternative for conventional tillage (CT). DSM modifies soil properties and creates a different microclimate from CT. So that, we should consequently consider these new conditions to develop or to adapt models. The aim of this study was to calibrate and validate the PILOTE [Mailhol, J.C., Olufayo, A.A., Ruelle, P., 1997. Sorghum and sunflower evapotranspiration and yield from simulated leaf area index. Agric. Water Manag. 35, 167–182; Mailhol, J.C., Zaïri A., Slatni A., Ben Nouma, B., El Amami, H., 2004. Analysis of irrigation systems and irrigation strategies for durum wheat in Tunisia. Agric. Water Manag. 70, 19–37], an operative crop model based on the leaf area index ( LAI) simulation, for corn and durum wheat in both DSM and CT systems in Mediterranean climate. In DSM case, simple model modifications were proposed. This modified PILOTE version accounts for mulch and its impact on soil evaporation. In addition root progression was modified to account for lower soil temperatures in DSM for winter crops. PILOTE was calibrated and validated against field data collected from a 7-year trial at the experimental station of Lavalette (SE of France). Results indicated that PILOTE satisfactorily simulates LAI, soil water reserve ( SWR), grain yield, and dry matter yield in both systems. The minimum coefficient of efficiency for SWR was 0.90. This new version of PILOTE can thus be used to manage water and yield under CT and DSM systems in Mediterranean climate.

Analysis of irrigation systems and irrigation strategies for durum wheat in Tunisia

To help identify an irrigation system and irrigation strategy to improve durum wheat production in the context of water scarcity of Tunisia, the PILOTE (operative water balance and yield estimation) model and the RAIEOPT (furrow irrigation) model are coupled. The first step was to choose the most efficient surface irrigation system (SIS) with its irrigation strategy. On the basis of field experiment data, an economic-optimization model allows the identification of the best SIS with its irrigation strategy for conditions of water scarcity in Tunisia. The furrow system with an inter-furrow spacing of 1.5 m and a strategy which consists on irrigating when the soil water reserve is 80% depleted are selected by the optimization model. Using “deficit irrigation” principles which establish a ratio between the amount of water applied to a given crop and a economically acceptable target yield value, irrigation strategies for sprinkler and the selected SIS are identified. RAIEOPT–PILOTE coupling is used to perform this analysis for SIS. The results of the simulations, based on climatic data spanning the last 20 years, raise questions about the suitability of sprinkler irrigation method for clay soil conditions in Tunisia. This paper also aims to contribute to future economic studies that will take into account social constraints. This study should allow managers to choose between sprinkler irrigation methods and SIS modernization.