Durum Wheat Crop Research Articles

Cropping practices impact fungal endophytes and pathogens in durum wheat roots

The benefit provided by chickpea (Cicer arietinum L.) to the following durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] crop is smaller than that provided by pea (Pisum sativum L.) in the Great Plains of America. Rotation crops and the specific cropping practices associated with them may impact soil fungal communities, which in turn could affect the productivity of subsequent crops. Two separate field experiments were carried out to test the effect of pea and chickpea crops and of foliar fungicide use in chickpea on the community of fungi hosted in the roots of a subsequent durum wheat crop. The fungal communities in the healthy and diseased roots of durum wheat at maturity were characterized using plate culture and PCR-based identification. The effect of cropping practices on root-associated fungal communities depended on root type and varied with year. Functionally important fungal taxa were affected by specific cropping practices. Endophytic fungal antagonists were less abundant after chickpea than after pea and after fungicide-treated chickpea than after untreated chickpea. The chickpea cultivar CDC Vanguard increased the abundance of highly virulent pathogens in durum wheat roots in comparison with the chickpea cultivar CDC Luna and pea. We conclude that the negative impact of chickpea on durum wheat yield could be due in part to an increase in fungal pathogens resulting from the suppression of endophytic fungal antagonists by chickpea.

Climate change in Algeria and its impact on durum wheat

According to IPCC reports, the Mediterranean basin and particularly the North African area are amongst the most vulnerable regions to climate change. However, the information concerning the North African zone is very limited, and studies on climate change have never been conducted in Algeria up to now. This paper aims at bridging this information gap and initiates a first research on the impact of climate change on durum wheat cropping, the most strategic commodity in the food system and in the national economy of Algeria. Climate projections for the distant future (2071–2100), obtained from the ARPEGE-Climate model of Meteo-France run under the medium A1B SRES scenario, are introduced into a simple agrometeorological crop model previously validated with field data. Two options for the sowing date are assessed: a dynamical date, chosen within the traditional sowing window by means of a rainfall criterion, or a prescribed date with supplemental irrigation on the same day. Crop development is modelled using thermal time, and maximum yield is determined from the accumulation of solar radiation. A water stress index is inferred from a daily water balance model, and actual yield is estimated from potential yield corrected by the water stress index. The model also takes into account the occurrence of dry periods during the growing season, which can induce partial or total failure of the crop cycle. Two stations, representative of two of the three agroclimatic areas where durum wheat is grown, were chosen: Algiers in the central northern region and Bordj Bou Arreridj in the eastern high plains. Climate change is not similar for both areas, but a tendency towards aridity is clear especially in spring. Future temperature and potential evapotranspiration increase in both regions with a maximum in spring and summer. In Algiers, rainfall will decrease throughout the year and mainly in spring and summer. Conversely, summer precipitation in Bordj Bou Arreridj will increase significantly. In both regions, the autumn rains will increase in the future climate, the possibilities of early sowing will be improved, crop cycle will be reduced, and harvest will take place earlier. In Algiers, yields tend to decrease in the future climate, whereas in Bordj Bou Arreridj, a dynamical (earlier) sowing will tend to keep yields at their current level.

Zinc application and green manuring enhances growth and yield in basmati rice (Oryza sativa L.)

Zn deficiency continues to be one of the key factors in determining rice production in India, which is very sensitive to low Zn supply in submerged rice soils. In view of the above facts, field experiments were conducted during rainy (kharif) seasons (April–November) of 2009 and 2010 for two consecutive years at the research farm of the Indian Agricultural Research Institute, New Delhi, to evaluate the effects of summer green manuring crops and zinc (Zn) fertilizer sources on growth and physiological development of basmati rice (Oryza sativa L.) in basmati rice–durum wheat cropping system. The experiment was conducted in a split plot design, keeping three green manuring crops, viz., Sesbania aculeata (Dhaincha), Crotalaria juncea (Sunhemp), and Vigna unguiculata (Cowpea) and one summer fallow treatment as main-plot treatments and six Zn sources, viz., control (no Zn application), ZnSO4·7H2O (21 % Zn), ZnSO4·H2O (33 % Zn), ZnO (82 % Zn), ZnSO4·7H2O + ZnO (50 + 50 %) and EDTA-chelated Zn (12 % Zn) in sub-plots, with three replications. For all the Zn treatments 5 kg Zn ha−1 was applied uniformly to rice crop during both the years. Sesbania aculeata (Dhaincha) residue incorporation and EDTA-chelated Zn (12 % Zn) treatments were found to be a better combination with respect to basmati rice growth and physiological development. There was a 13.97 % increase in grain yield of basmati rice with Sesbania aculeata (Dhaincha) incorporation over control (no green manuring) and 23.53 % increase with EDTA-chelated Zn (12 % Zn) application over control (no Zn application). The correlation among the various yield attributes and yield indicated that all the yield attributes were highly correlated with yield. Thus, Zn fertilization along with green manure incorporation can lead to better growth and physiological development for higher productivity of basmati rice.

YIELD, NITROGEN USE EFFICIENCY AND GRAIN QUALITY IN DURUM WHEAT AS AFFECTED BY NITROGEN FERTILIZATION UNDER A MEDITERRANEAN ENVIRONMENT

SUMMARYLimited information is available concerning the influence of nitrogen fertilization jointly on yield response, nitrogen use efficiency (NUE) and grain quality of durum wheat under semi-arid Mediterranean conditions. The study focused on evaluating, through a systematic study, over three seasons in southern Italy the effects of three nitrogen fertilization rates (0, 80 and 160 kg N ha−1– N0, N80and N160), on grain yield, yield components, nitrogen efficiency indices and grain quality characteristics of three durum wheat genotypes (‘Creso’, ‘Trinakria’ and ‘Line 25’) from different breeding eras to achieve a more sustainable fertilization management of the durum wheat crop. We found that nitrogen fertilization at 80 kg N ha−1was able to maximize the yield performances (2.1 t ha−1year–1) of the crop and keep NUE index at an acceptable level (16.3 kg kg−1). On the other hand, nitrogen fertilization at 160 kg N ha−1improved grain quality measured through protein (up to 14.3%) and dry gluten concentration (up to 12.8%), but had a detrimental effect on grain yield and nitrogen efficiency. Among the genotypes studied, ‘Trinakria’ showed the greatest potential to utilize nitrogen fertilization to improve grain yield and NUE (at N80) and quality (at N160), ‘Line 25’ made good use of N80both for yield and quality, whereas ‘Creso’ proved wholly unresponsive to nitrogen. The effect of N fertilization on grain yield and N use efficiency depends on rainfall distribution, giving the best results when about 80% of total rainfall occurred from sowing to heading. Overall, our data show that in seasons with regular rainfall in quantity and distribution, combining no more than 80 kg ha−1of nitrogen fertilization with genotypes characterized by a more efficient response to nitrogen, is a useful tool to improve the agronomic and quality performance of the crop, ensuring, at the same time, a more environment-friendly nitrogen fertilization.

Pyrosequencing reveals the impact of foliar fungicide application to chickpea on root fungal communities of durum wheat in subsequent year

Abstract Frequent application of foliar fungicide is essential for chickpea production due to the susceptibility of this plant to ascochyta blight. Chlorothalonil, pyraclostrobin, and boscalid are commonly used to control the disease in Saskatchewan. While fungicides are meant to target specific fungal pathogens, they may impact non-target organisms and alter soil microbial community structure. The effects of the typical 5-time foliar fungicide application program to chickpea CDC Vanguard on the fungal communities associated with seminal and adventitious roots of the following durum wheat crop were studied in a 2 yr field experiment. Root fungal communities were characterized through analysis of the ITS1 region of root metagenomic DNA at the genus level. One hundred and seven fungal genera were detected in durum wheat roots. Fusarium was predominant in both years. A three-way interaction of fungicide application, root type and year on fungal community structure was detected. Unlike Fusarium , the relative abundances of the genera Olpidium , Alternaria , and Cryptococcus were greater in 2010, a very wet year. Fungicide application to chickpea increased the relative abundance of Fusarium in the seminal roots of a subsequent durum crop in 2009, but did not affect the relative abundance of Fusarium in 2010. We could not detect a significant impact of fungicide application to chickpea on durum wheat yield in the subsequent year. The effect of changes in root fungal communities on durum wheat grain yield is discussed.

Wpływ sposobów pielęgnacji na zachwaszczenie łanu pszenicy twardej (Triticum durum Desf.) i zwyczajnej (T. aestivum L.)

A field experiment was conducted at the Experimental Station Krasne near Rzeszów in the years 2010–2012. The experiment was established in the split-plot design including the control treatment in 4 replications, on a soil classified as the good wheat complex. The aim of this study was to estimate and compare an effect of several methods of weed control, i.e. mechanical with harrowing , chemical (with the recommended and lowered dose of a herbicide) and combining both of those methods with a reduced dose of a herbicide on the state and degree of weed infestation of durum wheat (Triticum durum Desf.) and common wheat (T. aestivum L.) cultivars, Harrowing of durum wheat and common wheat crops, combined with spraying with a dose of the herbicide Granstar Ultra SX 50 SG reduced by a half, limited weed infestation as effectively as the chemical method with the recommended dose of a herbicide. A good effectiveness of harrowing in weed control, including the predominant taxons Chenopodium album and Stellaria media, was obtained in both durum wheat and common wheat cultivars crops. Durum wheat cultivars Durobonus and Duroflavus proved to be less competitive in relation to weeds as compared with common wheat. A similar species composition was observed in the weed communities of tested cultivars, and differences concerned the amounts and air-dry weight of weed species. Doświadczenie polowe prowadzono w Stacji Doświadczalnej Krasne koło Rzeszowa w latach 2010–2012. Eksperyment założono metodą split-plot z obiektem kontrolnym, w 4 powtórzeniach, na glebie zaliczanej do kompleksu pszennego dobrego. Celem badań było określenie i porównanie stanu oraz stopnia zachwaszczenia łanów odmian pszenicy twardej (Triticum durum Desf.) i pszenicy zwyczajnej (T. aestivum L.), w których stosowano różne sposoby regulacji zachwaszczenia: mechaniczny z bronowaniem zasiewów, chemiczny z zalecaną i obniżoną dawką herbicydu oraz połączenie metody mechanicznej i chemicznej z obniżoną dawką herbicydu. Bronowanie zasiewów pszenicy twardej i zwyczajnej połączone z opryskiwaniem zmniejszoną o połowę dawką herbicydu Granstar Ultra SX 50 SG ograniczało zachwaszczenie równie skutecznie, jak metoda chemiczna z zalecaną dawką herbicydu. Uzyskano dobrą skuteczność bronowania w zwalczaniu chwastów, w tym taksonów dominujących: Chenopodium album i Stellaria media, zarówno w zasiewach odmian pszenicy twardej, jak i zwyczajnej. Odmiany pszenicy twardej: Durobonus i Duroflavus okazały się mniej konkurencyjne w stosunku do chwastów w porównaniu z pszenicą zwyczajną. W strukturze florystycznej zbiorowisk chwastów poszczególnych odmian zaobserwowano podobny skład gatunkowy, a różnice dotyczyły ilości i powietrznie suchej masy występujących gatunków chwastów.

Targeted exploitation of gene pools of alien Triticeae species for sustainable and multi-faceted improvement of the durum wheat crop

Enlarging the genetic basis of essential crop species such as the polyploid wheats is a priority in breeding outlooks for the new millennium. To this end, one feasible approach to exploit the wide and largely untapped variation present in the gene pools of alien Triticeae species is chromosome engineering, which enables the transfer of alien chromosomal segments carrying targeted genes to wheat chromosomes. Recent progress in molecular marker technology, molecular cytogenetic techniques, and in genome knowledge has greatly enhanced the ability of chromosome engineering to contribute breeder-friendly germplasm, even in the case of durum wheat, considered more sensitive to genome manipulations than bread wheat. Using finely tuned chromosome engineering, stable incorporation into durum has been achieved for various alien segments containing genes for disease resistance, quality attributes, and even yield-related traits, both separately and in combination. The state of the art and the breeding potential of such transfers are reviewed and updated.

Residual effect of summer green manure crops and Zn fertilization on quality and Zn concentration of durum wheat (Triticum durum Desf.) under a Basmati rice–durum wheat cropping system

Field experiments were conducted during the summer-rainy (June–November) and winter (November–April) seasons of 2009–2010 and 2010–2011 at the research farm of the Indian Agricultural Research Institute, New Delhi, India. The objectives were to determine the residual effects of zinc (Zn) fertilizer sources [Ethylene diamine tetra acetic acid (EDTA)-chelated Zn (12% Zn), ZnSO4·7H2O (21% Zn), ZnSO4·H2O (33% Zn), ZnO (82% Zn) and ZnSO4·7H2O+ZnO (50%+50%)] and summer green manure crops [Sesbania aculeata (dhaincha), Crotalaria juncea (sunhemp) and Vigna unguiculata (cowpea)] on yield, Zn concentration and quality of durum wheat (Triticum durum Desf.) under a Basmati rice–durum wheat cropping sequence. Basmati rice was harvested at maturity and durum wheat (variety PDW 291) was grown to evaluate residual effects of Zn fertilizer sources and summer green manure crops. Beneficial residual effects of Zn fertilizer sources and summer green manures on durum wheat response were observed, with significant increases in all of the determined parameters, in comparison with the control (no Zn application or summer fallow in preceding Basmati rice). The rates of increase varied among Zn sources and summer green manures. Residual effect of S. aculeata incorporation led to a significant increase in grain and straw yields, Zn concentration and quality parameters of durum wheat. Among the Zn fertilizer sources, residual effect of EDTA-chelated Zn was found to be the greatest with respect to grain and straw yields, Zn concentration and quality parameters. Highest Zn concentration in durum wheat grain and straw was recorded with residual effect of EDTA-chelated Zn, followed by ZnSO4·7H2O, ZnSO4·H2O, ZnSO4·7H2O+ZnO, ZnO and control. S. aculeata incorporation and EDTA-chelated Zn treatments were found to be the best combination with respect to residual effects for higher quality durum wheat production.

Population Density and Distribution of Wheat Bugs Infesting Durum Wheat in Sardinia, Italy

Wheat is a very important crop in Italy, and is infested by wheat bugs belonging to the genera Eurygaster (Hemiptera: Scutellaridae) and Aelia (Hemiptera: Pentatomidae). Many wheat bug infestations have been reported in the north, south, and center of Italy, both in the past as well as recently. The present study was carried out in Sardinia, Italy, during two years (2007 and 2008). The objective of this study was to determine the species and distribution of wheat bugs in durum wheat fields in Sardinia, and to estimate their population density in order to know the incidence of the pest on the island. Sampling took place twice a year (May and June) in three zones, representative of durum wheat cropping in the island. Four species of wheat bugs were found; the predominant species was Eurygaster austriaca (Schrank), followed by Aelia germari (Kuster), Eurygaster maura L., and Aelia acuminata L. The average density of wheat bugs was low (1.1 individuals/m2), but in certain areas it was above the damage threshold (4 individuals/m2). For this reason, the conclusion of the study is that this pest should be monitored in order to control outbreaks and prevent their further spread.

Gross Irrigation Water Requirement for Durum Wheat Crop (Sham 3) At Mosul Area In Season 2009/2010

Gross Irrigation Water Requirement for Durum Wheat Crop (Sham 3) At Mosul Area In Season 2009/2010

Chickpea genotypes shape the soil microbiome and affect the establishment of the subsequent durum wheat crop in the semiarid North American Great Plains

Accumulating evidence supports the feasibility of creating biotic soil environments that promote root health using selected plant genotypes. Five years of field experimentation conducted in the semiarid grasslands of North America revealed genotypic variation in the influence of chickpea on the composition of the soil microbial community and on the establishment of the subsequent crop. A 2-year experiment documented the effects of four chickpea cultivars on the arable soil microbiome using cultural methods, the cloning and sequencing of soil-extracted DNA, and fatty acid methyl ester profiling. Cultivar CDC Frontier was characterized by low bacterial biomass, whereas Amit and CDC Anna selected similarly structured bacterial communities but contrasting soil fungal communities. Amit and CDC Anna became colonized by arbuscular mycorrhizal (AM) fungi to the same extent, but the arable soil planted with CDC Anna hosted the highest level of culturable fungal diversity, whereas the soil planted with Amit hosted the lowest. The highest diversity of culturable fungi and the richness of AM fungal ribotypes (11) were also associated with CDC Anna. Amit was preferentially associated with the antagonist species Penicillium canescens. Higher durum wheat stand density was found after CDC Anna than after Amit, indicating that microbial diversity is an important feature of productive soils. The influence of chickpea genotype on the arable soil microbiome and on the establishment of the subsequent durum wheat crop was related to the soil water reserve at depths of 30–120 cm and was eliminated when the chickpea crops experienced drought. Genetic variation in the influence of chickpea on the soil microbiome suggests the possibility of selecting genotypes to engineer beneficial soil biotic environments. Inadequate levels of soil water could limit the success of this strategy, however, in rainfed cropping systems of the semiarid grasslands of North America.

Wheat yield scenarios for rainwater harvesting at Northern Sinjar Mountain, Iraq

Iraq is part of West Asia and North Africa (WANA) region. The area is known as dry land, famous with gap of crop yield as a result of the water shortage problem. Six basins with total catchment area of 614.19 km 2 at rain-fed of Northern Sinjar District (Iraq) had been chosen to investigate both of the potential of rainwater harvesting (RWH) and three supplemental irrigation (SI) scenarios S1, S2, and S3 (100%, 75%, and 50% of full irrigation requirement) to support the wheat yield (bread and durum) under various rainfall conditions for the study period 1990-2009. The results indicated that, the total volume of harvested runoff can be considered for irrigation practices, that reached up to 42.4, 25.1, 0.6, 10.9 (× 10 6 m 3 ) during 1995-1996, 1996-1997, 1998-1999, and 2001-2002, respectively. The total irrigated area ranged between 10.9 - 5163.7 and 8.8 3595.7 (ha) for bread and durum wheat crop for the four selected seasons respectively. The yield scenarios for supplemental irrigation condition Y1, Y2, and Y3 give 68 - 9712, 94 - 12,999, and 105 - 22,806 Ton for bread wheat, and for durum wheat give 56 - 8035, 87 - 10,906, and 103 - 17,396 Ton.

Bacterial endophytes mediate positive feedback effects of early legume termination times on the yield of subsequent durum wheat crops.

Field crops influence the biotic properties of the soil, impacting the health and productivity of subsequent crops. Polymerase chain reaction and 454 GS FLX pyrosequencing of amplicons were used to clarify the legacy of chickpea and pea crops on the quality of the bacterial community colonizing the root endosphere of subsequent crops of wheat, in a replicated field study. Similar communities of root endosphere bacteria were formed in durum wheat grown after pea and chickpea crops when chickpea crops were terminated as early as pea (July). Termination of the chickpea crops in September led to the domination of Firmicutes in wheat root endosphere; Actinobacteria dominated the wheat root endosphere following early pulse crop termination. The architecture of wheat plants was correlated with the composition of its root endosphere community. High grain yield was associated with the production of fewer but larger wheat heads, the abundance of endospheric Actinobacteria and Acidobacteria, and the scarcity of endospheric Firmicutes. Pulse termination time affected wheat root endosphere colonization strongly in 2009 but weakly in 2010, an abnormally wet year. This study improved our understanding of the so-called "crop rotation effect" in pulse-wheat systems and showed how this system can be manipulated through agronomic decisions.

How does a stone mulch increase transpiration and grain yield in wheat under soil water deficit stress?

Stone mulch offers potential benefits for water conservation in many rain-fed agricultural systems of the arid regions. The effects of stone mulch on transpiration and grain yield were examined for a durum wheat crop grown under soil water deficit stress. In a greenhouse trial, stone mulches with two levels of ground coverage significantly decreased soil-surface evaporation and increased crop transpiration. The transpiration increase contributed to increases both in biomass and grain yield. Field experiments over two cropping seasons confirmed yield increases of 12% in soil half-covered and 24% in soil fully-covered by stones. These significant yield increases indicate the potential usefulness of stone mulch technology in rain-fed cereal cropping. It is suggested that stones should not be removed from cereal fields unless their presence obstructs management severely. It remains to develop technologies for effectively managing soils containing large numbers of sizable stones in order to obtain the benefits of the potential yield increase associated with their presence on the soil surface.

Long-term durum wheat monoculture: modelling and future projection

The potential effects of future climate change on grain production of a winter durum wheat cropping system were investigated. Based on future climate change projections, derived from a statistical downscaling process applied to the HadCM3 general circulation model and referred to two IPCC scenarios (A2 and B1), the response on yield and aboveground biomass (AGB) and the variation in total organic carbon (TOC) were explored. The software used in this work is an hybrid dynamic simulation model able to simulate, under different pedoclimatic conditions, the processes involved in cropping system such as crop growth and development, water and nitrogen balance. It implements different approaches in order to ensure accurate simulation of the mainprocess related to soil-crop-atmosphere continuum.The model was calibrated using soil data, crop yield, AGB and phenology coming from a long-term experiment, located in Apulia region. The calibration was performed using data collected in the period 1978–1990; validation was carried out on the 1991–2009 data. Phenology simulation was sufficiently accurate, showing some limitation only in predicting the physiological maturity. Yields and AGBs were predicted with an acceptable accuracy during both calibration and validation. CRM resulted always close to optimum value, EF in every case scored positive value, the value of index r2 was good, although in some cases values lower than 0.6 were calculated. Slope of the linear regression equation between measured and simulated values was always close to 1, indicating an overall good performance of the model. Both future climate scenarios led to a general increase in yields but a slightly decrease in AGB values. Data showed variations in the total production and yield among the different periods due to the climate variation. TOC evolution suggests that the combination of temperature and precipitation is the main factor affecting TOC variation under future scenarios. Incorporation of crop residues had a positive effect, in the first 35 cm the amount of carbon increase with both the future scenarios.

Surface albedo following biochar application in durum wheat

The agronomic use of charcoal from biomass pyrolysis (biochar) represents an interesting option for increasing soil fertility and sequestering atmospheric CO2. However, before moving toward large-scale biochar applications, additional research must evaluate all possible land–atmosphere feedbacks. Despite the increasing number of studies investigating the effect of biochar on soil physical, chemical and biological properties, only a few have been done on surface albedo variations on agricultural lands. The present work had the aim of characterizing the annual albedo cycle for a durum wheat crop in Central Italy, by means of a spectroradiometer measurement campaign. Plots treated with biochar, at a rate of 30–60 t ha−1, showed a surface albedo decrease of up to 80% (after the application) with respect to the control in bare soil conditions, while this difference tended to decrease during the crop growing season, because of the prevailing effect of canopy development on the radiometer response. After the post-harvesting tillage, the soil treated with biochar again showed a lower surface albedo value (<20–26% than the control), while the measurements taken in the second year after application suggested a clear decrease of biochar influence on soil color. The modeling of the surface energy balance highlighted changes in the partitioning of heat fluxes and in particular a substantial increase of ground heat fluxes on an annual basis.

Characterisation and management of Phalaris paradoxa resistant to ACCase-inhibitors

Phalaris paradoxa is a competitive grass commonly found in durum wheat crops of central and southern Italy. Among the 85 populations screened from 1998 to 2008 for resistance to ACCase-inhibitors and graminicide sulfonylureas, 17 resulted as being resistant to at least one ACCase inhibitor while none of the populations showed resistance to sulfonylureas. ACCase resistance in hood canary-grass seems to be spreading rather slowly in Italy. Out of the 17 populations, seven were characterised through outdoor dose-response pot experiments to investigate resistance levels and cross-resistance patterns to ACCase-inhibitors and multiple resistance to other mode of action. Molecular bases of resistance to the recently introduced DEN herbicide pinoxaden were also investigated. Six populations were confirmed to be ACCase-resistant with various cross-resistance patterns. Two populations were resistant to all tested ACCase herbicides, with pinoxaden resistance indexes (RI) based on survival ranging from 22 to 50. The two populations have been molecularly characterised for resistance to pinoxaden. A single point-mutation in the ACCase gene was identified in each population, causing the amino-acid substitutions of Ile1781Val and Asp2078Gly in 0478L and 0025, respectively. The results suggest that resistance of P. paradoxa to pinoxaden is due to an altered target site and different mutations cause different resistance levels. The biological characteristics of the species, mainly self-pollinated, and the absence of multiple resistance allow herbicides with different modes of action to be used for controlling ACCase-resistant populations. Chemical tools should be carefully used within integrated weed management strategies.

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.

Survey of dry pasta for ochratoxin A in Canada.

Ochratoxin A (OTA) was determined in 274 samples of dry pasta sold across Canada in 2004 to 2006. Ground sample was extracted with acetonitrile-water (6:4 [vol/vol]), filtered, diluted with phosphate-buffered saline, and cleaned with an immunoaffinity column. Analysis was by reversed-phase liquid chromatography with fluorescence detection, and in the second year by liquid chromatography-electrospray tandem mass spectrometry as well. For 2004 and 2005, the limit of quantitation was approximately 0.5 ng of OTA per g (signal-to-noise ratio of 10:1). In 2006, the limit of quantitation was estimated to be 0.2 ng of OTA per g. Incidence of contamination above 0.5 ng of OTA per g was 21, 18, and 66% in the years 2004, 2005, and 2006, respectively, reflecting the contamination variability of durum wheat crops and showing the importance of multiyear surveillance. Mean levels of OTA found in these 3 years were, respectively, 0.30, 0.28, and 0.76 ng/g, and maximum levels were, respectively, 1.8, 1.4, and 3.3 ng/g.

Durum wheat (Triticum durum Desf.) in rotation with faba bean (Vicia faba var. minor L.): long-term simulation case study

The aim of this work was to apply the CropSyst simulation model to evaluate the effect of faba bean cultivation as a break crop in the continuous durum wheat cropping system in southern Italy. The model was previously calibrated and validated for durum wheat and faba bean on data derived from experiments carried out in southern Italy (for different years and treatments), comparing observed and simulated crop growth, yield, soil water, and nitrogen output variables. The validation showed good agreement between simulated and observed values for cumulative above-ground biomass, green area index, and soil water content for both crops and grain yield for durum wheat; a negative correlation for grain yield in faba bean was observed due to a reduction in harvest index in the well-watered crop, which the model does not simulate well. Subsequently, a long-term analysis was carried out to study the effects on durum wheat of introducing a legume crop in rotation with the cereal in 2 and 3-year sequences. A long-term simulation, based on 53 years of daily measured weather data, showed that faba bean, due to a lower level of transpirated water (on average 247 mm for durum wheat and 197 mm for faba bean), allowed for greater soil water availability at durum wheat sowing for the cereal when in rotation with a legume crop (on average, +84 mm/m for durum wheat following the faba bean), with positive effects for nitrogen uptake, above-ground biomass, and grain yield of wheat. The yield increase of wheat when following a faba bean crop was on average +12%, but this effect was amplified in drier years (up to 135%). In conclusion, the case study offered the potential to confirm the positive results previously obtained in long/medium-term field experiments on the introduction of faba bean in rotation with durum wheat, as well as reduction in the chemical application of nitrogen.