缺锌条件下小麦的养分吸收状况及不同基因型的耐性差异

采用螯合-缓冲营养液（Chelator-buffer culture solution）进行培养试验,对缺锌条件下3种小麦基因型（绵阳19、邯6172、新麦13）的生长发育状况及对P、Cu、Fe、Mn营养的影响进行了研究,并且应用4种指标,即锌效率（缺锌与锌充足供应条件下小麦地上部干物质之比）、相对冠根比（缺锌与锌充足供应条件下小麦冠根比之比）、缺锌条件下小麦地上部的锌吸收量、干物质量,对3种小麦的耐缺锌能力进行了比较。结果表明,在锌缺乏条件下小麦地上部生长量明显降低,而根系依然能保持相对较强的生长发育能力;不同小麦基因型对缺锌的耐性存在明显差异,其中邯6172的耐性最强;在缺锌胁迫条件下,小麦地上部Cu、Fe、Mn含量及Cu／Zn、Fe／Zn、Mn／Zn均明显升高,地上部锌含量与Cu、Fe、Mn含量均呈极显著负相关,说明锌缺乏能够促进Cu、Fe、Mn在地上部的累积。与此相反,锌缺乏条件下小麦P含量及吸收量均明显降低,地上部磷、锌含量之间极显著正相关,但与Cu,Fe,Mn相似,缺锌后P从根系向地上部的转运率升高。同时,对缺锌耐性最强的小麦基因型邯6172在锌缺乏条件下,地上部Cu、Fe、Mn含量的升高与P含量的降低幅度均是3种供试小麦中最大的,似乎表明小麦对锌缺乏的耐性大小与对Cu、Fe、Mn的吸收能力及与对P吸收的抑制有关。     

Evaluation of Triticum aestivum germplasm from Croatia and Yugoslavia for aluminium tolerance

Summary Aluminium tolerance of 90 genotypes of Triticum aestivum L. germplasm from the breeding programmes of eight Croatian and Yugoslav institutions was evaluated in nutrient solutions having Al³⁺ activities of 0, 12.5 and 25M. Overall distribution of Al tolerance of wheat genotypes was skewed toward lower tolerance rankings. Average Al tolerance differed among gene pools created at different breeding institutions. Genotypes tolerant enough to be useful in the breeding programmes aimed at selecting cultivars with improved Al tolerance are identified in germplasm from four institutions. No correlation was found between chemical characteristics of soils used over the years by breeding institutions for their field trials and the Al-tolerance ranking of the corresponding germplasm material.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-4 relative root length, in % (25M Al³⁺/0 Al)     

Genotypic differences in wheat Al tolerance

Summary Aluminium tolerance of 83 genotypes from Croatian and Yugoslav Triticum aestivum germplasm was evaluated in nutrient solutions having Al³⁺ activities of 0, 12.5 and 25 M. Relative root length (25 M Al³⁺/0 Al) of various genotypes ranged from 2 to 97% (from very sensitive to tolerant to Al). No genotype with Al tolerance close to that of very tolerant cultivar Atlas-66 was found. Soil, climatic, fertilization, and liming effects that wheat plants giving seeds for the nutrient solution Al-tolerance screening had been subjected to during their growth cycle did not influence the Al-tolerance ranking. Significant correlation was found between screening wheat for Al tolerance in nutrient solutions and in acid Pseudogley soil amended with five rates of limestone in a greenhouse experiment. Seed protein concentration was significantly related to the Al-tolerance ranking (r² = 0.962). Such a significant correlation was not obtained in a case of rheological and other quality characteristics of seeds. Al-tolerant wheat genotypes identified in this study will be used in breeding for improved Al tolerance.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-2 relative root length, in % (12.5 M Al³⁺/0 Al) - RRL-4 relative root length, in % (25 M Al³/0 Al)     

Genotypic differences in Zn efficiency of Medicago species

Nineteen annual Medicago genotypes from eight species were grown in Mt. Compass sand at three levels of soil Zn application (0, 0.1 and 0.9 mg Zn kg^-1) to achieve Zn status from deficiency to adequacy. Genotypes differed in growth response: under Zn deficiency, those classified as Zn-efficient had less reduction in shoot growth, a higher root mass, greater concentration of Zn in the shoot and total Zn content per plant, and a stable shoot/root ratio compared with Zn-inefficient genotypes. While seed Zn content did not influence the Zn-efficiency ranking, it did affect yield, and so it plays an important role in yield response and Zn accumulation as Zn supply decreases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Morphological and physiological differences in the response of cereals to zinc deficiency

Greenhouse and growth chamber experiments were carried out using seven bread wheat (Triticum aestivum), three durum wheat (T. durum), two rye (Secale cereale), three barley (Hordeum vulgare), two triticale (x Triticosecale Wittmack) and one oat (Avena sativa) cultivars to study response to zinc (Zn) deficiency and Zn fertilisation in nutrient solution and in a severely Zn deficient calcareous soil. Visual Zn deficiency symptoms, such as whitish-brown necrotic patches on leaf blades, developed rapidly and severely in the durum wheat and oat cultivars. Bread wheat showed great genotypic differences in sensitivity to Zn deficiency. In triticale and rye, visual deficiency symptoms were either absent or appeared only slightly, while barley showed a moderate sensitivity. When grown in soil, average decreases in shoot dry matter production due to Zn deficiency were 15% for rye, 25% for triticale, 34% for barley, 42% for bread wheat, 63% for oat and 65% for durum wheat. Differential Zn efficiency among and within cereal species was better related to the total amount of Zn per shoot, but not to the Zn concentration in the shoot dry matter. However, in leaves of Zn efficient rye and bread wheat cultivars, the activity of Zn-containing superoxide dismutase was greater than in Zn inefficient bread and durum wheat cultivars, suggesting higher amounts of physiologically active Zn in leaf tissue of efficient genotypes. When grown in nutrient solution, there was a poor relationship between Zn efficiency and release rate of Zn-chelating phytosiderophores from roots, but uptake of labelled Zn (⁶⁵Zn) and its translocation to the shoot was higher in the Zn efficient rye and bread wheat cultivars than in inefficient bread and durum wheat cultivars. The results demonstrate that susceptibility of cereals to Zn deficiency decline in the order durum wheat > oat > bread wheat > barley > triticale > rye. The results also show that expression of high Zn efficiency in cereals was causally related to enhanced capability of genotypes to take up Zn from soils and use it efficiently in tissues. This revised version was published online in August 2006 with corrections to the Cover Date.     

Aluminium tolerance in wheat: correlating hydroponic evaluations with field and soil performances*

The objective of this study was to correlate root length of wheat (Triticum aestivum L.) genotypes grown in Al-containing, acidic hydroponic solutions, with root weights from acid-soil experiments and field scores from Brazilian acid-field trials. A total of 43 wheat genotypes, primarily from Brazil, were evaluated by growing seedlings for 4 days in hydroponic solutions containing 0.0–4.0 mg/l Al. The root growth rate of all the genotypes was reduced with the addition of Al to the solution and the Al-sensitive and Al-tolerant wheat genotypes were clearly identified. Genotypes with intermediate Al-tolerance levels showed variable root lengths in response to Al stress. Correlations between root length or a root tolerance index (RTI) in the Al solutions versus acid-soil experiments and acid-field trials were highly significant (r = 0.71–0.85, P < 0.01). The most significant correlation was observed among seedlings grown in 1 mg/1 Al. This study presents evidence that this short duration and simple screening technique provides a highly significant correlation with previous acid-soil Al-tolerance evaluations. Furthermore, the data obtained suggest that hydroponic screening of wheat seedlings for Al tolerance may be used in breeding programmes or in screening germplasm collections.     

Tolerance to paraquat is correlated with the traits associated with water stress tolerance in segregating F2 populations of barley and wheat

To identify scorable marker traits that can be used in cereal breeding programs for selecting drought tolerant individuals, we investigated the correlation among the drought-associated traits in two F₂ populations derived from the crosses made between drought tolerant and sensitive barley and wheat parental genotypes. The parental genotypes of these crosses also differed by at least three other traits – paraquat tolerance, leaf size, and the relative water content. These three traits were scored in two F₂populations of 80 individuals for each barley and wheat cross. Analysis of results indicated that the enhanced tolerance to paraquat was correlated with reduced leaf size and increased relative water content, two traits associated with water stress phenotypes of the drought tolerant barley and wheat parents. Our results suggested that the selection based on paraquat tolerance istechnically less demanding and thus useful for rapid screening of individuals for enhanced drought tolerance in segregating populations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Canola genotypes differ in potassium efficiency during vegetative growth

There is no knowledge about the differential capacity of canola genotypes to take up potassium (K) and produce dry matter under conditions of low soil K availability. Hence, 84 canola genotypes were screened for K efficiency in the glasshouse. Plants were grown in sealed pots containing K-responsive, sandy soil without or with K added. Twelve genotypes were selected for advanced screening in the glasshouse in a different K-responsive soil. Genotypes with a mean K efficiency ratio (the ratio of shoot dry weight at deficient and adequate K supply) greater than one standard error above or below the median genotype value were classified as K-efficient or K-inefficient, respectively. There were significant differences between genotypes in the K efficiency ratio in both screening experiments, indicating that genotypes responded differently to K availability. In the initial screening experiment, 19 genotypes were rated as K-efficient and nine genotypes rated as K-inefficient based on the K efficiency ratio. In the advanced screening experiment with 12 genotypes, three genotypes were rated as K-efficient and two as K-inefficient. Genotypes Wesbarker and Rainbow were K-efficient and Genkai K-inefficient in both experiments. Correlation of the K efficiency ratio with (i) shoot K content in the initial and advanced screening and (ii) shoot K concentration in the advanced screening, indicates that the observed differences in K efficiency were due to genotypic differences in both the uptake and the utilization of K. K-efficient genotypes have a potential to improve canola yields on soils with low K availability.     

高碳酸钙条件下供锌对不同基因型小麦生长和养分吸收的影响

为了探明CaCO3对不同基因型小麦Zn吸收的影响,采用人工春化后的小麦幼苗在温室中进行了水培试验。结果表明:缺Zn和在营养液中添加100 mg/L CaCO3对小麦分蘖和生长发育未表现出明显的不良影响,而供试的3种基因型小麦(远丰998、中育6号及小偃22)的分蘖数及长势有明显的差异。与缺Zn相比,供Zn使小麦根部P吸收量增加25.6%,但对N,K吸收无明显影响。供Zn显著提高了小麦植株各部分尤其是根中的Zn含量和吸收量,而不同基因型间无显著差异,添加CaCO3未降低对Zn的吸收。添加CaCO3后,小麦叶片叶绿素SPAD值降低21.4%,但对小麦植株的Fe吸收无明显影响。据此推测叶绿素SPAD值的降低并非由于CaCO3降低小麦对Fe的吸收而引起的,其原因有待进一步研究。而供Zn仅能增加小麦根部Fe吸收量,对地上部无明显影响。无论是否供Zn,Fe主要累积在小麦的根部,而供Zn加剧了这种累积。     

Aiuminium tolerance of durum wheat germplasm

Summary Aluminium tolerance of Macedonian durum wheat (Triticum turgidum L. conv. durum (Desf.) MacKey) germplasm was evaluated in nutrient solutions containing 0, 74 or 148 M of total Al. Relative root length (148 M Al/0 Al) of various genotypes ranged from 41 to 72% (from moderately sensitive to moderately tolerant to Al). No genotype with Al tolerance close to that of very tolerant T. aestivum cultivar Atlas-66 was found. Seed Ca concentration was positively (r=0.64, P0.05) and seed Fe concentration negatively (r=–0.71, P0.05) related to the relative root growth. Such a significant correlation was not obtained for seed concentrations of other nutrients or seed protein content.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-2 relative root length, in % (74 M total Al/0 M Al) - RRL-4 relative root length, in % (148 M total Al0 M Al)     

Origin,diversity and utilization of the Cuban germplasm of common bean (Phaseolus vulgaris L.)

Summary Wheat root characters which influence vital plant processes have scarcely been explored for their genetic control. This study was conducted to i) examine the diversity of root traits and associated shoot traits in spring wheat (Triticum aestivum L.) cultivars; ii) study the nature of genetic control of selected traits; and iii) examine associations among root and shoot traits. Three experiments were conducted in the greenhouse with plants grown in the vermiculite medium in clear plastic tubes. In the first experiment, 42 spring wheat cultivars were grown for three weeks and measurements were taken on root length, leaf length, root number, leaf number, root dry weight, and top dry weight. In the second study, 15F₁'s originating from a partial diallel mating of six cultivars along with the parents were evaluated for 4 weeks. The data on root length, leaf length, and root number were subjected to diallel analysis according to Griffing's method 4, fixed model. A third experiment consisted of studying 2 F₂ populations with 141 plants per population. In the first study the 42 cultivars exhibited a wide range of variation for all six traits. Diallel analysis revealed significant effects of both general combining ability (GCA) and specific combining ability (SCA) for root length, leaf length, and root number. Parents with high GCA estimates were identified. Significant positive correlation coefficients were found among root and shoot traits. Analysis of F₂'s for root length indicated quantitative nature of inheritance of root length.     

Comparison of the resistance and susceptibility to downy mildew [<Emphasis Type="Italic">Hyaloperonospora parasitica</Emphasis>, constant. (Pers. Ex Fr)] of nine <Emphasis Type="Italic">Brassica olearacea</Emphasis> accessions in laboratory,seedbed, and field screens

The relationship between resistance in seedlings, young and adult plants is studied for the pathosystem Brassica oleracea–Hyaloperonospora parasitica. Genotypes identified in the laboratory as resistant or susceptible or exhibiting a differential reaction to a selection of H. parasitica isolates were tested in 1997–1999 in seedbeds and fields under natural infestation. Isolates tested in the laboratory were grouped in five pathotypes, of which four were presented by isolates from Brittany, France. Genotypes susceptible to all pathotypes in the laboratory were also susceptible in the seedbed and field tests, while genotypes expressing a differential response to pathotypes were either resistant or susceptible. Accessions Everest, DEGC, ESPG and RS1105 exhibiting resistance to all pathotypes except I, were resistant in all environments and remained resistant in 2000–2002. Pathotype I was not prevailing in the field and results support the hypothesis that accessions resistant under laboratory conditions will be resistant under field conditions, provided the same pathotypes are present under the laboratory and field conditions.     

不同基因型冬小麦幼苗对缺锌的敏感性反应

采用砂培试验研究了不同小麦基因型对施锌的反应.通过比较小麦幼苗根冠比的大小(是否大于1),以及根据培养过程中植株的生长表现,将供试的25种小麦基因型划分为两类:即缺Zn敏感型和非敏感型.结果还表明,供Zn可以促进小麦地上部和根系的生长,均较大幅度提高了叶绿素SPAD值(25个小麦基因型中18个的增幅都超过10%),而根冠比则相对保持稳定.小麦种子中的锌含量、幼苗根冠比与小麦叶片叶绿素SPAD值之间均无显著性相关关系.由于地上部积累了较高浓度的Zn,缺Zn非敏感型可有效减轻缺Zn对其造成的危害.非敏感型与敏感型相比较,缺Zn条件下地上部和根系锌含量平均值分别高出96.6%和28.8%,而在供Zn条件下则高出47.6%和10.9%.施Zn对敏感型与非敏感型小麦体内磷含量并无显著性影响.小麦幼苗中P/Zn的大小主要受到小麦体内Zn含量变化的影响,与磷含量则无明显的关系.     

Carbon isotope discrimination and indirect selection for transpiration efficiency at flowering in lentil (Lens culinaris Medikus), spring bread wheat (Triticum aestivum L.) durum wheat (T. turgidum L.), and canola (Brassica napus L.)

Summary Carbon isotope discrimination has been proposed to indirectly select for transpiration efficiency in several C₃ species. To determine the effectiveness of carbon isotope discrimination to indirectly select for transpiration efficiency at flowering we measured: (i) variability for carbon isotope discrimination, (ii) the magnitude of the genotype-by-water regime interaction for carbon isotope discrimination, and (iii) the magnitude of the correlation between carbon isotope discrimination and both transpiration efficiency and dry matter at flowering. Ten lentil (Lens culinaris Medikus) genotypes, ten wheat genotypes (eight spring wheat (Triticum aestivum L.) and two durum wheat (Triticum turgidum L.)), and ten canola (Brassica napus L.) genotypes were grown in a greenhouse at 80, 50 and 30% field capacity. Above ground dry matter was harvested at 80% flowering and dry matter at flowering, water used, and carbon isotope discrimination determined. Genotype variation for carbon isotope discrimination was observed in lentil, spring wheat and canola at each water regime, and when averaged over the three water regimes. The largest range in carbon isotope discrimination among lentil and spring wheat genotypes was observed using the wet regime; whereas, the dry regime provided the largest range for CID in canola genotypes. In all species the genotype-by-water regime interaction for carbon isotope discrimination was nonsignificant. The correlation between carbon isotope discrimination and dry matter at flowering was inconsistent across water regimes and years. In addition, in all three crops, no correlation was observed between carbon isotope discrimination and transpiration efficiency at any of the water regimes, and when averaged over water regimes and years. These results suggests that under the conditions reported here, carbon isotope discrimination cannot be used effectively to indirectly select for transpiration efficiency in lentil, spring wheat, and canola.Abbreviations CID carbon isotope discrimination - DMF dry matter at flowering     

Variation for tolerance to high concentration of ferrous iron (Fe<Superscript>2+</Superscript>) in Australian hexaploid wheat

High concentration of reduced iron (Fe²⁺) in waterlogged acid soils is a constraint for growing wheat in high rainfall (waterlogged-prone) areas of Western Australia. Growing crop genotypes tolerant to high Fe²⁺ concentrations may be desirable in such situations, but there is no knowledge about the extent of variability in Fe²⁺ tolerance in the wheat germplasm. A bioassay for tolerance to high concentrations of iron in wheat was developed and optimised using Siete Cerros (Fe-tolerant) and BH1146 (Fe-intolerant) as control genotypes and a range of FeSO₄ concentrations (36, 313, 625, 1250, 1875, 2500 and 3125 μM Fe²⁺) in nutrient solution in a controlled-temperature environment. Increasing external concentration of iron decreased both shoot and root dry weight, increased shoot iron concentration and intensified the development of toxicity symptoms to a greater degree in intolerant BH1146 as compared to tolerant Siete Cerros. Increased iron supply negatively affected uptake of Ca (r = −0.41) and Mg (r = −0.40). The tolerant genotype Siete Cerros showed an improved avoidance/exclusion of high external concentration of Fe²⁺ compared with intolerant BH1146. The genotypic discrimination based on relative root dry weight and the development of toxicity symptoms was most pronounced at 625 μM Fe²⁺. This concentration was chosen for screening of 20 bread wheat and one durum genotype chosen from a preliminary screening of 94 Australian wheat genotypes. A relatively narrow but significant variation (22–38%) in terms of relative root dry weight under Fe²⁺ toxicity was observed among Australian advanced breeding lines and varieties. The presence of genotypic variation for Fe²⁺ tolerance across and within the Australian breeding programs could be exploited in a deliberate selection process to enhance Fe²⁺ tolerance in wheat. Durum wheat (Arrivato) and several Australian wheat varieties and advanced lines in this study were as tolerant to Fe²⁺ toxicity as Siete Cerros, a variety representing common parentage of iron-tolerant genotypes.     

Germination characters and early seedling growth of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) genotypes under salt stress conditions

Screening of wheat genotypes as salt tolerance through seed germination and early seedling growth is crucial for their evaluation. Seeds of 20 wheat genotypes were germinated in Petri dishes on a sand bed irrigated with saline (15 dS m_-1) and control solutions for 10 days and also tested at different salinity levels (control, 4, 6, 8, and 10 dS m^-1) which were artificially developed in the soil for 30 days. At 10 days, germination percentage, rate of germination, co-efficient of germination, germination vigor index, shoot length, root length, and seedling dry weight were found to be affected due to salinity. Salt tolerance index (STI) for seedling dry weight maintained a significant positive correlation with rate of germination, germination vigor index, shoot length, and root length, which indicates that these parameters could be used as selection criteria for screening wheat genotypes against salt stress. Significant differences in shoot length, root length, and seedling dry weight in 30-day-old seedlings were observed among selected wheat genotypes as well. From the overall observation of germination characters and early seedling growth, it was concluded that the wheat genotypes including Gourab, Shatabdi, Bijoy, Prodip, BARI Gom 26, BAW 1186, and BAW 1189 showed better salt tolerance as compared to others.     

锌胁迫对不同耐低磷玉米生长及磷、锌养分吸收的影响

用营养液培养方法研究了不同耐低磷玉米幼苗对缺锌胁迫的适应性差异.结果表明,低磷敏感基因型在缺锌时植株各部位锌含量和吸收量显著下降,且变幅均明显高于耐低磷基因型.缺锌处理影响玉米幼苗的磷含量,低磷敏感基因型地上部磷含量较对照显著上升,根系磷含量变幅不大;耐低磷基因型地上部磷含量变幅较小,根系磷含量则显著下降.低磷敏感基因型在缺锌时地上部磷利用率显著下降,根系磷利用率无明显变化,而耐低磷基因型的变化情况正好相反,根系磷利用率受影响的程度大于地上部.     

Major gene control of tolerance of bread wheat (Triticum aestivum L.) to high concentrations of soil boron

Summary The genetic control of tolerance of wheat to high concentrations of soil boron was studied for five genotypes. Each genotype represented one of five categories of response to high levels of boron, ranging from very sensitive to tolerant. Tolerance to boron was expressed as a partially dominant character, although the response of an F₁ hybrid, relative to the parents, varied with the level of boron applied. The F₁ hybrids responded similarly to the more tolerant parent at low B treatments and intermediate to the parents at higher treatments. Ratios consistent with monogenic segregation were observed for the F₂ and F₃ generations for the combinations (WI^*MMC) × Kenya Farmer, Warigal × (WI^*MMC) and Halberd × Warigal. The three genes, Bo1, Bo2 and Bo3, while transgressive segregation between two tolerant genotypes, G61450 and Halberd, suggested a fourth locus controlling tolerance to boron.     

Progress in improving aluminium tolerance in the perennial grass,phalaris

Aluminium (Al) tolerance of 11 cultivars, breeding populations and accessions of the perennial grass, phalaris (Phalaris aquatica L.), was investigated in low ionic strength nutrient solutions. The populations were chosen to determine whether a program to improve the tolerance of phalaris to acid soils had resulted in improved Al tolerance. Populations derived by backcrossing genes from a more Al-tolerant species, P. arundinacea L. (AT populations), were significantly more Al tolerant than populations based on pure P. aquatica. Smaller levels of improvement in Al tolerance had also been achieved within P. aquatica through a combination of selection in Al solutions and at acid soil field sites. The response of roots and shoots to Al stress was similar. Some differences in ranking were obtained depending on whether Al tolerance was defined by actual growth in Al solution or growth relative to the zero Al treatment. Performance in nutrient solution containing Al was highly correlated with second year yield and persistence at a field site with acid soil high in Al to depth. Actual root dry weight in nutrient solution containing Al gave a slightly higher correlation with the field data than root weight relative to the zero control. A tendency for root dry weight to segregate in the presence of Al was observed in some P. aquatica populations but not in the AT populations. It was concluded that a significant improvement in the Al tolerance of phalaris has been achieved through a program to introgress genes from P. arundinacea into P. aquatica.     

Phenotypic variation in boron-toxicity tolerance at seedling stage in durum wheat (Triticum durum)

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 result of this study supported the preliminary finding that small, though statistically significant, variation in B toxicity symptom scores exist in durum wheat. The higher CV of symptom scores found here was mainly due to one sensitive entry, Cakmak. If Cakmak was excluded from the analysis, the CV would be reduced by half, to 10%. Durum wheat genotypes which are more tolerant to B toxicity should be sought. Based on the results of this study, and of soil surveys and information collected in WANA, germplasm collected from Algeria, Iraq, Libya, Syria, and the Anatolian Plateau of Turkey should be screened first.Abbreviations B boron - WANA West Asia and North Africa