Morphological Traits Associated with Lodging Resistance of Spring Wheat (Triticum aestivum L.)

Throughout the world, lodging in cereals causes great losses in yield each year. A two year field study was conducted to determine the relationship of morphological traits to lodging resistance in spring wheat ( Triticum aestivum L.) breeding lines and to find easily measurable traits related to lodging resistance. A set of 15 breeding lines, representing a wide range of combinations of plant height and lodging resistance, was evaluated.
During the first year, 29 morphological traits were measured at two growth stages and correlated with the lodging score. Higher correlations were found for traits measured at anthesis (DC 65) than for traits measured at maturity (DC 92); most of the fresh weight traits correlated better to lodging resistance than did the corresponding dry matter parameters. During the second year the six traits of plant height, stem length, stem diameter, ear weight, stem weight and stem weight per cm were measured at anthesis and correlated with the lodging score.
From the pooled data of four experiments, significant correlations between the lodging score and single morphological traits were found for stem diameter and stem weight per cm. Thicker stems and heavier stems (mg per cm) were indicative for better lodging resistance. Stem diameter and stem weight cm⁻¹ explained 48.5 % and 49.7 %, respectively, of the phenotypic variation in lodging resistance. Multiple linear regression equations indicated that 77.2 % of the variation in lodging resistance was based on stem weight cm⁻¹ and on the weight of the ear.     

Glu-D1位点亚基缺失弱筋小麦新种质的创制及其品质分析

辐射诱变是一种重要的变异手段,为了丰富小麦的品质性状变异资源,通过采用60Co-?射线辐射普通小麦品种‘冀3235’幼胚愈伤组织的方法,获得辐射诱变处理的再生植株。对再生株后代种子进行麦谷蛋白亚基的SDS-PAGE分析,结果从中发现了不含Glu-D1位点编码的高分子量麦谷蛋白亚基的材料。经进一步的系谱选择,选育成了稳定遗传的7份材料。与对照‘冀3235’相比,这些株系的农艺性状无明显差异,醇溶蛋白A-PAGE电泳谱带也完全相同,仅在麦谷蛋白SDS-PAGE电泳图谱的Glu-D1位点上有差异（变异系缺少Glu-D1位点控制的亚基,对照‘冀3235’为2+12）。品质分析结果表明,Glu-D1位点缺失系的面粉品质发生了很大变化,其湿面筋没有检出,沉降值显著下降。这些变异系是培育弱筋小麦品种和评价Glu-D1位点功能的珍贵材料。     

Growth Properties and Ion Distribution in Different Tissues of Bread Wheat Genotypes (Triticum aestivum L.) Differing in Salt Tolerance

Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na⁺), potassium (K⁺) concentrations and K⁺/Na⁺ ratio in different tissues including root, leaf‐3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt‐tolerant genotypes (Karchia‐65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt‐sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na⁺‐specific effects within the plant. Grain yield loss in salt‐tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt‐sensitive ones was due to decline in grain number. Salt‐tolerant genotypes sequestered higher amounts of Na⁺ concentration in root and flag leaf sheath and maintained lower Na⁺ concentration with higher K⁺/Na⁺ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.     

Nitrate Assimilation and Nitrogen Harvest in Uniculm 'Gigas' Wheat (Triticum aestivum L.)

Contribution of the upper laminae designated as 7, 8 and 9 (flag), to the total reduced nitrogen was determined by two different methods; integration of nitrate reductase activity over the entire growing season of individual laminae, and laminae removal at ear emergence. The values obtained by these methods were: 20, 14, and 12 %, and 23, 15, 12 %, respectively. The in vivo nitrate reductase activity was relatively higher in the lamina 9, which contributed an extra 8 % towards total reduced nitrogen when the other laminae were removed from the shoot. No such compensatory response was observed when either lamina 7 or 8 was retained.     

Identification of Powdery Mildew Resistance Genes in Common Wheat (Triticum aestivum L.)

Major genes for resistance to powdery mildew were analysed in 24 Czechoslovakian wheat cultivars and, in part, in their parents. For this purpose individual isolates of the pathogen, able to differentiate host lines with known resistance genes, were selected. Eight of nineteen winter wheat cultivars do not possess any major resistance gene. Three cultivars have one and seven have two genes. One cultivar carries a combination of three genes (Pm2, Pm4b, Pm8). The most common resistance genes are Pm4b, Pm5 and Pm8. Pm2 is once combined with Pm6. Only one of five spring cultivars lacked a major resistance gene. Mlk is once present alone and twice combined with Pm5. There is one spring cultivar with a novel combination of three genes: Pm1, Pm5 and another gene needing further characterization. The observations are discussed with additional results of parent lines and further information on pedigrees.     

低温积累与光周期对小麦发育特性调控的分子机理研究进展

温度和光照是影响小麦发育的主要因素,不但决定了小麦生态型的区域分布,也通过调控小麦的发育阶段、器官建成、穗分化起始及进程等因素而影响小麦的产量。本文介绍了低温春化和光周期对小麦发育特性影响的分子基础,对其调控机制及互作模式研究进展进行了综述。     

Deep Roots are Pivotal for Regulating Post‐Anthesis Leaf Senescence in Wheat (Triticum aestivum L.)

Root activity plays a dominant role in grain filling in cereal crops. However, the importance of deep roots for regulating post‐anthesis leaf senescence is not clearly understood in wheat (Triticum aestivum L.). In this study, we used ³²P tracing to estimate the difference in wheat root activity at soil depths of 30 and 70 cm and the root restriction method to investigate the effects of vertical distribution of deep roots on leaf senescence, with non‐restricted plants as controls. Recovery of radioactive ³²P indicated that deep roots had significantly higher activity than upper roots in wheat. Root restriction at a soil depth of 50 cm caused significant decreases in the activities of superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), catalase (EC 1.11.1.6) and ascorbate peroxidase (EC 1.11.1.11) at 16 days after anthesis and thereafter resulting in an increase in malondialdehyde. As a result, chlorophyll levels and net photosynthesis decreased. Ultimately, the root‐restricted wheat produced a significantly lower grain yield than the non‐restricted controls. These data suggest that deep roots are pivotal for regulating plant senescence, duration of grain filling, and yield formation.     

小麦耐热性状鉴定及相关性状QTL研究进展

小麦是全球最重要的粮食作物之一,高温特别是开花期和灌浆期的高温胁迫严重影响小麦的产量和品质,鉴定、筛选小麦耐热种质资源,开展小麦耐热性分子育种是解决小麦耐热性的根本途径。本文分别综述了小麦耐热性状鉴定指标,目前鉴定出的小麦耐热分子标记以及潜在有育种应用价值的耐热分子标记,分析指出了与小麦耐热性密切相关的四个染色体区域,探讨了小麦小麦耐热性QTL鉴定中存在的问题。     

Intraspecific Variation in Nitrogen Uptake and Nitrogen Utilization Efficiency in Wheat (Triticum aestivum L.)

Twenty wheat ( Triticum aestivum L.) varieties differing in plant height were grown in soil culture and evaluated for differences in nitrogen uptake and nitrogen utilization efficiency (NUE) at limited (40 kg N ha⁻¹) and normal (120 kg N ha⁻¹) nitrogen supply. Nitrogen uptake showed 1.4- and 1.5-fold varietal variation at harvest for limited and normal N supply, respectively. NUE for dry matter production (NE1) exhibited 1.28- and 1.38-fold genotypic variation while NUE for grain production (NE2) varied by 1.25- and 1.21-fold at limited and normal N supply, respectively. Tall varieties were found to have higher N uptake and NUE for dry matter production, while dwarf cultivars had greater NUE for grain production. Nitrogen uptake was found to be strongly positively associated with dry matter production (r=0.85 and r =0.77 at limited and normal N supply, respectively), indicating an important effect of growth rate on N uptake. NUE for biomass production, as well as for grain production, was reduced as the supply of nitrogen was increased.     

Physiology of Drought Tolerance in Wheat (Triticum aestivum L.)

Correlation between lysine, tryptophan and prolamine contents during maturation of the maize kernel
Changes in the contents of total nitrogen, prolamine, tryptophan and protein bound lysine, and the relative nutritive quality of proteins were studied during the maturation of three normal maize varieties, grown under the same topographical and agrotechnical conditions, in two successive crop years.
Total nitrogen was determined according to Kjeldahl's method, prolamine by the turbidity test, lysine by Carpenter's method and tryptophan was assessed fluorometrically.
A significant decrease (p = 0.01) in total nitrogen, tryptophan and bound lysine content in the dry grain matter was found in the late milk and early dough ripeness stages of the maize kernel. Parallel with the decrease in these components, the relative nutritive quality of proteins also decreased during maturation. Prolamine, which was present in the early milk stage in low quantities, increased significantly (p = 0.01) with kernel maturity, reaching the highest level in the early dough ripeness stage. During further kernel maturation no significant changes in the components studied were observed. The correlation coefficients between the contents of prolamine and total nitrogen, lysine and tryptophan, during the ripening of maize kernel were highly significant (p = 0.001): -0.891, -0.938, -0.856, respectively in the first crop year and –0.844, -0.833, -0.867, respectively in the second crop year.     

Genetic control of boron efficiency in wheat (Triticum aestivum L.)

The genetic control of boron (B) efficiencyin wheat (Triticum aestivum L.) wasstudied for three genotypes representing Binefficient (I, Bonza), moderately Binefficient (MI, SW 41) and B efficient (E,Fang 60) categories. Boron efficiency wasexpressed as a partially dominant characterbut the phenotypes of F₁ hybrids,relative to parents, indicated geneticcontrol varying from recessive to additiveto completely dominant with different crosscombinations and B levels. Major geneswere identified from the evaluation ofF₂-derived F₃ populations derivedfrom intercrosses between the threeparents. Monogenic segregation was foundin Bonza × SW 41 and SW 41 × Fang 60crosses and digenic segregation resultedin Bonza × Fang 60. Among thethree wheat genotypes with widely differentB efficiency, genetic variation forresponse to B could be accounted for by twogenes, Bo _d 1 and Bo _d 2.     

Nitrogen Loss and Wheat (Triticum aestivum L.) Yields in Response to Zero-tillage and Sowing Time in a Semi-arid Tropical Environment

A net‐house experiment was conducted at the Indian Agricultural Research Institute, New Delhi, to study the effect of simulated zero‐tillage on the N loss through ammonia (NH₃) volatilization, and flux of inorganic N after the sowing of wheat and urea‐N application on two different dates. In addition, the effects of soil perturbation through simulated tillage vs. zero‐tillage, and of sowing time on the wheat yields (above and below‐ground) and N use were examined. Results showed significantly (P < 0.05) higher NH₃ volatilization loss of N in zero‐tillage than the tillage treatments, but no significant difference between early (18 November) or later (8 December) sowing wheat on such losses. Inorganic N, mostly NH‐N, was significantly higher in undisturbed soil on day 5, whereas on day 15, NO‐N was significantly higher in disturbed soil than the undisturbed (zero‐tilled) soil. There was little difference in NH‐N or NO‐N contents in soils between two dates of sowing. Plant parameters showed no significant (P > 0.05) differences among the treatments in terms of height, spike length, or number of grains per spike, grain and straw yields and root biomass and harvest index. Moreover, there were no significant differences among the treatments when N uptakes were compared. Our results thus suggest that after flooded rice, wheat can be grown successfully on zero‐tilled soils even when adopting sowing dates till early December. More N loss through NH₃ volatilization in zero‐tilled than tilled soils may not affect growth and yields of wheat, but needs to be reduced for N conservation and environmental reasons.     

小麦抗白粉病基因聚合体DH材料的分子标记鉴定

小麦白粉病是由Blumeria graminis f.sp. tritici引起的世界性病害,利用分子标记辅助选择进行抗白粉病基因累加,可延长品种抗病性寿命,有利于提高育种效率。本研究利用Pm4b的STS-PCR标记,Pm13和PmV的SCAR-PCR标记,以及与Pm12共分离的同功酶标记（α-Amy-1）对来自小麦与玉米杂交产生的双单倍体材料的7个株系和9个穗系的4     

花后灌水对小麦籽粒品质性状及产量的影响

在池栽防雨条件下,研究了小麦花后不同灌水时期、不同灌水次数对籽粒产量及品质性状的影响。结果表明,在花前限量灌水条件下（135 mm）,花后灌水（45～90 mm）可显著提高小麦籽粒产量及蛋白质产量;虽然多数品质性状在花后不灌水（CK）条件下获得最大值,但灌1水未引起品质性状的明显变化;随灌水次数增加,各品质性状变劣     

Physiological Responses of Wheat (Triticum Aestivum L.) –Aegilops Sharonensis Introgression Lines to Excess Copper

Two wheat lines (TL3 and TL5) derived from selection for Cu tolerance among wheat – Aegilops sharonensis hybrids were compared when grown as hydroponics at zero (control), 10⁻⁶ and 10⁻⁵  m CuSO₄. The morphometric measurements showed that the line TL5 with a more inhibited root system under 10⁻⁶  m CuSO₄ had a less inhibited shoot growth under 10⁻⁵  m CuSO₄ as compared to TL3. The decreased maximum efficiency of photosystem II and the more pronounced trend towards increased catalase activity suggested that despite the better shoot growth, the leaves of TL5 were more functionally injured. The increased content of carotenoids at excess Cu and the higher peroxidase and catalase activities of TL3 in control plants might contribute to its better stress tolerance. While no significant changes in enzyme activities were found at 10⁻⁶  m Cu, at 10⁻⁵  m the activities tended to increase. Although the close values of free phenolics concentrations in control plants, at Cu excess their content was higher in TL5 compared to TL3. The free phenolics content in roots at 10⁻⁶  m Cu decreased, and although higher at 10⁻⁵  m Cu, it remained below the control in TL3, and above the control in TL5. From the obtained results TL3 emerged to be more tolerant to excess Cu than TL5.     

施氮水平对冬小麦旗叶光合特性的调控效应

在大田试验条件下,对大穗型小麦品种兰考矮早八旗叶光合特性及氮素调控效应进行了研究。结果表明,旗叶叶绿素含量随籽粒灌浆进程呈逐渐降低的趋势。PSⅡ潜在活性、PSⅡ光化学的最大效率、荧光光化学猝灭系数等随生育进程呈先升高后降低的变化趋势,且均在开花期达到最大值,之后逐渐下降;荧光非光化学猝灭系数则在成熟期达到最大值。氮肥对旗叶光合特性有一定的调控效应,Chl,F_v/F_o,F_v/F_m及qP均随施氮水平的增加呈增加的趋势,其中Chl和F_v/F_o以N3（180 kg hm^-2）处理最大,F_v/F_m和qP（除孕穗期外）以N4（360 kg hm^-2）处理最大;qN则随施氮水平增加呈降低的趋势,以N4处理最小。适宜的施氮量（180 kg hm^-2）改善了兰考矮早八的光合色素性状,提高PSⅡ潜在活性及PSⅡ光化学的最大效率,减少荧光非光化学猝灭系数,从而有助于籽粒产量的提高。     

The Influence of Glyphosate on Germination Behaviour of Wheat (Triticum aestivum L.)

The germination behaviour of glyphosate-treated seeds of two wheat cultivars was investigated. Ten concentrations of the herbicide (480 g/L.) ranged from zero to 260 g. a.i./Fed. were applied to the dry seeds by soaking for two hours. Germination was then conducted in petri dishes on filter paper at average daily maximum and minimum temperatures of 19.65 and 6.15 °C in the laboratory. Seedling growth behaviour was recorded periodically at the 4th, 7th and 10th day of germination.
The results indicated that glyphosate treatment at different concentrations did not affect the germination percentage in both wheat cultivars. On the other hand, in comparison to the control, the herbicide treatment caused significant reduction in maximum seedling root and shoot lengths. The reduction increased proportionally by increasing the herbicide concentration. Treatments with high concentrations of the glyphosate caused significant reduction in total root number per seedling in cv. Sakha 8. At concentrations of 260, 130 and 65 g a.i./Fed. all seeds exhibited root aberration in both wheat cultivars.
Clear variation in cultivar susceptability to glyphosate treatment was observed, particularly at concentrations lower than 65 g a.i./Fed.
However, cv. Giza 155 seemed to possess better survival to glyphosate treatment than cv. Sakha 8 concerning root inhibition percentage and seedling part measurements. The results indicated the practical importance of the reactions of different genetic codes to the herbicide in the field including the crop and the weeds.     

Inheritance of Carbon Isotope Discrimination in Bread Wheat (Triticum Aestivum L.)

Summary Reliable selection of families with increased grain yield is difficult in breeding programs targeting water-limited environments. Carbon isotope discrimination (Δ) is negatively correlated with transpiration efficiency, and low Δ is being used for indirect selection of high wheat yield in rainfed environments. Yet little is known of genetic control and opportunities for improving selection efficiency of Δ in wheat. Half-diallel and generation means mating designs were undertaken to provide estimates of the size and nature of gene action for Δ in a range of wheat genotypes varying for this trait. Significant (P < 0.01) differences were observed for leaf tissue Δ among parents (19.3 to 20.7‰) and F₁ progeny (19.4 to 20.9‰) in the half-diallel. General (GCA) and specific combining ability (SCA) effects were significant (P < 0.05), while Baker's GCA/SCA variance ratio of 0.89 was close to unity, indicating largely additive gene effects. GCA effects varied from −0.38 to + 0.34‰ for low and high Δ genotypes `Quarrion' and `Gutha', respectively. GCA effects and parental means were strongly correlated (r = 0.95, P < 0.01) while directional dominance and epistasis contributed to small, non-additive gene action for Δ. Smaller Δ in F₁ progeny was associated with accumulation of recessive alleles from the low Δ parent. Narrow-sense heritability was high (0.86) on a single-plant basis. Generation means analysis was undertaken on crosses between low Δ genotype Quarrion and two higher Δ genotypes `Genaro M81' and `Hartog'. The F₁, F₂ and midparent means were not statistically (P > 0.05) different, whereas backcrossing significantly changed Δ toward the mean of the recurrent parent. Gene action was largely additive with evidence for additive × additive epistasis in one cross. Narrow-sense heritabilities were moderate in size (0.29 to 0.43) on a single-plant basis. Genetic gain for Δ in wheat should be readily achieved in selection among inbred or partially inbred families during the later stages of population development.