Factors affecting the genotype × environment interaction in spring triticale grown in a Mediterranean environment

The identification of the genotypic and environmental factors responsible for the genotype by environment interaction is essential in any breeding program. A Multi Environmental Trial (MET) including 3 years, 3 locations and 14 lines of spring triticale (× TriticosecaleWittmack) was carried out in a Mediterranean environment (Sardinia, Italy). Water available to the crops was calculated through a model run with the environmental variables and the phenological data recorded in each environment. Yield, yield components and heading date were used to perform an Additive Main effects and Multiplicative Interaction (AMMI) analysis. Interaction for yield was relevant only in 2 environments out of 8, one characterised by a late sowing, the other by the warmest pre-anthesis period. Correlations between Interaction Principal Component Axis (IPCA) scores and environmental and genotypic variables showed that genotype by environment interaction for yield and kernels per m² is related to interaction for phenology but not to the yield level. Yield level was significantly correlated with the water availability. Genotype by environment interaction for yield is mainly determined by thermal conditions in the pre-anthesis period, genotypic photoperiodic sensitivity and sowing time. This revised version was published online in August 2006 with corrections to the Cover Date.     

Challenges to wheat production in South Asia

Wheat is the second major staple crop, after rice, in India and Pakistan and is also gaining similar importance in Nepal and Bangladesh. Wheat production in South Asia has increased from 15 mt in 1960s to 95.5 mt during 2004–2005. It still needs to grow at the rate of 2–2.5% annually until the middle of 21st century. However, for India, recent estimations have shown a growth requirement of about 1.1%. Although the wheat improvement programs in these countries, with the active collaboration of national agricultural research centers (NARS) and CIMMYT, has made a significant progress, it is a matter of significant concern that wheat production has stagnated for last few years. Since there is little scope for increasing land area under wheat, the major challenge will be to break the yield barrier by pragmatic genetic and developmental approaches. The most serious constraints to wheat production in this region are a host of biotic and abiotic stresses. Although India has not faced any rust epidemic in the last decade, rusts continue to occupy the place of most dangerous pathogen for the region. Among the abiotic stresses, unusual warming trends during grain filling period are causing yield declines, especially in eastern and central India. There are other challenges that are specific to the highly productive rice–wheat cropping system predominant in the Indo-Gangetic plains. The total factor productivity of this system is declining due to depletion of soil organic carbon. Addition of organic matter to soil through green manuring and crop residue recycling, balanced fertilization, integrated nutrient management, diversification of rice-wheat system are some of the possible remedial measures to improve total factor productivity. The international linkages with CIMMYT needs to be strengthened more closely for developing more productive wheat genotypes and thus, achieving wheat targets in the South Asian region.     

Influence of winter and spring wheat genetic backgrounds on haploid induction parameters and trait correlations in the wheat × maize system

The interactive influence of winter and/or spring wheat genetic background on haploid induction parameters and trait correlation was studied by hybridizing five elite and diverse genotypes each of winter and spring wheat and their F₁s (winter × winter, spring × spring, and winter × spring, generated in a diallel design excluding reciprocals) with a single genotype of maize. Data were recorded with respect to per cent seed formation, embryo formation, and regeneration. High genetic variability was present among the wheat genotypes (parents + F₁s) for the three haploid induction parameters. Significant differences were obtained within and between different groups viz., spring wheats, winter wheats, spring × spring wheats, winter × winter wheats, and winter × spring wheats with respect to the three haploid induction parameters based on ANOVA. The winter genotypes (winter parents and winter × winter wheat hybrids) responded better than the spring groups (spring wheat parents, spring × spring and winter × spring wheat hybrids) with respect to embryo formation and winter × spring wheat hybrids yielded significantly the highest numbers of regenerants. Correlation studies amongst the haploid induction parameters indicated that the genes controlling seed formation and haploid plantlet regeneration are negatively correlated when the genetic backgrounds of both ecotypes are combined in winter × spring hybrids. Haploid embryo formation had no association with seed formation and regeneration in all genetic backgrounds, suggesting independent inheritance.     

Genetic analysis of grain mold resistance in white seed sorghum genotypes

Grain molds in rainy season sorghums can cause poor grain quality resulting in economic losses. Grain molds are a major constraint to the sorghum production and for adoption of the improved cultivars. A complex of fungi causes grain mold. Information on genetics of grain mold resistance and mechanisms is required to facilitate the breeding of durable resistant cultivars. A genetic study was conducted using one white susceptible, three white resistant/tolerant sources, and one colored resistant source in the crossing programme to obtain four crosses. P₁, P₂, F₁, BC₁, and BC₂, and F₂ families of each cross were evaluated for the field grade and threshed grade scores, under sprinkler irrigation. Generation mean analyses and frequency distribution studies were carried out. The frequency distribution studies showed that grain mold resistance in the white-grained resistance sources was polygenic. The additive gene action and additive × additive gene interaction were significant in all the crosses. Simple recurrent selection or backcrossing should accumulate the genes for resistance. Epistasis gene interactions were observed in colored resistance × white resistance cross. Gene interaction was influenced by pronounced G × E. Pooled analysis showed that environment × additive gene interaction and environment × dominant gene interaction were significant. The complex genetics of mold resistance is due to the presence of different mechanisms of inheritance from various sources. Evaluation of segregating population for resistance and selection for stable derivatives in advanced generations in different environments will be effective.     

Modelling nitrogen stress with probe genotypes to assess genetic parameters and genetic determinism of winter wheat tolerance to nitrogen constraint

Environmental and economical constraints in Europe will favour low nitrogen (N) input systems and wheat varieties adapted to moderate N deficiency. In this context, we studied the dynamics of genetic parameters according to N stress intensity and characterized the genetic determinants for plant tolerance to N deficiency. Thus, we combined N stress modelling with a genetic approach. Two hundred and twenty-two doubled haploid lines were experimented in the field for a range of nitrogen conditions. Those conditions were characterized by the Nitrogen Nutrition Index (NNI) of Récital. Grain Yield (GY) and Kernel Number (KN) were assessed. For GY and KN, and for each line, factorial regressions using NNI of Récital as environmental index were performed. In addition, we assessed the sensitivity to N stress (slopes of the regression) and the performances under low N conditions (predicted values for a NNI of 0.5). QTL detection was performed on these parameters as well as on KN and GY measured in each environment. G × N variance increased with N stress intensity whereas heritability and genetic variance decreased. 11 QTL regions were detected: 3 were N supply-specific QTL (on linkage groups 2A2, 3A and 4B) while 4 contained QTL detected under N⁺ and under N⁻ (2D1, 4B and 5A1). Out of these four, 2 coincided with QTL for factorial regression parameters (2D1 and 4B). Finally, 4 QTL were specific for factorial regression parameters (3B, 5A2 and 7B2). The role of genes commonly used in breeding programs (rht-B1 on 4B, and Ppd1 on 2D1) in plant adaptation to nitrogen constraint was highlighted. Future studies should focus on grain protein yield, another target for low-N breeding scheme.     

Effect of tire rubber ash and zinc sulfate on yield and grain zinc and cadmium concentrations of different zinc-deficiency tolerance wheat cultivars under field conditions

The aims of these field experiments were to investigate the effectiveness of soil application of rubber tire ash in comparison with soil and foliar applications of zinc (Zn) sulfate to increase Zn and decrease cadmium (Cd) concentrations in wheat grain. A two-year field experiment was conducted during the 2007–2008 and 2007–2008 growing seasons at Isfahan research field, Iran. Ten different Zn-efficiency bread wheat cultivars (Triticum aestivum L.) commonly cultivated in different parts of Iran were subjected to no Zn fertilizer addition (control), soil application of 40 kg ha⁻¹ ZnSO₄, soil application of 100 (for the first year) and 250 (for the second year) kg ha⁻¹ waste rubber tire ash, foliar application of Zn at the mid tillering stage, and foliar application of Zn at the early anthesis stage. In the foliar application, ZnSO₄ was sprayed at a rate of 0.66 kg Zn/ha. Foliar spray of zinc sulfate at early anthesis, in general, had no significant effect on the yield and grain Cd while significantly increased grain Zn concentrations of most cultivars. On average, the foliar Zn treatment at the mid tillering stage (0.66 kg Zn/ha), decreased the mean grain Cd concentration from 0.032 mg kg⁻¹ in the control treatment to 0.024 mg kg⁻¹. While the grain Zn concentrations of some cultivars increased with soil application of Zn sulfate, they were not affected or even decreased in other cultivars. For most studied wheat cultivars, pre-planting application of rubber tire ash in soil resulted in a significant decrease of grain Cd concentrations. The results show that the effectiveness of soil and foliar application of Zn on yield and grain Zn and Cd concentrations greatly depends on the cultivar. The currently recommended rates of soil applications of Zn to ameliorate Zn deficiency are sufficient to increase grain Zn and decrease grain Cd concentrations in some wheat cultivars, while they do not in the others. In this study, soil application of 250 kg rubber tire ash/ha and foliar spray of 0.66 kg Zn/ha at tillering stage were the most effective treatments to ameliorate Zn deficiency and to increase Zn and decrease Cd concentration in grains of most wheat cultivars.     

Causes of negative correlations between grain yield and grain protein concentration in common wheat

Summary In a study designed to investigate the nature and basis of the relationships between grain yield (GY) and grain protein concentration (GBC) in common wheat, 11 populations, including 4 homozygous-homogeneous and 7 heterozygous-heterogeneous populations, were evaluated in a space planted and a solid seeded trial. Analysis of yield and protein data from each population revealed that phenotypic and environmental correlations between GY and GPC were negative and highly significant, whereas genetic correlation was significant in only one of 7 segregating populations studied. These results suggested that the inverse relationships between GY and GPC, although phenotypically real, were not caused by genetic factors. It would appear that environmental factors, source-sink interactions, and dilution of protein by non-protein compounds were the major agents that caused undesirable associations between the two traits.Contribution No. of the Department of Plant Science, University of Alberta, Edmonton, Alberta, Canada T6G2P5     

Identification of site similarities in western and central Asia using CIMMYT international wheat yield data

Understanding the association among wheat growing locations allows plant breeders to better target crosses and identifies locations for germplasm exchange. To examine the relationship between yield testing sites in eight countries in western/central Asia, 291 data sets from CIMMYT's different international yield nurseries were combined into one analysis as no single nursery was well represented across the region; these nurseries represented wheat germplasm specifically developed for different agro-ecological zones including irrigated, semi-arid, high-rainfall, autumn- and spring-sown conditions. The shifted multiplicative model was used to group individual sites into clusters. Results revealed 18 site-by-site combinations as 'similar' to each other and 23 as 'contrasting' at a probability level of P < 15%. CIMMYT's main yield testing site in northern Mexico proved the best predictor for the region. Within the region two sites in Turkey and Iran were identified as possible sites for future regional testing. Overall the study showed that data from different yield nurseries can be combined to improve our understanding of site associations across western/central Asia to the benefit of both international and regional wheat breeders.     

铜、锰诱导吉富罗非鱼血细胞凋亡及铁、锌的干预作用

为了研究重金属铜与锰对吉富罗非鱼血细胞凋亡的影响以及铁、锌的拮抗作用,采用原子吸收分光光度法检测血液及饲料中重金属的含量,采用流式细胞术检测实验鱼血细胞凋亡情况。360 尾吉富罗非鱼幼鱼随机分为12 组,每组30 尾,分别以硫酸铜(0、2000 mg/kg)、硫酸锰(0、120 mg/kg)为攻毒组重金属源,以硫酸锌(20、320 mg/kg)、硫酸铁(150、350 mg/kg)为拮抗组金属源,通过饲料投喂的方式进行血细胞凋亡的研究,养殖周期为20 周。细胞凋亡分析结果表明,染铜组、染锰组实验鱼血细胞凋亡率显著高于对照组;补充铁和锌后,随着饲料添加铁、锌水平的增加,实验鱼血细胞凋亡率明显下降,但铁、锌干预组血细胞凋亡率显著高于对照组。实验表明,过量铜、锰可诱发实验罗非鱼血细胞凋亡;较高水平的铁、锌对铜、锰的毒性作用具有拮抗作用。     

Genotype by environment effects and selection for drought tolerance in tropical maize. I. Two mode pattern analysis of yield

Ten trials evaluated the performance of several late tropical maize populations (La Posta Sequía, Pool 26 Sequía and Tuxpeño Sequía) selected for tolerance to drought during flowering and grain filling and also for yield potential. Families (S₁ or full-sib) had been selected recurrently for six to eight years on an index of traits. Pattern (clustering and ordination) analysis was used to analyse the relative performance of entries that included cycles of selection for drought tolerance in the populations and non-drought tolerant checks. Mean environment (E) yields ranged from 1.0 to 10.4 t ha^-1. Analysis of variance showed that 97.9% of the total sums of squares was accounted for by E, and that, of the remaining sums of squares the G × E (genotype by environment interaction) was almost 3 times that of the contribution of G alone. Cluster analysis separated the checks, the earlier maturing drought tolerant entries and the later maturing drought tolerant entries. This was verified by principal component (PC) analysis of the G × E matrix. Grouping of the environments (i.e. based on entry performance), resulted in the separation of different types of droughts, and of medium and high yielding well-watered environments. The patterns of discrimination observed indicated that the yield gains under drought would have been unlikely to occur if selection had been done only in well-watered environments. Within each population, selection improved broad adaptation (higher mean yield) to both drought and well-watered environments and cycles of selection ‘jumped’ from non-drought-tolerant to drought-tolerant groups as their specific adaptation to drought environments increased.     

Genetics of androgenesis in winter and spring wheat genotypes

Androgenetic response and its inheritance was studied in nine winter type and two spring type wheat genotypes by crossing them in line × tester fashion. The 18 F₁ and 11 parental genotypes were raised in completely randomized block design with three replications and subjected to anther culture. Data were recorded with respect to per cent calli induction, percent regeneration and per cent green plant development. Analysis of variance revealed considerable genetic variation for all the three component traits of androgenesis. Both additive and non-additive genetic variances were involved in the androgenetic response with the preponderance of non-additive gene action in case of calli induction and additive gene action for regeneration and green plant development. Low estimates of heritability (narrow sense) for calli induction and moderate for regeneration and green plantlet development were obtained. The genotypes, Henies VII, Pnfjoumee, Saptdhara, Sentry, Purthi of winter wheat and HPW147 of spring wheat were identified as good general combiners for almost all the androgenetic parameters and have potential use in future haploidy breeding programmes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of plant density on grain yield,protein size distribution,and breadmaking quality of winter wheat grown under two nitrogen fertilisation rates

Nitrogen (N) and plant density are two crucial factors that affect winter wheat (Triticum aestivum L.) yield and quality, but little is known regarding the effects of interactions between these two factors on the amount and size distribution of protein fractions and quality traits. We grew the bread wheat cultivar Jinan17 in two successive seasons (2012–2013 and 2013–2014) at three densities of 120 plants m⁻² (low), 180 plants m⁻² [the usual rate for a multiple-spike cultivar with high tillering ability in the North China Plain (NCP)], and 240 plants m⁻² (high) and two levels of N fertilisation of 0 (low N availability treatment without N fertilisation) and 240 kg ha⁻¹ (the usual N rate for winter wheat production in the NCP) to evaluate the effect of N level × plant density interaction on grain yield, grain protein concentration, the amount and composition of protein fractions, dough development time, dough stability time, and loaf volume. The effect of plant density on Jinan 17 grain yield and quality differed between the two N levels. As plant density increased, all the parameters listed above decreased under 0 kg ha⁻¹ N fertilisation, but increased under 240 kg ha⁻¹ N fertilisation. Stepwise regression analysis showed that the dough rheological properties and breadmaking quality of Jinan 17 were affected by plant density under both N levels, primarily through changes in the polymerisation degree of glutenins in the flour.     

The relationship between grain weight and alpha-amylase in winter wheat: varietal comparison from UK field experiments

The relationship between Hagberg falling number and grain size was investigated in field-grown winter wheat varieties. Data was obtained for all varieties included in the UK Recommended List from 1997 to 2007. Overall, a negative association was found between thousand grain weight and Hagberg falling number. The negative association was detected between varieties in all years and within varieties in the majority of cases. Detailed Recommended List data from 2001 was used to examine variation in the relationship across 19 trial sites. Again, a negative association overall with both within and between variety associations was detected. However, there were also many cases where the association was not found. The association appears to be driven by both genetic and environmental factors; however, the association is not consistent enough to indicate a direct mechanistic link across all varieties.     

Genome-wide association study of grain iron and zinc concentration in common bean (Phaseolus vulgaris)

Common bean is one of the widely consumed food security crop in Africa, Asia and South America. It is a rich source of protein, minerals and micronutrients. High genotype by environment interaction is one of the main challenge in breeding for high grain micronutrient concentration. The objective of this study was to estimate SNP markers associated with grain Fe and Zn concentration using 289 common bean genotypes and 11,480 SNP markers. The study revealed that 43 quantitative trait loci (QTLs) were associated with grain Fe and Zn concentration. Five quantitative trait nucleotides (QTNs), that is, QTN Fe_1.1, QTN Fe_6.3, QTN Fe_6.5, QTN Fe_10.3 and QTN Fe_11.6 were detected both at Haramaya and Melkassa locations. Two of the markers, that is, QTN Fe_6.3 and QTN Fe_6.5, were located on chromosome 06 while QTN Fe_1.1, QTN Fe_10.3 and QTN Fe_ 11.6 were residing on chromosomes 01, 10 and 11, respectively. Among these, QTN Fe_11.6 had a large and positive consistent effect across locations. The five stable QTNs along with the potential candidate genes could be used for Fe biofortification through marker assisted selection.     

小麦芒长抑制基因B2的精细定位与候选基因分析

芒是小麦重要的穗部器官和形态特征,是小麦长期进化和适应环境的结果,对产量和抗旱性等具有重要影响。目前,对麦芒的遗传与发育还缺乏系统的研究,相关基因克隆或精细定位的研究尚未见报道。本试验利用短芒材料‘六柱头’与长芒材料‘石矮1号’构建的F2群体(SL-F2)对芒的遗传与发育进行了研究。细胞学观察表明,短芒主要是由细胞长度变短引起;遗传分析表明,‘六柱头’的短芒由显性单基因控制;借助Wheat660K SNP芯片的BSA分析和SL-F2群体的精细定位,确定‘六柱头’的芒长抑制基因是前人报道的B2位点,并将其定位到6B染色体4.84Mb的物理区间(471.28～476.12 Mb)内,该区段在中国春与矮抗58间具有良好的共线性。在B2定位区间共有61个基因,其中5个在中国春穗部特异表达,TraesCS6B02G264400在中国春和Azhurnaya幼穗表达差异显著。这些研究结果为B2基因的克隆、小麦芒形成机理的解析及育种中的应用奠定了基础。     

Drought and high temperature increases preharvest sprouting tolerance in a genotype without grain dormancy

Preharvest sprouting is common in cereals, which lack grain dormancy when maturing grain is exposed to rainfall or high moisture conditions. Environmental conditions such as drought and high temperature during grain filling have a large effect on the expression of sprouting tolerance. A dormant (DM 2001) and non-dormant (Cunderdin) hard white spring wheat were exposed to drought or irrigated conditions and either low or high temperature during grain filling. Dormancy and embryo sensitivity to ABA were analysed throughout grain filling. The conclusions from this investigation were as follows; firstly DM 2001 was more dormant than Cunderdin, with a four-fold lower germination index (GI) at maturity. Secondly during grain ripening drought increased dormancy and overrides any increase in dormancy with low temperature. Finally embryo sensitivity can be induced in a non-dormant genotype to the extent where the non-dormant genotype in a hot dry environment can have the same phenotype as a dormant genotype grown in a cool wet environment. In summary drought during grain filling increases dormancy suggesting breeders need to avoid drought when screening for sprouting tolerance in order to maximise the chances of identifying genetic differences in grain dormancy and avoid any maturity by drought interactions.     

Organic amendment and minimum tillage in winter wheat grown in Mediterranean conditions: Effects on yield performance,soil fertility and environmental impact

The experiment was conducted to evaluate the agronomic benefit of the application of organic fertilizers combined with different soil tillage on quantitative and qualitative components of winter wheat (Triticum durum Desf., cv. ‘Simeto’) and on chemical soil fertility parameters. The environmental impact, due to heavy metals introduced in soil-plant system, was further investigated. Soil tillage treatments consisted of conventional (CT) and minimum tillage (MT). Fertilization treatments were: mineral at 100 kg N ha⁻¹ (N_min); municipal solid waste compost at 100 kg N ha⁻¹ (N_comp); 50 kg N ha⁻¹ of both compost and mineral fertilizers (N_mix); sewage sludge at 100 kg N ha⁻¹ (N_ss). These treatments were compared with an unfertilized control (N₀). No significant difference was observed between the two soil tillage treatments for quantitative yield production, while among the fertilization treatments N_ss did not show any significant difference compared to N_min. At the end of the research, the fertility of the soil (oxidable carbon, total nitrogen, available phosphorus) was on average higher in N_comp and N_ss treatments compared to the N₀ and N_min ones. The overall distribution of heavy metals in soil-plant system respect to the different fertilizer treatments has not allowed to grouped their effects with Principal Components Analysis. This result showed that the amount of potential pollutants applied by organic amendments did not modified the dynamic equilibrium of the soil–plant system. The MT, as well as the fertilization with the application of sewage sludge (N_ss), allowed to reach productive performance similar to conventional management (CT with N_min). Here we demonstrate that, in the short term period, sustainable agronomical techniques can replace the conventional one with environmental benefit.     

Distribution and allelic expressivity of genes for hybrid necrosis in some elite winter and spring wheat ecotypes

The distribution and allelic expressivity of hybrid necrosis genes (Ne ₁ and Ne ₂) were studied in 21 winter (mostly exotic) and 43 spring type elite wheat genotypes, by crossing them with two known testers, C 306 (Ne ₁-carrier) and HD 2380 (Ne ₂-carrier).Ne ₁ gene was present in one north-west Himalayan winter wheat landrace, Shoure Local, but absent in the other winter as well as spring wheats. Ne ₂ gene was prevalent to a much lower extent in the exotic winter wheat germplasm (31.57%) as compared to the recently developed Indian and Mexican spring wheat semidwarfs (69.80%). This may suggest that breeders have tried to preclude hybrid necrosis by selecting for non-carrier genotypes in the development of exotic winter wheats in contrast to the situation in spring wheats. Based on the degree of expression of hybrid necrosis genes in the F₁ hybrids, the carrier genotypes were characterized with respect to the allelic strength of the hybrid necrosis genes. The 27 non-carrier genotypes of the two ecotypes identified in the present study have a greater potential use in future hybridization programmes so as to overcome the problem of hybrid necrosis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pattern analysis of genotype × environment interaction for striga resistance and grain yield in African sorghum trials

The parasitic weed Striga hermonthica (Del.) Benth. seriously limits sorghum [Sorghum bicolor (L.) Moench] production in Sub-Saharan Africa. As an outbreeder, S. hermonthica is highly variable with an extraordinary capacity to adapt to different hosts and environments, thereby complicating resistance breeding. To study genotype x environment (G x E) interaction for striga resistance and grain yield, nine sorghum lines, 36 F₂ populations and five local checks were grown under striga infestation at two locations in both Mali and Kenya. Mean squares due to genotypes and G x E interaction were highly significant for both sorghum grain yield and area under striga severity progress curve(ASVPC, a measure of striga emergence and vigor throughout the season). For grain yield, the entry x location-within-country interaction explained most of the total G x E while for ASVPC, entry x country and entry x location-within-country interactions were equally important. Pattern analysis (classification and ordination techniques) was applied to the environment-standardized matrix of entry x environment means. The classification clearly distinguished Malian from Kenyan locations for ASVPC, but not for grain yield. Performance plots for different entry groups showed differing patterns of adaptation. The ordination biplot underlined the importance of entry x country interaction for ASVPC. The F₂ derived from the cross of the striga-resistant line Framida with the striga-tolerant cultivar Seredo was the superior entry for both grain yield and ASVPC, underlining the importance of combining resistance with tolerance in striga resistance breeding. The observed entry x country interaction for ASVPC may be due to the entries' different reactions to climatic conditions and putative differences in striga virulence in Mali and Kenya. This revised version was published online in August 2006 with corrections to the Cover Date.     

播种方式与种植密度互作对大穗型小麦品种产量和氮素利用率的调控效应

为探明实现冬小麦进一步增产增效的调控途径,于2015—2016年和2016—2017年连续两个生长季,选用大穗型品种泰农18,设置2种播种方式(宽幅播种和常规条播)和7个种植密度(130×10~4、200×10~4、270×10~4、340×10~4、410×10~4、480×10~4和550×10~4株hm~(–2)),研究了播种方式与种植密度互作对大穗型小麦品种产量和氮素利用率的调控效应。结果表明,与常规条播相比,宽幅播种配合增密能够有效缓解单位面积穗数增加与单穗粒重降低、氮素吸收效率提高与氮素内在利用效率下降之间的矛盾,通过增加单位面积穗数和氮素吸收效率协同提高籽粒产量和氮素利用率。宽幅播种条件下获得最高产量和氮素利用率的密度为410×10~4株hm~(–2),显著高于常规条播条件下的最优密度(340×10~4株hm~(–2)),且其增产增效幅度亦显著高于常规条播。综上所述,宽幅播种配合合理密植具有进一步协同提高大穗型小麦品种产量和氮素利用率的潜力。在本试验条件下,宽幅播种(苗带宽8～10cm)与410×10~4株hm~(–2)密度相匹配是大穗型小麦品种泰农18获得更高产高效的最优组合。