Relationship between Carbon Isotope Discrimination and Mineral Content in Wheat Grown under Three Different Water Regimes

Carbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of the high cost for Δ analysis, attempts have been carried out to identify alternative screening criteria. Ash content (m_a) has been proposed as an alternative criterion for Δ in wheat and barley. A pot experiment was conducted to analyse the relationship between Δ and m_a in flag leaf and grain. Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate, intermediate and severe drought stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity, respectively. Δ and m_a in flag leaf and grain showed significant differences between the moderate, intermediate and severe drought stress levels. Significant correlations were found among genotypes for Δ and m_a in flag leaf under severe drought stress, and for Δ and m_a in grain under intermediate and moderate drought stress. In flag leaf at anthesis, Δ was negatively associated to K content and positively to Mg content. At maturity, Δ in grain was negatively correlated with Mg and Ca contents in flag leaf and grain, respectively. These results suggested that these traits may be potentially useful traits, which could be surrogates for Δ.     

Relationship between Carbon Isotope Discrimination, Ash Content and Grain Yield in Wheat in the Peninsular Zone of India

Carbon isotope discrimination (Δ) and ash content (m_a) have been proposed as indirect selection criteria for grain yield in wheat. The associations between Δ, m_a and grain yield were found, however, to depend highly on the environmental conditions, the organ sampled and the time of sampling. In this study, carried out in the warm conditions of the Peninsular Zone of India, the relationship between Δ, m_a and yield was studied in 30 bread and durum wheat cultivars under residual soil moisture stress (RSMS), post‐anthesis water stress (PAWS) and well‐watered (WW) conditions. Both Δ and m_a were analysed in young seedlings (four‐leaf stage), leaves at anthesis and grain at maturity. Ash content was also evaluated in leaves at booting stage and maturity. Grain Δ was lower under PAWS and RSMS than under WW, while seedling and leaf Δ did not significantly differ among water regimes. Grain yield was positively correlated to grain Δ under PAWS and negatively correlated to grain m_a under RSMS. A significant positive correlation was noted under RSMS and WW treatments between m_aL_m and grain yield. Ash content in leaf at maturity consequently appears to be a useful indirect selection criterion in environments where Δ does not show any correlation with yield. The results highlight the potential of Δ and m_a as indirect selection criteria for wheat yield in the conditions of the Peninsular Zone of India.     

Relationship between Carbon Isotope Discrimination,Mineral Content and Gas Exchange Parameters in Vegetative Organs of Wheat Grown under Three Different Water Regimes

Carbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of high cost for Δ analysis, attempts have been made to identify alternative screening criteria. Ash content (m_a) has been proposed as an alternative criterion for Δ in wheat and barley. A pot experiment was conducted to analyse the relationship between Δ, mineral content and gas exchange parameters in seedlings and leaves of bread wheat (Triticum aestivum L.). Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate (T₃), intermediate (T₂) and severe drought (T₁) stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity respectively. Δ and m_a in seedlings and leaves showed significant differences among the three water treatments. Significant positive correlations were found between Δ and m_a in seedlings and leaves at elongation and anthesis stages in severe drought stress (T₁). Δ was negatively associated with potassium (K) content in intermediate drought stress (T₂) and positively with magnesium (Mg) content in T₂ and T₃ (moderate drought stress) in flag leaf at anthesis. There were negative correlations between Δ and single‐leaf intrinsic water‐use efficiency (W_T) in T₂ and T₃ at anthesis stage. Stronger positive associations were noted between Δ and stomatal conductance (g_s) in T₁ and T₂ than in T₃ at anthesis. These results suggested that Δ is a good trait as an indirect selection criterion for genotypic improvement in transpiration efficiency, while m_a is a possible alternative criterion of Δ in wheat vegetative organs, especially in stressed environments. Significant association was found between Δ and K, Mg and Ca contents that would merit being better investigated.     

Carbon Isotope Discrimination, Leaf Ash Content and Grain Yield in Bread and Durum Wheat Grown under Full-Irrigated Conditions

Integrative physiological criteria, such as carbon isotope discrimination (Δ) and (mineral) ash content (m_a) have been found to be very useful, under drought conditions, to elucidate the association between yield gains and variation of photosynthesis‐related traits and orientate future breeding efforts. Information on this association is scarce under irrigated conditions. The relationships between Δ, m_a and yield were studied in bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. durum) under optimal (drip) irrigation in the arid conditions of north‐west Mexico. Carbon isotope discrimination was analysed on leaves at booting stage and anthesis and on grain at maturity, whereas ash content was measured on the flag leaf at anthesis and maturity. At anthesis, there were differences between bread and durum wheat during grain filling for Δ, but not for m_a. No relationship was found between grain yield and Δ. Leaf ash content at anthesis and maturity showed a broad variability within each species and were associated with grain yield. These results suggest that ash content in leaves could be also used as predictive criteria for yield not only under drought, but also under irrigated conditions, particularly when evaporative demand is high.     

Relationship between Carbon Isotope Discrimination and Grain Yield in Spring Wheat under Different Water Regimes and under Saline Conditions in the Ningxia Province (North-west China)

The relationship between grain yield and carbon isotope discrimination (Δ) was analysed in wheat grown under different water regimes in the Ningxia Province (north‐west of China). When the association was significant, the relationships between grain yield, Δ and other drought tolerance related traits, such as leaf ash content (m_a), chlorophyll concentration (Chl), relative water content (RWC), stomatal conductance (g_S) and the ratio of internal CO₂ leaf concentration to ambient CO₂ concentration (C_i/C_a), were also examined. Using correlation analysis, the relationships were determined during two consecutive years in a set of 20 spring wheat cultivars (landraces, improved varieties and advanced lines) under rainfed and irrigated conditions, including saline conditions. The relationship between Δ and yield within environments highly depended on the quantity of water stored in the soil at sowing, the quantity and distribution of rainfall during the growth cycle, and the irrigation before anthesis. Δ predicted grain yield under limited irrigation (post‐anthesis water stress) but not under pre‐anthesis water stress (rainfed conditions), fully irrigated and saline conditions. Under limited irrigation, grain Δ correlated significantly to grain yield leaf m_a at heading and maturity. It also significantly positively correlated to Chl, RWC, g_S and C_i/C_a assessed at anthesis. A precise characterization of the timing and intensity of the abiotic constraints experienced by the crop is consequently needed before implementing the use of Δ in wheat breeding programmes.     

Suitability of carbon isotope discrimination,ash content and single mineral concentration for the selection of drought‐tolerant winter rye

Carbon isotope discrimination (?) has been proposed as selection criterion for grain yield under dry conditions, and ash content (m_a) and mineral concentration were suggested as surrogates for ?. In this study, the relationship between grain yield, ?, m_a and mineral concentration (Si, Ca, K, Mg) was examined in 2011 and 2012 on 16 winter rye genotypes grown under severe drought, mild drought (2012 only) and well‐watered conditions. Analyses were performed on mature flag leaves and grains. Highly significant differences between water regimes occurred for all measured traits. ?, m_a and mineral concentrations were significantly correlated with grain yield under severe drought in 2011, but not in 2012 except for ? in flag leaf. ? was related to m_a and mineral concentrations. Although the correlations were quite inconsistent, the results indicate that the measured traits can potentially be used as selection criterion for drought tolerance in rye. For a final statement about the suitability of these traits in rye breeding, the results should be secured with a larger and more diverse set of genotypes.     

小麦旗叶性状与产量因素的相关与回归分析

以59个小麦品种(系)为试材,对旗叶性状与产量及产量因素作了相关与多元回归分析.结果表明,小麦旗叶的长、宽、叶面积、与茎杆的夹角、叶绿素含量与穗粒数、千粒重、穗粒重、产量等性状间的相关系数分别达显著或极显著水平,r=0.4851～0.7481.建立了旗叶性状与产量及产量因素的最优多元回归方程.     

Effect of Glaucousness on Carbon Isotope Discrimination and Grain Yield in Durum Wheat

The effect of glaucousness on yield and transpiration efficiency was studied in durum wheat under Mediterranean conditions. Two groups of 16 genotypes, with contrasting glaucousness, were compared over 2 years for flag leaf and kernel carbon isotope discrimination, residual transpiration, specific leaf dry weight, biomass and grain yield. Significantly higher carbon isotope discrimination and lower specific leaf dry weight were noted in the glaucous lines. No significant effect of glaucousness was found on residual transpiration. Glaucous genotypes also exhibited higher grain yield, which was strongly correlated to the carbon isotope discrimination values. Results suggest that glaucousness has a negative effect on transpiration efficiency, which could be related to modifications of leaf energy balance. Higher stomatal conductance, reflected by the high carbon isotope discrimination, could mainly explain the higher grain yield found in the glaucous lines.     

Genotypic association between grain yield and six agronomic traits in a cross between rice varieties of contrasting plant type

Summary Phenotypic and genotypic correlation coefficients as well as path analysis were computed to evaluate the genetic association between six agronomic traits and rice grain yield and also among the traits in a representative sample of F₇ lines in the tall Peta × semi-dwarf I-geo-tze cross maintained as an unselected bulk from F₃ through F₅. Data were taken on grain yield, duration from seeding to heading, panicle number, ratio of panicles to tillers, angle of the flag leaf, angle of the leaf below the flag leaf, and plant height on the two parents and 139 F₇ lines. The F₇ lines were divided into three groups based on plant height: tall, intermediate, and short (semi-dwarf).Differences in grain yield were highly significant among lines in the tall and short groups, and significant among the intermediate lines. Significant to highly significant differences among lines were obtained in each of the height groups for all of the agronomic traits except for the ratio of panicles to tillers in the intermediate and tall groups.Path analysis showed that among the semi-dwarf progenies, erect flag leaf angle made the largest positive contribution to grain yield, followed by high panicle number and early maturity. Among the intermediates, the erectness of the leaf below the flag contributed most to high yield and was closely followed by earliness in maturity. For the tall lines, erect leaves below the flag leaf and high panicle number contributed positively to yield, whereas tallness and late maturity had a negative effect.Phenotypic and genotypic correlation coefficients indicated that low grain yield was closely associated with tall stature, drooping leaves, and low panicle number in the tall lines. In the intermediate lines, low grain yield was associated with late maturity and drooping leaves. Among the semi-dwarf lines, high grain yield was correlated with erect flag leaves and a high ratio of panicles to tillers. When the lines in different height groups were combined, highly significant phenotypic correlations were obtained between high yield levels and erect leaves, a short plant stature, early maturity, or a high panicle number. Erect flag leaves and high yield levels were associated at a significant level. The genotypic correlation coefficients of the above paired traits were identical in sign and generally greater in value than the corresponding phenotypic correlation coefficients.Mail address: P. O. Box 583, Manila, Philippines.     

Association between Yield and Carbon Isotope Discrimination Value in Different Organs of Durum Wheat Under Drought

Carbon isotope discrimination (Δ) has been proposed as a selection criterion for transpiration efficiency and grain yield in drought‐prone environments for several C³ species, including cereals. Δ analysis, however, has mainly been concerned with grain or culm tissues and little work has been devoted to other organs. The objective of this study was to describe Δ variation in different organs and to examine the relationships between Δ and grain yield across environments. Six durum wheat genotypes with contrasted grain Δ were cultivated under rainfed conditions during three successive years at Montpellier (South of France). Δ was measured on flag leaf, stalk, awns, chaff and rachis sampled at anthesis and maturity, and on mature grain. Higher genotypic variation and closer correlation with yield were noted for grain Δ compared to other plant parts. The genotype ranking across years was more consistent for grain Δ than for other organs. Consequently, the grain seems the most effective plant part for Δ analysis in durum wheat under Mediterranean conditions. The study of Δ variation in other organs may be useful, however, to evaluate the contribution of those organs to grain filling and final yield according to environmental conditions.     

Contribution of Different Organs to Grain Filling in Durum Wheat under Mediterranean Conditions I. Contribution of Post‐Anthesis Photosynthesis and Remobilization

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post‐anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source–sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source–sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non‐destructive estimation of the variation in the contribution of different organs to grain filling.     

旗叶先衰型小麦生长后期顶三叶光合特性及其意义

经长期观察发现, 某些小麦品种的部分主茎或分蘖(异常茎)具旗叶较倒二叶先衰老的特征, 与常见的叶片衰老次序相反。为揭示这类品种的生物学特性, 探讨其理论意义和应用价值, 2005-2011连续6年, 以正常小麦为对照, 对其异常茎的叶绿素含量、光合特性参数、灌浆速率和粒重进行了比较研究。结果表明, 旗叶先衰型小麦异常茎的叶绿素含量、蒸腾速率、净光合速率在结实期的一定阶段呈现倒二叶超越旗叶; 异常茎上的根、茎、叶较正常茎发育充分且较为发达, 其灌浆速率也比正常茎快, 因而一些重要农艺性状较正常茎为优。上述表型的出现可能与特殊的灌浆机制相关, 不同于正常小麦旗叶作为向籽粒输送养分的主源于结实全程发挥作用的模式, 并最终造成他们的籽粒体积、千粒重和穗粒重分别比正常小麦高9.64%、10.35%和8.43%。对这类小麦的深入研究有助于完善小麦生长发育、灌浆结实以及衰老机制理论, 促进小麦产量的进一步提高。     

Genotypic variation for resistance to Septoria nodorum in triticale

Septoria nodorum leaf and glume blotch is an important disease of triticale (×_Triticosecale Wittm.) and can cause severe losses of grain yield in some regions. Quantitative genetic parameters for resistance were estimated for 2 years in two locations in triticale genotypes artificially inoculated with S. nodorum. The effect of infection was assessed by a visual symptom rating of flag leaves and spikes and by grain yield traits relative to an uninoculated control. The mean ratings of flag leaves and spikes, calculated from two to four ratings, were 2.6 and 3.9, respectively, with a range of six ratings for spikes and over five for flag leaves. Infection caused an 11.5% mean reduction in kernel weight per spike, which was the result of 13.2% lower 1000‐kernel weight. The number of kernels per spike and 50‐ml weight were little affected. For all relative grain yield traits, genotypic variation was small with high genotype‐environment interaction effects and thus moderate to low heritabilities. In contrast, for visual ratings genotypic variation was high, with low interaction effects leading to high heritabilities. Phenotypic correlation between flag leaf and spike ratings was low, indicating independent disease resistance mechanisms. The best association, although still moderate, was obtained between flag leaf rating and relative 1000‐kernel weight. Therefore, visual disease ratings do not satisfactorily assess the effect of Septoria infection on grain yield traits. The reduction in 1000‐kernel and possibly 50‐ml weight are good indicators, provided that multi‐environment tests are conducted.     

小偃54和京411及其杂交后代稳定优选株系光合特性的动态变化

以上海种植的小偃54和京411及其杂交后代稳定优选株系6号、7号和10号为材料,通过测定抽穗期剑叶的毫秒延迟发光(ms-DLE)和不同生育期倒数第1片功能叶的光合速率(P_n)、叶绿素含量(Chl)、比叶重(SLW)、F_v/F_m、ATP含量和P700还原初始速率来分析其光合特性的动态变化,为小麦育种选择中改善光合性能提供理论依据和技术途径。结果表明,小麦杂交优选后代6号株系的形态农艺性状近于小偃54,7号株系近于京411,10号株系的变异较大。不同基因型小麦及其杂交优选后代的光合特性与生育时期和衡量指标密切相关,P_n为分蘖期>抽穗期>灌浆期>拔节期,叶绿素含量为灌浆期>抽穗期>分蘖期>拔节期,ATP含量为灌浆期>拔节期>分蘖期>抽穗期,P700还原初始速率为灌浆期>抽穗期>拔节期>分蘖期,各生育期间的F_v/F_m无明显差异。小麦光合特性的超亲优势随生育时期而异,杂交优选后代10号株系的P_n和Chl在灌浆期有超亲优势,ATP含量在抽穗期有超亲优势,SLW和P700还原初始速率介于两亲本间。杂交优选后代株系10号聚合了P_n、Chl和ATP含量的超亲优势,其光合特性优于两亲本,而6号劣于两亲本,7号介于两亲本之间。     

Genetic gains for physiological traits associated with yield in soft red winter wheat in the Eastern United States from 1919 to 2009

Wheat (Triticum aestivum L.) breeding strategies can benefit from periodic evaluation of genetic gains for physiological and morphological traits, and their contribution to yield progress over time in a particular environment. The objective of this research was to expand the recent work at Virginia Tech on genetic yield improvement in soft red winter (SRW) wheat and determine the magnitude of progress for several physiological traits in 50 SRW wheat cultivars released from 1919 to 2009. Physiological traits evaluated here were extensively reported in the literature to be relevant for future wheat breeding as they directly contributed to yield increase under optimum and suboptimal environmental conditions; these traits include canopy temperature depression (CTD), flag leaf width (W), flag leaf area (LA), flag leaf dry weight (DW), flag leaf specific area (SLA), SPAD (soil plant analysis development) chlorophyll reading, and grain ¹³C isotope discrimination (Δ). Replicated experiments were performed at Warsaw and Holland, VA, in 2009–2010 and 2010–2011 growing seasons. Results showed that three traits consistently changed in magnitude over time and, at the same time, were significantly (p < 0.01) related to yield; they were LA, smaller leaf area-higher yields; DW, lighter leaves-higher yields; and Δ, higher Δ-higher yields. CTD decreased in magnitude and SLA, W, and SPAD chlorophyll reading did not significantly change over time. Our data suggest that further yield increase in the SRW wheat grown in eastern Unites States can be achieved through selection of cultivars with smaller leaves, and with high Δ.     

Compensative Effects of Chemical Regulation with Uniconazole on Physiological Damages Caused by Water Deficiency during the Grain Filling Stage of Wheat

Chemical regulation using plant growth regulators has proved to be potentially beneficial in water‐saving agriculture. This experiment was conducted with winter wheat (Triticum aestivum L. cv. ‘Jingdong 6’) to study the effect of chemical regulation on alleviation of water deficit stress during the grain filling stage. Uniconazole, a plant growth regulator, was foliar sprayed at 85 % (adequate irrigation) and 60 % (deficit irrigation) field capacity. Results showed that the distribution of ³H‐H₂O in roots and flag leaf, characteristics of vascular bundle in primary roots and internode below spike, roots activity, transpiration rate and stomatal conductance of flag leaf were negatively affected by deficit irrigation after flowering. Foliar spraying at the early jointing stage with 13.5 gha^?1 uniconazole was able to relieve and compensate for the harmful effects of deficit irrigation. Both the area of vascular bundle in primary roots and internode below the ear were increased by uniconazole, while root viability and their ability to absorb and transport water were increased. In the flag leaf, stomatal conductance was reduced to maintain the transpiration rate and water use efficiency (WUE) measured for a single wheat plant was higher. Uniconazole increased WUE by 25.0 % under adequate and 22 % under deficit irrigations. Under adequate irrigations, the ¹⁴C‐assimilates export rate from flag leaf in 12 h (E_12h) was increased by 65 % and 36 % in early and late filling stages, while under deficit irrigations, the E_12h of uniconazole‐treated plants exceeded that of control plants by 5 % and 34 % respectively. Physiological damages caused by water deficiency during the grain filling stage of wheat was alleviated by foliar spraying with uniconazole.     

小麦冷源功能叶片的显微结构和气体交换特性

小麦冷源具有明显降低小麦体温的作用,是培育冷型小麦的优质种质资源。论文通过常规石蜡切片的方法观察比较了冷源、冷型小麦小偃6号和暖型小麦9430功能叶片的显微结构,并在灌浆结实期测定了功能叶片的叶绿素含量、净光合速率、蒸腾速率和气孔导度,旨在揭示冷源功能叶片的结构和生理特性。结果表明,冷源旗叶叶片厚度分别比冷型小麦和暖型小麦高出19.3%和9.0%,倒二叶分别高出19.7%和5.7%,倒三叶分别高出37.2%和2.7%;冷源旗叶叶脉横截面积分别比冷型小麦和暖型小麦高出25.2%和37.7%,倒二叶分别高出5.9%和12.6%,倒三叶分别高出13.1%和33.3%;冷源旗叶、倒二叶和倒三叶中的叶脉间距分别比冷型小麦小偃6号同叶位功能叶片高出17.7%,2.0%和9.2%,分别比暖型小麦9430同叶位功能叶片低3.7%、6.8%和8.3%。随着籽粒灌浆的进行,冷源、冷型小麦和暖型小麦功能叶片的叶绿素含量、净光合速率、蒸腾速率和气孔导度均呈下降趋势,但冷源和冷型小麦在灌浆前、中、后期均较暖型小麦高,功能叶片衰老缓慢,功能期较长。     

Comparison of two crossing and four selection schemes for yield, yield traits, and slow rusting resistance to leaf rust in wheat

The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency. Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection schemes were: pedigree, modified bulk (F₂ and F₁-top as pedigree, selected lines in F₃, F₄, F₂-top, F₃-top as bulk; and pedigree in F₅ and F₄-top populations), selected bulk (selected plants in F₂, F₃, F₄, F₁-top, F₂-top and F₃-top as bulk; and pedigree in F₅ and F₄-top populations), and nonselected bulk (bulk in F₂, F₃, F₄, F₁-top, F₂-top and F₃-top; and pedigree in F₅ and F₄-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore, a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency. This revised version was published online in August 2006 with corrections to the Cover Date.     

Quantitative trait loci mapping for flag leaf traits in rice using a chromosome segment substitution line population

To study the genetic basis of rice flag leaf morphology, quantitative genetic analysis was conducted in a population of 37 chromosome segment substitution lines (CSSLs) of indica elite variety ‘Habataki’ in the background of japonica cultivar ‘Sasanishiki’ across three different environments. The CSSLs showed normal distribution with transgressive segregation, indicating that these four traits are controlled by polygenes. Moreover, analyses of variance showed that these traits were highly influenced by the growing environment, which are typical for polygenic quantitative traits. Seven quantitative trait loci (QTLs) on four chromosomes were detected in total: four for flag leaf width, one for flag leaf area and two for flag leaf angle. Two key QTLs, qFLW4 and qFLAG5 controlling flag leaf width and angle, respectively, were identified in all three environments. These QTLs could provide useful information for marker‐assisted selection in improving the performance of plant architecture with regard to leaf angle and area. Moreover, developed CSSLs with these QTLs information are also useful research materials to reveal the importance of leaf morphology in relation to grain yield.     

小偃54和京411及其杂交后代稳定优选株系光合特性的动态变化

以上海种植的小偃54和京411及其杂交后代稳定优选株系6号、7号和10号为材料,通过测定抽穗期剑叶的毫秒延迟发光(ms-DLE)和不同生育期倒数第1片功能叶的光合速率(P_n)、叶绿素含量(Chl)、比叶重(SLW)、F_v/F_m、ATP含量和P700还原初始速率来分析其光合特性的动态变化,为小麦育种选择中改善光合性能提供理论依据和技术途径。结果表明,小麦杂交优选后代6号株系的形态农艺性状近于小偃54,7号株系近于京411,10号株系的变异较大。不同基因型小麦及其杂交优选后代的光合特性与生育时期和衡量指标密切相关,P_n为分蘖期>抽穗期>灌浆期>拔节期,叶绿素含量为灌浆期>抽穗期>分蘖期>拔节期,ATP含量为灌浆期>拔节期>分蘖期>抽穗期,P700还原初始速率为灌浆期>抽穗期>拔节期>分蘖期,各生育期间的F_v/F_m无明显差异。小麦光合特性的超亲优势随生育时期而异,杂交优选后代10号株系的P_n和Chl在灌浆期有超亲优势,ATP含量在抽穗期有超亲优势,SLW和P700还原初始速率介于两亲本间。杂交优选后代株系10号聚合了P_n、Chl和ATP含量的超亲优势,其光合特性优于两亲本,而6号劣于两亲本,7号介于两亲本之间。