不同品种夏玉米主要性状与产量相关性分析

为了探索不同品种夏玉米产量与主要性状关系,采用田间试验,研究了中国生产上利用的15 个优良玉米杂交品种不同生育期的叶面积指数、叶面积指数增长率和光合势的变化及其与产量的关系。结果表明：15 个玉米杂交种中‘登海602’产量最高,玉米叶面积指数较高,具有较高的光合势;各玉米品种间的叶面积指数随生育进程均呈单峰曲线变化,在吐丝期达到最高,各玉米品种间存在差异,玉米叶面积指数增长率亦具有相同趋势;各品种光合势在整个生育期呈单峰曲线变化,峰值出现在吐丝期至乳熟期;拔节—苗期叶面积指数增长率与产量的直接通径系数最大;蜡熟—完熟期的光合势对产量的直接效应最大。苗期—拔节期和蜡熟—完熟期是玉米高产形成的关键时期。     

黄淮麦区高产小麦品种的产量结构及其生理基础的研究

研究了黄淮麦区具有不同产量潜力水平的小麦品种的产量结构及其相关生理基础。结果表明,随着小麦品种由低产型向高产型转变,每穗粒重,每穗粒数,千粒重,收获指数,生物产量均有所增加,其中以收获指数和每穗粒重所起的作用最大;在生理特征上,干物重呈现出拔节期递增、开花期递减、成熟期又表现递增的“Ｎ”型变化曲线,相对生长率的变化也呈同一趋势。旗叶净光合强度及叶绿素含量均呈递增趋势。开花期叶面积指数（ＬＡＩ）则呈     

利用京411为骨干亲本培育高产小麦新品种

提高产量潜力是我国小麦育种的首要目标.从1990年开始,本课题组以高产品种京411为骨干亲本,针对其主要缺点进行改造,取得一定进展.育成了中麦175等3个通过审定的品种,推广面积正在逐年扩大.总结选用和改造京411的经验与体会认为:通过增加穗粒数和粒重来提高稳重是提高产量潜力的重要途径.     

小麦骨干亲本繁6产量相关性状关键基因组区段的遗传效应

繁6是中国小麦育种最重要的骨干亲本之一, 明确其优良特性的遗传机制对小麦育种具有重要意义。本研究鉴定了39个繁6衍生品种的7个产量相关性状, 并利用全基因组SSR标记分析了繁6中控制这些性状重要遗传区段和基因位点在子代中的遗传效应。表型鉴定结果表明, 繁6产量相关性状在不同世代衍生品种中表现无显著差异, 表明这些性状在衍生品种选育过程中受到选择并稳定遗传。利用已获得的控制小麦产量相关“一致性” QTL区段的417个SSR标记进行分子扫描, 发现11个繁6特异SSR标记在其衍生后代中被高频率遗传。性状-标记关联分析表明, 21个来自繁6的特异SSR标记与产量相关性状极显著关联(P < 0.01)。同时鉴定出分别位于2A和5A染色体的Xgdm93.3-Xgwm526.2和Xbarc100-Xgwm156.1区段, 前者控制株高和小穗数, 后者控制千粒重。本研究证实, 上述两个与小麦产量相关性状关联的位点或区段在小麦产量育种进程中受到强烈的人为定向连续选择, 并在四川乃至西南麦区小麦产量育种中发挥了重要作用。     

小麦骨干亲本临汾5064单元型区段的遗传解析

利用分子标记解析骨干亲本临汾5064单元型区段在其衍生后代中的遗传规律, 可以为小麦分子育种提供依据。在临汾5064及其21个衍生品种(系)中, 395个SSR标记共检测出895个等位变异, 不同位点的等位变异为1~8个, 平均2.27个, 平均多态性指数为0.25。临汾5064及衍生后代中146个位点具有相同等位变异, 遗传贡献超过80%的位点有30个。实验结果表明, 临汾5064对衍生子一代和子二代的遗传贡献率分别为65.30%和64.24%, 且未随着世代的增加而明显下降。所有衍生后代与亲本完全相同的单元型区段有16个, 贡献率大于80%的染色体区段分布在所有染色体上。关联分析发现这些单元型区段存在重要农艺性状的QTL簇, 几乎都与重要农艺性状显著相关, 表明这些区段在育种过程中受到强烈选择。     

小麦早熟高产品种光合生理特性分析

对陕西关中地区当前推广的早、中、晚三种熟性8个高产小麦品种的光合生理特性进行了研究，以探明参试的早熟小麦品种高产的光合生理机能和进一步提高早熟小麦品种产量潜力的性状改良途径，结果表明，参试早熟高产小麦品种的光合生理物性是：1．灌浆高峰期蒸腾速率高；2．花期至灌浆高峰期有持续稳定的高净光合速率；3．花前同化产物对子粒干物质累积贡献潜势大；4．花后单株生物增长量远高于中、晚熟品种；5．花前同化产物转流系数高，花后干特质增长系数高，光合产物分配性能好，收获指数高。同时也进一步明确早熟高产小麦品种的生物学产量低于中、晚熟品种，其原因主要在于拔节期至开花期的生物学增长量少。进一步提高早熟小麦品种产量潜力的途径是保持或提高收获指数的同时，较大幅度地提高花期的生物学产量。     

贵州省小麦育种研究与分析

当前贵州小麦类型有:高产型、高效型、高值型,产量目标为350 kg/667 m2。决定小麦产量潜力的关键因素是产量性状和光合生理性状,高产小麦育种重点应进行单位面积有效穗、穗粒数、千粒重的遗传选择,花后光合速率、花后绿叶面积、灌浆高峰期单穗平均日增重、灌浆高峰持续时间、生物学产量、收获指数等性状的遗传改良已很重要。聚优交配是选育高产小麦新品种的有效育种技术。为了适应高产育种的纵深发展要求,要加强光合生理特性、性状遗传规律等基础理论研究和高产小麦大穗材料创新工作,同时要进行育种技术的改进。     

川麦42的1BS染色体臂对小麦主要农艺性状的遗传效应

川麦42的1BS染色体臂来源于人工合成小麦亲本Syn769。利用川麦42与含1BL/1RS易位系的四川小麦品种川农16构建的127个重组自交系(RIL, F₈),经3年4个环境的遗传评价,比较了川麦42的1BS和川农16的1RS染色体臂对小麦产量构成因子和产量的遗传效应。结果表明,RIL群体中川麦42的1BS染色体臂株系和川农16的1RS染色体臂株系在分蘖力、成穗率、全生育期、小穗数、收获指数和籽粒产量6个性状上存在显著差异; 1BS染色体臂有利于提高成穗率和收获指数,而1RS染色体臂有利于提高分蘖能力和增加小穗数,1BS株系的籽粒平均产量比1RS株系增加2.91%。鉴于1RS染色体臂上的抗条锈病基因丧失抗性,其携带的黑麦碱基因对加工品质有明显的负向作用,而川麦42的1BS染色体臂携带高抗条锈病基因YrCH42, 并对小麦籽粒产量有正向作用,因此建议在小麦遗传改良中利用川麦42的1BS替换1RS染色体臂。     

高产小麦新品种中麦415的选育

中麦415是中国农业科学院作物科学研究所国家小麦改良中心培育的高产、稳产小麦新品种,组合是京411/贵农11//京411。2010年12月通过国家品种审定,审定号为国审麦2010016。     

山东省小麦品种产量性状的演变与现状分析

研究了山东省及黄淮麦区建国以来小麦品种产量及相关性状的演变趋势以及当前高产新品种(系)相应性状的表现。随品种更替,产量水平不断提高。产量构成因素中,千粒重增幅最大,穗粒数在点播条件和大田条件下的演变趋势有所不同。株高降低,株型结构日趋合理,收获指数逐渐提高。从历史演变和品种现状综合分析表明,穗重是决定产量的主导因素。提高穗重应注意千粒重和穗粒数二因子协调发展,千粒重改良的潜力和作用可能更大些。对山东省及黄淮麦区今后小麦高产育种的途径进行了探讨。     

不同氮素处理对中麦175和京冬17产量相关性状和氮素利用效率的影响

本研究旨在了解我国黄淮和北部冬麦区不同施氮量和施氮模式对氮高效吸收和利用的影响,以及中麦175和京冬17产量对不同施氮处理的响应。2013-2014和2014-2015连续两年在河北吴桥和北京顺义两地种植两品种,观测不同施氮量和基追比处理下,冬小麦的群体特性、产量相关性状,以及氮素吸收效率(NUpE)和氮素利用效率(NUtE)。在吴桥点设0、60+0、120+0、120+60、120+120、120+180 kg hm?2 (基肥+拔节肥) 6个处理,在顺义点仅设前5个处理。在总施氮量0~240 kg hm?2 (吴桥)和0~180 kg hm?2 (顺义)范围内,随施氮量增加,归一化植被指数(NDVI)和气冠温差(CTD)提高,群体总粒数和成熟期生物量增加,进而产量提高;但继续增加施氮量会导致粒重、开花前干物质向籽粒转运量、转运率、对籽粒贡献率、收获指数、氮肥偏生产力、氮素吸收和利用效率降低。在不同施氮水平下,中麦175的产量和稳定性均优于京冬17,表现出穗数多、穗粒重稳定性好、群体活力持久、生物量和收获指数高、花前干物质积累量高和花后干物质转运能力强、氮素吸收效率高,这可能是其高产高效的重要基础。考虑到产量回报和经济效益,推荐中麦175和京冬17在黄淮麦区(北片)施氮量为180~240 kg hm?2,在北部冬麦区施氮量为120~180 kg hm?2。灌浆中后期,NDVI和CTD与穗数、产量和生物量相关性高,可作为快速评价品种氮肥敏感性的指标。     

江淮稻区杂交粳稻骨干亲本产量性状配合力的SSR标记位点鉴定

鉴定杂交粳稻亲本产量性状配合力的标记位点有助于利用分子标记辅助选择技术改良亲本配合力、提高杂交粳稻竞争优势水平。利用9个粳稻BT型不育系和10个恢复系, 按照北卡罗林那设计II (North Carolina Design II)配制90个F₁组合,在南京和盱眙两个环境下种植,测定了各亲本产量性状的配合力和SSR分子标记基因型;结合二者数据鉴定了6个产量性状配合力的标记位点。结果表明,在两个环境下综合评价配合力较优的不育系是BT-18A和武羌A,恢复系是C418。与亲本单株有效穗数、每穗总粒数、每穗实粒数、结实率、千粒重和单株日产量性状配合力显著相关的SSR标记位点,南京环境下分别检测到8、13、11、6、6和2个;盱眙环境下分别检测到12、21、8、15、10和7个;2个环境下都检测到的分别有4、11、5、3、5和1个。标记位点杂合基因型显示正向优势的,南京环境下占74% (34/46);盱眙环境下占53% (39/73)。2个环境下都检测到的标记位点中,有3个各自与3个产量性状配合力共相关;另有3个各自与2个产量性状配合力共相关;其余的只与单个产量性状配合力显著相关。数据库检索发现两环境下都检测到的标记位点中,有10个其附近存在控制相应性状的基因/QTL。讨论了利用鉴定出的标记位点改良粳稻恢复系产量性状配合力的策略。     

木薯单株产量与主要农艺性状的相关性研究

探讨木薯单株产量与主要农艺性状的相关性,以提高木薯育种效率,为木薯品种选育奠定基础。采用13 份木薯种质资源为试验材料,通过相关与通径分析等方法,探讨了11 个主要农艺性状与单株产量之间的相关性以及不同种质资源单株产量之间的差异性。结果表明：NK-2、NK-6、NK-7、NK-10、NK-11、‘新选048’与‘华南205’之间的单株产量呈显著差异;单株产量与块根数呈极显著正相关,与收获指数、生物产量、最长薯长、主茎高度呈显著正相关,与干物质含量呈显著负相关;通径分析结果表明,各农艺性状对单株产量的直接通径系数和决定系数的大小顺序一致,依次为：块根数、最长薯长、生物产量、主茎高度、叶保留高度、干物质含量、收获指数、地上部鲜重、淀粉含量、主茎粗、株高。由此表明,选育高产木薯需要关注的主要农艺性状有：块根数、最长薯长、生物产量、主茎高度、叶保留高度、干物质含量、收获指数等。     

Contrasting rice backcross inbred lines (BILs) for grain yield and heading under lowland reproductive stage moisture stress

Identification and understanding the role of physio-morphological drought responsive mechanisms leading to grain yield enhancement under water stress is a critical insight for designing appropriate strategies to breed drought-tolerant cultivars for any drought prone ecology. In this study, three pairs of contrasting BILs with varied maturity were characterized for several agronomical, physiological and morphological traits across a wide range of moisture stress environments at reproductive stage during 2012–2014. Within each group, BILs differ significantly for grain yield, heading, biomass and harvest index under drought stress, but showed similar yield potential, phenology and other traits under control condition. The most tolerant BIL, S-15 out yielded all BILs and standard checks under both conditions. Apart from superior agronomic performance, drought tolerant BILs maintained significantly higher assimilation rate, transpiration rate and transpiration efficiency compared to susceptible BILs under stress in all three groups. In addition, most tolerant BIL (S-15) showed significantly higher stomatal conductance than susceptible BIL (S-55) in early group. Among root traits, significant differences under stress was observed for root dry weight between contrasting BILs in each group, even though tolerant BILs had higher root length and root volume compared to susceptible BILs, which is non-significant. Hence, consideration of root traits an important strategy for drought avoidance in case of rice may not always contributes to significant yield improvement under moisture stress condition. Further, tolerant BILs also recorded significantly higher shoot dry weight and drought recovery score at seedling stage under stress. Our findings suggest that genotypes with higher photosynthetic efficiency and better plant water status are able to produce higher grain yield under drought stress environments.     

Relationship between grain yield and grain nitrogen concentration in winter triticale

Summary Ten hexaploid winter triticale lines were grown for two cropping periods at three locations in western Switzerland. Averaged across the six environments, the differences between lines were statistically significant (P=0.05) for grain yield, above-ground biomass, N uptake, grain N yield, nitrogen harvest index, grain N concentration and straw N concentration. There were significant line x environment interactions for all traits. Grain yield and grain N concentration were inversely related (r=–0.74^**). Diagrams in which grain yields were plotted against grain N concentration were used to identify lines with a consistently unusual combination of grain yield and grain N concentration. Despite comparable grain yields, Line 3 had a high grain N concentration, while that of Line 7 was low. Line 3 was superior to Line 7 in both N uptake and N harvest index. Averaged across environments and lines, the N harvest index was 0.73 which corresponds to N harvest indices reported for bread wheat in the same region. We considered the feasibility of developing triticale lines which would outperform the best recent ones in N uptake and partitioning. However, we doubted that this would bring about a marked increase in grain N concentration, because, in the long run, the expected genetic progress in grain yield will lead to a dilution of grain protein by grain carbohydrate increments.Abbreviations GNC grain N concentration - GNY grain N yield - GY grain yield - HI above-ground dry matter harvest index - NHI nitrogen harvest index - SNC straw N concentration - TB total above-ground biomass - TPN total plant N     

Estimates of selection parameters associated with harvest index in oat lines derived from a bulk population

Summary Harvest index of grain crops is defined as grain yield divided by total plant yield. We estimated the heritability percentages of harvest index and its components, grain yield and plant weight, the genotypic and phenotypic correlations among these three traits, and the genotypic correlations of harvest index with plant height, 100-seed weight, grain number, and heading date by using a population of 1200 F₉-derived oat lines tested in six environments. Furthermore, we examined the relative selection efficiencies of indirect selection for yield through harvest index and of index selection for yield through yield plus harvest index.Heritability percentages were computed by use of variance-component, standard-unit, and realizedheritability methods. The heritability percentages for harvest index, grain yield, and plant weight were similar, and averaged between 50 and 65 precent across environments. Standard-unit and realized heritability percentages agreed closely and generally were lower than those computed via the variance-component method. Expected heritability percentages for harvest index calculated by using grain and plant yield data agreed almost exactly with actual values. Genotypic correlations were 0.88 between grain yield and plant weight, 0.42 between harvest index and grain yield, and –0.07 between harvest index and plant weight. Genotypic and phenotipic correlations were similar in magnitude. Theoretical and actual genotypic and phenotypic correlations of harvest index with grain yield and plant weight agreed closely. Genotypic correlations, computed via parent-offspring relationships, between harvest index and plant height, 100-seed weight, grain number, and heading date averaged –0.41, 0.43, 0.00, and –0.33 respectively.Indirect selection for grain yield through harvest index was 43 percent as efficient as direct selection, and a selection index that combined harvest index and grain yield was no more efficient than direct selection for yield. Harvest index had little value as a selection criterion for grain yield improvement when unrestricted selection was used. Indirect selection for grain yield through harvest index, however, would be expected to retain lines with a more favorable combination of yield, plant height and heading date than would unrestricted direct selection for yield.Journal Paper No. J-7914 of the Iowa Agriculture and Home Economic Experiment Station, Ames, Iowa 50010, Project No. 1752.     

Genome-wide association analysis detecting significant single nucleotide polymorphisms for chlorophyll and chlorophyll fluorescence parameters in soybean (Glycine max) landraces

Chlorophyll fluorescence parameters are generally used to characterize the intrinsic action of photosystem II (PSII), which is interrelated with the photosynthetic capacity. Mapping of quantitative trait loci for chlorophyll fluorescence parameters and associated traits is important for genetic improvement in soybean. In this study, a genome-wide association analysis was conducted to detect key single-nucleotide polymorphisms (SNPs) associated with chlorophyll content (chl) and chlorophyll fluorescence using 1,536 SNPs in a soybean landraces panel. The analysis revealed significant correlations among chl and five chlorophyll fluorescence parameters, including maximum quantum yield of PSII primary photochemistry in the dark-adapted state (Fv/Fm), light energy absorbed per reaction center (ABS/RC), quantum yield for electron transport (ETo/ABS), probability that a trapped exciton moves an electron into the electron transport chain beyond QA⁻ (ETo/TRo), and performance index on absorption basis (PI_ABS). Genome-wide association analysis using a mixed linear model detected 51 SNPs associated with chl and chlorophyll fluorescence parameters. Among these identified SNPs, 14 SNPs were co-associated with two or more different traits in this study, and 8 SNPs were co-associated with soybean yield and yield components in our previous study. These significant SNPs will help to better understand the genetic basis of photosynthesis-related physiological traits, and facilitate the pyramiding of favorable alleles for photosynthetic traits in soybean marker assisted selection schemes for high photosynthetic efficiency.     

Genomic regions associated with grain yield and aspects of post-flowering drought tolerance in pearl millet across stress environments and tester background

A pearl millet mapping population from a cross between ICMB841 and 863B was studied for DNA polymorphism to construct a genetic linkage map, and to map genomic regions associated with grain and stover yield, and aspects of drought tolerance. To identify genomic regions associated with these traits, mapping population testcrosses of 79 F₃ progenies were evaluated under post-flowering drought stress conditions over 2 years and in the background of two elite testers. A significant genotype × drought stress treatment interaction was evident in the expression of grain and stover yield in drought environments and in the background of testers over the 2 years. As a result of this, genomic regions associated with grain and stover yield and the aspects of drought tolerance were also affected: some regions were more affected by the changes in the environments (i.e. severity and duration of drought stress) while others were commonly identified across the drought stress environments and tester background used. In most instances, both harvest index and panicle harvest index co-mapped with grain yield suggesting that increased drought tolerance and yield of pearl millet that mapped to these regions was achieved by increased partitioning of dry matter from stover to the grains. Drought stress treatments, years and testers interactions on genomic regions associated with grain and stover yield of pearl millet are discussed, particularly, in reference to genetic improvement of drought tolerance of this crop using marker-assisted selection.     

Environmental Adaptation and Stability Relationships between Grain Yield and some Agronomic Traits in Winter Oat

This study was conducted to determine the stability of grain yield, harvest index, plant height, and panicle length and to determine the association of grain yield with these traits in winter white oat ( Avena sativa L.) genotypes. The genotypes were grown in replicated tests in Ankara in 1985–1991. Each experiment year was regarded as an environment, and entry mean of each year was used as the environmental index. Stability parameters were estimated from the regression analysis as linear regression coefficient (b), deviations from regression (S²d) and coefficient of determination (r²).
Genotypes differed significantly for all traits and significant genotypes X environment interactions occurred for these traits. On the basis of estimates of stability parameters, A-24 genotype was stable for grain yield. Correlation coefficients between traits were inconsistent in good and poor environments except between grain yield and panicle length. The study suggested that these traits are differently affected by environmental changes and selection for panicle length might be effective as selection for grain yield in improving oats with high grain yield for diverse environments.     

Physiological attributes associated with yield and stability in selected lines of a durum wheat population

Further increasing yield potential remains one of the main objectives of wheat breeding, even in stressful environments. In general, past genetic gains were associated with increases in harvest index, and future gains should be related to greater biomass. Identifying genetic sources for such improvement may be relevant. Researchers of TRITIMED identified DH lines of durum wheat apparently possessing not only high yield potential but also good yield stability. We aimed to determine physiological attributes responsible for yield and stability among a set of genotypes derived from two parents (Cham 1 and Lahn) and four of the most promising lines of the DH population (2401, 2408, 2410, 2517). Seven field trials were carried out within the Mediterranean agricultural region of the Ebro Valley, under a wide range of conditions (ca 2–10 mg ha⁻¹). In four of these experiments, sub-plots were included with source-sink manipulations imposed after anthesis. Cham 1, a cultivar known for high yields in semi-arid conditions, showed the highest yield potential. Although it showed less yield stability than Lahn, even under the lowest yielding conditions its yield was not significantly lower than that of Lahn. RILs 2408, 2410, 2004 and 2517 slightly outyielded Lahn in high-yielding conditions, but under poorer environments they tended to yield less. Interestingly, yield differences were closely related to their biomass rather than harvest index. Thus yield differences relating to the number of grains per m² were due to differences in spike dry matter at anthesis, reflecting in part genotypic differences in crop growth from jointing to anthesis. In general grain weight did not respond to spike trimming after anthesis, although in two experiments the grain weight of Cham 1 did so. Thus, even the highest-yielding cultivar possessed grains that overall seemed more limited by its constitutive capacity to grow than by the availability of resources to reach this capacity (though occasionally they may be co-limited). Overall, the most interesting feature was the empirical evidence that improvement of biomass within elite material is a worthwhile objective.