Genetic diversity and path analysis for nitrogen use efficiency in popcorn inbred lines

Popcorn inbred lines with more efficient nitrogen use are better able to uptake nitrogen from the soil and convert it into higher grain yield, resulting in lower environmental and economic impacts caused by nitrogen fertilization. The objectives of this study were to (i) identify inbred lines superior in nitrogen use (ii) assess the genetic diversity between popcorn inbred lines under high and low N conditions and (iii) investigate the causal effects of several traits in nitrogen use efficiency (NUE). We evaluated 25 popcorn inbred lines under high and low N, and several traits related to NUE and its components were measured. Efficient and inefficient inbred lines under both N levels were identified and can be useful for generating a segregating population for quantitative trait loci mapping. The genetic diversity assessment based on phenotypic traits grouped the inbred lines into four clusters under both N levels, and the efficient inbred lines were grouped together, as were the inefficient lines. The most divergent inbred lines under high N were classified as efficient and intermediate and can be useful to generate a divergent breeding population with a high frequency of favorable genes for NUE. Nitrogen uptake efficiency (NUpE) was considered the most important trait for NUE. To improve the accuracy of selection for NUE, a selection index involving the total root length (TRL), daily growth and NUpE traits under both N levels is recommended, as these traits had high correlations with and direct effects on NUE.     

Mapping quantitative trait loci for tolerance to phosphorus-deficiency at the seedling stage in barley

Phosphorus (P) deficiency in soil is a major factor that limits barley yield production. Increasing the tolerance to P-deficiency of barley is one of the most cost-effective solutions. Quantitative trait loci (QTLs) controlling P acquisition, P utilization efficiency and biomass at the seedling stage were identified using a population of recombinant inbred lines (RILs) subjected to two P concentrations (low P (LP), 25 µM and normal P (NP), 250 µM). The population was derived from a cross between Baudin and CN4027, which is a Hordeum spontaneum accession. In two hydroponic trials conducted in 2014 and 2016, seventeen QTLs were detected on chromosomes 2H, 3H, 4H and 5H at the two P concentrations. Eight of these QTLs influenced P acquisition efficiency (PAE). Phenotypic variation explained by a particular PAE-related QTL ranged from 13.3 to 39.9%. One QTL designated as Qspue.sau-3H.01 was related to P utilization efficiency (PUE); the phenotypic variation explained by this QTL was 12.5% (NP concentration) and 13.1% (LP concentration), respectively. Strong associations were observed between biomass and P efficiency-related traits in our study. Two QTL clusters controlling biomass, PAE- and PUE-related traits simultaneously were stably identified in the intervals bPb3263664–bPb3931069 and bPb3264570–bPb4786261 on chromosome 3H at both P concentrations in both trials. The QTLs related to PAE, PUE and biomass are important for the P-tolerant phenotype and may offer valuable clues for fine mapping and map-based cloning of barley.     

不同磷水平下大麦分蘖期磷效率相关性状QTL定位分析

磷素营养与大麦品质及产量密切相关,磷高效遗传机制和品种改良是近年的研究热点之一。本研究利用由大麦栽培品种Baudin和种质材料CN4079杂交构建的重组自交系(RIL)群体,低磷胁迫(0.02 mmol L~(-1) KH_2PO_4)与正常供磷(0.2 mmol L~(-1) KH_2PO_4)条件下,对地上部和地下部磷素利用效率、磷素吸收效率和干重,以及分蘖数相关的QTL定位,并预测相关位点基因。表型鉴定结果表明,各性状在RIL群体中表现连续变异,并存在超亲分离。两种磷水平下,共检测到16个QTL,分布在2H、3H和5H染色体上,表型贡献率14.1%~28.5%。3H染色体上含有3个磷素利用效率位点,其增效等位基因均来源于Baudin,其中Qspue.sau-3H.1和Qrpue.sau-3H与控制磷素吸收效率的Qspae.sau-3H和Qrpae.sau-3H处于同一区段,而Qspue.sau-3H.2与控制分蘖数的位点Qtn.sau-3H处于同一区段。5H染色体上含有3个磷素吸收效率位点,其中Qspae.sau-5H.2和Qrpae.sau-5H的增效等位基因来自CN4079,且与控制磷素利用效率的Qspue.sau-5H和Qrpue.sau-5H,以及控制干重的Qsdw.sau-5H和Qrdw.sau-5H处于同一区段。在磷效率相关的4个区段中,除Qspue.sau-3H.1所处区间仅含有磷酸代谢与磷脂代谢相关基因外,其他区间均包含磷酸盐转运蛋白基因、磷酸代谢与磷脂代谢相关基因。     

Utilization of molecular markers for improving the phosphorus efficiency in crop plants

Phosphorus (P) is the second most growth limiting macronutrient after nitrogen and plays several important roles in all organisms including plants. In soil, P is available in both organic and inorganic forms. P deficiency reduces the growth and yield of several crop plants. Plants respond to P deficiency by the phenotypic changes especially by the modification of root architecture. Molecular marker‐assisted breeding (MAB) has been proposed as an important tool to identify and develop improved varieties of crop plants with efficient P‐use efficiency (PUE). Identification of quantitative trait loci (QTLs) for traits related to PUE has been considered as the first step in marker‐assisted selection (MAS) and improvement of crop yield programmes. In this review, we describe in detail on architectural changes of roots under P deficiency that are reported in various crops and discuss the efforts made to improve PUE using molecular marker tools. Details on QTLs identified for low P‐stress tolerance in various crop plants are presented. These QTLs can be used to improve PUE in crop plants through MAS and breeding, which may be beneficial to improve the yields under P‐deficient soil. Development of new and improved varieties using MAB will limit the use of non‐renewable fertilizers and improve PUE of key crop plants in low input agriculture.     

甘蓝型油菜重组自交系苗期磷效率的评价

设置低磷P1 (5 μmol L^-1)和高磷P2 (1 000 μmol L^-1)处理水培甘蓝型油菜重组自交系群体的135个株系及亲本的幼苗, 以地上部干重(SDW)、根干重(RDW)、根冠比(R/S)、主根长(AMRL)、地上部磷积累量(SPU)、总磷吸收量(TPU)、磷利用效率(PUE)作为耐性指标, 调查群体各株系和亲本间对缺磷反应的差异, 并对各性状参数与磷吸收、利用效率进行相关性分析。结果表明: (1) 低磷胁迫严重抑制甘蓝型油菜苗期生长, 所调查的各性状均表现出显著差异,其中地上部干重和根干重的变异系数较大;(2) 2种处理条件下, 各株系的地上部干重、根干重、根冠比和主根长4个性状均表现出显著分离, 并呈现正态分布,低磷处理的分离更为明显;(3) 相关性分析表明, 相对地上部干重和根干重可以作为磷效率的主要评价指标,为了避免遗传因素影响, 还应考虑低磷处理下基因型各性状的绝对差异;(4) 通过上述筛选指标,确定065﹑102﹑070为候选的极端磷高效基因型, 105﹑076﹑011等为候选的极端磷低效基因型。     

Generation mean analysis of phosphorus‐use efficiency in freely nodulating soybean crosses grown in low‐phosphorus soil

Freely nodulating soybean genotypes vary in their phosphorus (P) uptake and P‐use efficiency (PUE) in low‐P soils. Understanding the genetic basis of these genotypes’ performance is essential for effective breeding. To study the inheritance of PUE, we conducted crosses using two high‐PUE genotypes, two moderate‐PUE genotypes and two inefficient‐PUE genotypes, and obtained F₁, F_2, BC₁ and BC₂ populations. The inheritance of PUE was evaluated using a randomized complete block design. A generation mean analysis of phenotypic data showed that PUE was heritable, with complex inheritance patterns and the presence of additive, dominance and epistatic gene effects. Seed P, shoot P, root P, P‐incorporation efficiency and PUE were largely quantitatively inherited traits. There were dominance, additive × additive and dominance × dominance gene effects on PUE, grain yield, shoot dry weight, 100‐seed weight, root dry weight and shoot dry matter per unit P for populations grown under low‐P conditions. Dominance effects were generally greater than additive effects on PUE‐related indices. These PUE indices can be used to select P‐efficient soybean genotypes from segregating populations.     

作物磷效率相关性状的QTL分析研究进展

土壤缺磷是作物生产的主要限制因素之一。利用遗传育种的途径选育磷高效的作物新品种,结合传统的改土施肥方法,是经济、环保地解决土壤缺磷问题的有效措施。数量性状座位(QTL)的定位分析为磷效率的数量性状遗传学研究和磷高效品种的选育提供了有效的手段和途径。本文对近年来利用分子标记对磷效率及其相关性状进行数量性状QTL定位分析的研究成果进行了综述,讨论了作物磷效率遗传改良存在的问题,展望了该领域的发展前景。     

不同密度下玉米穗部性状的QTL分析

为研究玉米穗部性状对不同种植密度的遗传响应,以郑58和HD568为亲本构建的220个重组自交系群体为材料,于2014年春、2014年冬及2015年春分别在北京和海南进行3个种植密度的田间试验,调查玉米穗长、穗粗、穗行数和行粒数等表型性状。利用SAS软件计算穗部性状的最优线性无偏估计值(BLUP),并采用完备区间作图法进行QTL定位。结果表明,在3个种植密度下共检测到42个QTL,单个QTL可解释4.20%~14.07%的表型变异。3个种植密度下同时检测到位于第2染色体上控制穗行数的QTL。2个种植密度下同时检测到4个与穗粗、穗行数和行粒数有关的QTL,其中第4染色体上1个与穗行数有关的主效QTL,在低、中种植密度下可分别解释表型变异的10.88%和14.07%。此外,在第2、4和9染色体上检测到3个同时调控不同穗部性状的QTL。研究结果表明玉米穗部性状在不同种植密度下的遗传调控发生变化,在不同密度下共同检测到的稳定QTL可应用于精细定位或开发玉米耐密性分子标记用于辅助育种。     

Construction of a chromosome-assigned,sequence-tagged linkage map for the radish,Raphanus sativus L. and QTL analysis of morphological traits

The radish displays great morphological variation but the genetic factors underlying this variability are mostly unknown. To identify quantitative trait loci (QTLs) controlling radish morphological traits, we cultivated 94 F₄ and F₅ recombinant inbred lines derived from a cross between the rat-tail radish and the Japanese radish cultivar ‘Harufuku’ inbred lines. Eight morphological traits (ovule and seed numbers per silique, plant shape, pubescence and root formation) were measured for investigation. We constructed a map composed of 322 markers with a total length of 673.6 cM. The linkage groups were assigned to the radish chromosomes using disomic rape-radish chromosome-addition lines. On the map, eight and 10 QTLs were identified in 2008 and 2009, respectively. The chromosome-linkage group correspondence, the sequence-specific markers and the QTLs detected here will provide useful information for further genetic studies and for selection during radish breeding programs.     

Genotypic variation and relationships between seedling and adult plant traits in maize (Zea mays L.) inbred lines grown under contrasting nitrogen levels

Genotypes with better root development have good nutrient acquisition capacity and may yield better under limited nitrogen (N) conditions and consequently can help reduce the N fertilization rate and hence mitigate some economic and ecological problems. This study focused on the genotypic variation among diverse maize inbred lines for seedling and adult plant traits under contrasting N levels. Seventy-four lines were screened under high and low N levels in a climate chamber and in the field. High phenotypic diversity was observed for seedling and adult plant traits together with moderate to high broad-sense heritability estimates. Seedling total root length and root dry weight were significantly correlated with other root traits in maize. Of the adult plant traits evaluated in the field, the anthesis-silking interval and the leaf chlorophyll contents were significantly correlated with grain yield under both low and high N levels. In one location, the seminal root length was correlated with grain yield both under low and high N levels and the root dry weight was correlated with grain yield under high N. Selection indices based on secondary root traits along with grain yield could lead to an increase in selection efficiency for grain yield under N stress condition. By identifying lines with better root development, particularly lines with longer SRL, it may be possible to select inbred lines with higher grain yield particularly under low N condition.     

Combining ability and gene action for maturity and agronomic traits in different heterotic groups of maize inbred lines and their diallel crosses

Combining ability information is necessary for selection of suitable advanced lines for hybridization and identification of promising hybrids for development of improved varieties. A number of 14 maize (Zea mays L.) inbred lines and 91 related crosses were evaluated over two years, 2008 and 2009, in a temperate-zone of Iran. The objectives of the study were to identify the best general and specific combiners, heterosis and type of gene actions responsible for agronomic traits. Except for grain yield and growing degree day to milky, significant general (GCA) and specific (SCA) combining ability were observed for all traits. The Baker ratio for plant height (0.15), ear height (0.26), growing degree day to milky stage (0.04), and grain yield (0.002) showed the predominance of non-additive gene effects in the expression of these traits. The heterosis observed for grain yield, grain number, pollination period, ear and plant height was considerably higher than that observed for other traits. The correlations (r) of F₁ means and SCA effects were positive and significantly higher than that of r (F₁, mid-parents) and r (F₁, heterosis) for all the traits except cob percent, growing degree days to silking, and physiological maturity. MO17, K3547/5, and K3615/2 had negative GCA effects for growing degree day to milky stage and maturity. Among hybrids, MO17 × K3653/2, B73 × K3651/2, and K3545/6 × K3493/1 with positive SCAs for pollination period and grain yield had also negative SCA effects for degree day to silking and milky stages. Therefore, the use of these inbred lines and hybrids increases the response to selection for increasing grain yield and early maturity in maize.     

Genetic characterization of 218 elite CIMMYT maize inbred lines using RFLP markers

Characterization of genetic diversity among maize inbred lines can facilitate organization of germplasm and improve efficiency of breeding programs. A set of 218 phenotypically diverse inbred maize lines developed at CIMMYT for hybrid production was characterized using 32 RFLP markers to: (1) analyze the genetic diversity present; (2) define potential heterotic groups based on clusters formed with marker data; and (3) identify the most representative testers for each potential heterotic group. Lines were clustered using five different genetic distance measurements to find consensus non-hierarchical clusters. Dendrograms were produced to study hierarchical classification within smaller groups of lines. A very high average allelic diversity was seen in this germplasm. Lines did not cluster based on phenotype, environmental adaptation, grain color or type, maturity, or heterotic response (as determined based on hybrid performance with testers), but lines related by pedigree usually did cluster together. Previously defined testers from opposite heterotic groups were not genetically differentiated, and did not represent well their heterotic group. Discrete clusters were difficult to find; thus, potential heterotic groups will be difficult to suggest using RFLP markers alone. However, suggestions on how to use molecular markers and cross performance information to refine heterotic groups and select representative testers are presented.     

Estimating gene action,combining ability and heterosis for grain yield and agronomic traits in extra-early maturing yellow maize single-crosses under three agro-ecologies of Ghana

Maize (Zea mays L.) is the most important cereal crop produced in Ghana. However, yield of the crop is generally low, producing just about 1.7 t/ha. The low yield is attributed to continuous use of local/unimproved varieties. Generally, hybrid varieties have proven to out-yield the local/unimproved varieties due to improved vigour. Development of hybrid varieties depend on good understanding of combining ability and inheritance of important quantitative traits such as grain yield (GY). 45 half-diallel crosses generated from 10 extra-early maturing yellow inbred lines were evaluated in 2015 under rain-fed conditions. The objectives were to determine the genetic control, breeding value and estimate heritability for GY and agronomic traits of the inbred lines under contrasting growing environments in Ghana. General combining ability (GCA) and specific combining ability (SCA) were important in the inheritance of GY and agronomic traits of the inbred lines. However, GCA was more important than SCA across environments to suggest that additive gene action was more important than non-additive gene action in the inheritance of GY and agronomic traits in the inbred lines. High broad-sense heritability, for GY and other agronomic traits indicated preponderance of additive gene action in trait expression, thus, selection based on phenotypic expression could be feasible. Inbred lines P1, P4 and P8 were good combiners for high GY. The genotype, P4 × P8, was identified as the ideal and most yielding single-cross hybrid across research environments and should be further tested on-farm before commercialization.     

超甜玉米自交系主要农艺性状及鲜穗产量的主成分分析

为了研究影响超甜玉米鲜穗产量和主要农艺性状间的主次关系,应用多元统计方法,以30个超甜玉米自交系为试验材料,对株高、穗位高、叶片数、茎粗、秃尖长、穗长、穗粗、穗行数、行粒数、百粒重、出籽率、鲜穗产量等12个性状进行主成分分析。分析结果表明,前7个主成分的累计贡献率大于85%,说明前7个主成分就可以基本表达原12个性状所代表的遗传特征。前7个主成分主要包括产量因子、穗行数因子、穗粗因子、粒重因子、株高因子、茎粗因子和秃尖长因子,这些因子大致代表了供试自交系的综合指标,为超甜玉米自交系的性状综合选择提供了依据。     

不同轮回选择方法对玉米窄基群体的改良效果

利用轮回选择进行群体改良,是玉米种质扩增与改良的有效方法,能为选育优良自交系提供基本素材,进而提高选育自交系及杂交种的效率。本研究以玉米窄基群体P4C0及其经过不同轮回选择方法改良的10个群体为材料,通过多点田间表型鉴定和配合力测定,研究不同轮回选择方法对玉米窄基群体的改良效果,利用SSR分子标记分析不同轮回选择方法对群体遗传多样性的影响。结果表明,几种轮回选择方法都能有效改良群体的主要性状及其一般配合力(GCA)。以时间计算,控制双亲混合选择(MS)对群体P4C0主要性状及其GCA改良效果优于半同胞-S2:3(HS-S2:3)轮回选择,但在株高和穗位高的改良上,HS-S2:3选择效果较好。以轮次计算,开放改良对群体P4HSC1主要性状及其GCA的改良效果优于MS,但开放改良后,群体株高和穗位高有较大幅度的增加。不同轮回选择方法对群体遗传多样性和遗传结构的影响不尽一致。P4C0经过5轮MS后,在群体改良的低代,群体遗传多样性得到了较好的保持,而多代的改良导致群体遗传多样性下降;P4C0经过1轮HS-S2:3选择后,遗传多样性比P4C0有较大幅度的下降。P4HSC1经过1轮开放改良后,遗传多样性有较大幅度的增加。P4HSC1经过3轮MS改良后,群体遗传多样性呈增大的趋势,但每轮增加的幅度均较小。     

Genetic analysis of tropical quality protein maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) germplasm

Maize (Zea mays L.) is an important source of carbohydrates and protein in the diet in sub-Saharan Africa. The objectives of this study were to (i) estimate general (GCA) and specific combining abilities (SCA) of 13 new quality protein maize (QPM) lines in a diallel under stress and non-stress conditions, (ii) compare observed and predicted performance of QPM hybrids, (iii) characterize genetic diversity among the 13 QPM lines using single nucleotide polymorphism (SNP) markers and assess the relationship between genetic distance and hybrid performance, and (iv) assess diversity and population structure in 116 new QPM inbred lines as compared to eight older tropical QPM lines and 15 non-QPM lines. The GCA and SCA effects were significant for most traits under optimal conditions, indicating that both additive and non-additive genetic effects were important for inheritance of the traits. Additive genetic effects appeared to govern inheritance of most traits under optimal conditions and across environments. Non-additive genetic effects were more important for inheritance of grain yield but additive effects controlled most agronomic traits under drought stress conditions. Inbred lines CKL08056, CKL07292, and CKL07001 had desirable GCA effects for grain yield across drought stress and non-stress conditions. Prediction efficiency for grain yield was highest under optimal conditions. The classification of 139 inbred lines with 95 SNPs generated six clusters, four of which contained 10 or fewer lines, and 16 lines of mixed co-ancestry. There was good agreement between Neighbor Joining dendrogram and Structure classification. The QPM lines used in the diallel were nearly uniformly spread throughout the dendrogram. There was no relationship between genetic distance and grain yield in either the optimal or stressed environments in this study. The genetic diversity in mid-altitude maize germplasm is ample, and the addition of the QPM germplasm did not increase it measurably.     

源于陕A群、陕B群玉米自交系在不同密度条件下配合力分析

采用NC-II遗传设计,以郑58、昌7-2为测验种,与17份高密度条件下筛选的玉米自交系组配成34份杂交组合,2014—2015年分别于陕西杨凌、长武、榆林进行3种密度(45 000、67 500和90 000株hm–2)配合力分析试验。采用PROC VARCOMP分析不同密度条件下产量及耐密性相关性状的遗传效应,采用频率直方分布图研究不同密度条件下产量及耐密性相关性状一般配合力(GCA)平均数的变化规律,利用AMMI评价玉米自交系与杂交组合的稳定性。结果表明,产量、倒伏率、茎秆强度主要受加性遗传效应控制,空秆率主要受非加性遗传效应控制。加性遗传效应对产量及耐密性相关性状的贡献率随种植密度的增加呈上升趋势。玉米自交系产量、空秆率、倒伏率、茎秆强度的一般配合力频率均属于正态分布,随着种植密度的增加,产量GCA的平均值提高了0.28,空秆率GCA平均值降低了0.21,倒伏率GCA平均值降低了0.03,茎秆强度GCA平均值增加了0.02。玉米杂交组合产量与玉米自交系产量GCA密切相关(r=0.877**,r=0.811**,r=0.672**)。随着种植密度的增加,表现稳定的玉米自交系及杂交组合的数量呈上升趋势。因此,强化逆境选择压力,实施高密度选择策略,是增强玉米自交系耐密性和抗倒性,提升一般配合力,实现产量增益的有效措施。     

11份玉米自交系单株产量等性状的配合力与遗传参数研究

旨在研究玉米自交系单株产量等性状的配合力、遗传力及反交效应,为玉米自交系的选育和杂交种的组配提供依据。以11份玉米自交系为试材,按Griffing Ⅲ完全双列杂交法组配110个组合,观测杂交种的单株产量、株高、穗位高、雄穗分支数、雄穗主轴长、抽丝期和开花期等7个性状的表型数据,并对上述性状的一般配合力、特殊配合力、广义遗传力、狭义遗传力和反交效应进行估算。供试材料除雄穗主轴长的特殊配合力差异不显著外,其余性状的一般配合力和特殊配合力差异均达到极显著水平。JZ3和JZ6两个自交系单株产量的一般配合力为极显著正值,两对组合JZ9×JZ2和JZ2×JZ9、JZ6×JZ3和JZ3×JZ6的单株产量具有最大的正向SCA效应值,分别为40.68 g和35.24 g。单株产量的反交效应差异极显著,部分自交系的反交效应方差较大。7个性状的广义遗传力从大到小依次为,雄穗分支数、株高、开花期、穗位高、抽丝期、单株产量和雄穗主轴长;狭义遗传力从大到小依次为,雄穗分支数、株高、穗位高、开花期、雄穗主轴长、抽丝期和单株产量。试验结果表明单株产量性状的显性遗传方差占比最大,狭义遗传力最小,易受环境条件的影响,对该性状的选择适宜在晚代进行;单株产量性状具有显著的反交效应,故部分自交系需严格控制正反交方式。     

花期玉米(Zea mays)穗三叶叶形结构的遗传效应及配合力分析

为了剖析玉米叶形结构的遗传规律,进而拓宽优良株型自交系的遗传基础。本研究以12份不同叶形结构玉米自交系组配的32份F1杂交种为试材,在2个生态环境下,花期采用加性-显性-母体遗传模型(ADM)对其穗三叶叶长、叶宽、叶夹角、叶向值及叶面积进行遗传效应和配合力分析。结果表明:(1)玉米穗三叶叶长、叶宽及叶向值主要受基因的加性效应调控,其次是显性效应,同时还兼受加性×环境互作效应或母体×环境互作效应等遗传体系的调控,育种改良中宜在早代对其进行选择;叶夹角主要受基因的母体效应调控,其次是加性效应,另外还受加性×环境互作效应及母体×环境互作效应影响,育种中宜选择叶夹角较小的材料作为母本进行改良;叶面积只受基因的显性效应及显性×环境互作效应的调控,其应从较晚世代中进行遗传选择。(2)除父本叶长的一般配合力差异不显著外,父本其余性状的一般配合力和母本全部性状的一般配合力间差异均显著或极显著,且这5个叶形相关性状的全部特殊配合力间差异极显著。(3)从相应自交系各性状的一般配合力相对效应值分析发现,‘锋1999马’和‘锋1913硬’的综合性状表现优良,有利于组配出叶片大小适中及株型紧凑的优良耐密高产F1杂交组合。研究结果表明,玉米穗三叶5个叶形结构的遗传效应不尽相同,相应亲本5个叶形结构的一般配合和特殊配合力间存在明显差异,因此在玉米叶形结构遗传改良上应按照相应性状的遗传特征选择对应改良策略进行改良,并根据综合性状表现优良的亲本有目的地组配杂交组合,提高玉米理想株型育种效率。本研究为进一步剖析玉米叶形结构的遗传机理及玉米理想株型育种提供参考。     

不同来源玉米自交系植株性状特征分析

为了获得优良的玉米自交系，从而培育优良的玉米新品种，本研究通过统计分析和聚类分析对211 份不同来源的玉米自交系的11 个植株性状进行分析，并与玉米杂交种‘郑单958’和‘先玉335’的亲本自交系进行比较，从而筛选性状优良的玉米自交系。结果表明，自交系间除第一层气生根数呈显著差异外，其余均为极显著差异；各植株性状的变异系数均较大，其中雄穗分枝数的变异系数最大为27.99%，叶长的变异系数最小为6.04%；聚类分析将211 份自交系划分为9 个类群，G1~G4 类群包含192个自交系，占91%；与优良玉米杂交种‘郑单958’和‘先玉335’的亲本自交系进行比较，筛选出14 个植株性状优良的自交系。总之，本研究采用的211 份不同来源的玉米自交系材料之间遗传差异大，代表类型丰富，研究结果具有代表性。11 个植株性状之间均存在不同程度的相关性。聚类分析筛选出14 个植株性状优良的自交系，可为优良植株性状新品种选育提供参考。