Cultivar evaluation and trait analysis of tropical early maturing maize under Striga-infested and Striga-free environments

Striga hermonthica is a major constraint to maize (Zea mays L.) production in sub-Saharan Africa. The use of secondary traits that have high heritability and genetic correlation with grain yield can improve the precision with which Striga resistant genotypes are identified. Fifteen early cultivars were evaluated under Striga-infested and Striga-free conditions for 2 years at Mokwa and Abuja, Nigeria. The objective was to examine their performance based on multiple traits under stress and non-stress conditions and analyze the interrelationship among traits using genotype-by-trait (GT) biplot so as to assess the value of traits used in the base index for selection for Striga resistance and improved grain yield (YLD). TZE-W DT STR C₄ had the best performance based on multiple traits while TZE-W DT STR C₄, TZE-Y DT STR C₄, Multicob Early DT, and TZE-W DT STR QPM C₀ were the closest to the ideal cultivar when Striga infested. Ears per plant, Striga damage at 8 and 10 weeks after planting, and ear aspect (EASP) were the most reliable traits for selecting for resistant genotypes. Striga emergence count at 8 and 10 weeks after planting were not among the reliable traits identified for selection for improved grain yield and their inclusion in the base index needs to be further verified. EASP had high correlation with grain yield and was one of the most reliable traits for selection for increased grain yield under Striga infestation and should be included in the index.     

玉米品种先玉335的血缘系谱及主要农艺性状遗传分析

利用先玉335品种(PH6WC×PH4CV)P1、P2、F_1、B1、B2、F2共6个世代,运用主基因+多基因遗传模型和六世代联合分析方法,进行农艺性状株高、穗位高、穗重、穗粒重、穗轴重、穗长、穗行数、秃尖长、百粒重、出籽率的遗传分析。结果表明,株高、穗重、穗粒重、穗轴重、穗长、穗行数6个性状均为2对主基因加、显、上+多基因加、显混合遗传模型;秃尖长、百粒重两个性状为2对主基因加、显、上+多基因加、显、上混合遗传模型;穗位高为1对主基因加性+多基因加、显混合遗传模型;出籽率为多基因加、显、上遗传模型。株高、穗轴重、百粒重以主基因遗传为主、多基因遗传为辅。穗重、穗粒重、穗行数以主基因遗传为主;穗长主基因遗传、多基因遗传同等重要;秃尖长以多基因遗传为主,主基因遗传为辅;穗位高、出籽率多基因起决定作用。     

旱稻数量性状的遗传参数分析

从广义遗传力、遗传相关、遗传进度和选择指数等几个方面,分析了57份旱稻品种的株高、有效穗数、主穗长度、主穗粒数、千粒重、单株粒重和剑叶长/宽7个主要数量性状的遗传潜力和选择效果.分析结果表明：株高、剑叶长/宽、单株粒数、主穗长度、千粒重的广义遗传力较高,有效穗数、单株粒重的广义遗传力偏低;单株粒数、单株粒重、有效穗数3个主要产量构成因素的遗传变幅较大,在该群体中对这3个性状进行选择的潜力较大;产量性状中的单株粒数和千粒重与单株粒重本身均有一定的遗传潜力,预期遗传进度也较大,特别是单株粒数的预期遗传进度较大;单株粒重与单株粒数、千粒重间存在显著或极显著的遗传正相关,主穗长度与有效穗数间存在极显著的遗传负相关,因此可以通过提高单株粒数和千粒重来间断增加单株产量;用单株粒重与单株粒数、千粒重和有效穗数构成的选择指数进行综合选择,相对效率高达219.34%,比直接选择单株粒重提高了119.34%,显著高于对单株粒重的直接选择,因此采用这个指数对单株粒重进行间接选择效果较为理想.     

水稻籼粳交衍生系产量相关性状的遗传效应与杂种优势

采用包括基因型与环境互作效应的加性—显性遗传模型（AD模型）,对不同环境下水稻籼粳交衍生系产量相关性状的遗传效应与杂种优势进行研究。结果表明,播抽天数、每穗总粒数、每穗实粒数和千粒重性状以基因的加性主效应为主;结实率和株高性状以基因的显性主效应为主;基因型×环境互作效应明显影响产量相关性状表现,以显性×环境互作为主,其中播抽天数、单株谷重、千粒重和穗长的显性×环境互作效应尤为明显。杂种优势研究表明,由遗传主效应控制的杂种优势除单株有效穗数外,其余8个性状均表现正向群体平均优势;基因型×环境互作杂种优势分析表明,单株谷重、单株有效穗数、每穗实粒数、千粒重、株高和穗长6个性状杂种优势的稳定性较好。遗传效应分析结果表明,明恢413、97gk1037、明恢118和明恢417在多个性状上表现以遗传主效应为主,环境互作效应较弱,具有较好的环境稳定性,表明该4个籼粳交衍生品系在籼粳杂种优势利用中具有较高的利用价值。     

江苏沿江地区新选玉米自交系产量及产量构成性状的配合力分析

选用热带、亚热带等种质选育的9 个代表性自交系,按GriffingⅢ双列杂交设计方法,配制成正、反交共72个F1组合,在江苏省南通和南京两个地点对参试自交系4个性状进行一般配合力和特殊配合力分析。结果表明：在新选自交系间杂种F₁代小区产量、行粒数的变异中,非加性遗传方差大于加性遗传方差;在穗行数、千粒重的变异中,加性遗传方差大于非加性遗传方差。小区产量、千粒重性状一般配合力好的自交系是S7和S3;穗行数一般配合力较好的自交系是S6、S3和S9;行粒数一般配合力较好的自交系是S9和S2。综合4个性状评价,S3最好,其他依次为S7、S2、S5和S1。导入了热带、亚热带种质的S9行粒数一般配合力有所提高。除行粒数外,其他性状的反交效应均不显著。     

30个旱稻品种的主要农艺性状与相关分析

利用SAS等软件对30个旱稻品种的千粒重、株高、单株有效穗数等10个主要农艺性状进行了遗传力、遗传进度、相关系数等参数的分析，特别是进行了性状间的通径分析。结果表明：单株粒数、千粒重、结实率对旱稻单株产量的提高是至关重要的，而穗长、主茎杆粗、单株有效穗数对单株产量作用不大，甚至会出现负相关作用。因此认为，通过对单株粒数、千粒重、结实率的选择，有助于旱稻的培育，加强灌浆期的管理可以有效提高单株产量。     

Study of gene effects for cotton yield and Verticillium wilt tolerance in cotton plant (Gossypium hirsutum L.)

Verticillium wilt (VW), caused by Verticillium dahliae Kleb., is a destructive disease of cotton (Gossypium hirsutum L.). The use of resistant cultivars has long been considered the most practical and effective mean of control. The aim of this work was to study the quantitative genetic basis of Verticillium wilt resistance in Upland cotton by using five genotypes and their possible crosses without reciprocals selecting simultaneously for resistance and desirable agronomic characteristics. Five cotton cultivars and 10 F1s from half-diallel crosses were analyzed for VW resistance. The seed cotton yield, the number of bolls/ plant, and boll weight were measured and Verticillium wilt index (VWI) was estimated during two crop seasons in two different sites each year always on plots with naturally infested soil. Genetic components of variance were analyzed using the Hayman model. Analysis of variance for all characters showed significant differences between genotypes, without genotype-site interaction in most cases. Both, additive genetic variance component (D) and dominance genetic variance components (H1 and H2) were presented in all characters, except for VWI. D was the most important component for boll weight and VWI. Boll weight was the most correlated character with seed cotton yield and VWI. Broad sense heritability was high for boll weight and VWI, moderate for seed cotton yield and low for bolls per plant. Narrow sense heritability was moderate for boll weight, and high for VWI.     

宁麦9号×镇麦168小麦F2群体产量相关性状的遗传模型分析

为给小麦遗传育种中产量性状改良提供参考,利用相关性分析和植物数量性状主效基因与微效多基因混合遗传模型对(宁麦9号×镇麦168)F₂代162个单株的有效穗数、株高、穗长、总小穗数、穗粒数以及单株粒重进行了联合分离分析。结果表明,该群体农艺性状均属于受多基因控制的数量性状,其中有效穗数和单株粒重仅受微效多基因调控,株高和总小穗数符合“两对加性-显性-上位性主基因”+“加性-显性多基因”混合遗传,而穗长和穗粒数则符合“两对加性主基因”+“加性-显性多基因”混合遗传。株高、穗长和总小穗数3个性状的主基因遗传力分别为64.98%、51.22%和47.12%,可能存在效应较大的QTL。     

籼稻稻米营养品质性状的种子、细胞质和母体遗传相关分析（英文）

 利用9个籼型不育系和5个籼型恢复系进行不完全双列杂交，同时分析了早籼稻米蛋白质含量、蛋白质指数、赖氨酸含量、赖氨酸指数以及赖氨酸含量与蛋白质含量的比值等营养品质成对性状间种子、细胞质和母体等多种遗传相关。结果证实蛋白质含量与蛋白质指数等多数成对性状间的种子加性和显性相关、细胞质相关以及母体加性和显性相关系数均为显著正值，对这些性状进行间接改良有效。但赖氨酸含量与蛋白质含量的比值同蛋白质性状的关系则以显著负相关为主，表明选择高蛋白质含量或蛋白质指数的单株将会显著降低该比值。正向的种子和母体显性相关以及细胞质相关可以同时显著提高杂交稻组合中赖氨酸含量和赖氨酸指数以及赖氨酸含量与蛋白质含量比值。对于主要受加性相关控制的成对性状进行间接选择具有较好的效果，而杂交稻育种中则以利用显性相关为主。     

Gene effects for cotton-fiber traits in cotton plant (Gossypium hirsutum L.) under Verticillium conditions

Verticillium wilt (VW), caused by Verticillium dahliae Kleb., has become one of the most serious problems in cotton (Gossypium hirsutum L.). The use of resistant cultivars has long been considered the most practical and effective means of control. The objective of this work was to study the quantitative genetic basis of fiber traits under Verticillium conditions in upland cotton by using five genotypes and their possible crosses without reciprocals, selecting simultaneously for quality fiber, resistance, and agronomic characteristics. Five cotton cultivars and 10 F₁s from half diallel crosses were analyzed for quality fiber under VW conditions. The fiber length, uniformity, strength, elongation, and micronaire were measured during two crop seasons at two different sites each year, consistently in plots with soil naturally infested with Verticillium. Genetic components of variance were analyzed using the Hayman model. Analysis of variance for all traits showed significant differences between genotypes, with the genotype–site interaction in most of the studied traits except for fiber length and micronaire. Both the additive genetic variance component (D) and dominance genetic variance components (H1 and H2) were present in all traits. D was the most important component for uniformity, strength, elongation, and micronaire. Elongation was the trait most correlated with seed-cotton yield. Strength and micronaire were the traits most correlated with VWI. Broad-sense heritability was high for all the traits studied. Narrow-sense heritability was high for uniformity, strength and elongation, and moderate for length and micronaire.     

小麦新品系鄂麦28及其系选后代的农艺性状及产量特点

小麦新品系鄂麦28具有中抗赤霉病、抗穗发芽、高产稳产等突出特点。为利用其剩余变异,从其群体中系统选择了30个新品系,2018-2019年度通过武汉和襄阳两地的田间鉴定试验,比较了它们的产量及其构成、株高、生育期等性状,并利用小麦21对核心SSR引物对鄂麦28典型单株进行遗传相似性检测。结果表明,18S314、18S325、18S239、18S331等4个高产品系经核心引物检测,所有位点与鄂麦28典型单株基因型一致,可作为鄂麦28优系进行利用。18S278和18S279两个品系具有特异性,产量较高,可以作为新品系进行利用。18S268、18S293、18S317、18S318等4个品系特异性不明显,但产量较高,且田间农艺性状表现出一定的差异,也可作为新品系进一步利用。     

大豆主要农艺性状的遗传分析

大豆农艺性状和产量性状属数量性状遗传,本研究以不完全双列杂交组合为材料,以朱军(1997)提出的混合模型方法分析大豆形态和产量性状的加性、显性和上位遗传效应.结果表明,大豆的株高、节数、粒重、粒数及总荚数等性状受基因显性效应影响,且显性方差比率最大;节数、单株产量、百粒重等性状受加性效应的影响,但作用较小;株高和单株粒数也受到上位效应的影响,但作用较小.各形态性状的广义遗传率较高,但狭义遗传率却较低.单株产量与株高、粒数、总荚数呈极显著正相关,与百粒重呈负相关.在各遗传分量中,各相关系数以显性相关系数为主.     

红麻亲本与杂交组合产量、品质性状的遗传效应分析

采用双列杂交遗传设计和加性-显性遗传模型，分析了7个红麻杂交亲本和21个F1组合的11个产量与品质性状，结果表明：(1)株高、鲜皮厚、千粒重、纤维支数同时受到加性和显性效应的控制；而茎粗、单株干皮重、单株干茎重、皮骨比、出麻率、单株纤维重、精洗率、纤维强力主要受显性效应控制。(2)对红麻亲本遗传效应估测结果表明，各亲本不同性状的遗传效应不同。可根据亲本对每个性状的不同遗传效应表现，在育种和杂种优势利用上加以选择利用。综合分析表明，福红2号、福红992和非洲裂叶3个亲本具有提高株高、茎粗、鲜皮厚、单株干皮重、单株干茎重、出麻率、皮骨比、精洗率、单株纤维重的正向遗传效应：福红2号和福红9922个亲本还具有提高纤维强力与纤维支数的遗传效应。上述结果可为红麻遗传改良和杂种优势利用提供一定的科学依据。     

Inheritance pattern and genetics of yield and component traits in opium poppy (Papaver somniferum L.)

Opium poppy (Papaver somniferum L.) is an important medicinal plant produces more than 80 alkaloids belonging to various tetrahydrobenzylisoquinoline derived classes. These alkaloids are obtained from the capsules and straw of the plant. Information on the nature and magnitude of gene effects are required for genetic improvement. Therefore, the continuous assessment of newer breeding materials is mandatory on part of breeders. The objective of this study was undertaken to understand the particular gene action involved in the inheritance of yield and component traits. Two families (VG26 × VG20 and SG35II × VE01) of opium poppy were analyzed to study the gene actions involved in the inheritance of yield and component traits (plant height, leaves per plant, capsules per plant, peduncle length, capsule index, seed and straw yield per plant and morphine content). Simple additive, dominance, and epistatic genetic components were found to be significant. Dominance effect (‘h’) was higher than additive effect (‘d’) for capsule index and morphine content. Digenic interaction indicated the prevalence of dominance × dominance (‘l’) followed by additive × dominance (‘j’) type epistasis. The opposite sign of dominance (‘h’) and dominance × dominance (‘l’) indicated duplicate epistasis for all the traits. Biparental mating followed by recurrent selection involving desired recombinants may be utilized to improve the component traits.     

Application of Molecular Markers in Breeding for Nitrogen Use Efficiency

Summary

Nitrogen use efficiency (NUE) is defined as dry matter yield produced per unit of N supplied and available in the soil. NUE is approximately 33% for cereal production worldwide. Increased cereal NUE must accompany increased yield needed to feed the growing world population. Consequently, continued efforts are needed to include plant selection under low N input which is not often considered a priority by plant breeders. Molecular markers have accelerated plant breeding in a number of areas including biotic (disease and insect) resistance and abiotic (drought, low nitrogen fertilization and frost) tolerance. Marker-based technology has already provided scientists with a powerful approach for identifying and mapping quantitative trait loci (QTL) and would lead to the development of a better understanding of genetic phenomena. Two main NUE studies have been discussed. The first study identified QTL for NUE in maize involved the grain yield and secondary morphological traits of interest, such as plant height, ear leaf area, ears per plant and kernels per ear. This was compared with second study of QTL for yield and its components with genes encoding cytolistic gult-amine synthestase and leaf N0₃ ^- content. These secondary traits were correlated with yield and demonstrated segregation with high heritability under low nitrogen conditions. Marker assisted selection (MAS) should be able to offer significant advantages in cases where phenotypic screening is particularly expensive or difficult, including breeding projects involving multiple genes, recessive genes, late expression of the trait of interest, seasonal considerations, or geographical considerations. In addition to reducing costs of conventional breeding, MAS also has the potential to generate time savings. Possibly, the greatest contribution of QTL mapping to plant breeding will be the basic understanding of the genetic architecture of quantitative traits, thereby relating specific genetic loci with the biological mechanisms associated with desirable phenotypes.     

Developmental Analysis of Genetic Behavior of Brown Rice Width in indica-japonica Hybrids

One of the most effective ways of enhancing rice yield is the utilization of the strong inter-subspecific hybrid heterosis between indica rice and japonica rice in replacement of inter-varietal hybrid heterosis being widely applied. Recently, great progress has been made to increase rice yield in several countries e.g. Japan, Korea, China etc [1]. For example, an indica-japonica hybrid rice combination ‘Xieyou 9308’, which was derived from an indica cytoplasmic male sterile line Xieqingzao…     

Genetic analysis and validation of quantitative trait loci associated with reproductive-growth traits and grain yield under drought stress in a doubled haploid line population of rice (Oryza sativa L.)

Drought is a major constraint for rice production and yield stability in rainfed ecosystems, especially when it occurs during the reproductive stage. Combined genetic and physiological analysis of reproductive-growth traits and their effects on yield and yield components under drought stress is important for dissecting the biological bases of drought resistance and for rice yield improvement in water-limited environments. A subset of a doubled haploid (DH) line population of CT9993-5-10-1-M/IR62266-42-6-2 was evaluated for variation in plant water status, phenology, reproductive-growth traits, yield and yield components under reproductive-stage drought stress and irrigated (non-stress) conditions in the field. Since this DH line population was previously used in extensive quantitative trait loci (QTLs) mapping of various drought resistance component traits, we aimed at identifying QTLs for specific reproductive-growth and yield traits and also to validate the consensus QTLs identified earlier in these DH lines using meta-analysis. DH lines showed significant variation for plant water status, reproductive-growth traits, yield and yield components under drought stress. Total dry matter, number of panicles per plant, harvest index, panicle harvest index, panicle fertility, pollen fertility, spikelet fertility and hundred grain weight had significant positive correlations with grain yield under drought stress. A total of 46 QTLs were identified for the various traits under stress and non-stress conditions with phenotypic effect ranging from 9.5 to 35.6% in this study. QTLs for panicle exsertion, peduncle length and pollen fertility, identified for the first time in this study, could be useful in marker-assisted breeding (MAB) for drought resistance in rice. A total of 97 QTLs linked to plant growth, phenology, reproductive-growth traits, yield and its components under non-stress and drought stress, identified in this study as well as from earlier published information, were subjected to meta-analysis. Meta-analysis identified 23 MQTLs linked to plant phenology and production traits under stress conditions. Among them, four MQTLs viz., 1.3 for plant height, 3.1 for days to flowering, 8.1 for days to flowering or delay in flowering and 9.1 for days to flowering are true QTLs. Consensus QTLs for reproductive-growth traits and grain yield under drought stress have been identified on chromosomes 1 and 9 using meta-QTL analysis in these DH lines. These MQTLs associated with reproductive-growth, grain yield and its component traits under drought stress could be useful targets for drought resistance improvement in rice through MAB and/or map-based positional analysis of candidate genes.     

小麦农艺性状的主基因+多基因遗传分析

为明确小麦重要农艺性状的遗传组成,并筛选适于QTL的性状,以西农817和中国春为亲本,构建F2、F3群体,采用P1、P2、F1、F2、F3五世代联合分析方法,研究了株高、有效分蘖、小穗数、穗粒数、穗长、穗下节间距、小穗着生密度等产量相关性状的遗传模型.结果表明,7个性状不仅受基因的控制,同时也受到不同程度的环境影响.其中,穗长、穗粒数符合多基因遗传模型,无主基因存在;株高、小穗数、小穗着生密度符合一对加显性主基因+加性-显性多基因混合遗传模型;穗下节间距符合一对完全显性主基因+加性-显性多基因模型;有效分蘖符合一对负向完全显性主基因+加性-显性多基因模型.     

12个玉米群体产量相关性状的密度效应分析

以蒙群1、蒙群2、蒙群3、蒙群4、蒙A群、蒙B群、蒙C群共7个自有群体和中综5号、中综7号2个国内合成的群体以及3个加拿大引进群体C群1、C群2、C群3为供试材料研究产量相关性状的密度效应。试验设计采用二因素裂区试验设计,密度为主区,2个处理,分别为75 000、150 000株/hm²;玉米群体为副区,共12个处理。通过增密效应分析得出,在秃尖长、穗行数、行粒数、穗长、穗粗、百粒重产量性状中,行粒数和穗长适宜作为耐密的选择指标,蒙群2、蒙群4、蒙A群、蒙B群4个群体的耐密性优于其他8个群体;在抗性性状中,倒伏率和空秆率是衡量耐密性的重要指标,蒙A群、蒙群1、蒙群4、C群1、中综7号群体的耐密性优于其余7个群体。综合产量与抗性指标,蒙A群、蒙群4适宜增密种植,蒙群1、蒙B群、蒙C群、中综7号群体可适当增密,C群2、C群3、蒙群3、蒙群2、C群1、中综5号群体不适于增密。     

高配合力双低油菜细胞质雄性不育基因的遗传及细胞质效应

采用Ｍ×Ｎ设计,研究不育基因在１５个杂种Ｆ１的遗传效应。结果表明：Ｆ１性状的基因效应比较复杂,由加性效应、显性效应、母体效应和剩余共同决定的,其中植株高度和芥酸含量的遗传简单,分别由母体效应和加性效应决定。单株产量和千粒重这两个性状的遗传最复杂,是由加性、显性、母体、上位性和超显性等效应共同决定的。在相同的核背景下,３８４Ａ、２１７Ａ两种不育胞质对产量性状如一次分枝角果数、全株总有效角果数、单株产量有一定的正效应;对病毒病和菌核病的抗性则因细胞质、细胞核的不同而异。