Biomass partitioning and genetic analyses of salinity tolerance in sunflower (Helianthus annuus L.)

Biomass partitioning was studied in sunflower (Helianthus annuus L.) inbred lines and their hybrids differing in salinity resistance. Differential biomass partitioning was observed among resistant and susceptible lines as well as within resistant lines, which were grown in large pots. Traits such as number of dead leaves and total number of nodes may be used as dominant markers for understanding the mechanism of resistance to salinity. Multi-location trials differing for salinity levels showed low and non-significant heritabilities across the environment for biochemical traits showing their sensitivity to the environment and a significant G X E interaction. Thus selection could only possible within the salinity level for these traits. Contrastingly, morphological traits such as number of nodes showed significant heritabilities (narrow or broad sense) across the environment. These traits may be exploited by the selection of inbred lines across or with salinity levels. Among various salinity levels, 12 dSm^?1 was found to be feasible for screening and selection as it promoted the additive type of gene action.     

Effects of Population Density on the Vegetative Growth of Leafy Reduced-stature Maize in Short-season Areas

Maize hybrids which produce more leaves above the ear, with leaf area indices similar to conventional hybrids, which require fewer corn heat units to flowering and maturity, and tolerate higher population densities, should be better adapted for production in short season areas than currently available hybrids. Leafy reduced-stature maize hybrids, which have only recently been developed, have traits which address these criteria. The objective of this study was to evaluate the effects of different population densities (50 000, 100 000, 150 000, and 200 000 plants.ha⁻¹) on the vegetative growth of one leafy reduced-stature (LRS), one non-leafy reduced-stature (NLRS), and two conventional control hybrids (Pioneer 3979, < 2500 CHU, and Pioneer 3902, 2600–2700 CHU) at two locations. There were no differences among population densities for leaf number above the ear; however leaf area index increased as population density increased for all hybrids. The LRS hybrid had a greater average leaf number above the ear (2.7 and 2.0 more leaves than NLRS and the control hybrids, respectively). As a result the leaf area index value of LRS was much greater than the NLRS and similar to the conventional hybrids, but LRS matured substantially before the conventional hybrids. The LRS hybrid required fewer corn heat units to reach flowering and maturity and had more time for grain filling than the conventional hybrids. Therefore, LRS hybrids show promise for production in short season areas where maize cultivation is not economical due to shortness of growing season.     

Genetic analysis of thrips resistance in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> [L.] Walp.)

Flower bud thrips, Megalurothrips sjostedti is the most severe field pest of cowpea that causes massive flower abortion which eventually results to substantial yield reduction in Africa. There is paucity of information on the mode of gene actions controlling inheritance of resistance to flower bud thrips in cowpea in the literature. The objectives of study were to assess the genetic variability for thrips resistance among the cowpea germplasm, determined the mode of inheritance of genes that conferred resistance and both broad and narrow-sense heritability estimates for the inheritance of thrips resistance in cowpea. Twelve cowpea lines were used in crosses in the screen house at IITA, Ibadan. The mating was accomplished using North Carolina design II to generate 48F₁ hybrids, which were eventually evaluated with the parents. Data on number of peduncles, number of pods and number of thrips per flower were recorded and subjected to analysis of variance using random model by SAS 9.2. Significant variability was observed for most agronomic and thrip-adaptive traits among the cowpea germplasm, parental-lines and F₁ genotypes evaluated. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant (P < 0.01) for number of pods per plant and other traits under the research environment. The GCA effect accounted for 68.82–80.07% of the total variation among hybrids for all traits except days to flowering; SCA explained less than 50% of the total variation. Narrow-sense heritability estimates ranged from 7.53 (days to flower) to 63.92% (number of peduncles per plant). Additive gene action largely controlled the inheritance of yield components and other traits under thrips infestation and these traits were moderately heritable.     

爆、甜、糯玉米生育后期叶片光合特性的比较

以爆裂玉米、甜玉米和糯玉米3种类型特用玉米为试材,系统比较研究了生育后期叶片光合特性在类型间和叶位间的差异。结果表明,玉米叶片的光合特性存在类型间差异,糯玉米叶片的光合特性明显优于爆裂玉米和甜玉米,叶片的光合速率(P_n)、叶绿素含量(Chl)、蒸腾速率(T_r)和气孔导度(G_s)均表现为糯玉米＞甜玉米＞爆裂玉米;3类玉米的光合特性存在叶位间差异,中部叶片光合速率表现为糯玉米>甜玉米和爆裂玉米,下部叶片光合速率的类型间差异不显著,上、中部叶片叶绿素含量表现为甜玉米＞爆裂玉米＞糯玉米;相关分析表明,叶绿素含量、蒸腾速率、气孔导度与光合速率显著或极显著正相关。总之,各类型玉米的上部和中部叶片光合特性都优于下部叶片,其中糯玉米上部和中部叶片的光合速率、光合速率高值持续期、叶绿素含量和蒸腾速率都大于甜玉米和爆裂玉米,甜玉米和爆裂玉米下部叶片光合性能的衰减在时间上早于糯玉米。     

不同类型玉米组织对亚洲玉米螟幼虫存活和生长发育的影响

亚洲玉米螟(Ostrinia furnacalis (Guenée))是中国玉米生产上最重要的害虫,严重影响玉米的产量和质量。由于不同类型玉米对亚洲玉米螟的抗性程度不同,影响玉米螟的存活和生长发育,同一品种的不同组织器官对玉米螟的存活和发育影响也不相同。笔者在室内研究了高油玉米、糯玉米、甜玉米和普通玉米等的不同组织对亚洲玉米螟幼虫存活、生长和发育的影响。结果表明,不同类型玉米在不同生育期的组织器官对亚洲玉米螟幼虫的存活、生长和发育的影响不同。高油玉米298的心叶组织最适合玉米螟幼虫的存活和生长发育,而心叶期抗螟品种邢抗2号和的心叶不利于玉米螟幼虫的存活、生长和发育。玉米螟幼虫在高油玉米、甜单8号和白糯4号的雄穗上存活率高,幼虫体重较重,而在邢抗2号雄穗上的存活率和幼虫体重最低。甜单8号玉米苞叶总体上比较适合亚洲玉米螟幼虫生长和发育,而白糯4号和邢抗2号的苞叶对亚洲玉米螟幼虫生长发育有明显的不利影响。甜单8号、农大108和高油298的花丝适宜玉米螟幼虫生长和发育。而超甜2号和邢抗2号2个品种的花丝对玉米螟幼虫生长和发育有不利影响。超甜2号玉米的穗轴适宜玉米螟生长和发育,玉米螟幼虫在甜单8号和白糯4号穗轴上取食存活率和化蛹率高,但蛹重较轻。邢抗2号穗轴对玉米螟生长发育有不利影响。在邢抗2号和农大108籽粒上取食同特用玉米籽粒上取食的幼虫相比,其幼虫体重显著或极显著低,幼虫发育历期极显著长,说明特用玉米籽粒比普通玉米的籽粒更适合亚洲玉米螟的生长发育。研究结果还表明,在甜玉米、糯玉米等特用玉米中,不同组织器官对亚洲玉米螟有一定程度的抗性,可以通过抗螟品种筛选加以利用。     

Genetic and environmental variability in some agronomical and botanical characters of common vetch (Vicia sativa L.)

Summary Twenty-four lines of common spring vetch (Vicia sativa L.), extracted at random from a collection of about 180 lines, were tested for four years at one location. Data on vegetative, reproductive and forage quality characters were recorded and analysed for three years. Appreciable total genetic variability was found in most vegetative and reproductive characters, and only very little in forage quality characters. Compared with lotal genetic variability, large environmental variability was observed in most vegetative and forage quality traits. Reproductive characters, in general, were less influenced in this respect.Forage and seed yield were negatively correlated, which was partly due to the influence of the number of days to flower. Selection for high forage yield is expected to improve by selecting plants with little branching, high % DM and longer stems with many leaves. Selection for high seed yield (number per unit area) is expected to improve with increased number of pods per stem.There were indications that crude fibre content was a better forage quality selection index than protein content, especially if combined with percentage of leaves in total DM. Selection for improved forage quality is expected to increase lodging.Some resistance to Apion sp. and Stemphyllium seedling rot was found in the material tested.Contribution from the Volcani Center, Agricultural Research Organization, Bet Dagan, Israel, 1972 Series, No 2050-E.     

不同玉米自交系南方锈病的抗性评价

通过对14个骨干玉米自交系4～5叶期接种南方锈病病原菌,分析了在温室和大田种植条件下,不同自交系在不同发育时期的抗感表现和危害程度。结果表明,自交系齐319表现抗病,其余自交系则表现不同程度的感病;随着玉米的发育进程,南方锈病在感病玉米植株迅速蔓延,开花授粉期叶片被锈菌夏孢子堆覆盖,植株褪绿,不能正常进行     

Components of resistance to late leaf spot and rust among interspecific derivatives and their significance in a foliar disease resistance breeding in groundnut (Arachis hypogaea L.)

Late leaf spot (LLS) and rust cause substantial yield losses and reduce the fodder and seed quality in groundnut (Arachis hypogaea L.). Adoption of resistant cultivars by the semi-arid tropic farmers is the best option to overcome yield losses. Knowledge on components of resistance to these diseases should facilitate the development of groundnut cultivars with enhanced resistance to LLS and rust. The objectives of the experiments were to study the genetic variability and relationships among components of resistance to LLS and rust, and assess their significance in disease resistance breeding. Fifteen interspecific derivatives for LLS and 14 for rust and a susceptible control, TMV 2, were evaluated in a randomised complete block design with two or three replications under greenhouse conditions. The experiments were repeated twice. Genotypic differences were highly significant for all the traits studied. Resistance to LLS is due to longer incubation and latent periods, lesser lesions per leaf, smaller lesion diameter, lower sporulation index, and lesser leaf area damage and disease score. Selection based on components of resistance to LLS may not lead to plants with higher retained green leaf area. The remaining green leaf area on the plant should, therefore, be the major selection criteria for resistance to LLS in breeding programs. Resistance to rust is due to longer incubation and latent periods, fewer pustules per leaf, smaller pustule diameter, lower sporulation index, and lesser leaf area damage and disease score. Rust resistant components appear to work additively, therefore, selection based on resistance components together with green leaf area retained on the plant should be the basis of selecting for resistance to rust in breeding programs. ICGV 99005, 99003, 99012, and 99015 for rust and ICGV 99006, 99013, 99004, 99003, and 99001 for LLS are the better parents for use in resistance breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

93份甜玉米种质材料的相关性与聚类分析

重庆市农业科学院近年引进或选育的来自不同地区的甜玉米种质材料,部分种质资源遗传背景较为模糊,对进一步通过杂交方式选育优良品种造成一定障碍。本研究以重庆市农业科学院近年选育或引进的93份来自不同地区的甜玉米种质材料为研究对象,对吐丝期、成熟期、株高、穗位高、总叶片数、穗长、穗粗、轴粗、秃尖长、穗行数、行粒数、单穗粒重、百粒重共13个性状进行统计分析,单因素方差分析表明,各性状均达到了显著水平,说明13个性状均存在真实的差异,变异系数差别最大的是秃尖长,为27.5%,变异系数最小的是生育期和成熟期,为2.4%。对其农艺性状进行相关性分析表明,产量性状与植株性状相关性较高,单穗粒重与吐丝期、株高、穗位高、总叶片数、穗长、行粒数呈显著正相关。通过聚类分析,93份材料可以划分为4个类群,结果较符合已知亲缘关系。93份材料遗传变异丰富,为甜玉米自交系创制、性状改良提供了部分可利用的资源,可为后续甜玉米杂种优势利用及新组合测配提供参考。     

Genetics of the timing of vegetative phase transition in a maize population

Variability for the timing of transition from juvenile to adult vegetative phases in maize (Zea mays L.) is assumed to be genetically regulated and has been associated with disease and pest tolerance. The objective of this work was to estimate the genetic variances of vegetative phase transition and its correlation with yield and its components. Full‐sib and half‐sib families were developed in a maize synthetic, following the Design I mating system. Progenies were evaluated in randomized complete block design with sets within replications in north‐western Spain for 2 years. Phase transition‐related traits showed significant additive variance, no interaction with environment and high heritability (above 65%). Correlation coefficients indicate that selection for delayed transition should not affect yield or its components. Therefore, selection for delaying phase transition could be used as a indirect selection, without expecting detrimental effects on yield.     

Towards sweet cherry (<Emphasis Type="Italic">Prunus avium</Emphasis> L.) breeding: phenotyping evaluation of newly developed hybrids

An increasing demand for cherry production (Prunus avium L.) in Greece led to the development of new high quality sweet cherry cultivars. Self-incompatibility in cherry is one of the most challenging issues for the species’ cultivation and top breeding priority. Τhe present study focuses on the development of new hybrids with improved traits such as productivity, fruit size, organoleptic characteristics and self-compatibility. For this purpose, thirty different cultivars were crossed and produced hybrids that were evaluated according to 34 morpho-physiological characteristics. The results were analyzed using the XLSTAT (version 2014.1) software and a dendrogram was constructed using the agglomerative hierarchical clustering method. Optimal hybrid clustering was achieved when characteristics of great economic importance such as fruit shape and size, growth habit and days to blooming were included in the analysis. Based on the results, new sweet cherry hybrids with the special character of self-compatibility were developed. Our findings provide crucial new information for sweet cherry future breeding programs and cultivation.     

Evaluation of Barley (Hordeum vulgare L.) Landrace Populations Originating from Different Growing Regions in the Near East*

This study characterizes barley (Hordcttm vulgare L.) garmplasm that evolved under continuous cultivation in highly drought-prone areas of the Near East. Landrace population:) originating from 70 locations in Syria and Jordan were evaluated under field conditions in Tel Hadia, Svria, on the basis of single head-row progeny performance. Significant genetic variation was found for all traits recorded: seed colour, kernel row number, growth habit, awn barbing, days to heading, culm length, leaf widths, awn length, early growth vigour, lodging score, and mildew resistance. For most traits, large proportions oi the total variation were tound between head progenies tvhh.in single populations. The qualitative traits, growth haba, seed colour, and awn barbing showed higher variation indices in populations originating from the drier regions ol Syria. Populanons from tbe drier regions; headed slightly earlier, had narrower leaves, longer eulms and tended to be more susceptible to lodging and mildew than populations originating in the higher rainfall areas in Syria. For all traits, the variance components resulting from differences among populations within a particular growing region, as well as those among populations from differences regions, were highly significant. This indicates that this germplasm stock contains materials with adaptability to these diverse growing conditions. The vanabili:y present within populations, as well 25 that among populations with similar adaptability, is sufficient to allow successful election for productivity-related traits.     

玉米品种对不同地区玉米南方锈菌的抗性评价

为明确我国各地区玉米品种对玉米南方锈病的抗性水平,为品种推广和抗病品种科学布局提供依据,利用85个玉米品种对海南三亚、广东河源、广西河池和湖南邵东4个地区的玉米南方锈菌菌株进行了田间抗病性比较试验。结果表明,相同品种对不同地区来源菌株的抗性水平有差异。综合各地区玉米南方锈菌的抗性评价可知,玉研505、鲁宁184、蠡玉88、太平洋99和绿海200等9个品种对玉米南方锈病的抗性最强,优迪598、三北63、联创839和冠玉911等19个品种次之,禾新9号、德禹M8、宁玉502、新玉27和晨强808等17个品种抗病性最弱。供试品种中,表现为高抗、中抗和感病的品种百分比分别为10.59%、22.35%和67.06%,说明我国玉米品种整体上表现为对玉米南方锈病抗性较差,病害容易流行,需注意预防。     

Development of NILs from heterogeneous inbred families for validating the rust resistance QTL in peanut (Arachis hypogaea L.)

Heterogeneous inbred families segregating for rust resistance were identified from the two crosses involving susceptible (TAG 24 and TG 26) and resistant (GPBD 4) varieties of peanut. Rust‐resistant (less than score 5) and rust‐susceptible (more than score 5) plants were identified in each HIF and evaluated under rust epiphytotic conditions. The set of plants belonging to the same HIF, but differing significantly in rust resistance, not in other morphological and productivity traits, was regarded as near‐isogenic lines (NILs). Largely, rust‐resistant NILs had GPBD 4‐type allele, and susceptible NILs carried either TAG 24 or TG 26‐type allele at the three SSR loci (IPAHM103, GM1536 and GM2301) linked to a major genomic region governing rust resistance. Comparison of the remaining genomic regions between the NILs originating from each of the HIFs using transposon markers indicated a considerably high similarity of 86.4% and 83.1% in TAG 24 × GPPBD 4 and TG 26 × GPBD 4, respectively. These NILs are useful for fine mapping and expression analysis of rust resistance.     

Development of genic molecular markers linked to a rust resistance gene in cultivated groundnut (Arachis hypogaea L.)

Development of molecular markers for different economically important traits in cultivated groundnut has progressed at slow pace. Although many genomic SSR markers were developed in both the wild and cultivated groundnut, the genetic linkage map in the species is still not saturated. Availability of a large number of ESTs in GenBank opened up the possibility of integrating new markers and to identify markers closely linked to agronomic traits. EST-SSR markers are also considered as genic molecular markers. In this study, 259 EST-SSR markers were developed by mining 5,184 Arachis hypogaea ESTs from NCBI database. These EST-SSRs and 34 resistance gene candidate markers were used for association and genetic mapping of rust resistance in cultivated groundnut. From these, Cer2, SSR_GO340445, SSR_HO115759, SSR_GO341324 and RGC 2 had a significant association with rust resistance based on locus-by-locus AMOVA and/or Kruskal?CWallis ANOVA. Some of these associated markers also had protein activity related to biotic stress responses. Through genetic mapping, EST-SSR markers SSR_GO340445 and SSR_HO115759 were found closely linked to a rust resistance gene at 1.9 and 3.8?cM distances, respectively. These markers are thus suitable candidates for marker assisted selection in groundnut. The tight linkage of SSR_GO340445 would be helpful to screen BAC clones and to isolate rust resistance gene in groundnut.     

The inheritance and biochemistry of resistance to Sclerotinia sclerotiorum leaf infections in sunflower (Helianthus annuus L.)

Summary Resistance of sunflower leaves to attack by Sclerotinia sclerotiorum was studied by infecting them, in the field, with agar disks containing Sclerotinia mycelium. Resistance levels were determined by the length of lesions after a given period. There were significant differences in reaction between both sunflower hybrids and inbred lines. Different Sclerotinia isolates gave the same classification of sunflower genotypes. The results of trials repeated in one year or different years were significantly correlated. The general combining ability variance/specific combining ability variance ratio was 1.35. Strict sense heritability was 0.61±0.03. The midparent-offspring correlation coefficient was significant, but the relation between per se values of the male parents used with the values of their hybrids was much closer than that for the female parents. Mean heterosis for resistance was 28.9%, compared with the midparent. The results of the leaf resistance test are frequently correlated with levels of resistance to root attack by Sclerotinia. Possible use of this test in breeding both directly for leaf resistance and indirectly for root resistance are discussed. H.P.L. Chromatography studies of the phenols present in healthy and infected leaves distinguished 19 compounds, all of the inhibitin type. There was a large increase in phenol content in leaves infected by Sclerotinia, for all genotypes. However, more especially in uninfected leaves, the contents of 3 chromatogram peaks, numbered 4, 6 and 9, showed a close relation with levels of Sclerotinia resistance. It is proposed that these compounds could be used as markers of certain types of resistance.     

Identifying open-pollinated populations of field corn as sources of cold tolerance for improving sweet corn

Sweet corn has poor cold tolerance and adaptation to the European Atlantic coast. Our objectives were to identify sources of favorable alleles for improving cold tolerance of three sweet corn hybrids, to compare sources of cold tolerance and early vigor, and to provide additional information on the relationships among different classes of loci and estimators of favorable alleles for cold tolerance. Each of ten field corn populations was crossed to four sweet corn inbreds. The field by sweet corn hybrids, the populations, the inbreds and the target hybrids were evaluated under cold conditions. Estimates of the mean frequencies of four classes of loci in the populations, and six estimators of favorable alleles (lp_lμ', PTC, UBND, NI, PNG_g, and PNG_ceg) and GCA were computed. The population by inbred crosses were significantly different for emergence proportion and survival. Correlations between lp_lμ', UBND, PTC and NI were high for emergence proportion. Most estimates of favorable alleles were significantly different from zero but not among populations. PTC was used to choose the best potential donor populations. The US Corn Belt Dent population AS-3(HT)C3 and the Spanish flint population Oroso were the best potential donors of favorable alleles for emergence proportion and survival under cold conditions, respectively. The ability to germinate and survive under cold conditions may be necessary, but it does not ensure adaptation to cold humid springs. This revised version was published online in July 2006 with corrections to the Cover Date.     

玉米种质资源大规模多年多点多病害的自然发病抗性鉴定

病害是影响玉米生产的重要因素。利用品种的抗性是控制玉米病害的经济、安全和有效措施。2016—2019年间,在黄淮海和东华北地区,首次对2000份来源广泛且遗传背景丰富的玉米种质资源进行了多年多点多病害的田间自然发生条件下抗病性鉴定,部分材料在西北地区也进行了田间鉴定,重点调查了小斑病、茎腐病、瘤黑粉病、弯孢叶斑病、南方锈病、粗缩病、大斑病、灰斑病和丝黑穗病的抗病性。综合4年共10个不同环境的自然发病下抗性鉴定数据表明,自然发病鉴定的结果受环境因素影响较大,表现为年度间和地域间的差异。在所有鉴定的病害中,小斑病在多个年份和多个鉴定点的发病均比较充分, 11份种质对该病害表现出稳定抗性;茎腐病、大斑病和灰斑病,在不同年份的部分鉴定点发病较为充分,对这3种病害表现抗病的种质分别为440、356和423份,综合抗性鉴定结果具有较大的参考价值;弯孢叶斑病、瘤黑粉病和粗缩病仅在1个鉴定点发病较为充分,南方锈病和丝黑穗病在所有鉴定点均发生较轻,鉴定结果有待进一步验证。本研究筛选出一批在不同环境条件下对多种病害均具有稳定抗性的材料,其中JN15、953、沈977、68122、K21、SC24-1、17MC7211、17MC7223、郑591、161191等种质的综合抗性突出,对种质的利用及后续人工接种精准鉴定的种质选择具重要参考价值。     

Relationship between phenotypic and genetic diversity of parental genotypes and the specific combining ability and heterosis effects in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

The purpose of the study was to evaluate the relationship between the genetic distances (GD) and phenotypic distances (PD) of parents and the specific combining ability (SCA) and heterosis effects. The experiment comprised 18 parental genotypes of wheat (Triticum aestivum L.) and 76 F₂ hybrids, obtained after crossing in a line × tester scheme. Parents and hybrids were examined in a field experiment conducted in a block design with three replications. SCA as well as mid-parent heterosis effects were estimated for selected morphological and technological traits. PDs and GDs were investigated between pairs of parental genotypes. GD between parental genotypes was evaluated by using randomly amplified polymorphic DNA markers. Heterosis was observed in all hybrids, and protein content exhibited the highest heterosis among the seven examined traits. The relationship between PD and GD as well as the SCA and mid-parent heterosis effects were evaluated using correlation coefficient. The correlation between PD, SCA and heterosis were low and not significant for the examined traits, whereas the correlation between SCA, heterosis and GDs were significant for protein content and rheological properties. The results indicate that GDs between parents can be used to predict performance of hybrids for selected technological traits.     

云南省近年审定鲜食玉米品种的主要性状分析

对云南省2016-2020年审定的18个鲜食玉米品种进行生育期、产量、农艺性状、品质性状和抗病性分析,为云南省鲜食玉米优良品种筛选、新品种选育和生产实践提供科学依据。结果表明,参试品种的性状表现存在一定差异,云甜玉10号产量最高,但是抗病性较差,需尽早预防病害。广良甜27号、金穗甜11号和双甜318产量较高,农艺性状适中,口感风味较佳,抗病性方面优势明显。2个甜玉米品种（云甜玉9号、美玉甜007）和2个糯玉米品种（大玉糯1号、甜糯302）的产量较高,其他性状适中,但是抗病性稍欠缺,需要选择合适的季节和地区种植,并预防病害。