Should spring wheat breeding for organically managed systems be conducted on organically managed land?

Organic spring wheat (Triticum aestivum L.) producers in the northern Great Plains use cultivars which have been bred for conventional management systems or heritage cultivars released before the widespread use of synthetic fertilizers and pesticides. To investigate the feasibility of organic wheat breeding and to determine common genetic parameters for each system, we used a random population of 79 F₆-derived recombinant inbred sister lines from a cross between the Canadian hard red spring wheat cultivar AC Barrie and the CIMMYT derived cultivar Attila. The population, including the parents, was grown on conventionally and organically managed land for 3 years. Heritability estimates differed between systems for 6 of the 14 traits measured, including spikes m⁻², plant height, test weight, 1,000 kernel weight, grain protein, and days to anthesis. Direct selection in each management system (10% selection intensity) resulted in 50% or fewer lines selected in common for nine traits, including grain yield, grain protein, spikes m⁻², and grain fill duration. The results of this study suggest that indirect selection (in conventionally managed trials) of spring wheat destined for organically managed production would not result in the advance of the best possible lines in a breeding program. This implies that breeding spring wheat specific to organic agriculture should be conducted on organically managed land.     

Genetic variation among and within populations of <Emphasis Type="Italic">Cordia africana</Emphasis> in seed size and germination responses to constant temperatures

Cordia africana Lam. is a commercial timber species that grows naturally throughout sub-Saharan Africa and tropical Arabia. At present very little is known about genetic variation in this species and baseline information is needed to initiate improvement programs in Ethiopia. Thus, the objectives of the study were to quantify the inter- and intra-population variations in seed size traits and germination responses to different constant temperature regimes. Seeds were collected from 30 open-pollinated families within each of the five populations representing the natural distribution of the species in Ethiopia. To examine seed size variations, seed length, seed width, and 1,000-seed weight were quantified. Inter- and intra-population variations in seed germination were investigated under different constant temperature regimes from 20 to 35°C in climate chambers. Significant variations in seed length, width and weight were detected both at inter- and intra-population levels, and family heritabilities of 0.63–0.76 showed that much of the phenotypic variation in seed size traits were additive genetic variation. Significant variation in germination was also found among and within populations as well as between the different constant temperature regimes. Generally the variation in germination was considerably higher within population than between populations. The optimal temperature for germination of C. africana seeds was 25–30°C with family heritabilities for germination ranging between 0.20 and 0.33, depending on the germination temperature.     

内蒙古白绒山羊母羊产羔效应的遗传分析

[目的]探讨内蒙古白绒山羊产羔数的遗传规律。[方法]对2000-2007年出生的22 721只内蒙古阿尔巴斯白绒山羊羔羊的初生重及3 044只母本羊产羔数进行统计分析。[结果]最小二乘方差分析表明,性别、胎次和出生类型对羔羊初生重有显著影响;约束性最大似然法分析表明,胎次、群体和母体效应对产羔数有显著影响。羔羊初生重遗传力单羔为0.16,双羔为0.40,全部为0.17。[结论]该研究为下一步建立内蒙古白绒山羊高繁殖性能品系奠定了一定的基础。     

Estimates of Heritability of Larval and Early Juvenile Growth Traits in Red Drum (Sciaenops ocellatus)

ABSTRACT

Eighteen to 29 families of red drum were generated via spontaneous spawning of multiple sets of three dams?×?two sires. In 2002, offspring from spawning events were grown in separate larval ponds to a mean TL of 30.4 mm. In 2003, offspring from spawning events were individually passive integrated transponder (PIT)-tagged and grown in “common-garden” tanks from 121.9 to 166.6 mm. Offspring in both experiments were assigned to parents based on genotypes at four microsatellite loci. Heritability estimates were 0.24?±?0.06 (larval TL) and 0.48?±?0.16 (juvenile-specific growth rate in length) and indicate a significant genetic component for both traits.     

Genetic improvement of sorghum for grain mould resistance: I. Performance of sorghum recombinant inbred lines for grain mould reactions across environments

Grain mould on sorghum is an important disease worldwide, which causes considerable qualitative and quantitative damage. Success in breeding for grain mould resistance has been limited because of many mechanisms governing resistance, complex genetics and environmental influence. Objectives of this study were to characterize 200 recombinant inbred lines (RILs) from a cross between ‘296 B’ (susceptible elite parent) and ‘B 58586’ (resistant parent) for grain mould reaction (GMR) at physiological maturity (PM) and at harvest maturity (HM), and to identify sources of resistance. The RILs were characterized in six environments (3 years × 2 locations) for GMR. Five RILs were identified with GMR on par with the resistant parent across various environments. The results of stability analysis for GMR at PM and HM stages showed difference. At PM, there was a significant genotype (G) × environment (E) (linear) interaction plus significant environmental effects for GMR. However, at HM, there was not a significant G × E (linear) interaction but environment effects were significant for GMR. These indicated that part of variation was predictable at PM while the variation was not predictable at HM as it was entirely influenced by environment. It is concluded that grain mould occurring before PM is influenced by genetics and to some extent by environment while that occurring after PM is influenced by environment. Therefore, host plant resistance would be better assessed at PM than at HM, and identification of quantitative trait loci (QTL) which show consistency in expression across environments, even in diverse environments, would be desirable for marker-assisted selection programs.     

Antioxidant enzymes in cabbage: Variability and inheritance of superoxide dismutase,peroxidase and catalase

Cruciferous vegetables are important source of dietary nutrients and antioxidants. Antioxidants have been touted as beneficial for enhancing plant stand and mitigating the effects of biotic and abiotic stresses. The objective of the present study was to determine variability for superoxide dismutase, peroxidase and catalase activity; its transmissibility; and correlation. Samples were harvested at fresh market stage, frozen immediately in liquid nitrogen and placed at −80 °C for assay. The genotypes, namely 83-2, Red Cabbage, KIRC-1-1, ARU Glory, Kinner Red, MR-1, AC-208, Red Rock Mammoth, KIRC-8 and KIRC-1A showed higher activity of antioxidant enzymes and therefore could be useful cascade in breeding for developing cultivars with high antioxidant activity. Enzymatic antioxidant activity showed 1.6, 12.8, and 18.2-fold difference for superoxide dismutase, peroxidase and catalase, respectively. Significant differences for enzymatic antioxidants among germplasm indicate towards the existence of substantial amount of variation. All enzymatic antioxidants showed high heritability along with low genetic advance as percentage of mean indicated the predominance of non-additive genes and provide good prospects for hybridization, and synthetics and hybrid development. The present information, therefore, could be used to develop antioxidant potential cultivars that will enhance in general the stress tolerance ability of plants, shelf life of produce, and healthy/better plant stand by enjoying antioxidants.     

甘蓝型油菜主要脂肪酸的主基因+多基因遗传分析

以低芥酸油菜品系APL01与高芥酸品种M083杂交所获得的6个基本世代（P1、P2、F1、B1、B2和F2）为材料，利用主基因+多基因混合遗传模型对油菜主要脂肪酸进行遗传分析，结果表明：棕榈酸和廿碳烯酸均由2对加性-显性-上位性主基因+加性-显性多基因控制，棕榈酸的主基因以显性效应为主，加性效应较小，廿碳烯酸的主基因加性效应与显性效应并重。硬脂酸、油酸、亚油酸和亚麻酸均由2对加性-显性-上位性主基因+加性-显性-上位性多基因控制，硬脂酸的主基因以加性效应为主，显性效应较小，主基因的遗传率为75.00%~92.45%，多基因的遗传率较小；控制油酸的2对主基因的加性效应值分别为14.38和9.92，显性效应值分别为-2.24和-0.44，上位性效应以加加上位为主，主基因的遗传率较大，为81.93%~92.68%，多基因的遗传率较小；控制亚油酸及亚麻酸的主基因加性效应均大于显性效应，上位性效应中以加加上位和显显上位为主。芥酸由2对加性-显性主基因控制，加性效应为-12.27和-8.83，显性效应值较小，分别为0.35和1.69，无上位性效应，也无多基因存在，主基因的遗传率较大，为92.54%~96.72%。     

大豆转化系数的研究：Ⅱ,大豆杂交后代表观收获指数和粒茎比的遗传研究

用表观收获指数和粒茎比不同的12个亲本配制11个组合,对其后代表观收获指数和粒茎比进行了研究。结果表明,大豆F_1代表观收获指数和粒茎比存在一定的杂种优势,其优势程度因组合而异。表观收获指数和粒茎比在F_2代均呈广泛分离,多数组合表现出超亲现象,其遗传属于数量性状遗传,无母体效应。F_2、F_3代,表观收获指数和粒茎比与中亲值相关显著。F_2代表观收获指数和粒茎比的广义遗传力分别平均为46.19％和37.47％。可将表观收获指数和粒茎比(?)入高产育种、高光效育种和株型育种的选择指标。     

陆地棉主要纤维品质性状的遗传力、遗传相关和选择指数的估测

1983至1985三年间,在合肥市安徽农学院试验农场,研究了陆地棉四个杂交组合的纤维长度、细度、强度和断裂长度的遗传力,遗传相关和选择指数。结果表明:长度、细度的遗传力属于中等,强度、断裂长度的遗传力偏低;强度与断裂长度表现出极显著的正相关,而与细度则成中等程度的负相关。利用选择指数进行选择,选择效率有随参加选择性状数的增加而提高的趋势。     

Measurement of genetic and environmental variation in barley (Hordeum vulgare) grain hardness

In this study, we assessed a broad range of barley breeding lines and commercial varieties by three hardness methods (two particle size methods and one crush resistance method (SKCS—Single-Kernel Characterization System), grown at multiple sites to see if there was variation in barley hardness and if that variation was genetic or environmentally controlled. We also developed near-infrared reflectance (NIR) calibrations for these three hardness methods to ascertain if NIR technology was suitable for rapid screening of breeding lines or specific populations. In addition, we used this data to identify genetic regions that may be associated with hardness. There were significant (p<0.05) genetic effects for the three hardness methods. There were also environmental effects, possibly linked to the effect of protein on hardness, i.e. increasing protein resulted in harder grain. Heritability values were calculated at >85% for all methods. The NIR calibrations, with R² values of >90%, had Standard Error of Prediction values of 0.90, 72 and 4.0, respectively, for the three hardness methods. These equations were used to predict hardness values of a mapping population which resulted in genetic markers being identified on all chromosomes but chromosomes 2H, 3H, 5H, 6H and 7H had markers with significant LOD scores. The two regions on 5H were on the distal end of both the long and short arms. The region that showed significant LOD score was on the long arm. However, the region on the short arm associated with the hardness (hordoindoline) genes did not have significant LOD scores. The results indicate that barley hardness is influenced by both genotype and environment and that the trait is heritable, which would allow breeders to develop very hard or soft varieties if required. In addition, NIR was shown to be a reliable tool for screening for hardness. While the data set used in this study has a relatively low variation in hardness, the tools developed could be applied to breeding populations that have large variation in barley grain hardness.