云南小油菜主要农艺性状的相关及通径分析

对17份云南小油菜材料的主要农艺性状进行相关及通径分析的结果表明,各性状与单株产量的相关遗传力均小于单株产量的遗传力,因此利用某一个性状作间接选择比对单株产量作直接选择的效率低。通过株高、二次有效分枝数和单株角果数对单株产量进行直接选择或间接选择,效果都不明显或有负面影响;一次有效分枝数、角果粒数和分枝部位对单株产量的影响是通过直接作用和间接作用来实现的;在早期对一次有效分枝角果数与二次有效分枝角果数两个性状的选择会更加有效,同时进行间接选择会增强效果。     

保护地黄瓜苗期性状遗传分析

 以6份保护地黄瓜自交系为试材, 采用完全双列杂交设计轮配法(不含反交) 配制15 个组合, 研究了黄瓜苗期子叶面积、真叶面积、地上部鲜样质量、株高和下胚轴长度的遗传规律。结果表明:单株子叶面积、真叶面积和地上部鲜样质量的遗传以显性效应为主, 广义遗传力分别为93. 3 %、97. 2 %和94. 3 % , 狭义遗传力分别为35. 3 %、43. 7 %和52. 9 %; 株高和下胚轴长度的遗传以加性效应为主, 广义遗传力分别为98. 2 %和97. 8 % , 狭义遗传力分别为78. 2 %和87. 6 %。控制这些性状的基因可能是寡基因或寡基因组。     

葡萄杂交后代主要经济性状的遗传倾向

通过对10个杂交组合与5个自交后代801个株系的遗传变异分析结果表明:果粒重量、含糖量和含酸量的遗传均符合数量性状连续变异的遗传特点。子代果粒重量小于亲本值,并趋向小粒亲本,出现超高亲个体的比例较低,平均遗传传递力为70.34％。欧美杂交种品种间杂交和欧亚种与欧美杂交种间杂交传递力高于欧亚种品种间杂交;可溶性固形物含量均值接近亲本值,超高亲比例大,表明含糖量遗传中加性效应较大,在后代中选择高含糖量单株的潜力大,组合传递力为101.7％,欧美杂交种品种问杂交传递能力较弱,而欧亚种与欧美杂交种杂交,性状传递能力较强;含酸量的遗传中含有较大比例的负向非加性效应,子代含酸量大大高于亲本值,后代含酸量普遍升高,超低亲单株比例低,选择难度较大。平均组合传递力为134％,欧亚种品种问杂交遗传传递力高于欧美杂交种品种间和欧亚种与欧美杂交种种间杂交。     

A review of genetic parameter estimates for wool, growth, meat and reproduction traits in sheep

Genetic parameters for a range of sheep production traits have been reviewed from estimates published over the last decade. Weighted means and standard errors of estimates of direct and maternal heritability, common environmental effects and the correlation between direct and maternal effects are presented for various growth, carcass and meat, wool, reproduction, disease resistance and feed intake traits. Weighted means and confidence intervals for the genetic and phenotypic correlations between these traits are also presented. A random effects model that incorporated between and within study variance components was used to obtain the weighted means and variances. The weighted mean heritability estimates for the major wool traits (clean fleece weight, fibre diameter and staple length) and all the growth traits were based on more than 20 independent estimates, with the other wool traits based on more than 10 independent estimates. The mean heritability estimates for the carcass and meat traits were based on very few estimates except for fat (27) and muscle depth (11) in live animals. There were more than 10 independent estimates of heritability for most reproduction traits and for worm resistance, but few estimates for other sheep disease traits or feed intake. The mean genetic and phenotypic correlations were based on considerably smaller numbers of independent estimates. There were a reasonable number of estimates of genetic correlations among most of the wool and growth traits, although there were few estimates for the wool quality traits and among the reproduction traits. Estimates of genetic correlations between the groups of different production traits were very sparse. The mean genetic correlations generally had wide confidence intervals reflecting the large variation between estimates and relatively small data sets (number of sires) used. More accurate estimates of genetic parameters and in particular correlations between economically important traits are required for accurate genetic evaluation and development of breeding objectives.     

Genetic background of maternal behaviour and its relation to offspring survival

Maternal behaviour is becoming increasingly important in animal production. Selection for increased litter size at birth in pigs and sheep puts higher demands on the ability of dams to raise large litters. In pig production, the use of loose housing systems for lactating sows increases the importance of good maternal behaviour. Extensive production systems (e.g., ecological farming and outdoor production), where there is a small degree of supervision of the animals, also leaves a greater responsibility with the mother to care for her young. The environment provided by the dam is important for the survival and growth of the offspring in many species. Several behaviour traits of the mother play a role for the offspring's chances of survival and a good start in life. Examples of such behaviour traits are responsiveness towards signals from the offspring (pigs), aggressive behaviour towards the offspring (pigs and sheep), nursing behaviour (pigs and sheep), and fear behaviour (pigs, sheep, and cattle). Some of these traits are in part genetically controlled, and thus possible to improve by selection. Behaviour traits are, however, often difficult to observe and record on a large scale. By studying behaviour, we can gain further understanding about factors affecting survival of the young, and increase our chances to improve maternal behaviour. Improved maternal behaviour would increase the welfare for both mother and young.     

Heritability of clinical tail-biting and its relation to performance traits

Clinical tail-biters were identified over a 12-month period at a commercial nucleus pig-breeding farm that had a history of tail-biting problems. The breed, gender, and relative size of the tail-biters were recorded. Using pedigree data for all the pigs on the farm at the time of observations, the heritability of the tail-biting behaviour was estimated for purebred Large White (LW) and Landrace (LR) pigs. The incidence of tail-biting was 2.8% for Large White and 3.5% for Landrace (breed effects, P<0.10). Tail-biting was found to be heritable in Landrace (h²=0.05±0.02, P<0.05 as a 0-1 trait, equivalent to h²=0.27 as a continuous trait), but not heritable in Large White pigs (h²=0.00±0.00, as a 0-1 trait). In the Landrace population, tail-biting was unfavourably genetically correlated with leanness [lean tissue growth rate (LTGR; r_g=0.27, P<0.05), and back fat (BF) thickness at 90 kg (r_g=−0.28, P<0.05)]. It is concluded that past selection for desirable production traits may have resulted in increased predisposition to exhibit tail-biting behaviour. From the correlations and covariance matrix reported, it would be possible to develop a selection index to reduce the predisposition to exhibit tail-biting behaviour through selective breeding.     

Age trends of genetic parameters of spiral grain in hybrid larch F1 and implications for efficiency of early selection

Age trends in variance components and heritability were estimated from the spiral grain angle of rings 2–25, as counted from the pith in hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F₁. Age-age genetic and phenotypic correlations and the optimum selection age for spiral grain were also calculated. Wood samples were collected from 95 29-year-old trees belonging to 19 full-sib families in a progeny test plantation in Hokkaido, northern Japan. Spiral grain angle data were obtained by the splitting method. Mean grain angles at growth rings used for the analyses were calculated as the arithmetic mean of angles up to respective rings. Generally, the additive genetic variance for mean grain angle decreased with increasing ring number. Although dominance variance was comparatively high near the pith, it decreased to zero in subsequent growth rings. Highest heritability estimates of mean grain angle occurred at ring 4 and then declined with age, ranging from 0.45 down to 0.20. Age-age phenotypic correlations were higher than genetic correlations, especially those involving early growth rings. Optimum selection ages for spiral grain based on genetic and phenotypic correlations were estimated as 3 and 4 years (cambial age), respectively, in which maximum gain efficiency per year were obtained.     

Genetic variation in wood stiffness and strength properties of hybrid larch (Larix gmelinii var. japonica × L. kaempferi)

Genetic parameters for wood stiffness and strength properties were estimated in a 29-year-old hybrid larch stand (Larix gmelinii var. japonica × Larix kaempferi). The study included 19 full-sib larch families from Hokkaido, northern Japan. Implications of these genetic parameters in wood quality improvement are subsequently discussed. Traits included in the analyses were the dynamic modulus of elasticity of green logs (E _log), the modulus of elasticity (MOE), the modulus of rupture (MOR), compression strength parallel to the grain (CS) in small clear specimens, wood density (DEN), and diameter at breast height (DBH). DEN had the lowest coefficients of variation and MOE the highest. The narrow-sense heritability estimates of E _log, MOE, MOR, and CS were 0.61, 0.44, 0.60, and 0.43, respectively, and those of DEN and all mechanical properties increased from an inner to outer position within the stem. E _log and DEN had high positive phenotypic (0.52–0.83) and genetic (0.70–0.92) correlations with MOE, MOR, and CS. The mechanical properties of the inner position of the stem had rather high phenotypic and genetic correlations with those of the outer position and overall mean. The predicted gains in wood stiffness (E _log and MOE) were higher than those of the strength properties (MOR and CS). The predicted correlated responses in MOE, MOR, and CS when selecting for E _log and DEN were 72.6%–97.8% of a gain achievable from direct selection of these traits. DBH showed an insignificant correlation with all mechanical properties, although selection of this trait had a slightly negative effect on the mechanical properties.     

牙鲆(Paralichthys olivaceus)家系生长性状遗传效应分析

牙鲆(Paralichthys olivaceus)优良养殖新品种培育是防止其品种退化和提高经济效益的主要途径,数量性状遗传评估是牙鲆育种的主要方法之一.本研究利用已建立的牙鲆核心群体建立42个牙鲆家系,分别测量140、170、200、380日龄各家系生长相关性状(体重、全长和体宽),通过MINQUE、REML和BLUP方法对其进行数量遗传分析.结果显示,不同时期生长性状的变异系数为10.56％-38.62％,其中,体重的变异系数最大,全长和体宽的变异系数都较小,不同性状的变异系数均随着日龄的增加而减小.3个性状的加性方差分量比率为(0.13±0.01)-(0.29±0.06),随机方差分量比率为(0.71±0.06)-(0.87±0.01),狭义遗传力为(0.13±0.01)-(0.29±0.06),广义遗传力为(0.15±0.01)-(0.54±0.06),以上遗传参数均达极显著性水平(P＜0.01).综合比较3个性状在不同时期的遗传效应,结果发现,F0990、F1005、KS和F0719这4个群体亲本都为极显著正向效应,F0751、F0768、F0780、F09121、F0927和RS这6个群体亲本都为极显著负向效应(P＜0.01),其余的亲本均为一般效应.表型相关系数在0.82-0.96之间,遗传相关系数在0.72-0.97之间.利用BLUP方法对380日龄测量的数据进行育种值估算,结果发现,亲鱼体重育种值为14.63-100.05,其中,体重育种值最高的亲鱼个体为F1005-8、F09119-11、F09125-4、F0915-57、F09104-12、F1264、F0908-38、F0927-20、F1005-53、F0990-6、F09125-7、F0751-14和F1005-42.家系平均体重育种值为20.87-35.60,其中,平均体重育种值最高的家系为F1416、F1428、F1442、F1418、F1427、F1408、F1402、F1412和F1446.以体重育种值为依据选留的家系育种值与根据表型值选留的家系育种值比较可得:体重育种值选择比其表型值的选择效率高81.91％,育种值选育更好.本研究为牙鲆优良家系的建立及新品种的培育筛选出了性状优良的亲本和家系,同时为牙鲆育种计划的制定提供了重要理论依据.     

结球甘蓝自交系抽薹与开花性状配合力及遗传力分析

对6个甘蓝自交系的抽薹期与开花期性状配合力进行分析,并估算其遗传参数,为筛选时耐期抽薹品种提供理论依据.采用Griffing完全双列杂交方法Ⅳ对6个结球甘蓝优良自交系的抽薹期和开花期性状进行配合力和遗传力分析.结果表明:自交系05521-2和04M9-2的一般配合力均较好,具有作为耐抽薹亲本材料的潜力;抽薹期性状的广义遗传力和狭义遗传力分别为92.6%和50.04%;开花期性状的广义遗传力和狭义遗传力分别为92.09%和67.28%,抽薹期和开花期性状主要受加性效应基因控制,在早世代着手对结球甘蓝的抽薹期和开花期性状的选择是有效的.