杉木种子园中无性系间结实和种子品质差异研究

在观察的31个无性系中丰产的约占20％,产量约占总产30％;中等的占60％弱,产量占54％;低产的占20％强,产量约占17％。结实的广义遗传力hw~2平均0.66。不同无性系在雌雄花比、雌花序结构、球果大小和分枝稠密度等方面存在差异。一般植株“偏雌性”、聚生雌花序占优势,球果大、树冠表面积大而分枝稠密的无性系结实量高;反之,“偏雄性”、单生雌花序为主、球果小、树冠表面积小而分枝稀疏的无性系结实量低。据72个无性系的分析,大粒种子无性系约占21％,中粒的约占47％,小粒的占32％;高发芽率无性系占23.6％,中发芽率的占57％,低发芽率的占19.4％。大粒种子无性系的发芽卒往往高于中、小粒种子无性系;而发芽势有相反趋势。     

Standard errors of heritabilities based on perennial observations,with application to Yorkshire Fog grass

Summary The variance of heritability ratios are considered for cases where data from perennial genotypes are collected serially over time. A random effect model for randomised complete blocks at a single location is examined. Estimation of the variance of estimates of heritability is presented for three types of heritability definition.Estimators are applied to two characters in a Yorkshire Fog grass germplasm collection evaluated for two years at one site. The precision of such heritability estimates is discussed. Estimators for the multiple sites model are available also, from the author.     

三交水稻的育种研究Ⅲ.三交中晚稻主要农艺性状的配合力和遗传力分析

用4个纯合不育系菲A、中9A、金23A和珍汕97A，4个杂合不育系菲A/协青早B、中9A/协青早B、金23A/协青早B和珍汕97A/协青早B，3个恢复系752、测64-7和优米2号，按8×3 NCⅡ交配设计对16个性状的配合力进行分析。结果表明，所有性状的一般配合力和特殊配合力均达到了显著或极显著水平。在播始历期、穗长、千粒重、结实率、有效穗     

Genetic and Environmental Factors Influencing Gestation Length in Lusitano Horses

Breeding and parturition records collected over a period of 35 years in the Alter Real stud of Lusitano horses were used to calculate gestation length (GL). The 1027 gestations by 209 mares mated to 60 stallions had a mean GL of 338.1 ± 9.26 days. The mixed model analysis of variance indicated that the sex of the foal and inbreeding of the dam and foal had no significant effect on GL (P > .05). On the other hand, GL increased linearly with mare age, with an estimated regression coefficient of 0.155 ± 0.069 days/year (P < .05). Year and conception month affected GL (P < .05), with longer gestations observed when breeding occurred between January and April, followed by a decline of about 5 and 10 days in GL of mares bred in May and in June–July, respectively. Important differences were observed between stallions (P < .05), with most stallions resulting in a distribution of GL in an interval of ±5 days. The inclusion of the mare as a random effect in the mixed model resulted in an estimated repeatability of GL of 0.427, indicating that mares tend to be regular in having long or short gestations across their lifetime. Variance components estimated in an Animal Model resulted in heritability estimates of 0.39 for maternal genetic effects and 0.19 for direct genetic effects, with no association between the two components. Overall, the mare seems to have the major genetic influence on GL in Lusitano horses, but environmental factors, such as month of conception and also the age of the mare, have a noticeable effect.     

春小麦主要性状配合力及遗传力的初步分析

为了解春小麦品种主要性状的遗传力和杂交亲本的配合力,按Griffing的第2种双列杂交设计方案对8个春小麦品种的6个主要性状进行了配合力测定。其结果为:6个性状的两种配合力的方差均达5%显著水准,一般配合力方差明显大于特殊配合力方差。不同亲本、不同性权的配合力差异较大。一般地说,某个性状值高,其一般配合力也高。同时估算了6个性状的广义遗传力和狭义遗传力。     

大豆主要品质性状遗传及其配合力分析

利用７个脂肪与蛋白质含量不同亲本的１２个组合，研究了脂肪、蛋白质及总量含量的遗传特点及其配合力和遗传力等参数。结果表明：①三性状均是数量性状，Ｆ２呈常态分布，Ｆ２与中亲值几乎机等，且用中亲值预测Ｆ２更可靠。②脂肪、蛋白质含量均以基因的加性效应为主，而总量含量则加性和非加性效应均存在，且后者略占优势。③脂肪与蛋白质含量的遗传力估值较高，从Ｆ２代起可对其直接选择，而总量含量则不宜在Ｆ２代进行直接选择。     

Quantitative genetics and heritability of growth-related traits in hybrid striped bass (Morone chrysops ♀ × Morone saxatilis ♂)

Commercially farmed, hybrid striped bass - female white bass (Morone chrysops) crossed with male striped bass (Morone saxatilis) - represent a rapidly growing industry in the United States. Expanded production of hybrid striped bass, however, is limited because of uncontrolled variation in performance of fish derived from undomesticated broodstock. A 10 × 10 factorial mating design was employed to examine genetic effects and heritability of growth-related traits based on dam half-sib and sire half-sib families. A total of 881 offspring were raised in a common environment and body weight and length were recorded at three different times post-fertilization; parentage of each fish was inferred from genotypes at 10 nuclear-encoded microsatellites. Dam and sire effects on juvenile growth (weight and length) and growth rate were significant, whereas dam by sire interaction effect was not. The dam and sire components of variance for weight and length (at age) and growth rate were estimated using a Restricted Maximum Likelihood algorithm. Estimates of broad-sense heritability of weight, using a family-mean basis, ranged from 0.67 ± 0.17 to 0.85 ± 0.07 for dams; estimates for sires ranged from 0.43 ± 0.20 to 0.77 ± 0.10. Estimates of broad-sense heritability of growth rate (based on weight), using a family-mean basis, ranged from 0.69 ± 0.12 to 0.82 ± 0.09 for dams and from 0.69 ± 0.13 to 0.81 ± 0.08 for sires. Similar results were obtained with length data. Both genetic and phenotypic correlations between weight and length were close to unity. High genetic (0.98-0.99) and phenotypic (0.79) correlations between growth rates measured at two time intervals suggested that selection for growth rate at an early life stage could affect growth rate at a later life stage. Estimates of general combining ability (GCA) for growth rates differed significantly among dams and among sires, whereas estimates of specific combining ability (SCA) for each dam × sire combination did not differ significantly from zero. These results suggest that additive-effect genes contributed to the differences in juvenile growth.     

Response to selection for harvest body weight of Oreochromis shiranus

Realised and predicted responses to selection were obtained for harvest body weight of Oreochromis shiranus from two generations of selection at the National Aquaculture Centre, Domasi, Malawi. The realised response was estimated from the difference in the least squares means of selected and unselected control populations, while the predicted response was obtained from the difference of the mean breeding values between generations. The realised (13.2%) and predicted (14.4%) responses for harvest body weight over the two generations of selection were not significantly different (P > 0.05). The intensity of selection from F₁ to F₂ (0.66) and from F₂ to F₃ (0.59) was low due to availability of few selection candidates per family at harvest caused by mortality, tag loss and the need to form broad heterogeneous multi-strain F₂ and F₃ populations. Within generation, the heritability estimates for the F₁ (0.31 ± 0.09), F₂ (0.31 ± 0.10) and F₃ (0.35 ± 0.11) generations were moderate. Across generation, the heritability estimate was low (0.14 ± 0.27). Within generation, the magnitude of the common full-sib effect was moderate (0.08-0.09) and not significantly different from zero (P > 0.05). However, across generations, the common full-sib effect was high (0.27 ±0.05) and significantly different from zero (P < 0.05). A substantial correlated selection response due to selection for increased harvest body weight was observed for both tagging body weight and for survival from tagging to harvest; for tagging body weight 22.8% from F₁ to F₂ and 15.9% from F₂ to F₃; for survival 7.2% from F₁ to F₂ and 13.8% from F₂ to F₃. The results are discussed in relation to the maximisation of the genetic gain in the future generations while constraining the rate of inbreeding.     

玉米籽粒性状配合力及其遗传的研究

按完全双列杂交设计，对6个玉米自交系组配的28个组合的粒长、粒宽、粒宽、籽粒体积、比重和粒重6个性状进行通经分析和配合力分析。结果表明，粒重主要取决于籽粒体积．而将粒的长、宽、厚通过体积对粒重发生作用．粒长、粒厚、体积和拉重4个性状主要受基因加性效应的控制。因此，通过基本选择，改良籽粒体积，可以提高玉米产量。籽粒性状较好的自交系是水口黄、云248和云145；组合是水口黄×云248和水口黄×云145。