矩形区组方“RBS”设计及其在树木育种中的应用Ⅱ.“RBS”增广设计

本文介绍矩形区组方“RBS”增广设计及其在树木育种中的应用,“RBS”增广设计的方差分析和遗传分析的数学模型,并举例介绍其计算过程．     

Application of theoretical growth functions for Mongolian oak (Qurcus mongolica)

Four alternative functions are used for fitting tree height and diameter growth models for mongolian oak. (Quercus mongolica Fisch. et Turcz.). The data set includes 1250 random trees and 755 dominant trees coming from 510 temporary plots. The resultsshow that the Richards function is the best model for predicting height. diameter at breast height (DBH) and dominant height from age. The average growth curve of dominant height is used as a guide curve for the construction of a site index table which is partially validated using an independent data set. The Mitscherlich function is the best model for estimating height and dominant height from DBH. (Responsible Editor: Chai Ruihai)     

叶籽银杏的杂交变异

通过杂交途径，对叶籽银杏进行5年选育研究，共选育出4个银杏叶用观赏新品种，并繁育了性状稳定的苗木1．1万余株。本文对亲本植株，授粉和育苗，品种筛选和嫁接繁育等作了简要论述，并对选育出的4个新品种形态特点作了具体介绍，文章最后点明了通过杂交途径，进一步的筛选优化这一方法在园林绿化和盆景艺术中具重大的应用价值和广阔的发展前途。     

Research on Evaluation of Forest Ecological Benefit

Forests possess many kinds of ecological functions,which, if expressed in monetary value, would be moreimpressive and definite to make the public as well asthe government recognize its comprehensive effectsand values, and to enhance their consciousness of forestresources protection. However, to date there is nostandard system about how to evaluate forest ecologicalbenefits. Therefore, it is exigent for us to find out howto identify its public benefits and to make scientificevaluation on variou…     

Stem taper functions for maritime pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.) in Galicia (Northwestern Spain)

A total of 31 taper functions from 3 different groups of models (single, segmented and variable-form taper functions) were fitted to diameter-height data from 203 Pinus pinaster trees sampled across even-aged stands in Galicia (northwestern Spain). Most of the taper functions analyzed showed problems of multicollinearity as indicated by the condition number. A second-order autoregressive CAR(2) error process was incorporated into the models to minimize the effect of autocorrelation inherent in the longitudinal data used, and to provide valid tests of significance for model parameter estimates. In general, variable-form taper functions provided the most accurate predictions. The flexibility and predictive performance of the variable-form model developed by Kozak (For Chron 80(4):507–515, 2004) indicated its usefulness for estimating diameter at a specific height, merchantable volume, and total volume of Maritime pine in the study area.     

叶用银杏的研究进展

对银杏叶的有效成分、药理作用、栽培技术等方面的最新研究成果进行了全面综述，并对我国叶用银杏产业发展提出了建议。     

Genetic evaluation of growth of Kenya Boran cattle using random regression models

Data consisting of 18 884 weight records collected from 1273 Boran cattle from birth to 24 months of age were used to estimate covariance functions and genetic parameters for growth of Boran cattle using random regression (RR) models under a situation of small herd size and inconsistent recording. The RR model fitted quadratic Legendre polynomials of age at recording for additive genetic and permanent environmental effects. Genetic variance increased from birth, reaching an asymptotic value at 455 days and was maximum at 525 days of age after which it gradually dropped. Permanent environmental variance increased throughout the trajectory. Estimates of temporary environmental variance were heterogeneous across ages. Direct heritability and permanent environmental variance as a proportion of phenotypic variance fluctuated greatly during the early ages but later stabilized at intermediate to later ages; the estimates ranged from 0.11 to 0.33 and from 0.18 to 0.83, respectively. Genetic correlation estimates were positive, ranging from 0.10 to unity. The estimates declined with increasing in lag between the age points. Phenotypic correlation pattern was erratic between early ages, negatively low (-0.02) between the extreme data points and moderate to highly positive (>0.50) between intermediate and later points, with prominent spikes along the diagonal. It is concluded that RR models have potential for modelling growth of Boran cattle, notwithstanding conditions of small herd sizes and inconsistent recording.     

Genetic heteroscedasticity of teat count in pigs

The genetic improvement in pig litter size has been substantial. The number of teats on the sow must thus increase as well to meet the needs of the piglets, because each piglet needs access to its own teat. We applied a genetic heterogeneity model to teat counts in pigs, and estimated a medium heritability for teat counts (0.35), but found a low heritability for residual variance (0.06), indicating that selection for reduced residual variance might have a limited effect. A numerically positive correlation (0.8) was estimated between the breeding values for the mean and the residual variance. However, because of the low heritability of the residual variance, the residual variance will probably increase very slowly with the mean.     

Genomic additive and dominance variance of milk performance traits

Milk performance traits are likely influenced by both additive and non‐additive (e.g. dominance) genetic effects. Genetic variation can be partitioned using genomic information. The objective of this study was to estimate genetic variance components of production and milk component traits (e.g. acetone, fatty acids), which are particularly important for milk processing or which can provide information on the health status of cows. A genomic relationship approach was applied to phenotypic and genetic information of 1295 Holstein cows for estimating additive genetic and dominance variance components. Most of the 17 investigated traits were mainly affected by additive genetic effects, but protein content and casein content also showed a significant contribution of dominance. The ratio of dominance to additive variance was estimated as 0.64 for protein content and 0.56 for casein content. This ratio was highest for SCS (1.36) although dominance was not significant. Dominance effects were negligible in other moderately heritable milk traits.