A model calculation approach towards the optimization of a standard scheme of seed‐parent line development in hybrid rye breeding

The importance of hybrid rye (Secale cereale L.) breeding has steadily increased over the last decades. This paper presents results of model calculations aiming to optimize the number of candidates, testers to assess combining ability and test locations at each selection stage of a standard scheme of seed‐parent line development. Two variants of the scheme differing in the number of stages and the cycle length are investigated. Optimization criterion is the expected selection gain per year under the restriction of a fixed budget. Prediction of selection gain rests on quantitative–genetic and economic parameters estimated from breeders’ data. Optimization covers different genetical and economical situations. Results show that the optimum number of testers to assess combining ability depends on the relative amount of dominance variance. The efficiency of a breeding scheme strongly increases with decreasing cycle length. A larger budget should mainly be used to increase the number of candidates at all selection stages. Recommendations for practical breeding schemes are given. We conclude that model calculations are a valuable tool for the optimization of breeding schemes.     

Selection, propagation and cultivation of Pinus massoniana clones for pulp use

Based on the growth, wood property of the ortets, and rooting abilities of cuttings, 32 Pinus massoniana clones for pulp use were selected from forests of superior provenance, mixed families, and progeny test of seed orchard by two-step selection. The average height and DBH growth of three-year-old clones were 28.6% and 16.7%, respectively, higher than those from seedlings, and average gain of wood density reached 8.7%. Rooting rate of all these clones was over 80%, 28% higher than the clones selected by a single step. A cutting orchard of 0.33 hm² on the hillside was constructed to intensively produce cuttings according to the tests on construction methods, pruning, and fertilization. A total of 50,000 grade I, 37,500 grade II, and 62,500 grade III cuttings were collected per hectare of this cutting orchard each time, and were cut three times each year. With all the above techniques, 48 hm² of clonal forests for pulp use of those clones had been planted in five places in Fujian Province. Container stecklings are more likely to increase the planting survival rate. __________ Translated from Scientia Silvae Sinicae, 2004, 40(1): 64–69 [译自: 林业科学]     

Nondestructive detection of insect infested chestnuts based on NIR spectroscopy

Insect feeding is a significant postharvest problem for processors of chestnuts (Castanea sativa, Miller). In most cases, damage from insects is ‘hidden’, i.e. not visually detectable on the fruit surface. Consequently, traditional sorting techniques, including manual sorting, are generally inadequate for the detection and removal of chestnuts with hidden damage. For the most part, the only method currently used by processors is a flotation system, in which chestnuts are placed in salt water and those that float are discarded. Flotation is unreliable, and a more effective method for detection of insect damage would benefit industry and consumers alike. In this study, the feasibility of using NIR spectroscopy to detect hidden insect damage is demonstrated. Using a genetic algorithm for feature selection (from 2 to 6 wavelengths) in combination with a linear discriminant analysis routine, classification error rates as low as 16.81% false negative, 0.00% false positive, and 8.41% total error were achieved, with an AUC value of 0.952 and an Wilk's λ of 0.403 (P < 0.001). A Savitzky–Golay first derivative spectral pretreatment with 13 smoothing points was used. The optimal features corresponded to Abs [1582 nm], Abs [1900 nm], and Abs [1964 nm]. These results represent an average of 55.3% improvement over a traditional flotation sorting system.     

Identification of quantitative trait loci (QTLs) for seed protein concentration in soybean and analysis for additive effects and epistatic effects of QTLs under multiple environments

Soybean protein concentration is a key trait driver of successful soybean quality. A recombination inbred lines derived from a cross between ‘Charleston’ and ‘Dongnong594’, were planted in three environments across four years in China. Then, the genetic effects were partitioned into additive main effects, epistatic main effects and their environment interaction effects by using composite interval mapping, multiple interval mapping and composite interval mapping in a mixed linear model. Forty‐three quantitative trait loci QTLs were identified on 17 of 20 soybean chromosomes excluding Ch 7, Ch 8 and Ch 17. Two QTLs showed a good stability across multiple environments, qPRO20‐1 was detected under four environments, which explained 4.4–9.95% phenotypic variances and the allele was from ‘Charleston’ among four environments. qPRO7‐5 was detected under three environments, which explained 7.2–14.5% phenotypic variances and the allele was from ‘Dongnong 594’, three pathway genes of protein biosynthesis were detected in the interval of qPRO7‐5. The additive main‐effect QTLs contributed more phenotypic variation than the epistasis and environmental interaction. This indicated that it is feasible by marker‐assisted selection to improve soybean protein concentration.     

How to maintain improved cultivars

Improved cultivars loose their identity and healthiness unless maintained properly. Contaminating and degrading forces, such as outcrossing, volunteer plants, mixing, natural selection, mutation and seed-borne diseases, are at the root of this. Maintenance selection can prevent this deterioration. How it is carried out depends on the reproduction system of the crop. Crops are therefore classified into four categories; typical cross-pollinating crops, self-pollinating crops with a substantial amount of outcrossing, typical self-pollinating crops with little outcrossing, and the vegetatively reproduced crops. Generally some of the “breeder seed” is used to plant a small plot with spaced plants. A fair number of healthy plants of the cultivar type is selected and the seed is harvested per plant. The progenies of the selected plants are grown in small plots. Non-uniform or deviating plots and plots with a seed-borne disease are removed. The seed of the progenies that are healthy, uniform and similar (and so of the cultivar type) are harvested per progeny to be tested next season on larger plots. The same selection is applied and only the seed of the progenies that are healthy, uniform and similar are harvested together to produce the “breeder seed”. The details of this maintenance selection vary with the reproduction system, the multiplication rate of the crop and the possibilities available to the breeder. Seven crops, potato, common bean, barley, wheat, faba bean, quinoa and maize are discussed here as they represent the different reproduction systems and multiplication rates, while being important Andean food crops.     

24年生马尾松生长、形质和木材基本密度的种源变异与种源区划

利用设置在浙江省淳安县姥山林场的24年生49个产地的马尾松种源试验,以研究和揭示已达主伐年龄时马尾松生长、形质和木材基本密度的种源差异和地理变异模式,通过聚类进行种源区划并选择优良种源.结果表明:马尾松生长、形质和木材基本密度皆存在显著的种源差异,种源胸径、树高和材积生长及树干通直度呈典型的纬向倾群变异模式,这种变异主要是由其产地水热资源条件差异引起的.较之于北部种源,南部的种源生产力水平高且树干通直.种源木材基本密度虽与产地经纬度相关性较小,但却与产地年均温、1月均温、无霜期和≥10℃积温呈显著的负相关.性状遗传相关分析结果显示,选择生产力高的速生种源可同时改良树干通直度 会明显降低其木材基本密度.根培种源聚类结果,可将马尾松划分为南部、中部和北部3个种源区,并分别纸浆材和锯材筛选出19个和6个优良种源,这些优良种源主要来自马尾松的南部种源区,部分来自中部种源区.     

住宅电气设计浅谈

随着我国社会经济的发展,家用电器逐渐增多,特别是空调等大功率电器进入普通家庭,使住宅设计由纯照明向多功能发展.针对目前现代化住宅电气设计中的问题进行剖析,其内对用电负荷、系统配置、设备选择、防雷接地、消防及智能化系统的设计进行了一系列解释.     

Development of Elongated Uppermost Intemode CMS Lines for Hybrid Rice Breeding in India

Development of cytoplasmic male sterile （CMS） lines with elongated uppermost internode （EUI） trait provides a genetic option to eliminate the use of GA3 in hybrid rice. During the past two decades, extensive work has been carried out on the subject that resulted in identification of several mutants with EUI trait for use in developing cytoplasmic/thermo-sensitive genic male-sterile lines with complete panicle exsertion （Okuno and Kawai, 1978; Rutger and Carnahan, 1981; Shen et al., 1987; Yang et al., 2000; 2002; Gangashetti et al., 2004）. Two recessive genes （eui-1 and eui-2） mapped on chromosome 5 and 10 respectively have so far been reported to control the internode elongation in rice （Librojo and Khush, 1986; Yang et al., 2001; Ma et al., 2004）. Considerable progress has been made in China in exploiting ＇eur gene for development of hybrid rice parental lines （Yang et al., 2000; 2002; Zhang et al., 2002）.     

Effects of high- vs. low-yield environments on selection for increased biomass yield in switchgrass

No information is available on the effects of different biomass yield environments on selection efficiency in switchgrass (Panicum virgatum L.) breeding improvement. This study was conducted to assess the effects of high- and low-biomass yield environments (HYE and LYE, respectively) on recurrent selection for general combining ability (RSGCA) in a lowland population of switchgrass (NL-94). The top 14 of 65 NL-94 C₀ parent plants were selected based on biomass yield of half-sib (HS) progeny tested for one post-establishment year under HYE and LYE conditions. Nine of the 14 C₀ parent plants were the same based on HS performance under HYE and LYE. Selected plants were intercrossed to produce NL-94 HYE and NL-94 LYE C₁ populations. One hundred and twenty-five HS C₁ progeny families (60 NL-94 HYE and 65 NL-94 LYE) were evaluated for biomass yield for 3 years (2002–2004) under HYE and LYE conditions. The HYE produced about 2.5 times higher biomass yields than the LYE in both C₀ and C₁ HS progeny tests. Estimated additive genetic variance and predicted gains from selection (ΔG) were high in the C₁ populations indicating that RSGCA should achieve higher biomass yields. Mean biomass yields of C₁ HS families originating from the LYE protocol were significantly higher than those of families originating from the HYE protocol in both HYE and LYE performance tests, suggesting greater selection response under LYE in the C₀ population. The estimates of narrow-sense heritability ( ) and ΔG from the C₁ populations indicate that positive response to selection for biomass yield is possible in subsequent cycles of selection under either HYE or LYE, with a possible small advantage for HYE.     

水稻抗纹枯病QTL qSB-9TQ和抗条纹叶枯病基因Stv-bi的聚合育种

以携带抗纹枯病QTL qSB-9^TQ的籼稻品种特青和携带抗条纹叶枯病基因Stv-bⁱ的粳稻品种镇稻88为优良等位基因供体亲本,江苏省推广的粳稻品种武育粳3号和武粳15为受体亲本,分别杂交并连续回交。在回交及自交分离世代,利用开发的覆盖目标基因区间的双侧分子标记对目标基因进行辅助选择。至回交BC₄F₁世代,同一遗传背景2个回交方向的中选单株间聚合杂交,获得2个目标基因位点均纯合的聚合F₃株系。条纹叶枯病抗性鉴定和纹枯病抗性接种鉴定结果表明,聚合株系对条纹叶枯病均表现抗病;以0~9级评级标准评价,聚合株系的纹枯病较相应的轮回亲本分别低1.1~1.6级和0.8~1.4级。结合回交低世代抗性鉴定结果分析,自行开发的分子标记对目标基因的辅助选择是有效的。讨论了抗纹枯病育种及分子标记辅助选择聚合育种的相关问题。