不平衡巢式设计遗传模型分析

虽然巢式试验设计在动植物育种中得到广泛应用,但是在不平衡数据条件下有关遗传参数估计和假设检验统计量的计算还存在着很多问题。文中针对不平衡数据条件下的巢式试验设计,使用固定效应模型和随机效应模型估计相关的遗传参数并进行相应的统计假设检验。对于固定效应模型,使用约束线性模型方法推导出亲本配合力估计及亲本间配合力假设检验统计量的计算公式。对于随机效应模型,采用混合线性模型中的方差分析法,推导出方差分量估计的计算公式,并给出方差分量估计标准误以及方差分量假设检验统计量的计算方法,进而给出遗传力计算公式及其标准误的近似计算方法。最后,用VC++编写多种形式巢式设计遗传模型的各种遗传参数估计和假设检验统计量计算的Windows应用软件,供林木遗传育种工作者使用。     

Density effects on environmental variance and expected response to selection in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

The study aimed to address the optimal plant population density in maize that maximizes phenotypic expression and differentiation, and lessens environmental effects on genotypic expression in terms of the response to selection. A set of seven short-season hybrids (Rom set) was tested under rainfed conditions (2006, 2007) in Romania, and a set of seven long-season hybrids (Gr set) was tested with irrigation (2007) in Greece. Experimentation was conducted under ultra-low (ULD), low (LD), middle (MD), and high (HD) densities (0.74, 2.51, 4.20, 8.40 plants/m² for the Rom set, and 0.74, 3.13, 6.25, 8.33 plants/m² for the Gr set). Phenotypic expression and differentiation for grain yield were highest at the ULD. Coefficient of variation (CV) for grain yield, ear length and kernel row number decreased as density decreased. Environmental conditions and hybrid plant-yield potential (i.e., maximum yield per plant) were crucial for the optimal density that achieved the lowest environmental variance. For the Rom set the lowest CV for grain yield was obtained at the LD in the unfavourable season and at the ULD in the favourable season. The less acquired variance was achieved at the ULD for the highest yielding hybrids and at the LD for the lowest yielding hybrids, revealing a negative association between plant-yield potential and optimal density. Concluding, a density proximal to the ULD approximates absence of competition in maize, and optimizes three determinant parameters for successful selection: selection intensity, heritability and phenotypic differentiation.     

鲜切荸荠保鲜工艺技术的研究

将新鲜荸荠经过清洗、挑选、去皮,在复合护色剂溶液中浸泡10min分钟后,甩干并包装,在温度4℃的条件下贮藏12d,测定其褐变度(BD)和多酚氧化酶活性(PPO)。通过用不同的包装材料对荸荠进行包装实验,结果表明,LDPE袋不适合于荸荠贮藏保鲜,样品表面色泽与风味都无法保持;PA/PE袋可以极好地保持荸荠色泽洁白与风味正常。同时还发现,PA/PE包装荸荠在低温(4℃)下贮藏1个月内可保持不胀袋;鲜切荸荠经紫外光照射50min后,在温度4℃下贮藏21d,经微生物培养,样品菌落总数为4.78×105cfu/g,在温度25℃下贮藏7d,经过微生物培养,样品菌落总数为4.86×105cfu/g,均不超过食品菌落总数的安全标准值5.0×105cfu/g。     

Morphological and chemical characteristics of doubled haploids of flue-cured tobacco combining resistance to Thielaviopsis basicola and TSWV

Thielaviopsis basicola and Tomato spotted wilt virus (TSWV) are the most important problems in a moderate climate zone. Previously obtained doubled haploids (DH) of F₁ hybrids of the flue-cured line WGL3 resistant to Th. basicola and the dark-cured line PW-834 carrying RTSW-al gene provided the research material. Biological tests and SCAR markers linked with TSWV were applied to confirm resistance of DH. Lines combining resistance to TSWV and Th. basicola were evaluated for morphological and chemical characteristics. Most of DH were significantly shorter than parents but two lines, 31/A/2 and 31/B/3, were close to the flue-cured WGL3. Usually DH possessed fewer leaves while one of them 31/B/3, exceeded parental forms. The doubled haploids flowered later than their parents. The most negative effect was reduced area of mid-position leaves of DH. It might be explained by a recombination during microsporogenesis in F₁, however the influence of ‘Polalta’-derived RTSW-al gene cannot be excluded. Extensive line to line variation for nicotine and sugars content was not associated with the genes for TSWV and Th. basicola resistance. Biological tests and field performance of DH revealed potential to overcome the negative effect of coupling between the RSTV-al gene and genes responsible for the morphological deformations.     

Phosphorus forms in forest soil colloids as revealed by liquid‐state 31P‐NMR

Nanoparticles and colloids affect the storage and hence the availability of P in forest ecosystems. We investigated the fine colloids present in forest soils and their association with inorganic and organic P. To differentiate between the different P forms, we performed liquid‐state ³¹P‐nucelar magnetic resonance (³¹P‐NMR) measurements on forest bulk soil extracts, on colloid extracts and on the electrolyte phase of their soil suspensions. The ³¹P‐NMR spectra indicated that soil nanoparticles and colloids were more enriched with organic than with inorganic P forms compared to the electrolyte phase. The P concentration was enriched in the colloidal fraction in comparison to the bulk soil and the phosphate diesters were more dominant in the colloidal fraction when compared to the bulk soil. The colloidal P‐diester to P‐monoester ratios were 2 to 3 times higher in the colloidal fraction than in the bulk soil. In contrast, relatively large percentages of inorganic P were found in the electrolyte phase. Supplementary (not shown) Data are available at the JuSER Server (juser.fz‐juelich.de, reference number: FZJ‐2016‐01739) https://juser.fz‐juelich.de/record/283057 .     

Changes in the activity and abundance of the soil microbial community in response to the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP)

Purpose

The application of organic and inorganic fertilizers to soil can result in increased gaseous emissions, such as NH₃, N₂O, CO₂, and CH₄, as well as nitrate leaching, contributing to climate warming and ground and surface water pollution, particularly in regions with hot climates, where high temperatures and high soil nitrification rates often occur. The use of nitrification inhibitors (NIs) has been shown to effectively decrease nitrogen (N) losses from the soil-plant system.

Materials and methods

Non-disruptive laboratory incubation experiments were conducted to assess the extent to which temperature (20 and 30 °C) and nutrient source (mineral and organic fertilizers) influence the rate of carbon (C)- and N-related microbial processes in soil in response to the NI 3,4-dimethylpyrazole phosphate (DMPP). Furthermore, short-term changes in the ability of microbes to degrade C substrates were evaluated in disruptive soil microcosms using microbial community-level physiological profiling and the abundance of the bacterial 16S rRNA gene as a measure of total bacterial population size.

Results and discussion

DMPP reduced net nitrification after 2 and 4 weeks of incubation at 30 and 20 °C by an average of 78.3 and 84.5 %, respectively, and with similar dynamics for mineral or organic fertilization. The addition of labile organic matter with cattle effluent led to a rapid increase in C mineralization that was significantly reduced by DMPP at both temperatures, whereas no changes could be detected after the addition of mineral fertilizer. The culturable heterotrophic microorganisms showed metabolic diversification in the oxidation of C sources, with organic fertilizer playing a major role in the substrate utilization patterns during the first week of incubation and the DMPP effects prevailing from day 14 until day 28. Furthermore, the copy number of the bacterial 16S rRNA gene was reduced by the application of DMPP and organic fertilizer after 28 days.

Conclusions

Our results show the marked efficiency of DMPP as an NI at elevated temperatures of incubation and when associated with both mineral and organic fertilization, providing support for its use as a tool to mitigate N losses in Mediterranean ecosystems. However, we also observed impaired C respiration rates and bacterial abundances, as well as shifts in community-level physiological profiles in soil, possibly indicating a short-term effect of DMPP and organic fertilizers on non-target C-related processes and microorganisms.

     

Acclimation of apple spur leaf nutrient concentrations and gas exchange to summer-pruning

Foliar concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, and chlorophyll were measured in shade-adapted and sun-adapted spur leaves of apple cvs ”︁Golden Delicious” and ”︁Granny Smith” as well as in shade-adapted leaves after summer-pruning. The shade-to-sun transition of summer-pruned leaves resulted in concentration changes towards the level of sun-adapted leaves, which were accompanied by significant increases in net photosynthesis and transpiration rates as well as maximum photosynthesis rates. Gas exchange parameters of fully expanded spur leaves after the shade-to-sun transition did not differ from those of sun adapted leaves. This indicates the capacity of fully expanded apple spur leaves to adapt to a new light environment and supports the hypothesis that nutrients are distributed to leaves growing under the highest light intensity in order to maximize their photosynthesis.     

RELATIVE SUSCEPTIBILITY OF SOME PRUNUS ROOTSTOCKS IN HYDROPONICS TO IRON DEFICIENCY

The susceptibility of eleven Prunus rootstocks to iron (Fe) deficiency was studied in hydroponics by growing them with 20 μM Fe, 0 μM Fe or 3 μM Fe+10 mM sodium bicarbonate. Based on the intensity of leaf chlorosis, the peach-almonds PR 204/84, Stylianidis K and KID2, produced at the Pomology Institute of Naoussa (Greece), showed the same or even greater tolerance than GF 677, the Greek peach-almond Retsou x Nemaguard, the plum-almond Myrandier 617 and the peaches GF 305, IDS 37, Greek wild peach seedling the greatest susceptibility whereas the plums St. Julien GF655/2 and Myrobalan 29C intermediate. Rootstocks without Fe presented significantly lower nitrogen and Fe whereas with bicarbonate significantly lower nitrogen, phosphorus, Fe and zinc. Root ferric chelate reductase activity was significantly increased in ?Fe rootstocks but negatively correlated with their tolerance; physiological and morphological changes were observed along a zone of a few centimeters length, 1–2 mm behind the root tip.