模拟降水量变化对荒漠草原土壤酶活性的影响及其相关因素分析

为明确荒漠草原土壤酶活性对降水格局改变的响应机制, 该研究基于宁夏荒漠草原降水量不同梯度变化(减少50%、减少30%、自然降水、增加30%和增加50%)的野外试验(2014年开始试验), 于2016年5-7月采样, 测定分析不同降水梯度2年后对土壤酶活性的影响, 并分析酶活性与植物生物量、微生物生物量C∶N∶P生态化学计量特征以及土壤理化性质的关系。结果表明: (1)与自然降水量相比, 减少30%降水量对3种土壤酶活性均无显著影响, 减少50%降水量显著降低了土壤蔗糖酶活性(^P < 0.05); 增加降水量显著提高了土壤蔗糖酶和磷酸酶活性(^P < 0.05), 但对脲酶活性无显著影响。(2)减少降水量对植物生物量影响较小(尤其减少30%降水量), 但不同程度地降低了微生物生物量C、N、P, 提高了微生物生物量C∶N和C∶P; 增加降水量则不同程度提高了植物生物量及微生物生物量C、N、P。(3)土壤蔗糖酶和磷酸酶活性随植物及微生物生物量增加而增加; 对土壤酶活性影响显著的土壤因子包括: 含水量、NO₃^- N、NH₄⁺ N、C∶P、有机C、全N、C∶N和pH (P < 0.05)。研究认为, 减少降水量(尤其是减少30%降水量)对土壤酶活性影响较小, 增加降水量促进了植物的生长、刺激微生物活性, 进而提高了土壤酶活性, 但随着植物生物量增加, 土壤有机C输入增多, 磷酸酶活性相应增强并促进了有机P的矿化, 导致土壤微生物P限制增加。     

Close linkages between leaf functional traits and soil and leaf C:N:P stoichiometry under altered precipitation in a desert steppe in northwestern China

Leaf functional traits are important for characterizing plant nutrient strategies. The C:N:P stoichiometric balance in soils and plants, which could indicate types of nutrient limitation, is altered under changing precipitation patterns. However, whether such alterations affect leaf functional traits remains unclear. We conducted a three-year simulated precipitation experiment in a desert steppe in northwestern China to determine changes in leaf photosynthetic traits and nutrient conservation traits in five plant species and tested the relationships of these traits with soil and leaf C:N:P stoichiometry. The five species showed few changes in their leaf traits under drought conditions, but they adjusted these traits (especially P traits) under extremely wet conditions (50% increase in precipitation). Improved leaf photosynthetic N and P use, lowered leaf P uptake, and enhanced leaf N resorption might help Lespedeza potaninii to rely less on soil nutrients in extremely wet environments than other species do. Leaf photosynthetic traits were regulated primarily by soil and leaf C:N:P stoichiometry. Leaf nutrient conservation traits were controlled by both leaf C:N:P stoichiometry and soil properties (i.e., enzyme activity and microbial biomass), a condition especially true for P traits. The results suggest that precipitation-induced alteration in the C:N:P stoichiometric balance might have important influences on plant nutrient use strategies and even on the nutrient cycling of desert steppes.

     

Rotavirus Vaccination Coverage among Children Aged 2-59 Months: A Report from Guangzhou,China

Objective

We aimed to estimate the Lanzhou lamb rotavirus (LLR) vaccination coverage (VC) and timeliness among children aged 2 to 59 months in Guangzhou, China.

Methods

An electronic system-based VC survey was conducted using stratified cluster random sampling.

Results

We reported an overall Lanzhou lamb rotavirus vaccine coverage of 25.3% among children aged 2-59 months (2-8 months, 2.6%) in Guangzhou, China.

Conclusion

Great efforts should be taken to increase LLR VC in eligible children in Guangzhou, China.     

八倍体小偃麦染色体组分析

本文对普通小麦与长穗偃麦草(Elytrigia elongata=Agropyron elongatum.2n=70)杂交选育出来的5个八倍体小偃麦的染色体组进行了研究。通过八倍体小偃麦与普通小麦杂交,八倍体小偃麦相互间杂交,观察了杂种F_1花粉母细胞减数分裂行为。根据观察结果,讨论了长穗偃麦草染色体组的构成,认为长穗偃麦草的染色体组为E_1E_2F_2F_2N较为合适。在此基础上,确定了5个八倍体小偃麦的染色体组:7430为ABDE_1,68为ABDF_1,693为ABDF_1,7631为ABDF_2,784为ABDN。另外,还讨论了八倍体小偃麦染色组的重组问题。     

Development and Molecular Cytogenetic Identification of a Novel Wheat–Leymus mollis Lm#7Ns (7D) Disomic Substitution Line with Stripe Rust Resistance

Leymus mollis (2n = 4x = 28, NsNsXmXm) possesses novel and important genes for resistance against multi-fungal diseases. The development of new wheat—L. mollis introgression lines is of great significance for wheat disease resistance breeding. M11003-3-1-15-8, a novel disomic substitution line of common wheat cv. 7182 –L. mollis, developed and selected from the BC₁F₅ progeny between wheat cv. 7182 and octoploid Tritileymus M47 (2n = 8x = 56, AABBDDNsNs), was characterized by morphological and cytogenetic identification, analysis of functional molecular markers, genomic in situ hybridization (GISH), sequential fluorescence in situ hybridization (FISH)—genomic in situ hybridization (GISH) and disease resistance evaluation. Cytological observations suggested that M11003-3-1-15-8 contained 42 chromosomes and formed 21 bivalents at meiotic metaphase I. The GISH investigations showed that line contained 40 wheat chromosomes and a pair of L. mollis chromosomes. EST-STS multiple loci markers and PLUG (PCR-based Landmark Unique Gene) markers confirmed that the introduced L. mollis chromosomes belonged to homoeologous group 7, it was designated as Lm#7Ns. While nulli-tetrasomic and sequential FISH-GISH analysis using the oligonucleotide Oligo-pSc119.2 and Oligo-pTa535 as probes revealed that the wheat 7D chromosomes were absent in M11003-3-1-15-8. Therefore, it was deduced that M11003-3-1-15-8 was a wheat–L. mollis Lm#7Ns (7D) disomic substitution line. Field disease resistance demonstrated that the introduced L. mollis chromosomes Lm#7Ns were responsible for the stripe rust resistance at the adult stage. Moreover, M11003-3-1-15-8 had a superior numbers of florets. The novel disomic substitution line M11003-3-1-15-8, could be exploited as an important genetic material in wheat resistance breeding programs and genetic resources.     

八倍体小偃麦与普通小麦杂交选育抗旱小麦品种的研究

利用八倍体小堰麦与普通小麦杂交,通过连续选择选育出抗旱小麦品种小偃５９７,试验结果表明,小偃５９７抗旱,叶组织细胞膜的稳定性（７．６％）,叶片持水力（５１．６０％）和叶组织相对含水量（７７．０６％）高,株高８５ｃｍ,白粒,角质,品质优。每公顷６７５０ｋｇ。     

Molecular cytogenetic identification of a wheat–<Emphasis Type="Italic">Aegilops geniculata</Emphasis> Roth 7M<Superscript>g</Superscript> disomic addition line with powdery mildew resistance

Aegilops geniculata Roth is an important germplasm resource for the transfer of beneficial genes into common wheat (Triticum aestivum L.). A new disomic addition line NA0973-5-4-1-2-9-1 was developed from the BC₁F₆ progeny of the cross wheat cv. Chinese Spring (CS)/Ae. geniculata SY159//CS. We characterized this new line by morphological and cytogenetic identification, analysis of functional molecular markers, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and disease resistance evaluation. Cytological observations suggested that NA0973-5-4-1-2-9-1 contained 44 chromosomes and formed 22 bivalents at meiotic metaphase I. The GISH investigations showed that the line contained 42 wheat chromosomes and a pair of Ae. geniculata chromosomes. EST-STS multiple loci markers and PLUG (PCR-based landmark unique gene) markers confirmed that the introduced Ae. geniculata chromosomes belonged to homoeologous group 7. FISH identification suggested that NA0973-5-4-1-2-9-1 possessed an additional pair of 7M^g chromosomes, and at the same time, there were structural differences in a pair of 6D chromosomes between NA0973-5-4-1-2-9-1 and TA7661 (CS-AEGEN DA 7M^g). After inoculation with powdery mildew (Blumeria graminis f. sp. tritici, Bgt) isolates E09, NA0973-5-4-1-2-9-1 exhibited a powdery mildew resistance infection type different from that of TA7661, and we conclude that the powdery mildew resistance of NA0973-5-4-1-2-9-1 originated from its parent Ae. geniculata SY159. Therefore, NA0973-5-4-1-2-9-1 can be used as a donor source for introducing novel disease resistance genes into wheat during breeding programs with the assistance of molecular and cytogenetic markers.     

宁夏燃煤电厂周边土壤、植物和微生物生态化学计量特征及其影响因素

大气酸沉降增加对陆地生态系统的影响已得到了广泛证实,但有关酸沉降累积下工业排放源周边植被-土壤系统元素平衡特征及其影响机制的研究较少。燃煤电厂是主要的工业酸排放源之一。因此,以宁东能源化工基地3个燃煤电厂为观测点,研究了电厂周边土壤-植物叶片-微生物生态化学计量特征,分析了叶片和微生物生物量生态化学计量特征与降水降尘S、N沉降量及土壤性质的关系。结果表明：土壤和微生物生物量C ： N ： P生态化学计量特征变异系数较大,叶片各指标的变异系数较小。与受人类活动影响较少的其他同类型区相比,研究区具有较高的土壤有机C水平和N、P供给,且P相对于N丰富。植物可能主要受N限制,而微生物主要受P限制;土壤及微生物元素间均存在极显著的线性关系（P<0.001）。叶片全C与全N、全P均无显著的关系（P>0.05）。叶片全N、全P和N ： P具有高的内稳性。微生物生物量N ： P内稳性较强,但生物量N和P内稳性较弱,对土壤环境的变化反应敏感;SO₄^2-沉降有助于促进叶片对P的摄取和微生物对C、N、P的固持。少量NO₃^-沉降有利于叶片N摄取,但持续增加的NO₃^-沉降可能会使土壤P受限性增强,进而抑制叶片P摄取和微生物生物量积累。土壤酶活性、Ca²⁺和含水量亦显著影响着植物和微生物元素生态化学计量关系（P<0.05）。因此,今后还需结合多个电厂的土壤性质和植被状况,从较长时间尺度上深入揭示酸沉降增加对工业排放源周边植被-土壤系统元素平衡特征的影响机制。