Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf δ15N

Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf δ¹⁵N and biomass production for the plant functional groups. Seven dominant plant species—three legumes, two forbs, one grass, one sedge—were analyzed for N, P, and δ¹⁵N 2 years after fertilization with one of the three N forms: NO$ _3^- $ , NH$ _4^+ $ , or NH₄NO₃ at four application rates (0, 7.5, 30, and 150 kg N ha^–1 y^–1). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co‐limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above‐ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf δ¹⁵N indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e.g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.     

红壤丘陵区不同生态重建中红壤的微生物学性状

研究了中国科学院红壤生态试验站的优化农业生态模式的长期定位试验地里的常绿针叶林地(马尾松林)、落叶阔叶林地(小叶栎)、针阔混交林地(湿地松-小叶栎)、自然恢复地(受到人为干扰)、茶园地、柿子园地和花生地等样地，并且在附近选了疏草荒地作为对照。结果发现，不同生态重建模式与对照相比，在微生物学性状上均有很大程度的提高。总的趋势是农用果园地好于林地，林地好于自然恢复地。在剖面分布上，也有明显的层次差异，即随土层的增加而减少。     

3个STR位点在中国7个民族遗传距离中的研究

应用PCR技术、质量分数4%变性聚丙烯酰胺凝胶电泳及银染技术,研究了D16S539,D7S820和D13S7133个STR位点在新疆锡伯族和哈萨克族中的遗传结构,结合汉族、黎族、朝鲜族、藏族和维吾尔族相同位点的相关遗传资料,应用亲缘系数和遗传距离研究了7个民族间的遗传关系,并根据遗传距离绘制遗传系统树。结果显示,汉族、朝鲜族、黎族、藏族和锡伯族为一群,而新疆哈萨克族和维吾尔族为一群。其中,汉族与朝鲜族遗传距离最近,其他依次为黎族、藏族和锡伯族。     

Estimation of genetic parameters for reproductive traits in connectedness groups of Duroc,Landrace and Yorkshire pigs in China

The objective of this study was to estimate group- and breed-specific genetic parameters for reproductive traits in Chinese Duroc, Landrace, and Yorkshire populations. Records for reproductive traits between April 1998 and December 2017 from 92 nucleus pig breeding farms, which were involved in the China Swine Genetic Improvement Program, were analysed. Due to weak genetic connectedness across all farms, connectedness groups consisting of related farms were used. Three, two and four connectedness groups for Duroc, Landrace and Yorkshire were firstly established according to the genetic connectedness rating among farms. For each connectedness group a five-trait animal model was implemented, and via restricted maximum likelihood procedure the genetic parameters were estimated for five reproductive traits i.e., total number born (TNB), number born alive (NBA), litter weight at farrowing (LWF), farrowing interval (FI) and age at first farrowing (AFF). The average of heritabilities among connectedness groups ranged from .01 (for FI in Yorkshire) to .30 (for AFF in Duroc). Estimates of repeatability for litter traits ranged from .14 to .20 and were consistent for each breed, and for FI, the estimates varied from .01 to .11 across breeds and groups. The estimated genetic correlations among litter traits (i.e., TNB, NBA and LWF) were all significantly high (>.56) and similar across breeds. Averaged genetic correlations over three breeds were −.25, −.27, −.18, −.04, −.10, −.02, and .28 for FI-TNB, FI-NBA, FI-LWF, AFF-TNB, AFF-NBA, AFF-LWF and FI-AFF, respectively. The standard errors of the estimates were all very low (<0.01) in most situations. Results from this study suggest that selection based on TNB which is currently used in dam line selection index can improve NBA and LWF simultaneously. However, care should be taken on FI and AFF as they are both greatly influenced by non-genetic factors such as management and measurement.     

中国不同地区烟草寄生疫霉(Phytophthora parasitica var. nicotianae)菌株的随即多态性DNA扩增分析

来自中国云南、辽宁、山东3省的烟草寄生疫霉（Phytophthora parasitica var.nicotianae)菌株的致病性已被划分为3种致病类型组，即强致病性组、中致病性组和弱致性组。上述省是中国的烟草主产区，选自云南省的15个烟草寄生疫霉菌株、山东省的13个烟草寄生霉菌株和辽宁省的20个烟草寄生疫霉菌株，选择3个烟草栽培品种在温室内进行接种试验测定不同菌株的致病性分化。提取受试菌株的DNA，利用PCR技术对受试苗菌株的模板DNA进行随机多态性扩增分析，对扩增DNA片段谱带借助于UPGMA分析法构建遗传树，结果表明，受试菌株被划分为4个遗传聚类组，每个遗传聚类组内包括不同的烟草寄生疫霉致病性菌株，而且来自于不同烟区相同的致病性菌株和每种致病性的不同菌株皆不属于同一个遗传聚类组内。结果表明RAPD－PCR的遗传标记分析结果与不同致病性组的划分未有明显的区别。因此，随机多态性DNA图谱的相同与不同不能当作区分来自不同烟区的烟草寄生疫霉的致病性分化的分子检测的工具。     

优质抗病高配合力中籼两用核不育系隆科638S的选育及应用

利用传统育种技术与分子标记辅助选择技术有机结合,成功培育出了株型理想、不育转换起点温度低于23.5℃、育性稳定、异交性好、配合力强的两用核不育系隆科638S,于2014年通过湖南省品种审定。全基因组重测序分析结果表明,隆科638S含有约56.0%的早籼稻遗传背景,以及约8.7%的粳稻遗传背景,为充分利用“早晚生态型间和籼粳亚种间”双重杂种优势奠定了遗传基础。依据分子设计和杂种优势群理论,按“双亲抗性基因互补”和“双亲品质基因一致性”配组原则,高效培育出一批绿色、优质、广适、高产的隆两优系列品种,迅速成为我国南方杂交水稻主栽品种,推动了长江流域杂交中籼品种的更新换代。     

紫云英翻压还田对稻田土壤团聚体组成及其碳氮的影响

紫云英翻压还田是南方传统稻田土壤培肥增产的主要措施。依托连续12年田间定位试验,通过设置CK（不施化肥,紫云英不还田）、单施化肥（GM0）和4个梯度的紫云英翻压量（GM1-4）处理,分析连续多年紫云英翻压还田对稻田土壤团聚体组分、团聚体中碳氮含量和储量,并通过傅里叶红外光谱测定各粒级有机官能团类型及相对含量,探讨连续多年紫云英翻压还田对土壤团聚体组分及其碳氮分布的影响。结果表明,在该土壤中粒级>2 mm土壤团聚体含量最高,占总量的61.12%～68.53%,其次是2～0.25 mm粒级团聚体。紫云英翻压还田较单施化肥处理提高了>2 mm粒级团聚体所占百分比（5.93%～9.91%）。紫云英翻压还田提高了粒级>0.053 mm团聚体中有机碳含量和各个粒级中全氮含量,其中粒级>0.25 mm团聚体的碳氮含量与紫云英翻压量之间呈现出显著正相关关系。紫云英翻压还田分别显著提高了19.42%～37.09%有机碳和22.31%～40.13%氮的总储量,其中粒级>2 mm团聚体中碳氮储量随着紫云英翻压量的增加而增加。>2 mm粒级团聚体中碳氮的分布也随着紫云英的翻压还田而增加。通过傅里叶红外光谱认为土壤各粒级团聚体中脂肪族有机碳和芳香族有机碳以及N-H官能团含量也随着紫云英翻压还田而增加,其中N-H官能团含量与紫云英翻压量之间呈现出显著的正相关关系。紫云英翻压还田同时提高了各团聚体中1 630/2 850+2 940和1 720/2 850+2 940相对比值,其中>2 mm和2～0.25 mm粒级团聚体中1 630/2 850+2 940相对强度比值与紫云英翻压量之间均呈显著性相关关系。综上,紫云英翻压还田不仅有利于改善稻田土壤团聚体组分,增加有机碳和全氮在土壤团聚体中的储存,还提高了团聚体有机碳的活性和稳定性,从而有助于提升稻田土壤肥力。     

芝麻产量性状与品质性状的典型相关分析

以15个芝麻品种(品系)为材料,根据生物学意义将15个性状归纳为4个性状组,对性状和性状组基因 型值进行相关分析和典型相关分析,并建立了由多个农艺性状间接改良品质性状的综合选择指数。结果表明:对 单株产量影响最大的因素是农艺性状(株高、果轴长、始蒴部位)和产量构成因子(蒴粒数、千粒重) ,而且农艺性状 与产量构成因子以正相关为主,因此可以同步改良农艺性状和产量构成因子以进一步提高产量潜力;含油量与主 要农艺性状、产量构成因子以及种子容重呈正相关,而与粒宽和蛋白质含量呈显著负相关,因此含油量和产量可以 协调发展,同步提高,而且可以通过籽粒性状间接辅助选择高产、高含油量的芝麻新品种。     

Potassium Uptake in Relation to Drought Tolerance of Chickpea Under Rain-Fed Conditions

Potassium is accumulated in substantial amount in water stressed plants, contributing to osmotic adjustment. Eight varieties of chickpea were field grown according to randomized block design with three replications during two consecutive crop seasons to explore the role of K uptake in drought tolerance of chickpea under rain-fed conditions. Plant water relation and other physiological parameters were measured at 70 days after planting, while potassium uptake and yield parameters were recorded at harvest. The varieties were divided into high (HKU), medium (MKU) and low (LKU) K uptake groups, using average K uptake across the seasons. All the data were statistically analyzed group-wise. The HKU, followed by MKU and LKU (i.e. HKU>MKU>LKU) gave the highest values for most of the parameters studied including seed yield and crop biomass. The HKU also exhibited the lowest osmotic potential together with maintenance of elevated water content and turgor in plants compared to MKU and LKU. There was significant season-group interaction regarding most parameters including seed yield and crop biomass. However, such an interaction was not significant regarding K uptake, though varietal group pattern of K uptake was similar to that of seed yield and crop biomass (i.e. HKU>MKU>LKU), indicating that promising chickpea varieties might be selected under rain-fed conditions using K uptake.     

黄麻和红麻纤维磨木木质素的红外光谱特征

从黄麻和红麻纤维中分离出磨木木质素,利用红外光谱分析了两种麻纤维磨木木质素的特征峰及归属,得知磨木木质素中有复杂的官能团,含有羟基、羰基、甲基等基团,木质素结构中含有相当数量的紫丁香基单元。根据黄麻和红麻纤维磨木木质素的红外光谱吸收峰强度,推断其结构属于阔叶木类木质素化学结构GS型木质素。