冀西北地区不同生态系统枯落物的水文效应

[目的]揭示不同植被生态系统枯落物水文效应的差异,为张家口地区生态空间格局优化提供支撑。[方法]基于样地调查和统计分析方法,分别对冀西北地区张家口市森林、农田和草地3种生态系统的枯落物在生长季末期持水能力及其与生物量之间的关系进行分析。[结果]①森林生态系统枯落物的最大持水量(30.7t/hm~2)、有效拦蓄量(22.97t/hm~2)、有效拦蓄率(187.49%)和吸水速率(5.84g/h)4个指标均优于其他两类生态系统。②草地枯落物的各项水文指标均值皆高于农田,最大持水率甚至高于森林生态系统。③枯落物生物量与其最大持水量和有效拦蓄量呈显著正相关关系,而枯落物占生态系统总生物量的比例随总生物量增加呈幂数下降。[结论]如果造林营林方式正确,森林生态系统能够提升区域水源涵养水平,同时草地的水源涵养能力不容忽视,市域内大范围的耕地向草地扩展,将直接影响区域的水源涵养能力。以生物量表征的生态系统固碳能力与枯落物蓄水所反映的水源涵养能力之间的响应关系在生态系统不同尺度下具有不同的表现,在对区域生态空间格局进行优化时,需明确特定环境下不同生态系统类型枯落物的水源涵养能力及其变化对其他生态服务功能的影响,从而实现各生态系统平衡发展。     

贵州省城乡人口变化与建设用地扩张的脱钩关系

[目的]研究贵州省人口与建设用地变化的关系,以促进土地资源优化配置。[方法]利用贵州省2000—2017年城乡人口及建设用地数据,采用脱钩模型和GIS空间分析方法,研究城乡人地关系演化过程。[结果]贵州省城镇人口持续增加,乡村人口逐年减少;城乡建设用地面积不断扩大,城镇和乡村建设用地同向增长。2000—2008年,贵州省城乡人口变化与建设用地扩张关系为强负脱勾类型,乡村人口与乡村建设用地变化为强负脱钩类型,城镇人口与城镇建设用地变化为扩张负脱钩类型。农村人口减少伴随着建设用地增加,农村人地关系处于较不合理状态;城镇人口和建设用地二者均增长,但建设用地增幅快于人口增幅。[结论]贵州省应积极推动农村宅基地流转,提高城乡建设用地集约利用水平,促进城乡融合。     

家蚕Ras3基因全长cDNA克隆及在感染BmNPV家蚕组织中的表达谱分析

Ras(rat sarcoma viral oncogene homolog)蛋白是GTPase超家族成员之一,该蛋白质可以将细胞外信号传导到不同的细胞,从而调控细胞的吞噬作用、凋亡、抗微生物侵染的酶防御系统等生理过程.运用RACE技术,从家蚕中肠中克隆出一个新的BmRas3基因,该基因cDNA全长987 bp,包含5'UTR(153 bp)、3'UTR(279 bp)和一个编码184个氨基酸残基的ORF(555 bp).BmRas3具有小G蛋白的典型特征,其氨基酸序列中含有3个GTP/GDP结合结构域,1个效应子结合结构域以及1个烯丙基化的CAAX基序.多重比对发现BmRas3与海波斯莫科马属蛾(Hyposmocoma kahamanoa)Rap1、斜纹夜蛾(Spodoptera litura)Rap-1b、烟草天蛾(Manduca sexta)Rap1的序列相似性较高,系统进化分析也显示BmRas3与这些蛋白质的亲缘关系最近.BmRas3在食桑期的表达量高于眠期;在感染BmNPV的家蚕中肠和脂肪体中,BmRas3的表达量有不同程度提高,且与正常对照相比差异显著,暗示BmRas3可能作为免疫活化因子,在家蚕抵抗BmNPV的入侵过程中发挥着重要作用.研究结果为下一步探讨BmRas3对BmNPV感染的应答提供了理论基础.     

籽用西葫芦新品种比较试验

为了解决新疆昌吉地区籽用西葫芦品种繁杂、产量不高、效益不好等问题,从山西省引进10个籽用西葫芦新品种,通过田间试验比较分析了各品种的生育期、植物学性状、果实性状、籽粒性状、抗病性及产量等指标,初步筛选出3个适合新疆昌吉地区种植的籽用西葫芦品种,分别为籽瑞宝、ZHL-3和华仁九号,3个品种白粉病、病毒病发病率均在10%及以下,667 m~2籽粒产量175 kg以上。     

Morphological and Compositional Analysis of Two Walnut (Juglans regia L.) Cultivars Growing in China

Plant Foods for Human Nutrition - Two selected walnut cultivars (Xiangling and Jizhaomian) growing in China were analyzed in terms of proximate and mineral composition, fatty acid and amino acid...     

Effects of cardiac contractility modulation on ventricular electrical remodeling in rabbits with chronic heart failure

AIM: To investigate the effects of cardiac contractility modulation (CCM) on ventricular electrical remodeling in a rabbit model of chronic heart failure. METHODS: The rabbits were divided into sham group, heart failure(HF) group and HF+ CCM group. The rabbit model of chronic heart failure was established by ligating the ascending aortic root. Then electrical stimulations during the absolute refractory period were delivered lasting 6 h everyday for 4 weeks in rabbits of HF+ CCM group. The QTc and ventricular effective refrective period (VERP) were recorded. The protein and mRNA levels of Kv1.4, Kv4.3 and connexin 43 (Cx43) were determined by Western blot and RT-qPCR. RESULTS: Compared with sham group, QTc were significantly prolonged in HF rabbits at week 12 (P<0.05). CCM therapy shortened QTc of rabbits with heart failure at week 16 (P<0.05). Compared with sham group, VERP significantly increased in HF group and HF+ CCM group, while CCM therapy shortened VERP of rabbits with heart failure at week 16 (P<0.05). Compared with sham group, the mRNA and protein levels of Kv1.4, Kv4.3 and Cx43 were decreased in HF group and HF+ CCM group (P<0.05). However, CCM therapy restored the mRNA and protein levels of Kv1.4, Kv4.3 and Cx43 of rabbits with heart failure (P<0.05). CONCLUSION: CCM suppresses ventricular electrical remodeling in heart failure and the underlying mechanism may be associated with increasing Kv1.4, Kv4.3 and Cx43 expression.     

Stoichiometric features of C,N, and P in soil and litter of Tamarix cones and their relationship with environmental factors in the Taklimakan Desert,China

Journal of Soils and Sediments - The main objectives of this study were to explore the soil and litter carbon (C), nitrogen (N), and phosphorus (P) stoichiometric features in the Tamarix cones...     

Remediation of saline-sodic soil using organic and inorganic amendments: physical,chemical, and enzyme activity properties

Purpose

Crops grow poorly in saline-sodic soils, and the productivity of these soils can be dramatically improved with proper amendments. Current research mainly focuses on either organic or inorganic soil amendments, whereas few studies address options of combining organic and inorganic amendments. The objective of this study was to develop new organic and inorganic soil amendments which can lower the soil pH, replace sodium, and improve soil structure.

Materials and methods

Polyhalite (PL), microporous potassium-silicon-calcium mineral fertilizer (MF), furfural residue (FR), and fulvic acid (FA) were mixed with four different ratios to produce organic and inorganic soil amendments: PLFR, PLFA, MFFR, and MFFA. And their optimum mixing ratios were determined by comparing the potassium, calcium concentrations, and pH of filtrate after dissolution. Then, a leaching experiment was conducted by packing mixtures (mass ratio of soil to amendment = 219:1, equivalent to 13 t/hm²) of the saline-sodic soil with each one of these amendments plus two contrasts, gypsum (GP), and no amendment (CK). And the remediation effect was compared by pH, EC, ESP, texture, organic recombination degree of clay, saturated hydraulic conductivity, water-stable aggregates fraction, and enzyme (urease, alkaline phosphatase, and catalase) activities of soil.

Results and discussion

After four times leaching experiment, soil treated with PLFR had lower pH and 25.86% lower exchangeable sodium than untreated soils. The water-stable small macroaggregate fractions and saturated hydraulic conductivity of the MFFR-treated soils were significantly increased by 133% and 31%, respectively. Also, the total soil and heavy fraction organic carbons of the soils treated with MFFR in addition to its alkaline phosphatase activity were all significantly higher than the other treatments.

Conclusions

The results revealed that MFFR has more potential as a soil amendment to improve soil structure and quality and thus help in the development and use of saline-sodic lands for agriculture.