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1.
土壤呼吸是全球碳循环的主要流通途径,但半干旱草地土壤呼吸对全球变化和人类干扰的响应机制尚不清楚。该研究以科尔沁沙质草地为研究对象,研究氮沉降增加、人类干扰(火烧、刈割)及其交互作用对沙质草地整个植物生长季(2017年5-9月)土壤呼吸的影响。结果表明,土壤呼吸呈明显的季节动态变化,在7月最高。氮沉降增加使根呼吸显著提高42%,土壤呼吸显著增加17%(P0.001),但对微生物呼吸无显著影响。火烧使根呼吸显著提高25%(P0.01),但使微生物呼吸降低13%(P0.001),从而导致土壤呼吸未显著增加(P0.05)。刈割显著降低了土壤温度,诱导微生物呼吸和根呼吸分别降低13%(P0.001)和20%(P0.05),从而显著抑制土壤呼吸(P0.001)。氮沉降增强了火烧对土壤呼吸的促进作用,但未显著影响刈割对土壤呼吸的抑制作用。氮沉降、火烧和刈割对土壤呼吸的不同影响可对全球变化背景下沙质草地土壤碳循环的预测和天然草地的科学管理提供参考。  相似文献   

2.
[目的]揭示不同立地条件下黄花补血草种群生长、繁殖与土壤水分的差异,为黄花补血草的管理提供科学依据。[方法]选取4个不同沙丘类型的黄花补血草地斑块作为试验样地,研究黄花补血草的生长、繁殖以及水分等。[结果](1)不同立地类型黄花补血草种群的生长与繁殖特征存在明显差异,它主要反映在单株地上生物量、高度、冠幅和密度方面;(2)不同类型的沙丘上黄花补血草单株生殖枝数、花量均存在显著差异的相关性;(3)不同立地类型的黄花补血草土壤含水量存在明显差异,但是在不同的土壤深度上土壤的含水率的差异不显著,丘间地不同土壤深度的土壤含水率差异比较大。[结论]干旱荒漠生境条件下最适宜生长的黄花补血草的沙丘类型为丘间地。  相似文献   

3.
为探讨桃园生草不同条件还田对土壤微生物、酶活性及有效态养分的影响,以清耕为对照,设置生草自然还田、生草刈割还田、生草刈割配施有机物料腐熟剂还田3个处理,连续开展3年定位试验。采集根际和非根际土壤,研究桃园生草不同条件还田对土壤微生物数量、土壤酶活性以及土壤不同形态氮、钾含量的影响。结果表明:生草不同条件还田提高了根际土壤微生物的数量,生草刈割配施有机物料腐熟剂还田显著提高了根际和非根际土壤细菌和真菌的数量,较其他处理分别提高21.2%~48.2%和11.7%~17.0%,生草刈割后,配施有机物料腐熟剂能加速秸秆的腐熟与微生物繁殖;与清耕对照相比,桃园生草不同条件还田均能显著提高土壤酶活性,生草刈割配施有机物料腐熟剂的土壤脲酶活性、过氧化氢酶活性、蔗糖酶活性较其他处理分别提高10.2%~45.4%,26.8%~56.9%,20.5%~30.7%;桃园生草还田对土壤养分的积累具有正效应,以生草刈割配施有机物料腐熟剂还田效果明显,其不仅增加了土壤无机态氮和有机态氮含量,减少了氮素损失,同时还显著提高土壤速效钾和水溶性钾含量,较其他处理的土壤速效钾和水溶性钾含量分别提高12.6%~15.6%和11.4%~39.1%。综上,桃园生草刈割配施有机物料腐熟剂还田为提高土壤微生物数量、土壤酶活性及氮钾养分供应的较好途径,为果园生草精细化管理提供科学依据。  相似文献   

4.
[目的]对青土湖人工输水区白刺群落物种组成及土壤特性进行研究,以揭示研究区白刺灌丛生态系统的健康状况,为科学保育研究区灌丛沙堆以及生态恢复和防沙治沙工作提供科学依据。[方法]通过野外植被调查和对距水面不同距离白刺沙堆的土壤理化特性进行分析研究。[结果]①所调查群落中共有植物种18种,隶属6科17属,其中一年生草本8种,多年生草本6种,灌木植物4种,群落结构简单,物种相对单一。②距水面不同距离白刺群落0—60 cm土层土壤含水量,随着土层的加深呈现逐渐增加的趋势,随着距水面边缘距离的增加,白刺沙堆的土壤含水量逐渐降低,在200 m后趋于平稳;土壤机械组成主要以细砂粒为主,粗砂粒次之,黏粒含量相对较低;距水面0—100 m土层深度0—40 cm粗砂粒含量降低,黏粉粒含量较大。③青土湖人工输水区属于湖积沙区,土壤养分均属于严重缺乏,各养分含量均较低,且含量不均,土壤均处于偏碱性状态;土壤有机碳、全氮、速效钾含量表聚现象明显;距水面相同距离范围内土壤全磷、全钾、碱解氮和速效磷含量差异不显著(p0.05),且随土层变化规律不明显。④有机碳含量与土壤全氮、全磷、速效钾、电导率之间呈显著正相关(p0.05),电导率和全氮、全磷、速效钾之间呈极显著正相关(p0.01),土壤有效养分含量与对应元素总含量相关性不显著(p0.05)。[结论]距青土湖水面不同距离植被群落结构简单,很多种为单属单科;水面形成区影响白刺沙堆土壤水分,增强细砂粒在近水面区域的沉降,土壤养分含量总体偏低,且含量不均,"表聚"现象明显。  相似文献   

5.
人工植被恢复初期草灌竞争是影响植被恢复效果的重要因素之一。依托实际工程,研究了植被恢复第一年杂草控制措施对灌木的影响,以期为裸露坡面植被恢复工程提供科学参考。研究结果表明:①3个刈割时间处理对灌木生长影响显著,刈割时间越晚对灌木生长的不利影响越大,刈割应在杂草出苗半个月内及时完成;②刈割留茬高度对灌木生长影响显著,以群落内灌木高度为留茬高度参考值;③用精喹禾灵和禾草净喷施处理后,杂草在一周内出现死亡,对灌木生长高度和密度促进作用显著;④精喹禾灵3个时间处理的效果为6月份处理7月份处理8月份处理,7月份和8月份处理效果不明显。  相似文献   

6.
盐碱草甸植被退化对土壤硝化作用强度的影响   总被引:1,自引:0,他引:1  
为了解不同退化阶段盐碱草甸草原土壤硝化作用强度特征及其影响因素,采用空间代替时间的方法,以松嫩平原盐碱草甸草原植被退化过程中4种典型植物群落为对象,以未做处理为参照,设置刈割、施氮和刈割同时施氮3种处理,测定了土壤的硝化作用强度(NI)、pH值、电导率(EC)、含水量(SMC)和有效磷(OP)、硝态氮(NO-3-N)、铵态氮(NH+4-N)及全氮(TN)的含量。结果显示:(1)土壤NI与pH值、电导率、含水量、OP和NO-3-N呈极显著正相关关系(p<0.01);通过逐步回归分析的方法得出土壤NI的重要影响因子,重要影响因子对土壤NI影响强弱表现为:pH值>有效磷含量>含水量>硝态氮含量,并推断土壤硝态氮含量可作为土壤NI的一个重要表征参数。(2)未作处理时,星星草群落与碱蓬群落土壤硝化作用强度分别为13.4,13.5 mg/(kg·h),显著高于羊草群落和退化羊草群落的5.0,2.5 mg/(kg·h),刈割和施氮处理分别使星星草群落土壤NI提高96.88%,253.77%,混合处理使其提高413.70%,显著高于其他3种植物群落,由此可见,在人为刈割和施氮肥的干预下,星星草群落土壤铵态氮可能更易转变为硝态氮,氮素流失的风险也更大,因此可认为星星草群落处于盐碱草甸退化过程中的关键阶段。  相似文献   

7.
[目的]阐明宁夏风沙区苹果园土壤质量演变过程,为该区域苹果园管理与发展、苹果产业可持续发展及脱贫富农提供依据。[方法]以宁夏沙坡头区2年生(2 a)、5年生(5 a)、10年生(10 a)和25年生(25 a)苹果园为研究样地,以周围荒地为对照(CK),分析各样地土壤理化性质变化特征及其相关关系,并根据土壤质量综合技术评价标准进行苹果园土壤质量评价。[结果]①随林龄增加,土壤含水量、土壤电导率、土壤全氮、土壤有机碳、土壤速效钾、速效磷和水解性氮均呈现上升趋势,而土壤C/N和土壤温度均呈现下降趋势。土壤黏粉粒、土壤pH值和土壤硒含量呈现先升高后降低趋势,而土壤容重呈现先降低后增加趋势,且均在10 a时出现最值(峰值或谷值)。但土壤孔隙度表现为不同样地间无显著差异性。②苹果园土壤粗砂粒和黏粉粒与土壤温度及土壤C/N呈显著负相关(p0.01),而与土壤含水量、土壤全氮及有机碳呈显著正相关(p0.01)。土壤粗砂粒与土壤速效钾及土壤水解性氮呈显著正相关(p0.01)。土壤含水量与土壤温度及土壤C/N呈显著负相关(p0.01),而与土壤全氮、有机碳、土壤速效钾和水解性氮呈显著正相关(p0.01)。土壤容重与土壤黏粉粒、土壤含水量、土壤全氮及有机碳呈负相关(p0.05)。土壤养分指标之间均存在正相关关系(p0.05)。但土壤孔隙度和土壤硒与其余指标间均无相关性(p0.05)。③综合土壤物理、化学及营养指标,土壤质量综合得分排序表现为:25 a10 a5 a02 aCK。[结论]在宁夏风沙区种植苹果经济林5 a左右即可改善土壤理化性质,10 a时促进土壤质量性状显著提高,特别是土壤硒含量处于较高水平,并且随着种植年限增加,宁夏沙区苹果园土壤质量持续改善。  相似文献   

8.
[目的]分析黄土丘陵区不同土地利用类型土壤呼吸速率释放特征,为揭示该区域不同立地类型C循环特征奠定基础。[方法]采用LI-8100土壤碳通量测量系统于2014年11月至2015年7月,对标准径流小区红豆草、苜蓿、撂荒地和梯田苜蓿、沙打旺5种地类土壤呼吸速率及其地表温度、土壤温度(5cm)、土壤含水量进行观测。[结果](1)土壤呼吸速率日变化表现为昼高夜低的单峰型曲线,与温度的变化趋势一致,年均土壤呼吸速率表现为:沙打旺(梯田)2.27μmol/(m~2·s)红豆草1.79μmol/(m~2·s)苜蓿1.77μmol/(m~2·s)苜蓿(梯田)1.62μmol/(m~2·s)撂荒地0.77μmol/(m~2·s);(2)土壤呼吸速率呈现明显的季节变化特征,夏季最高,春季和秋季次之,冬季最低。夏季与春、秋、冬3季土壤呼吸速率差异显著(p0.05);(3)土壤呼吸速率与地表温度和土壤温度(5cm)的相关性均达到显著水平(p0.05)。除撂荒地外,各样地土壤呼吸速率与土壤温度(5cm)的相关度均高于其与地表温度的相关度,各样地土壤温度(5cm)Q10值介于1.94~3.00;(4)土壤呼吸速率与土壤含水量之间线性相关不显著(p0.05),但与土壤温度(5cm)和土壤含水量的交互作用显著相关(p0.01)。[结论]梯田土壤呼吸速率总体表现优于坡地,裸露地表在恢复植被的过程中,土壤环境质量显著提升。  相似文献   

9.
通过研究边坡位置、恢复年限和刈割对类芦(Neyraudia reynaudiana)绿化边坡土壤肥力的影响,结果表明:(1)边坡坡面、坡底种植槽和坡顶自然山地的土壤肥力有明显差异,坡底种植槽和坡顶自然山地土壤养分含量高,坡面养分含量较低;(2)随着恢复年限的增加,边坡土壤肥力改善明显,有机质含量显著增加,基本上达到了园林绿化种植土质量要求;(3)秋冬季对边坡草本植物类芦和芒草(Miscanthus sinensis)等进行刈割,对土壤肥力的影响显著,刈割后坡面土壤肥力下降,土壤有机质、全氮、全钾、有效磷含量均降低,因此需要控制坡面植物的刈割频度。  相似文献   

10.
农田改为农林(草)复合系统对红壤CO2和N2O排放的影响   总被引:1,自引:0,他引:1  
以鄂南玉米地、紫穗槐/玉米地、香根草/玉米地、紫穗槐林地、香根草草地与撂荒地6种土地利用类型为研究对象,利用静态箱法,对夏玉米生长期间土壤CO2和N2O通量及影响因子进行了测定,研究我国北亚热带丘陵红壤区农田改变为林(草)地和农林(草)复合系统后土壤CO2和N2O排放特征。研究结果表明:(1)土地利用方式改变后,撂荒地土壤CO2排放量明显低于其他5种土地利用类型,但紫穗槐/玉米地、单作玉米地、香根草/玉米地、紫穗槐林地、香根草草地5种土地利用类型之间土壤CO2排放量差异不显著。(2)玉米生长期间,6种不同土地利用方式下,土壤N2O排放总量从高到低依次为紫穗槐/玉米地(508 g·hm-2·a-1)、紫穗槐林地(470 g·hm-2·a-1)、撂荒地(390 g·hm-2·a-1)、香根草/玉米地(373 g·hm-2·a-1)、香根草草地(372 g·hm-2·a-1)、单作玉米地(285 g·hm-2·a-1)。(3)土壤CO2通量与土壤有机碳、土壤微生物生物量碳和土壤含水量无显著相关关系;土壤N2O通量与土壤氮素净矿化率呈显著线性相关,但与土壤无机氮和土壤含水量无显著相关关系。农田改变为农林(草)复合系统可能潜在地增加土壤CO2和N2O排放;农田改变为林(草)地可能潜在地减少土壤CO2排放,增加土壤N2O排放。  相似文献   

11.
Increasing the knowledge of the molecular diversity of a crop is essential for extending its genetic base, identifying cultivars and selecting parental varieties for breeding programs. In this sense, Cucurbita maxima Duch. is poorly characterised. Nineteen accessions of this species and 8 related Cucurbita accessions were included in a genetic diversity analysis. For this purpose, Random Amplified Polymorphic DNA markers (RAPDs), which analyse neutral variability, and Sequence-Based Amplified Polymorphism (SBAPs), which preferentially amplify coding regions of the genome, were used. While the UPGMA cluster and the principal coordinates analysis obtained using RAPDs did not group the different accessions according either to fruit morphological criteria or to passport data (origin and agro-climatic conditions), the principal coordinates analysis obtained using SBAPs grouped the different pumpkin accessions fundamentally according to the type of use (human consumption, animal fodder or ornamental). This passport trait is reported to be associated with agronomic breeding characters of interest. The usefulness of both types of markers for discriminating accessions of breeding interest is discussed.  相似文献   

12.
Twenty nine germplasm lines of Chenopodium quinoa and two of Chenopodium berlandieri subsp. nuttalliae were evaluated for 12 morphological and 7 quality traits for two test seasons. The 19 traits were analyzed for cluster and principal component analysis. The first four PCs contributed 78.70 % of the variability among the germplasm lines. The first PC accounted for 39.5% of the variation and had inflorescence/plant, plant height and stem diameter as the traits with largest coefficients, all with positive sign. The characters with greatest positive weight on PC2 were days to maturity (0.309), inflorescence length (0.260) and branches/plant. All the germplasm lines were grouped into six clusters based on average linkage method. Cluster III had high values for seed yield and most of the quality traits but showed a small seed size. The dendrogram separated the two lines of C. berlandieri subsp. nuttalliae from the quinoa lines.  相似文献   

13.
Mulberry (Morus L.) is essential for the sericulture industry as the primary feed for the silkworm Bombyx mori L. in India, with its long tradition of practicing sericulture, has a large number of indigenous cultivars. Since knowledge on the genetic divergence of these cultivars/varieties is essential for proper conservation and utilization, Inter Simple Sequence Repeat (ISSR) profiling was employed to assess genetic relationships among 34 mulberry accessions, collected from different regions of India. By using 12 ISSR primers, which produced 72 markers displaying a high degree of polymorphism (94.4%), genetic dissimilarity coefficients were calculated for each pair of the accessions and clustering of the accessions with Unweighted Pair Group Method using Arithmetic average (UPGMA) analysis was done to unravel the genetic diversity among the accessions. The dissimilarity coefficients varied from 0.111 to 0.692. UPGMA analysis generated a dendrogram with six groups and five isolates. Clustering of the accessions did not correspond with the information on the geographic origin of many of the accessions. Two-dimensional representations of the relative positions of the accessions with regards to divergence using the first two canonical variates as co-ordinate axes revealed considerable variability among the cases in each group. Further, Discriminant Function Analysis (DFA) showed changes in the geographic origin of 11 accessions and species status of 20 accessions.  相似文献   

14.
以20个大杯香菇品种和辐射选育新株系为材料, 分析了大杯香菇品种和辐射选育新株系蛋白质及其构成的17种氨基酸含量间的多元相关、回归和聚类关系, 并采用生物统计方法分析品种和新株系的蛋白质及各种氨基酸间的关系。结果表明: 大杯香菇辐105号新株系子实体中天门冬氨酸、苏氨酸、甘氨酸、丙氨酸、胱氨酸、缬氨酸、异亮氨酸、苯丙氨酸、蛋白质含量最高, 与部分品种和新株系子实体间差异显著或极显著, 且大多数氨基酸间及其与蛋白质含量之间存在显著或极显著正相关关系; 各种氨基酸与蛋白质含量之间分别有5种呈一次曲线关系, 10种呈二次曲线关系, 2种呈三次曲线关系; 采用系统聚类的方法可将蛋白质及17种氨基酸含量聚为4个大类, 对每类中的典型性状如精氨酸、亮氨酸、胱氨酸和蛋氨酸含量进行优化, 可有效提高大杯香菇品质育种中蛋白质构成的改良效率。  相似文献   

15.
Genetic variation within the U.S. cucumber collection (Cucumis sativus var. sativus L. and var. hardwickii (Royle) Alef.) was assessed by examing the variation at 21 polymorphic isozyme loci and comparing the results of this investigation with a similar previous analysis of 14 loci. About 29% (15 of 51) of the enzyme systems examined in an initial survey were polymorphic. Seven loci (Ak-2, Ak-3, Fdp-1, Fdp-2, Mpi-1, Pep-gl and Skdh) which were not previously used to estimate genetic diversity, were assessed. On average, 1.4 loci were polymorphic per enzyme system and 2.2 alleles were present per polymorphic locus. The frequency of polymorphisms was relatively low for Fdp-1(2) (0.01), Mpi-1(1) (0.03), and Skdh(1) (0.02). Principal component and cluster analyses of allelic variation at polymorphic loci separated a diverse array of 757 cucumber accessions from the U.S. National Plant Germplasm Systesm's (NPGS) collection into distinct groups by country (45 nations examined). All accessions of C. s. var. sativus were isozymically distinct from C. s. var. hardwickii, which were themselves dissimilar from each other. Data suggest that C. s. var. hardwickii is not a feral derivative of extant C. s. var. sativus populations. The allelic profile of C. s. var. sativus accessions originating from Burma, Thailand, Indonesia, Hong Kong, Zimbabwe and Ethiopia were distinct from the other accessions examined. Allelic fixation has occurred at Pgd-2 in accessions from Burma, and at Ak-2 in accessions from Zimbabwe and Ethiopia. Some of the countries examined that were in close geographic proximity (e.g., Thailand, Indonesia and Hong Kong) contained accessions with similar isozyme profiles. Accessions are fixed for certain alleles [e.g., Gr(1) (100%), Fdp-1(1) (100%) and Mpi-2(2) (50%) for accessions from Thailand, Indonesia and Hong Kong]. Grouping countries by continent or sub-continent (i.e., North and South American, China, Eastern Europe, Western Europe) and by numbers of accessions examined (i.e., India/Burma, Iran, Japan, Turkey, and remaining accessions) was used to identify accessions with unique allozymic profiles [PIs 209064 (USA), 257486 (China), 188749 (Egypt), 285607 (Poland), 369717 (Yugoslavia), 357844 (Poland), 255936 (Netherlands), 183127 (India), 200818 (Burma), 200815 (Burma), 137836 (Iran), 227013 (Iran), 227235 (Iran), 451976 (Japan), 181752 (Syria), 181874 (Syria), 169383 (Turkey), 171613 (Turkey)].  相似文献   

16.
Three hundred and sixteen accessions belonging to four species of the genus Lolium were analysed for morphological differentiation following field trials. Principal component analysis (PCA) was shown to explain over 74% of the variation with the date of ear emergence, spike height and flag leaf length and width being responsible for the major differentiation. L. perenne separated into two groups following PCA, cluster analysis and k-means clustering, as a result of floral initiation in the sowing year. Those accessions that did not attain floral initiation until the second year were found to be from northern Europe. The inbreeder L. temulentum was separated from the three outbreeding species, L. perenne, L. multiflorum and L. rigidum, which are themselves distinct from each other although there is some introgression between them, especially between L. multiflorum and L. rigidum. The results are discussed in relation to selection of a core collection of Lolium accessions.  相似文献   

17.
A large collection of melon (Cucumis melo L.) germplasm has been established at the Section of Genetics and Plant Breeding, Bari University (Italy). In the present work, data regarding the variation of 20 bio-agronomical traits recorded on entries and landraces collected in Albania and Apulia region (Southern Italy) are reported. The main objective of the study was to assess and describe, by means of univariate and multivariate analyses, the genetic diversity in the collection composed by genotypes classified in the Inodorus and Cantalupensis groups. The results obtained showed a large variation for all the traits examined. Furthermore, it was possible to identify valuable genotypes for future breeding programmes aimed at improving melon traits, particularly for the Inodorus group, which is an important crop in many Southern Italian sites. Genotypes of interest were especially selected for earliness and lateness, fruit shape, soluble solids content, storage time and fruit firmness.  相似文献   

18.
One hundred landraces of maize from Northern Spain werecharacterized on the basis of twenty-two morphological traits,and seventeen ecological variables (climatic, edaphic andtopographic) associated with the collection site. Highbroad-sense heritabilities ( > 0.6) were foundfor plant height, ear height, ear node number, ear length,mid-ear diameter, rows of kernels, kernels per row, cob weightand days to silking. Seven different groups were obtained withcluster analysis using plant and cycle traits, and discriminantanalysis showed that leaf area, ear shape, tassel branches, rows ofkernels, plant height, cob weight, and ear length were the mostimportant traits for taxonomic classification. Seven populations withpromising breeding value were detected.  相似文献   

19.
The narG gene is frequently used as a molecular marker for bacterial nitrate-reducing community analysis. In this study, a new set of primers targeting the narG gene was designed and applied to semi-nested polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) assay. The potential of the new primers was verified on DNA directly extracted from soils from five different experimental sites distributed in Central and Southern Italy. Specificity of the primers was determined by excision, amplification, and sequencing of bands resolved by DGGE. A phylogenetic analysis showed the correlation between the sequences retrieved from the soils studied and the narG sequences from β and γ-Proteobacteria. These primers expanded the existing molecular tools for ecological study on the size and diversity of nitrate-reducing bacterial community in soil.  相似文献   

20.
[目的]为满足乌兰布和沙漠绿洲防护林体系构建对优良造林树种选择的要求,对多个品种速生杨在乌兰布和沙区绿洲的适应性进行评价。[方法]以北抗、08、中林等系列的20个引进速生杨品种为研究对象,当前主要造林树种新疆杨为参照,运用系统聚类分析和多因素模糊综合评判方法对20种速生杨在乌兰布和沙漠绿洲地区生长初期适应性进行综合评价。[结果]08-01,创新、中林2005,北抗16-22,08-02,08-03,中林315,08-07,天黑、京2等10个品种在速生性、成活状况、抗病虫害能力方面均明显优于新疆杨;京6,北抗16-27,Simplot,08-09,08-08,08-14等6个品种各项评价指标与新疆杨接近;辽宁杨(鲁×山)、北抗16-8,08-04,DN-34等4个树种综合评价适应性低于新疆杨。[结论]08-01等10个品种能够在乌兰布和沙漠绿洲地区良好生长,可以作为该区造林和植物资源收集储备的备选树种。京6等6个品种综合评价适应性中等,辽宁杨(鲁×山)等4个品种适应性较差,无法在该区正常生长。  相似文献   

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