云南栽培稻生态型矿质元素含量的多样性   总被引：5，自引：0，他引：5  

曾亚文  刘家富  汪禄祥  张洪亮  普晓英  杜娟  杨树明 《作物学报》2006,32(6):867-872

用ICP-AES测定了新平县相同生态条件下种植653份云南稻资源糙米8种矿质元素含量，并按丁颖的栽培稻生态型对其遗传多样性进行了研究。结果表明，云南水稻改良品种糙米P、Fe和Zn含量比地方稻种分别下降10.53%、14.76%和35.16%，但改良品种特别是粳稻Ca含量比地方种高, 8种矿质元素以Ca的多样性指数最大；糙米P、Ca、Mg、Fe、Zu、Cu和Mn平均含量以粳稻的Mg、Fe和Zn，水稻的P、K和Mg，陆稻的Fe和Zn，糯稻的K和Fe，早稻的Mg和Fe相对较高。8种矿质元素平均遗传多样性指数依次为粳>籼,陆>水,粘>糯,早中稻>晚稻和地方种>改良种,且P>K>Mn>Mg>Cu>Zn>Fe>Ca；其变异系数依次为Fe>Ca>Cu>Zn>Mn>K>Mg >P。  相似文献   

Study on the Changes of the Amount of Microorganism and Microbial Biomass Carbon in Soil of Greenhouse Cropping   总被引：3，自引：1，他引：3  

王珊  李廷轩  张锡洲  周建新 《中国农学通报》2005,21(4):198-198

通过对四川省温江、双流两地不同设施种植年限土壤中微生物数量及其生物量碳的研究,结果表明,不同设施种植年限大棚土壤中的微生物数量是露地的1.63~3.50倍,且大棚土壤中好气性微生物总数随种植年限的增加有逐渐降低的趋势,三大微生物数量占微生物总数的比例中,细菌表现为随设施种植年限的增加而增加;放线菌和真菌表现为下降;露地土壤微生物多样性指数分别是设施年限为1a、2a和4a的大棚土壤的1.29倍、2.28倍和3.45倍,前者明显高于后者。随设施年限的增加,土壤微生物生物量碳、有机碳及微生物对有机碳的利用率都表现  相似文献   

Trade-offs between on-farm varietal diversity and highly client-oriented breeding — a case study of upland rice in India     

D. S. Virk  J. R. Witcombe 《Genetic Resources and Crop Evolution》2007,54(4):823-835

On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives. Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa, where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used to test the significance of the differences between individual years. In all states, this revealed a significant reduction in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining diversity.  相似文献   

Nitrogen fertilization reduces diversity and alters community structure of active fungi in boreal ecosystems     

Steven D. Allison  China A. Hanson 《Soil biology & biochemistry》2007,39(8):1878-1887

Nitrogen (N) availability is increasing in many ecosystems due to anthropogenic disturbance. We used a nucleotide analog technique and sequencing of ribosomal RNA genes to test whether N fertilization altered active fungal communities in two boreal ecosystems. In decaying litter from a recently burned spruce forest, Shannon diversity decreased significantly with N fertilization, and taxonomic richness declined from 44 to 33 operational taxonomic units (OTUs). In soils from a mature spruce forest, richness also declined with N fertilization, from 67 to 52 OTUs. Fungal community structure in litter differed significantly with N fertilization, primarily because fungi of the order Ceratobasidiales increased in abundance. We observed similar changes in fungal diversity and community structure with starch addition to litter, suggesting that N fertilization may affect fungal communities by altering plant carbon inputs. These changes could have important consequences for ecosystem processes such as decomposition and nutrient mineralization.  相似文献   

The impact of mowing as a management strategy for wet meadows on spider (Araneae) communities     

Marie-France Cattin  Carolin Banašek-Richter 《Biological conservation》2003,113(2):179-188

Meadows are often managed by mowing to prevent succession and brushwood encroachment. This management practice is efficient to maintain plant diversity, but the effect on arthropod groups is less well known. We sampled spiders in the Grande Cariçaie (Switzerland), a site of nature conservation importance, in two types of wet meadows, an unmanaged site and one 2-years-old mown conditions. Numbers of individuals for the most abundant families, diversity measures, and indicator taxa were compared among vegetation and treatment types. The results indicate that the less mobile spiders and species linked to litter or dead reeds, including rare species, are reduced by mowing. Present management consists in triennial mowing of 2-4 ha non-contiguous sectors. We investigate the conflict between the need to mow the meadows to maintain them, and the negative effect of mowing on spider communities. We therefore propose a new management scheme aimed at maintain the vegetation while lessening its negative effects on spider communities by providing refuges.  相似文献   

Estimating floristic integrity in tallgrass prairie     

John B. Taft  Christopher Hauser 《Biological conservation》2006,131(1):42-51

Indices are needed in habitat conservation and restoration to provide repeatable measures relevant to conservation goals. A monitoring and research program was established at Nachusa Grasslands in north-central Illinois (USA) to assess progress in tallgrass prairie restoration and reconstruction efforts and evaluate the effectiveness of indices used to measure community-level properties related to vegetation integrity. Indices selected for comparison included standard diversity measures (e.g., Shannon-Weiner Index, Evenness, Species Richness) and indices developed specifically to estimate vegetation integrity. These latter indices included two unweighted diversity indices, the Species Richness Index and Native Richness Index, and two indices weighted by characteristics of species composition, the Floristic Quality Index (FQI) and its component Mean Coefficient of Conservatism (Mean C). A coefficient of conservatism (CC) is an integer ranging from 0 to 10 assigned a priori to each taxon in a regional flora that estimates the fidelity of a species to natural areas (non-native and most ruderal species are assigned 0 or low values, respectively; species known primarily from natural areas are assigned higher values). All indices compared in this study were calculated using vegetation data collected from equal-sized sampling grids stratified across seven prairie units. The units included remnants and plantings representing a wide range of habitat quality. The FQI and Mean C explained the most variation among sites and were most effective at distinguishing recognized qualitative differences indicating they can be more informative than traditional species-diversity measures in assessing floristic integrity within community types. The FQI and Mean C are applicable to both quantitative ecological monitoring and plotless survey methods.  相似文献   

Differences in the diversity of oribatid mite communities in forests and agrosystems lands     

Julio Arroyo  Juan Carlos Iturrondobeitia   《European Journal of Soil Biology》2006,42(4):259-269

A field study was conducted in the province of Burgos (Castile, NW of Spain) to assess the role and influence of the different anthropic use of soil on the oribatid mite communities (Acari, Oribatida).Soil samples from 20 representative soil sites of the Castilian upland steppes, with cultured, pastureland or forest soil uses, were taken in spring and autumn 2000. Thereafter, soil samples were analysed in terms of their mesofaunal biodiversity, measured using the real and relative diversity of the oribatid mite communities.Collected individuals were identified to species level, being altogether 111 Oribatid species. Results from communities' ordination analysis showed clear gradients based on community variables. One of these was defined by plots with high values of diversity and species richness which correspond to the less anthropic natural soils, mainly oak forest. In contrast, the most anthropic agrosystems soils, including extensive cereal crops, most of them receiving only mineral fertilisation or having human management, were placed in opposite gradients. Differences in biodiversity between crop lands and natural soils were also confirmed by ANOVA. The seasonality, measured in terms of difference between spring and autumn plots, played a minimum role in explaining differences of diversity. Nevertheless autumn diversity values were slightly higher than those of spring, except for crops.  相似文献   

Dramatic decline in bat species richness in Singapore, with implications for Southeast Asia     

David J.W. Lane  Tigga Kingston 《Biological conservation》2006,131(4):584-593

Literature searches and recent surveys of the bat fauna of Singapore indicate that of the 24 species of Microchiroptera and six species of Megachiroptera documented for this small equatorial island just 15 and 5, respectively, are still present. These recorded declines in chiropteran species richness almost certainly understate the true losses as extensive land transformation/habitat loss (>95%) and biota loss occurred early in Singapore’s colonial history before comprehensive surveys of bats were made. In an effort to reconstruct the pre-settlement bat fauna, we inferred an upper bound of pre-settlement species richness using a checklist from a well-known bat assemblage in neighbouring Peninsular Malaysia, and a lower bound based on species common to Peninsular Malaysia, Borneo and Sumatra. The Singapore records were compared with these two species list predictions. Based on this analysis, we infer that between 60 and 72 species would have inhabited Singapore before 1819. We also estimate that between 33% (based on the confirmed inventory) and 72% of the species (based on the upper-bound estimate of species richness) are now locally extinct. For Microchiroptera the data suggest that the documented local extinction rate of 38% may project to between 69% and 75%. Forest-dependant bats are particularly affected and comprise a much lower proportion of the bat fauna than is seen in intact forest in Peninsular Malaysia. All hipposiderids and 40% of the documented rhinolophid taxa have been lost and almost half (6) of the surviving microchiropteran species are locally endangered. Projected local extinction rates for Megachiroptera raise the documented value (17%) to about 60%, with most of the survivors being widespread species known to forage in cultivated or secondary forest habitats or to commute long distances between fragmented resources. The dramatic decline in Singapore bat species richness and a concomitant change in chiropteran guild and trophic structure (Microchiroptera vs. Megachiroptera) reflect patterns of diversity change seen elsewhere in the region in response to loss of forest habitat. In Singapore, the decline in diversity (species richness and abundances) for both mega- and microbats may also relate to urbanisation and deliberate or accidental destruction of bats and their roost sites in a land that has one of the highest human population densities on the planet. Although these losses (actual and inferred) represent a microcosm of mainly local extinctions, a wider geographical extrapolation over the 21st century indicates that heavy deforestation in progress in Southeast Asia might be expected to lead to extinction of many bat taxa, with upper-bound estimates of regional species losses exceeding 40% and global extirpation anticipated for at least 23% of Southeast Asia’s bat fauna by 2100.  相似文献   

Diversity and distribution patterns of enset landraces in Sidama, Southern Ethiopia     

Bizuayehu Tesfaye  Peter Lüdders 《Genetic Resources and Crop Evolution》2003,50(4):359-371

Diversity and distribution of enset landraces (clones) were investigated in 300 randomly selected peasant households at ten different locations in the Sidama region of Ethiopia using presence-or-absence data. A total of 86 named landraces were recorded, making the region an area of remarkably high enset landrace diversity. A substantial fraction of the landraces had a restricted distribution range and low abundance while a number were moderately common with the remaining few being cosmopolitan. Regional distribution was positively correlated with local abundance, such that more widespread landraces were also typically more abundant (r = 0.78, p < .01). Landrace diversity was not evenly distributed throughout the region, the highest diversity being recorded in mountain areas (r = 0.71, p < .05). Farmers exchange planting materials extensively, resulting in a fairly high (up to 70%) coefficient of similarity among sites. Implications for the collection and conservation of enset genetic resources are discussed.  相似文献   

Genetic Relationship between <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. Trees from North-western to South Spain Based on Morphological Traits and Isoenzymes     

A.?M.?Ramos-Cabrer  S.?Pereira-LorenzoEmail author 《Genetic Resources and Crop Evolution》2005,52(7):879-890

This study is focused in the main chestnut growing areas from north- to south-western Spain. We studied 50 accessions corresponding to 22 cultivars named by local growers; 11 from Andalucía, 9 from Castilla-León, and 2 from Extremadura. These were compared with 22 types classified previously in Galicia (82 accessions). Ten morphological traits and five isoenzyme systems were used to classify them and establish genetic relationships. A lower genetic variability has been found in Extremadura (middle Spain) and Andalucía (south) than in Galicia (north western) which may be because of the lower importance of the crop in those areas and the geographic barriers between them. Galicia could be the origin of the types found in Castilla-León, Extremadura, and south-western Andalucía, and the types found in Central Andalucía were closer to those found in Castilla-León and Extremadura. Most accessions studied (117/132) could be classified positively, making 37 out of 44 cultivars found from northern to southern Spain. Three groups of synonymies were found in Castilla-León: ‘Brava’ and ‘Negral’, ‘Gallego’ and ‘Injerto’, and ‘Rapega’ and ‘Verdello’. Most of the Spanish types have been propagated as a principal clone. Variability within the types is important and must be considered to select the best clones as cultivars.  相似文献