首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 422 毫秒
1.
Four methods of obtaining seeds of wild species of plants for long-term conservation in Gene Banks were compared. (a) From collections growing within botanic gardens; (b) by making sample collections from wild populations and bulking up stocks by regeneration under cultivation; (c) by making arrangements with external collectors; (d) by organising plant collecting expeditions.Collections from plants in botanic gardens were unsatisfactory material on which to base collections. Regeneration under cultivation depends on expertise and knowledge of the plant's cultural requirements which were frequently not available, leading to unacceptably heavy losses of individuals and selection of populations, during cultivation. Collecting seeds directly from populations of wild plants was, scientifically, the most successful method and costings showed it also to be economically the least demanding of resources.The results suggest that, except in special cases—perhaps with rare plants where natural populations are small—every effort should be made to obtain initial collections of seed which are large enough to fulfil all the purposes intended by long-term conservation. Collections of small numbers of seeds which require bulking up before they can be used should be avoided, as a waste of effort, time and plant resources.  相似文献   

2.
Tea is a very important cash crop in Vietnam as it provides crucial income and employment for farmers in poor rural areas. Unfortunately, the dominance of long-term, conventional tea cultivation has caused severe soil health degradation and environmental pollution. At the same time, as tea production may provide a better net income compared with other annual crops such as rice and vegetables, farmers have been converting parts of their allocated land to cultivate tea plants. Little is known about the benefit of agroecological management as an alternative to conventional tea management practices, and thus, there is a need to understand how it can improve tea yields, quality and the livelihoods of the farmers. Conducted in Northern Vietnam from 2019 to 2022, this study examined the impacts of agroecological tea management practices on soil health indicators, tea yield and quality, and net income of tea farmers. We showed that agroecological management practices significantly enhanced soil organic matter by 0.8% and soil pH by 0.5 units on average. Conversely, conventional management based on chemical fertilizer applications, significantly increased soil total nitrogen by 0.15%–0.2%. No significant differences were observed between soil texture and other soil chemical characteristics. Soil biological parameters were also significantly higher in agroecological tea soil and root samples than in conventional tea plots. Average AMF frequency and intensity of the agroecological tea roots were 98% and 37%, respectively, compared with 73% and 15% of the conventional tea roots. Likewise, soil macrofauna and mesofauna abundance in the agroecological tea plantations was 76 individuals/m2 and 101 individuals/100 g fresh soil on average, respectively, while that of conventional tea farms were 34 and 63 individuals/100 g fresh soil, respectively. Interestingly, a comparison between the converted and nonconverted lands did not show any significant effect of the conversion on soil physicochemical and biological characteristics, apart from tea root AMF colonization. Conventional tea management consistently resulted in higher tea yield and yield components, even though the differences were not always statistically significant. Despite lower tea yields, agroecological tea adopters earned around USD 8400 ha/year more than the farmers still practicing conventional management. This study shows that it is economically and environmentally more sustainable to produce organic tea than conventional tea, and our results should encourage more farmers to adopt such agroecological practices in Northern Vietnam.  相似文献   

3.
The North-eastern region of India is rich treasure of various Citrus species. A vast reservoir of Citrus diversity exists in wild, semi wild form and is found scattered here and there without commercial cultivation and much care. The edaphic and climatic set up as well as the physiographic condition of the region makes it possible to grow a number of species, landraces and probable hybrids of Citrus without any care. But of now with the population increase, changing attitude of the farmers towards some newly introduced cash crops there is genetic erosion of the valuable resources and most of them are in verge of extinction. So, it is the high time for the scientific community to exploit all the rare and endangered resources of Citrus of north eastern region and for their conservation. In addition molecular and morphological characterization of the reported germplasm, evaluation and screening against biotic and abiotic stresses should also be needed to safeguard the existing population of Citrus and for future Citrus improvement programme.  相似文献   

4.
Villages in Jigme Singye Wangchuck National Park, central Bhutan, report livestock depredation by wild carnivores including leopard (Panthera pardus), tiger (Panthera tigris), Himalayan black bear (Ursus thibettanus), and dhole (Cuon alpinus). In a survey of 274 households in six different geogs (sub-districts) within the park, 21.2% of households surveyed reported losses of a total of 2.3% of their domestic animals to wild predators over 12 months. This loss equated to an average annual financial loss equal to 17% (US$ 44.72) of their total per-capita cash income. Total reported losses during 2000 amounted to US$ 12,252, of which leopard and tiger kills accounted for 82% (US$ 10,047). Annual mean livestock loss per household (of those that reported loss) was 1.29 head of stock, equating to more than two-thirds of their annual cash income of $250. Lax herding, inadequate guarding practices, and overgrazing may have contributed to livestock losses. Approximately 60% of the households lacked proper stables for corralling their livestock at night and there was a significant correlation between the number of livestock lost and the distance between the household and the grazing pasture. Overall, reported predation rates have increased since the inception of the park in 1993 and since implementation of the Forest and Nature Conservation Act in 1995, which prioritises some of Bhutan’s key livestock predators for conservation. We propose livestock intensification programmes, including pasture improvement, and financial compensation as short-term measures to reduce conflict between people and predators. In the long-term, we recommend that the feasibility of an insurance scheme should be tested, the possibility of relaxing the resource use restrictions in the Forest and Nature Conservation Act of 1995 be explored, and that farmers should be involved in managing human-wildlife conflicts - particularly through improving their own herding and guarding practices, and building proper corralling facilities and adopting reliable corralling procedures.  相似文献   

5.
Loess is abundant in the foreland basins of the Himalayas. However, it is poorly developed within the intermontane basins of the western Himalayas and Karaloram. Selected sections were studied from the Swat Himalaya and the Karakoram Mountains. Fieldwork and sedimentological analysis including grain size, mineralogy and microfabric showed that the loessic sediments have been reworked and some have undergone weak pedogeneses. These silts are not true loess, rather a “loessic colluvium”. Thermoluminescence (TL) dates from the loessic sediments in sections from the Swat valley provided younger ages than earlier workers had suggested. This is consistent with reworking of the loess in these areas. It is concluded that care must be taken when using loessic silts for TL in similar mountainous terranes.  相似文献   

6.
Balh Valley in the northwestern Himalayas in India is well known for cultivation of high-value cash crops and vegetables. The Indo-German Agricultural Project executed four decades ago in the valley has been the driving force for agrarian development in the valley, but crops are still grown under nutrient-starved conditions, giving low productivity compared to national averages. To demonstrate and disseminate the integrated nutrient management (INM) technology in the irrigated ecosystem of Balh Valley, efforts were funded by the Indian Farmers' Fertilizers Cooperative Limited (IFFCO) to develop sustainable crop production systems under cash crops and vegetables following an appropriate technology transfer model by Krishi Vigyan Kendra (KVK), Sundernagar, India. For effective technology transfer, field demonstrations, method demonstrations, farmers' training camps, field days, and numerous field conventions were organized in addition to extending soil testing, literature supply, promotional seed and fertilizer input supply, and training of agro-cooperative society personnel who deal with seed and fertilizer input supply in the region. The greater extension gaps in tomato–blackgram and potato–Kharif onion crop sequences indicated need for effective technology transfer tools for high adoption of technology in these production systems in the valley. Potato–Kharif onion cropping system using INM technology resulted in greater system productivity in terms of blackgram equivalent yield (76.7q ha?1) and gross (3,06,920 ha?1) and net returns (2,22,295 ha?1), followed by tomato–blackgram and green pea–okra production systems, respectively, using an appropriate technology transfer model. The study also revealed improvement in available nitrogen (N)–phosphorus (P)–potassium (K) and organic carbon (C) pool of the soils besides crop productivity and profitability in field trials under INM practices over farmers' practiced plots. Knowledge before the study about soil testing, dose and time of application of organics, chemical fertilizers, and their integrated use ranged from 9 to 41%, whereas knowledge increases after the study ranged between 55 to 88%. The INM technology adoption rate after 1 year of project completion ranged between 66 to 70%, whereas soil testing was done by only 35% of farmers. Thus, INM technology adoption rate was greater following the appropriate technology transfer model based on critical analyses of fertilizer use, existing production systems, and appropriate interventions for technology transfer. This comprehensive study under the IFFCO-KVK Collaborative Project attempts to highlight that an effective technology transfer model can play a key role in adoption of INM technology for sustainable production systems in the developing world, especially for resource- and knowledge-poor farmers of collateral socioagroeconomic environments of developing nations.  相似文献   

7.
Land‐use and cover changes around Budongo Forest Reserve (BFR) were analysed from multi‐temporal LandSat images (1988 and 2002) and associated field‐based studies in 2003–2004. Three major land‐use and cover classes: forest/woodland, sugarcane plantations and grassland/shifting‐cultivation/settlements were clearly discriminated. The area under sugarcane cultivation increased over 17‐fold, from 690 ha in 1988 to 12729 ha in 2002, with a concomitant loss of about 4680 ha (8·2 per cent) of forest/woodland, mainly on the southern boundary of BFR. Land‐use and cover changes were a result of (a) agricultural expansion, (b) increasing human population, exacerbated by large influxes of refugees, (c) conflicts of interest and political interference in the management of BFR and (d) unclear land tenure. Agriculture is the main land‐use practice and source of income to local people, with commercial sugarcane and tobacco as the primary cash crops. Individual smallholder sugarcane plantations covered distances ranging from 30 to 1440 m along the BFR edge, with no buffer zone, resulting in direct conflicts between farmers and forest wild animals. There is an ever‐increasing need for more land for agricultural expansion, resulting in continued loss of forest/woodland on private/communal lands and encroachment into BFR. This unsustainable agricultural expansion and the local people's perception of BFR as an obstacle to agriculture, threatens the conservation of its threatened wild plants (e.g. Raphia farinifera) and the endangered chimpanzees. Therefore, their sustainable management for both development and conservation will require strong and incorruptible institutions that will seek a balance between resource exploitation and conservation. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

8.
Agricultural land in lowland Vietnam is scarce due to population growth. Hence, cultivation is increasingly practised on the steep upland slopes. Factors affecting resource use, soil fertility and household economics were studied in six villages of the Black Thai ethnic group in northwest Vietnam. Farmers were interviewed about their individual household situation. Yield development of major crops and cropping patterns in upland cultivation over the last 50 years were recorded in group discussions. In addition, soil fertility was analysed on different land‐use units. Formerly predominant upland rice changed to maize and cassava production at present. Decreasing soil fertility and a shift from subsistence to market‐oriented production, facilitated by new maize varieties and better access to markets are major causes. The Black Thai farmers economy has improved in recent years. The decline in soil fertility is concealed by higher maize yields from new varieties, and soil fertility conservation ranks low among farmers' priorities. The improved economy of the individual households might be of short duration if farmers cannot be sensitized to new resource management options. These have to be developed in line with farmers' priorities and the fragile environment of Vietnam's uplands. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

9.
尽管基因工程技术可以增加作物产量, 但转基因作物是否对农田生态产生影响受到广泛关注。本研究通过田间定位试验, 应用群落生态学方法研究了转CryIAb基因抗虫水稻"Mfb"连续2年在传统栽培和半野生条件下对稻田杂草群落组成及多样性的影响。调查结果显示: 转CryIAb基因稻"Mfb"与非转基因稻"明恢86"田间杂草种类没有显著差异。稻田杂草的频度和密度与栽培方式有关, 半野生稻田杂草的频度和密度显著高于传统稻田, 但相同栽培条件下, 转基因稻"Mfb"与非转基因稻"明恢86"田间杂草频度和密度在整个生长期内均无显著差异。半野生稻田物种丰富度(Sr)指数明显大于传统稻田; 相同栽培条件下, 相同生长时期抗虫转基因水稻"Mfb"与其非转基因对照"明恢86"对稻田杂草群落丰富度的影响差异不显著。稻田杂草群落优势度(D)、均匀度(J)以及多样性(H)各处理、各生长时期内转基因稻与非转基因稻相比均没有显著差异。稻田杂草Shannon-Wiener多样性指数变化无明显规律, 相同栽培方式相同生长期的抗虫转基因水稻"Mfb"与其非转基因对照"明恢86"的Shannon-wiener指数差异不显著。综合上述分析, 转CryIAb基因抗虫稻对稻田杂草群落的组成及多样性没有显著影响。  相似文献   

10.
We evaluated the impacts of a macronutrient deficiency on the community structure of root-associated bacteria in potato (Solanum tuberosum) cultivation. Potato plants were cultivated in a long-term experimental field under a nitrogen, phosphorus, or potassium deficiency, and roots were sampled at the early flowering stage. Amplicon libraries of 16S rRNA gene were constructed for root-associated bacteria, and bacterial diversity was analyzed by means of pyrosequencing. Statistical analyses showed significantly lower species evenness in the nutrient-deficient plots compared with the value in a plot with standard fertilization. Phylogenetic analyses revealed that the abundance of Rhizobium spp. increased dramatically in all plots under a macronutrient deficiency.  相似文献   

11.
为推广和普及设施桃栽培技术，实现设施桃的优质、高产、稳产，增加果农的经济收益，通过相关文献梳理了设施桃栽培的生长特性，栽培过程中品种选择，光照、温度、湿度、水肥调控管理以及果实采前采后管理。  相似文献   

12.
Field survey data of sorghum landrace populations grown by traditional farmers in four adjacent communities in the Ethiopian Highlands are used to analyze and project the local risk of loss of individual landraces under three scenarios: wild population, traditional farming and agricultural modernization. The risk of loss in the wild population scenario is based on landscape ecology theory which evaluates total population size, spatial distribution and patch occupancy, with high values for each factor and the sum of the factors decreasing the risk. This wild population analysis forms the basis for comparison with the other scenarios. In the traditional farming scenario, the deliberate actions of farmers must be taken into account through the recognition that the farmers favour various traits of the sorghum for specific reasons – yield, taste, storability, etc. – and will balance plant numbers according to quantity and quality requirements. In the agricultural modernization scenario, which includes the introduction of high-yield varieties and the tendency toward monocultures and agricultural chemical use, the traits of the landraces that are most likely to be displaced are hypothesized, as are those of the landraces that are likely to be retained on the basis of cultural or other factors. It is planned to follow up this baseline study with a long-term time-series study of the same communities to assess the validity of our projections.  相似文献   

13.
Ethiopian pastoralists and farmers use fire for regrowth of young green shoots and food crops, respectively. As a result, useful plants and wild animals are also affected. The intensity, frequency and magnitude of fires in the Gambela region (Baro-Akobo river basin) have been aggravated by the recent resettlement scheme and mechanized farming. Fires have (i) changed the physiognomy of plants; (ii) reduced the number of indispensable plant species; (iii) pushed wild animals to neighbouring areas; and (iv) brought soil erosion. If the present fire occurrences continue, this region of rich biodiversity will become desertified. © 1998 John Wiley & Sons, Ltd.  相似文献   

14.
Abstract. Crops grown on virgin upland Vertisols of Zambia, are reported to perform rather poorly. However, subsoiling followed by repeated cultivation over two years apparently improves crop growth. Highest yields were recorded under long-term cultivation (12 years). To evaluate the reasons for these differences in crop response to Vertisol management, physical and hydrodynamic characteristics of soil profiles were studied in three soil management systems. The management systems were: uncultivated or virgin land; land cultivated for two years; and land cultivated for 12 years. The mean soil aggregate size decreased with increased time of cultivation, mostly due to the decrease of the largest sized aggregates. The surface horizon dried more slowly on the long-term cultivation plot. A comparison of the hydraulic conductivities indicated that water intake in the deeper layers improved with increased period in cultivation. Oxygen diffusion measurements showed good aeration at field capacity, to a depth of 0.32m on the long-term cultivation plots, but only to 0.17 m and 0.25 m for 2 years cultivation and virgin plots respectively. Repeated cultivation was beneficial in improving surface soil tilth and in improving subsurface drainage, thus removing the problem of a perched water table which occurred close to the soil surface under natural conditions.  相似文献   

15.

The state of Kerala in India, a part of the Western Ghats–Sri Lanka biodiversity hotspot, is blessed with rich biodiversity including agrobiodiversity. Richness in crop diversity is attributed to the wide topographic and climatic niches, long history of outside contacts, personal craving for experimenting new crops, practice of high-density multi-species cropping system, etc. Evidence from several field exploration trips, herbarium survey, reliable literature and other sources has revealed that 306 crop taxa (excluding medicinal and aromatic plants, ornamentals and forestry species) belonging to 290 species coming under 179 genera and 61 families, are being cultivated in different areas of this state. This includes crops belonging to crop-groups—cereals and millets (11), pseudocereals (2), pulses (7), oilseeds (7), fibres (3), forages (14), fruits and nuts (107), vegetables (86; 18-being tuber crops), spices and condiments (20), plantation crops (10) and others (29). Of 306 taxa, 63 occur in the wild state as well; 43 are of only recent cultivation (<?15 years) or under trial cultivation by innovative farmers; and 43 are confined only in (sub)temperate hills. This is more than double (104% increase) the earlier estimate of crops made during 2011, which also included species of medicinal/aromatic/ornamental value (5), not under cultivation in Kerala (3), mistaken identity (3) and synonym (1). We provide here user-friendly crop-group wise categorization of taxa with their vernacular names for easy cross reference. This communication also discusses about the issue of botanical misidentification of crop plants, species of doubtful cultivation status, specialty crops, potential exotic crops, etc.

  相似文献   

16.
Crops were domesticated from wild plants not too long ago and have subsequently diverged from the wild ones, especially in traits used by humans. Whether divergence between the cultigen and wild forms has also lead to reduced reproductive compatibility is unknown for many species. Chicory (Cichorium intybus L.) has been bred as a crop at least since Roman times. To test if this has led to a loss in reproductive compatibility with wild chicory, we planted cultivar, wild, and F1 hybrid plants into two field plots, and let them pollinate freely. On 2?days, in the beginning and middle of the flowering season, we counted the numbers of flowering capitula and open flowers per capitulum, which in combination with counts of viable pollen per flower were used to estimate the expected proportion of seeds fathered by cultivar, wild, and hybrid plants. Open capitula on wild and hybrid plants were marked, and when seeds were ripe we determined whether cultivar, wild or hybrid plants had pollinated the seeds, using AFLP markers. Cultivar plants fathered much fewer seeds than expected, both on wild and hybrid plants, suggesting that some degree of incompatibility has evolved between cultivar and wild chicory. Hybrid plants fathered more seeds than expected on some of the hybrid plants, indicating that hybrids do not suffer much from outbreeding depression. Our study thus suggests that cultivated and wild chicory, even though they belong to the same species, have diverged to an extent where reproduction between them is somewhat impaired.  相似文献   

17.
Short-term erosion rates by overland flow under forested conditions are considered in relation to long-term valley development. Five catenas which are representative of the range of valley forms in the study area were selected, and the nine unit landsurface model was used as a sampling framework to locate experimental plots within the catenas.Factors affecting data validity include the spatial and temporal sampling pattern, and human-induced changes to the physical environment. Over the longer time-scale of valley development, problems in extrapolating the short-term data include establishing the time period within which valley development has occurred, and identifying and estimating the effects of climatic fluctuations on process intensities.The results show that, in the long-term context, measured contemporary erosion rates are ‘reasonable’ for three of the five catenas, but that considerable additional experimental work is required to resolve the identified problems. In some instances the means by which relevant data may be obtained are not apparent.  相似文献   

18.
The Ebro River valley in Northeast Spain experiences regularly strong west-northwest winds that are locally known as cierzo . When the cierzo blows, wind erosion may potentially occur on unprotected agricultural lands. In this paper the first results of field measurements of soil characteristics and saltation transport in the Ebro River valley near Zaragoza are presented. An experiment was conducted on a silt loam soil in the summers of 1996 and 1997. Two plots of 135×180 m were both equipped with a meteorology tower, three saltiphones (acoustic sediment sensors) and ten sediment catchers. The plots were different with respect to tillage practices. One plot received mouldboard ploughing followed by a pass of a compacting roller (conventional tillage—CT), whereas the other plot only received chisel ploughing (reduced tillage—RT). Soil characterizations indicated that soil erodibility was significantly higher in the CT plots than in the RT plots. Consequently, no significant saltation transport was observed in the RT plots during both seasons. In the CT plot, four saltation events were recorded during the 1996 season and nine events during the 1997 season. Most events were preceded by rainfall during the previous one or two days, which reduced saltation transport significantly. It is concluded that the occurrence of wind erosion in the Ebro River valley depends on the timing and type of tillage, distribution of rainfall and soil-surface crusting. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

19.
Communities of arbuscular mycorrhizal fungi (AMF) are strongly affected by land use intensity and soil type. The impact of tillage practices on AMF communities is still poorly understood, especially in organic farming systems. Our objective was to investigate the impact of soil cultivation on AMF communities in organically managed clay soils of a long-term field experiment located in the Sissle valley (Frick, Switzerland) where two different tillage (reduced and conventional mouldboard plough tillage) and two different types of fertilization (farmyard manure & slurry, or slurry only) have been applied since 2002. In addition, a permanent grassland and two conventionally managed croplands situated in the neighborhood of the experiment were analyzed as controls. Four different soil depths were studied including top-soils (0–10 and 10–20 cm) of different cultivation regimes and undisturbed sub-soils (20–30 and 30–40 cm). The fungi were directly isolated from field soil samples, and additionally spores were periodically collected from long-term trap culture (microcosm) systems. In total, >50,000 AMF spores were identified on the species level, and 53 AMF species were found, with 38 species in the permanent grassland, 33 each in the two reduced till organic farming systems, 28–33 in the regularly plowed organic farming systems, and 28–33 in the non-organic conventional farming systems. AMF spore density and species richness increased in the top-soils under reduced tillage as compared to the ploughed plots. In 10–20 cm also the Shannon–Weaver AMF diversity index was higher under reduced tillage than in the ploughed plots. Our study demonstrates that AMF communities in clay soils were affected by land use type, farming system, tillage as well as fertilization strategy and varying with soil depth. Several AMF indicator species especially for different land use types and tillage strategies were identified from the large data set.  相似文献   

20.
The objective of this study was to evaluate the effects of organic and inorganic fertilizers on the yield and quality of sugar beet genotypes (Beta vulgaris L.). Therefore, a field trial was carried out in Peshawar, Pakistan, during the winters in 2012–2013. The field experiment was conducted in a randomized complete block design with split plots, having three replications. Fertilizer treatments (control, composted manure Higo Organic Plus at 5 t ha?1, Maxicrop Sea Gold seaweed extract at 5 L ha?1, farm yard manure at 10 t ha?1, inorganic nitrogen–phosphorus (NP) at 90:60 kg ha?1, NP at 120:90 kg ha?1 and NP at 150:120 kg ha?1) were allotted to main plots, while genotypes (Sandrina, Serenada and Kawe Terma) were allotted to the sub-plots. Plots treated with the application of NP at 120:90 kg ha?1 produced the highest beet yield (76.4 t ha?1) and sugar yield (11.1 t ha?1), and had the second highest polarizable sugar content (14.52%) and more economic return (Rs. 553,000 per hectare) as compared to control plots. Sugar beet genotype Serenada had significantly higher beet yield (55.5 t ha?1) and sugar yield (7.9 t ha?1) and a higher economic return (Rs. 380,000 per hectare) than the other genotypes. Sugar beet genotype Serenada supplied with NP at 120:90 kg ha?1is recommended for the general cultivation in the agro-climatic conditions of Peshawar valley.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号