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Jami MJ Salehduost A Negarestan H 《Pakistan journal of biological sciences: PJBS》2010,13(20):993-999
Coral reefs are specialized communities that develop clear, well-lit tropical and subtropical water; they provide shelter and canopy for great variety of organisms, living in mean temperature of 20 degrees C. Coral Bleaching and mortality have been associated with elevated seawater temperature. The aim of the study was to investigate coral bleaching and evaluate health condition of the corals. Distribution of coral reefs around Kish Island was determined by the Timed Swim (TS) technique. This survey carried out in 2 times (May and October, 2009) in 2 depths of 3-5 m and 6-10 m. Two Divers swam in constant speed for a set amount of time in three dive sites. The timed swim survey around the Kish Island showed that the most healthy live hard coral assemblages were found in the site called Persian Gulf seaport, whereas the greatest percentage of bleached corals were located in Jurassic Park station, located at the southeast of the Island. Branching corals (Acropora sp.) were bleached among all 3 stations and no sign of recovery could be detected. In Big coral site suitable substrate for accumulation of living organisms including Echinometra mathaie (sea urchin) existed due to presence of great amount of algae on dead corals and rocks. Based on the observation, it seems that the cause of reef destruction in Kish Island fall in to two categories, natural and human impacts. 相似文献
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Cassava yields in Africa are small and it remains unclear which factors most limit yields. Using a series of farm surveys and on-farm and on-station trials in Uganda and western Kenya, we evaluated the importance of abiotic, biotic and associated crop management constraints for cassava production in a range of socio-economic settings as found in smallholder farms in the region. Average yields under farmer management were 8.6 t ha−1, but these were more than doubled to 20.8 t ha−1 by using improved crop establishment, improved genotypes and 100–22–83 kg ha−1 of single-nutrient N–P–K fertilizers. A farm survey revealed large yield differences between farms. Less endowed farmers harvested less cassava per unit area than better endowed farmers (difference of 5.9 and 9.7 t ha−1 in Kenya and Uganda, respectively); differences were associated with less access to labour, poorer soils, and premature harvesting by less endowed farmers. Analysis of 99 on-farm and 6 on-station trials showed that constraints for cassava production varied strongly between sites and years. Poor soil fertility, early water stress and sub-optimal weed management limited cassava production by 6.7, 5.4 and 5.0 t ha−1, respectively, when improved crop establishment and genotypes were used. Pests and diseases were relatively unimportant, while weed management was particularly important in farmer fields during a dry year in Kenya (yield gap of 11.6 t ha−1). The use of complementary analytical tools such as multiple regression and boundary line analysis revealed that many fields were affected by multiple and interacting production constraints. These should be addressed simultaneously if significant productivity improvements are to be achieved. This will be more difficult for less endowed than for better endowed farm households, since the former lack social and financial capital to improve management. 相似文献
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《Journal of Crop Improvement》2013,27(1-2):299-323
SUMMARY Salinity is a major problem that negatively impacts agricultural activities in many regions in the world, and especially the Near East and North Africa region. Generally, salinity problems increase with increasing salt concentration in irrigation water. Crop growth reduction due to salinity is generally related to the osmotic potential of the root-zone soil solution. This will lead to certain phenological changes and substantial reduction in productivity. Salinity also affects the soil physical properties. Sewage treated wastewater is an alternative water source for irrigation. Using such wastewater will provide a new water resource to expand agricultural activities as well as reduce the environmental pollution. Each country in the region has a unique system of rules and regulations to protect the quality of water resources. Important aspects that should be taken into account when using wastewater for irrigation are discussed, including some information on the different irrigation systems used in the region, and the factors leading to success of using saline water for economic crop production. Information on the use of saline water or marginal saline soils for wheat production and improvement of irrigation systems, including old land irrigation systems, under Egyptian conditions is also presented. The regional experiences and the future prospects of using saline water for crop production that vary greatly among countries in the Near East and North Africa region are summarized. This article also presents information on special cultivation methods, such as protected agriculture and soilless culture that can help in alleviating the salinity effects. Finally, the article includes some examples on the inherited knowledge for saline agriculture that conveys the grower's experience in the Near East and North Africa region where several living examples for unique and sustainable cultivation system are still in operation. One of the most impressive cultivation techniques for bio-saline crop management in Egypt is the Edkawy production system. 相似文献
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Mathew M. Abang Bassam Bayaa Barakat Abu-Irmaileh Amor Yahyaoui 《Crop Protection》2007,26(12):1723-1732
Broomrapes (Orobanche spp.) are aggressive and damaging parasitic weeds which have a tremendous impact on agriculture in East Africa, the Mediterranean region and the Middle East. Despite the availability of technologies to control broomrapes in economically important crops, Orobanche infestation continues to increase, threatening the livelihoods of millions of farmers. Many of the technologies developed have not been effectively disseminated and there has been little or zero adoption by farmers—who continue to use ineffective management practices that exacerbate the problem. The adaptation and dissemination of appropriate management practices are major priorities in broomrape control. However, such work must take into consideration the specific socio-economic characteristics of individual farming systems. Orobanche is a community threat and effective management requires a community-based integrated management approach. Recognizing the central role of farmers in parasitic weed management, a technical cooperation project (TCP) involving FAO, ICARDA and seven countries in the Near East and North Africa (NENA) region was implemented to improve the dissemination of knowledge and skills by using a farmer field school approach: a form of education that uses experiential learning methods to build farmers’ expertise. This paper reviews conventional Orobanche research and development approaches, and highlights weaknesses in the management of the parasitic weed using these approaches as opposed to participatory approaches. The benefits and challenges of participatory farming system approaches in relation to integrated broomrape management (IBM) are also discussed. Lessons learned from achieving community ownership of, and institutional support for, IBM could be applied to other sectors (e.g. public health) in which there is a need for institutional learning and reform. Recommendations are made that include regional collaboration within the framework of a proposed Near East and North Africa Orobanche Management Network (NENAOMAN). 相似文献
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Although the beneficial effect of arabinoxylan (AX) has been recognized for breadmaking, the available information about the effect of these compounds in gluten-free systems is scarce. In the present study, maize AX was tested in gluten-free breads using a yeast-leavened lean formulation based on rice flour and corn starch and two shaping models: pans and by dropping dough. The effect of the AX level (0%–5%) and hydration (70%–85%) were determined. Breads produced were analyzed in texture, morphology and crumb structure. The breads from the pan shaping model did not show significant differences in the crumb hardness. Moreover, the control breads presented better springiness, cohesiveness and resilience compared to AX breads. For the breads from the dropping dough model, those containing AX had lower hardness and chewiness and higher 2D area, height, cell density and surface area compared to control breads, especially at higher AX levels. Yet, AX caused a detrimental effect in springiness, cohesiveness and resilience. The hydration affected the hardness, 2D area, height, cell density and mean cell area in breads containing AX, finding better results in breads with 80% water absorption. This research demonstrated that even when AX are capable to improve the hardness and crumb structure of gluten-free breads, they could cause a detrimental effect in other textural characteristics. 相似文献
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Ice structuring proteins (ISPs) are proteins that can modify and inhibit the growth of ice. ISPs may improve the quality of frozen dough by stabilizing ice crystals and maintaining the texture of frozen dough. In this study, effects of ISPs from winter wheat were examined on the thermophysical properties of dough, which include freezing point depression, freezable water fraction, apparent specific heat, and effective thermal conductivity. The thermophysical properties were measured by differential scanning calorimetry (DSC) and line source probe methods. The results showed that, compared to the control, adding 0.6% ISPs induced a maximum freezing point depression of 0.23 °C and decreased the amount of freezable water by 8%. ISPs had little effect on the apparent specific heat and the effective thermal conductivity in the unfrozen ranges. However, the thermophysical properties in the frozen ranges were significantly affected by ISPs. The determined thermophysical properties are important to model heat transfer during freezing of dough. 相似文献
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《Field Crops Research》2003,83(1):91-100
An attempt is made to quantify the long-term benefit from the sustained production of sugarcane in South Africa using nematicides to reduce the damage caused by nematodes in each crop. The study was conducted using data from the plant crop and four or five ratoon crops from two trials located on similar sandy soils. Treatments comprised aldicarb and an untreated control, applied to a total of 10 sugarcane cultivars. Two cultivars were common to both sites. The plant parasitic nematode communities were similar at both sites except that Meloidogyne javanica was absent from one site. Yield of ratoon crops was correlated with the yield of the plant crop. Annual losses from nematodes were similar over successive crops. Data from both sites showed there to be a significant, positive correlation between yield of the nematicide treated plots and size of the response to treatment. Over a 4-year period, M. javanica alone was responsible for 30% of the losses, equivalent to 15 t cane/ha per year. The long-term effect of nematodes on sugarcane production was measured after calculating a logarithmic function from the observed yields of successive ratoons. Without a nematicide the time taken for the yield to decline to a threshold of 40 t cane/ha per year ranged from a minimum of 1 year in the M. javanica infested site to a maximum of 9 years in the other site. Treatment with a nematicide increased this period considerably. On the site with M. javanica it took a projected 20 years before the yield of one of the cultivars reached the threshold and 43 years for the same cultivar at the other site. The use of a nematicide increased long-term production, on average, by a factor of 3 at the M. javanica infested site and a factor of 5 at the other site. Differences between cultivars in the rate at which ratoon yields declined meant that, over time, the best cultivars at both sites were not the ones which gave the greatest annual yields during the first few crops after planting. 相似文献
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马铃薯种植方式的研究 总被引:2,自引:0,他引:2
马铃薯是建平县种植业结构调整中的优势作物,常年栽培面积都在1.5万hm^2左右,建平是辽宁省马铃薯生产第一大县。传统的低垄单行切块栽培方法,马铃薯产量低而不稳;采用高垄双行整薯栽培方式显著地提高了大薯率,降低了小薯率,从而提高了马铃薯产量。在山坡地通过加大种植密度,不仅可以提高马铃薯产量,而且有利于获得更多的适合做种的小整薯。 相似文献
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花生主要经济性状遗传特点分析 总被引:3,自引:0,他引:3
用16个F4:5家系的384个株系和8个亲本、1个对照种为材料,研究了花生亲本5个产量性状和2个品质性状的遗传特点,讨论了在花生杂交组合选配上的应用。(1)亲本性状值与其一般配合力表现正相关。在产量性状的基因效应中,加性效应占优势,在品质性状上则是加性效应和非加性效应均很重要。(2)相对遗传力的变异较为复杂,既因亲本而异、又因性状而异,在单株饱果数、籽仁产量、出仁率、脂肪含量上小值亲本对大值亲本占优势,在百仁重、蛋白质含量上大值亲本占优势。(3)在组合选配时,应选用重要性状都好的品种作亲本、且双亲性状值差异不宜太大,即用“优×优”组合模式,以确保杂种后代中分离出较多期望型个体。 相似文献
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玉米间套作种植方式研究综述 总被引:16,自引:1,他引:16
阐述了国内外有关玉米间套作种植方式的研究进展,分析了间套作的生态效应、生理效应以及对作物病虫草害的影响和控制水土流失的作用,提出我国间套作应注意的关键问题。 相似文献
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稻田增氧模式对水稻籽粒灌浆的影响 总被引:6,自引:0,他引:6
为考查水稻产量形成和灌浆动态对不同稻田增氧模式的响应特征,于2008年和2009年,以国稻1号和秀水09为材料,长期淹水田块为对照(CK),采用过氧化尿素(T1)、过氧化钙(T2)和干湿交替灌溉(T3)的稻田增氧模式,监测并采用Richard方程模拟水稻籽粒灌浆过程。 国稻1号产量依次为T3>T1>T2>CK,秀水09产量依次为T3>T2>T1>CK。2008年,国稻1号T1、T2和T3分别比CK增产11.6%、8.5%和13.6%,秀水09增产6.6%、9.2%和9.4%。2009年,国稻1号T1、T2和T3分别比CK增产16.8%、14.4%和23.0%,秀水09增产14.6%、17.2% 和17.4%。不同增氧模式对水稻灌浆过程的影响表现为:1)灌浆过程均符合Richards方程(拟合度>0.989);2)强、弱势粒的最大粒重均有提高、粒重差异减少、灌浆同步性提高;3)两水稻品种的弱势粒均得到充分灌浆,其中增氧延长了国稻1号弱势粒的灌浆时间、增大了秀水09弱势粒灌浆速率。增氧模式下,弱势粒充分灌浆和结实率提高是水稻产量增加的主要原因。 相似文献
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Potato processing is becoming particularly popular in developing countries and French fries are the main product being developed. This paper describes the South African frozen French fry industry, identifying aspects for improvements for further growth. Although South Africa produces over two million tonnes of potatoes per year, only 17 to 20% are processed, mainly as frozen French fries. While this is a larger production achievement than in the past, trends in consumption show that the frozen French fry industry has potential for further growth. Industry expansion is limited by the shortage of suitable raw potato stock linked to cultivar and potato production capacity constraints for frozen French fry processing. The country relies mainly on two processing cultivars produced in localized areas, for which yields are also threatened by unpredictably detrimental weather conditions. Produce shortages often lead to subsequent importation of products from other countries. The lack of cultivar-specific information on the amount of land used, production tonnages and yield achievements restricts diagnosis of specific factors contributing to this shortage. Based on the overall crop performance, a region-based approach is suggested to improve yield achievements of the few cultivars used for frozen French fry processing in the country. This could be achieved by optimizing natural resource management, particularly irrigation, fertilizer and land use, in the four agro-climatic regions contributing to the processing industry. Furthermore, the number of French fry processing cultivars can be increased by increasing financial investment on local breeding efforts to develop new cultivars and by focusing foreign cultivar adoption on processing needs to increase the genetic diversity and safeguard against the effects of climate change. 相似文献
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比较不同种植模式对巴西香蕉生长及产量的影响。结果表明:在不同种植模式下,茎高、茎围、叶长、叶宽的生长规律相似;各处理的茎围、叶宽、青叶数、果指数、抽蕾率、果穗轴尾部直径之间无显著差异;茎高、叶长、吸芽数、果指长度与果指围度、果穗轴头部直径之间除了D2(矩形单行植,株行距为2.0 m×3.0 m,种植密度为1 666株/hm2)与D3[矩形宽窄行植,株行距为1.5 m×(3.0+1.0)m,种植密度为3 333株/hm2]有显著差异外,其他无显著差异,而且茎围、青叶数、吸芽数、果指数、果指长度与果指围度、果穗轴头部与尾部直径均随种植密度的增加而减少;现蕾期与果生育期随种植密度的增加而有所延长且收获期较分散;单果重、单株产量随种植密度的增加而减少,单位面积产量则随种植密度的增加而增加,差异极显著。 相似文献
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Active compounds from natural products have been widely studied. The anti-tumor effects of 13-acetoxysarcocrassolide isolated from Formosan soft coral Sarcophyton crassocaule on bladder cancer cells were examined in this study. An MTT assay showed that 13-acetoxysarcocrassolide was cytotoxic to bladder female transitional cancer (BFTC) cells. We determined that the BFTC cells underwent cell death through apoptosis by flow cytometry. Due to the highly-migratory nature of the BFTC cells, the ability of 13-acetoxysarcocrassolide to stop their migration was assessed by a wound healing assay. To determine which proteins were affected in the BFTC cells upon treatment, a comparative proteomic analysis was performed. By LC-MS/MS analysis, we identified that 19 proteins were up-regulated and eight were down-regulated. Seven of the proteins were confirmed by western blotting analysis. This study reveals clues to the potential mechanism of the cytotoxic effects of 13-acetoxysarcocrassolide on BFTC cells. Moreover, it suggests that PPT1 and hnRNP F could be new biomarkers for bladder cancer. The results of this study are also helpful for the diagnosis, progression monitoring and therapeutic strategies of transitional cell tumors. 相似文献
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气候变暖情况下播期对陇东旱塬春玉米的影响 总被引:1,自引:0,他引:1
选取陇东旱塬区主栽玉米先玉335为试验材料,在4月5日至5月5日设置7个播期对陇东旱塬春玉米生长发育、产量形成和水分利用的影响进行研究。结果表明,不同播期玉米各生育阶段积温存在差异,全生育期所需活动积温与有效积温受播期影响显著,播期提前或推后均可以在一定程度上增加陇东旱塬春玉米产量,但播期提前较推后可以获得更高产量。株高随播期的推迟增高,穗长、穗粒数、秃尖长等果穗性状指标没有显著差异。从研究结果来看,陇东旱塬4月5~20日播种春玉米均可获得较高产量,但4月5日播期耗水量显著高于其他播期,水分利用效率较低。 相似文献
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以1981—2010年度商丘市小麦生长季的气象数据为资料,系统地研究了小麦生育期冻害发生规律,深入地分析了形成原因。研究表明:该区小麦冻害10年10遇,重灾年率为10年8遇。与常年相比,冻害的发生频率呈现变化不大,危害程度呈现冻害有所减轻的趋势;时期呈现冻害初冬和早春逐渐减少,越冬和晚霜逐渐增多的态势;空间分布呈现冻害东部重,西部次之,中部轻的特征。从冻害形成原因上来看,该区每年冬初至春末冷暖空气交替频繁,气候多变,低温灾害性天气多;另外,由于耕层浅、播量过大、水肥管理不适等人为因素也会造成小麦易遭受冻害。 相似文献