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91.
通过分析海参养殖的现状,结合鼠尾藻的生物和生态特点,阐述了鼠尾藻是海参养殖水体理想的生物修复藻类。并对功能藻的概念及其应用前景进行了叙述。  相似文献   
92.
Powdery mildew is one of the most important melon pathogens all over the world. So far, many genes conferring resistance to powdery mildew of melon have been described, but few of these have been finely mapped or cloned. Two F2 populations derived from Ano2 × Hami413 and Ano2 × Queen were used to map the powdery mildew resistance gene by methods of Bulked Segregation Analysis (BSA), comparative genomics and Resistance Gene Analogues (RGA) mapping. It was found that the resistance to powdery mildew in Ano2 was conferred by a dominant gene, and the gene was named Pm-AN. The genetic analysis revealed that Pm-AN located between two codominant markers RPW and MRGH63B in linkage groupV. The genetic distances between Pm-AN and these two markers were 1.4–1.8 and 1.6–2 cM. No recombination was found between Pm-AN and markers ME/E1, SRAP23. Pm-AN was located in a RGA-rich region and cosegregated with the RGA marker MRGH5 and the resistance gene Vat. Synteny analysis showed that markers in this region were collinear between melon and cucumber. Segregation distortion was found in this region using both Ano2 × Hami413 and Ano2 × Queen F2 populations, and the distortion was more distinct in Ano2 × Hami413 F2 population. The center of segregation distortion was located in the RGA rich region harboring Pm-AN.  相似文献   
93.
关超 《中国农学通报》2011,27(23):47-50
为探讨NPN(non protein nitrogen 非蛋白氮 简称NPN)补充料在奶牛养殖业中的作用,选取相关材料和方法进行研究。中国荷斯坦奶牛32头随机分为试验组和对照组,每组16头。试验组在精料中用NPN补充料取代一定数量的常规蛋白质补充料,对照组饲喂常规饲料,不添加NPN补充料。经过60天的试验,结果表明:试验组奶牛总产奶量16108 kg,比对照组的15289 kg增产819 kg,平均每头每日增产0.85 kg,以当地鲜奶时价2 元/kg计,计算出日增收1.7 元。再来计算饲料成本,在用NPN补充料替换出常规蛋白质补充料胡麻饼时,精饲料总成本降低544 元,即试验组比对照组饲料成本节省544 元,通过相关计算可得试验组平均每头每日节约饲料成本0.57 元。从而得出NPN补充料对奶牛产奶量及经济效益的影响结果,对其在生产中推广应用有指导作用。  相似文献   
94.
扬州园林植竹造景史考   总被引:1,自引:0,他引:1  
根据历史文献资料,探讨了扬州园林的植竹造景历史。扬州历代园林竹景建造的特点主要是以竹名园、以竹名景和以竹辅景。  相似文献   
95.
陕西黄河湿地是我国中、西部国际候鸟的主要栖息地之一和内陆候鸟迁徙通道上的重要驿站,区内生境多样,鸟类资源十分丰富。通过对湿地内高生芦苇区、低矮芦苇区、盐碱地、农田、鱼塘、莲池、滩涂、林地等不同生境类型的鸟类分布情况进行的调查分析,结果共记录到16目39科132种,较2005年增加了3科13种,为陕西黄河湿地鸟类资源保护提供了科学依据。  相似文献   
96.
着重介绍了黑龙江省哈尔滨市城市夜景照明设计,分析城市灯光夜景照明设计存在的问题,为提高城市环境规划质量提出建议。  相似文献   
97.
节水的含义值得深入讨论,如单从字面上理解,往往被认为就是节约用水,实际上节水的含义深广,并不局限于用水的节约。它包括水资源(地面水和地下水)的保护,控制和开发,并保证其可获得的最大水量进行合理经济利用,也有精心管理和文明使用自然资源之意。因此,对节水需作广义理解,节水为水管理的一个不可分割的重要部分。  相似文献   
98.
[目的]精确评估皖南山区土壤侵蚀量并分析其时空变化特征,为区域水土流失综合治理提供科学依据.[方法]在GIS技术的支持下,利用研究区日降雨数据,30 m分辨率DEM,土壤数据和土地利用等数据,采用中国土壤流失方程(CSLE)估算皖南山区土壤侵蚀模数,并分析2000,2010和2018年近20 a研究区土壤侵蚀时空变化特...  相似文献   
99.
‘Deep incorporation of corn straw’ (CSDI) is to concentrate the burial of corn straw into the subsurface soil layer (20–40 cm) and to break the plough pan, thereby creating a loosened plough layer (0–20 cm) and a fertile subsurface soil layer. However, its impacts on soil organic carbon (SOC) and the microbial community remain poorly understood. A field experiment was conducted to investigate the effects of 1-year CSDI (CD1), 3-year CSDI (CD3) and 5-year CSDI (CD5) on soil aggregates and aggregate-associated SOC, as well as bacterial and fungal community characteristics (examined by the high-throughput gene sequencing method). The results demonstrated that SOC and soil fungal diversity were decreased by CD1, but increased by CD3 and CD5. Compared with the control, CD5 promoted 2–0.25 mm soil macroaggregation, significantly increased SOC by 8.94% and aggregate-associated SOC by 5.96%–8.84%, consequently improving the physical protection of SOC by soil aggregates. CD3 and CD5 enhanced the richness and diversity of soil bacteria and fungi, and altered community composition. For soil bacteria, the relative abundance of Acidobacteria and Chloroflexi was increased, while that of Firmicutes, Gemmatimonadetes, Sphingomonas and Bacillus was decreased. For soil fungi, the relative abundance of Ascomycota, Zygomycota, Mortierella and Fusarium was greatly improved, but that of Basidiomycota was reduced. These obvious variations in microbial community structure were beneficial to straw degradation and SOC accumulation. Overall, the optimization of microbial community with CSDI plays a positive role in promoting soil organic matter, nutrient cycling and carbon sequestration, and thus improving soil fertility.  相似文献   
100.
Land use change and grassland degradation are two of the most critical problems ubiquitously found in arid and semi-arid areas in Northern China. Energy fluxes, including net radiation (Rn), latent heat flux (LE), sensible heat flux (H) and soil heat flux (G), were examined over an entire year (December 2005 to November 2006) in different steppe ecosystems – the steppe and cropland in Duolun and the fenced and grazed steppe in Xilinhot – in Inner Mongolia based on direct measurements from four eddy-covariance flux towers. The seasonal changes in Rn, LE, H and G of the four sites were similar, with very low values during the period of snow cover from December to February, followed by a gradual increase in the growing season. The opposite seasonal patterns of the LE and H fraction resulted in significant seasonal changes in Bowen ratio (β). Human activity in cropland ecosystems not only resulted in a rapidly shift between LE and H, but also triggered a decrease in latent heat fraction because of a shortened growing season of crop plants. The significantly positive relationships between canopy surface conductance (gc) and LE/LEeq of all of the study sites suggested that a lack of precipitation coupled with high VPD conduced remarkable decreases of stomatal conductance. This could impede the latent heat partitioning of available energy (Rn − G) in semi-arid ecosystems, Inner Mongolia. The obvious decrease in the values of gc and the decoupling factor (Ω) in both the cropland and the degraded steppe suggested that land use change could depress latent flux fraction and increase its sensitivity to air and soil drought.  相似文献   
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