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1.
王家录  李维杰  王勇  任娟  高敏 《水土保持研究》2021,(2):217-223,F0003
为了了解重庆石漠化地区植被恢复以及生态环境治理状况,选取重庆石漠化地区归一化植被指数(NDVI)及气象数据,利用趋势分析、变异系数分析以及偏相关分析等方法,重点探讨了重庆石漠化地区2005-2014年NDVI的时空变化特征,并分析了NDVI变化与气候因子之间的相关性。结果表明:(1)重庆石漠化地区NDVI年际变化总体上呈增加趋势,增加速率为0.08/10 a,其中渝东北地区增长速率相对较高,达0.09/10 a,而NDVI季节变化存在一定差异性,春季增长最为显著,主要分布于渝东北、渝中和渝西地区;(2)渝东北石漠化地区NDVI呈增加趋势的区域范围较大,这对于三峡库区生态环境改善以及水土保持起着至关重要的作用;渝东南、渝中和渝西石漠化地区NDVI整体保持不变,而NDVI呈减小趋势的区域主要分布于乌江流域;(3)重庆石漠化地区2005-2014年NDVI变异系数相对较低,以稳定为主;(4)重庆石漠化地区降水和气温分别与NDVI之间正相关性都大于负相关性。总体上降水量的增加一定程度促进了三峡库区植被的生长,而温度的降低一定程度上抑制了乌江流域植被的生长。  相似文献   
2.
定甩刀防缠式香蕉秸秆粉碎还田机设计与试验   总被引:1,自引:1,他引:0  
针对香蕉秸秆粉碎机具缠绕造成秸秆粉碎率不达标等问题,该研究设计了一种定甩刀防缠式香蕉秸秆粉碎还田机。在粉碎过程中,粉碎定刀与高速运转中的Y型甩刀对香蕉秸秆形成三点支撑,进而实现秸秆粉碎与避免秸秆缠绕。其中,Y型甩刀由2个L型刀片组合的Y型粉碎刀与甩刀构成。确定了各关键部件的结构参数、动定刀排列组合方式及香蕉秸秆粉碎过程受力分析,明确了影响粉碎效果的主要因素为机具前进速度、粉碎刀辊转速以及Y型甩刀折弯角。以前进速度、刀辊转速和甩刀折弯角为试验因素,以香蕉秸秆粉碎合格率和抛撒不均匀度为评价指标,进行三水平三因素正交田间试验,确定优化参数组合为前进速度1.85 m/s,刀辊转速1 500 r/min,Y型甩刀片折弯角140°,此时香蕉秸秆粉碎合格率为95.1%,抛撒不均匀度为14.6%,满足香蕉秸秆粉碎作业性能要求。与已有秸秆粉碎机进行性能对比试验,结果表明,该研究研制的定甩刀防缠式香蕉秸秆粉碎还田机秸秆粉碎合格率提高了1.7个百分点,防缠性能更优。该机具的研制对解决蕉区秸秆粉碎还田关键技术问题具有重要意义和应用价值。  相似文献   
3.
为进一步研究国产人工打洞法所结沉香中的化学成分,本研究采用硅胶柱色谱、Sephadex LH-20、半制备高效液相等色谱方法从其乙酸乙酯萃取物中分离纯化得到2个单体化合物。根据核磁共振(NMR)、质谱(MS)等波谱数据分别鉴定为2-(2-苯乙基)色酮二聚体(+)-3′,3′′′-dihydroxy-4′,4′′′-dimethoxyaquisinenone G (1)和aquilasinenone F (2),其中化合物1为新化合物。抗氧化活性测试结果表明,化合物1和2都对DPPH自由基具有一定的清除能力,其中化合物2的IC50 值为(64.6±1.6)mol/L,阳性对照为L(+)-抗坏血酸。  相似文献   
4.
The quality and safety of agricultural products is the technique focus of the strategy of rural vitaliza⁃tion. Carbamate pesticide residues are seriously threatening the safety of agricultural product and human life and health. Nowadays, the common detection methods are instrument-based for carbamate pesticide residue, which dis⁃ satisfy the request of an on-site rapid, sensitive and simultaneous detection for multiple carbamate pesticide resi⁃ dues. Based on the home-made monoclonal antibodies against carbofuran and carbaryl respectivity, a microarray for rapid and simultaneous detection of multiple carbamate pesticide residues was developed within 30 min. Under the optimized conditions, the limits of detection(LODs)were found to be 0.11 and 0.09 ng/g, while the linear ranges were 0.33-3000 and 0.18-1500 ng/g for carbofuran and carbaryl respectively. By using spiked peanut samples, it recorded recoveries of 88.4%-98.3%, 90.1%-118.8% for carbofuran and carbaryl respectively. The RSD of intraarray were found at 9.0%, 3.5%, while the RSD of inter-array were recorded at 12.3%, 16.3% respectively. The de⁃ tection results of the microarray were highly consistent with that of HPLC-MS/MS. This proposed microarray provid⁃ ed an on-site high-sensitivity, simultaneous and rapid detection of carbofuran and carbaryl, and could be widely used in the fields of agricultural product quality safety, food safety and environmental monitoring.  相似文献   
5.
In the present study, the location, histology and number of corpuscles of Stannius (Sc), which are endocrine glands associated with the kidneys of teleost fish, were investigated for the first time in Lake Van fish (Alburnus tarichi), an anadromous and endemic inhabiting Turkey's Lake Van Basin. The Sc, which were ovoid or spheroid and white or cream in colour, were found to vary in number between three and five among the examined fish. The glands were located in the caudal part of the kidney, and either partially or completely embedded, and found to be present on both the ventral and dorsal surface of either side of the caudal part of the kidney. The Sc were surrounded by a connective tissue capsule that penetrated and divided the gland into incomplete lobules. Two types of cells were determined in the parenchyma of the gland. Type-I cells were predominant throughout the parenchyma and larger than the second (type-II). In the type-I cells, the cytoplasm was observed as weakly or moderately eosinophilic with haematoxylin and eosin staining and weakly or moderately acidophilic with Mallory's triple staining. In the type-I cells, the cytoplasm exhibited weak to moderate periodic acid-Schiff staining and slight or uniform staining with aldehyde fuchsin. The type-II cells were round, had a darkly stained spherical nucleus and were dispersed among the type-I cells. They displayed no cytoplasmic staining with the abovementioned stains.  相似文献   
6.
Understanding yield potential, yield gap and the priority of management factors for reducing the yield gap in current intensive maize production is essential for meeting future food demand with the limited resources. In this study, we conducted field experiments using different planting modes, which were basic productivity(CK), farmer practice(FP), high yield and high efficiency(HH), and super high yield(SH), to estimate the yield gap. Different factorial experiments(fertilizer, planting density, hybrids, and irrigation) were also conducted to evaluate the priority of individual management factors for reducing the yield gap between the different planting modes. We found significant differences between the maize yields of different planting modes. The treatments of CK, FP, HH, and SH achieved 54.26, 58.76, 65.77, and 71.99% of the yield potential, respectively. The yield gaps between three pairs: CK and FP, FP and HH, and HH and SH, were 0.76, 1.23 and 0.85 t ha~(–1), respectively. By further analyzing the priority of management factors for reducing the yield gap between FP and HH, as well as HH and SH, we found that the priorities of the management factors(contribution rates) were plant density(13.29%)fertilizer(11.95%)hybrids(8.19%)irrigation(4%) for FP to HH, and hybrids(8.94%)plant density(4.84%)fertilizer(1.91%) for HH to SH. Therefore, increasing the planting density of FP was the key factor for decreasing the yield gap between FP and HH, while choosing hybrids with density and lodging tolerance was the key factor for decreasing the yield gap between HH and SH.  相似文献   
7.
Quantification of currently attainable yield and fertilizer requirements can provide detailed information for assessing the food supply capacity and offer data support for agricultural decision-making. Datasets from a total of 5 408 field experiments were collected from 2000 to 2015 across the major wheat production regions in China to analyze the spatial distribution of wheat yield, the soil nutrient supply capacity(represented by relative yield, defined as the ratio of the yield under the omission of one of nitrogen(N), phosphorus(P) and potassium(K) to the yield under the full NPK fertilizer application), and N, P and K fertilizer requirements by combining the kriging interpolation method with the Nutrient Expert Decision Support System for Wheat. The results indicated that the average attainable yield was 6.4 t ha~(-1), with a coefficient of variation(CV) of 24.9% across all sites. The yields in North-central China(NCC) and the northern part of the Middle and Lower reaches of the Yangtze River(MLYR) were generally higher than 7 t ha~(-1), whereas the yields in Southwest China(SWC), Northeast China(NEC), and the eastern part of Northwest China(NWC) were usually less than 6 t ha~(-1). The precentage of area having a relative yield above 0.70, 0.85, and 0.85 for N, P, and K fertilizers accounted for 52.3, 74.7, and 95.9%, respectively. Variation existed in N, P, and K fertilizer requirements, with a CV of 24.8, 23.9, and 29.9%, respectively, across all sites. More fertilizer was needed in NCC and the northern part of the MLYR than in other regions. The average fertilizer requirement was 162, 72, and 57 kg ha~(-1) for N, P_2O_5, and K_2O fertilizers, respectively, across all sites. The incorporation of the spatial variation of attainable yield and fertilizer requirements into wheat production practices would benefit sustainable wheat production and environmental safety.  相似文献   
8.
在丝绸之路经济带的大背景下,中国农产品的贸易发展速度加快,经济链条得到延伸。陕西省作为丝路经济带的起点,其农产品的发展却面临着来自国内外农产品的强力冲击,为了能够更好地满足经济全球化的市场需求,促进我国农业经济的发展,强化对于陕西省农产品的品牌建设。本文通过对陕西省农产品品牌现状的分析,围绕品牌观念、技术支撑、市场开发三个方面,基于政府和企业角度探讨陕西省农产品品牌建设的对策,并据此提出了加快陕西省特色农产品品牌发展的建议,以期对陕西省农产品品牌建设提供创新思路。  相似文献   
9.
研究籼粳杂交稻钵苗摆栽超高产栽培模式下适宜的控释氮肥运筹。试验于2016—2017年在安徽庐江进行,以当地高产籼粳杂交稻甬优1540为供试品种,设置控释氮肥一次性基施(single basal application of CRNF,BC)、与尿素分蘖肥配施(basal application of CRNF combined with urea top-dressing at the tillering stage,BC+TU)、与尿素穗肥配施(basal application of CRNF combined with urea top-dressing at panicle initiation,BC+PU)三种运筹模式,以尿素分次施肥(conventional high-yield fertilization,SU)和不施氮肥(0N)为对照,研究控释氮肥运筹对钵苗摆栽籼粳杂交稻产量、氮肥吸收利用及相关农艺指标的影响。结果表明,控释氮肥阶段释放基蘖肥:穗肥比例为7∶3,较传统优化氮肥运筹SU(6∶4)整体表现基蘖肥冗余,穗肥不足,因而BC和BC+TU处理显著降低了钵苗摆栽籼粳杂交稻产量和氮肥利用效率。与BC和BC+TU处理相比,BC+PU通过基肥减量和尿素穗肥配施,在保证水稻营养生长期基本氮素供应的同时,显著增加了穗分化至成熟期氮素吸收,促进了穗分化至成熟期光合物质生产能力,在稳定有效穗数和千粒重的同时,显著提高了钵苗摆栽籼粳杂交稻每穗粒数、结实率和产量,很好的匹配了钵苗摆栽籼粳杂交稻全生育期氮素需求。BC+PU两年的产量和氮肥利用率分别为12.2~13.1 t hm-2和43.8%~44.1%,分别较BC显著提高7.4%~9.2%和48.5%~59.9%,较BC+TU显著提高8.0%~11.9%和63.9%~74.5%。另外,BC+PU的产量和氮肥利用率与SU无显著差异,但由于大幅降低了施氮人工成本,最终提高净收益6.5%~12.3%。在籼粳杂交稻钵苗摆栽超高产栽培模式下,采用70%控释氮肥+30%尿素穗肥处理可有效取代常规尿素分次施肥,获得无显著差异的水稻产量和氮肥利用效率,同时进一步提高经济效益。  相似文献   
10.
不同水肥条件下夏玉米/冬小麦农田生态系统碳平衡研究   总被引:3,自引:0,他引:3  
农田生态系统碳平衡取决于农作物固定碳量和土壤异养呼吸排放碳量。为揭示水肥用量对农田生态系统碳平衡的综合影响,设置3个灌水水平:高水、中水和低水(W1、W0.85、W0.7夏玉米季分别为90、76.5、63mm,冬小麦季分别为140、119、98mm),4个施氮水平:高氮、中氮、低氮和不施氮(N1、N0.85、N0.7、N0夏玉米季分别为300、255、210、0kg/hm2,冬小麦季分别为210、178.5、147、0kg/hm2),4个施磷水平:高磷、中磷、低磷和不施磷(P1、P0.85、P0.7和P0夏玉米季分别为90、76.5、63、0kg/hm2,冬小麦季分别为150、127.5、105、0kg/hm2)进行了田间试验。结果表明:不同水肥处理下夏玉米/冬小麦农田生态系统表现为碳汇,夏玉米季净生态系统生产力固碳量(CNEP)为6805~7233kg/hm2,冬小麦季CNEP为5842~6434kg/hm2,夏玉米CNEP高于冬小麦。在高、中、低肥水平下,增加灌水量,夏玉米/冬小麦周年净初级生产力固碳量(CNPP)提高2.48%~5.96%,土壤微生物异养呼吸碳释放量(CRm)增加2.15%~15.20%,净生态系统生产力固碳量(CNEP)增加1.16%~6.47%。在高、中、低供水水平下,增加施肥量,夏玉米/冬小麦周年CNPP增加2.95%~3.43%,土壤CRm增加5.23%~18.67%,CNEP增加0.93%~2.79%,CNEP增加比例与供水水平呈负相关。在低水条件下,氮磷肥配施处理夏玉米/冬小麦农田周年CNEP较单施氮、磷肥分别增加4.86%、7.34%,且氮磷肥交互作用显著(P<0.05),水肥供应水平相差15%时对冬小麦农田CNEP有显著的正交互作用。氮磷肥配施、水肥协调供应均有助于促进夏玉米/冬小麦农田生态系统的净碳输入,在节水节肥原则下,夏玉米和冬小麦分别在W0.85N0.85P0.85和W0.7N0.85P0.85水肥供应条件下有利于增加农田CNEP。  相似文献   
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