作物种植变化对资源与环境影响的能值分析:以湖北省1978—2015年作物种植变化为例

采用能值分析和弹性分析方法相结合评价湖北省作物种植变化对农业生产效率和资源环境的影响。结果表明,1978-2015年间湖北省农业生产效率较高,环境可持续性较强,但是近年来农业生产环境压力增大,环境负荷率略有上升趋势。各能值指标变化的空间差异也较明显,其中江汉平原地区能值投入率和能值产投比较高,同时环境负荷率最高,表明其可持续发展指数较低,增速较缓;东西部地区农业能值投入率和能值产投比均较小,环境负荷率较低,表明其可持续发展能力较高,且增长速率较快,环境压力也较小。1978-2015年湖北省水稻、棉花和豆类作物播种面积比例对可持续发展指数的弹性系数为负值且富有弹性,蔬菜和水果作物播种面积比例对可持续发展指数的弹性系数呈现波动,由正值转为负值再转为正值。由于湖北省环境负荷率较大主要是由化肥施用量较大引起的,因此湖北省未来农业发展在注重效率的同时要高度关注农业生态环境,减少单位面积化肥施用量,减轻农业生产导致的环境压力,促进农业可持续发展。

沿黄稻区水稻种植变化及影响因素分析——以河南省原阳县为例

以河南省沿黄稻区原阳县为例,对其水稻的种植变化及其影响因素进行研究。结果显示:1979—1998年水稻播植面积和单产同步上升,1999—2006年播种面积上升,但单产下降,2007—2018年播种面积下降,单产上升至平稳;空间上,水稻种植重心大致自西向东移动,由113.85°E移到113.97°E。影响水稻播种面积的主要因素依次为居民消费水平、农业收入占比、农村用电量、农业机械总动力、总劳力、化肥使用量。研究成果可为区域生态保护、农业发展和耕地可持续利用提供参考。

中国农业种植结构变化对生产效率的影响--基于专业化分工的视角

近年来我国粮食作物和经济作物播种面积占比不断变化,南方地区和北方地区的农作物种植结构呈现出专业化分工的趋势。这种农业种植结构变化是否会对生产效率产生显著影响?为了探究该问题,本文基于2000—2018年省级面板数据,运用随机前沿生产函数模型,评估中国过去二十年农业种植结构变化对农业总产值和生产效率的影响。研究表明,过去二十年中国种植结构发生了显著变化,南方的粮食作物占比在不断下降,经济作物占比在不断上升;而北方的粮食作物占比在不断上升,经济作物占比在不断下降,地区之间呈现出专业化分工的趋势性特征。实证分析发现,这种结构性专业化分工趋势对中国农业总产值产生了显著影响,不仅促进中国农业总产值的提高,还提高了中国农业生产效率水平,表明亚当·斯密关于专业化分工的理论正在中国农业生产领域发挥作用,专业化分工带来的农业种植结构变化正在快速推动中国农业生产效率的提高。

唐代茶叶种植地域变化的探究--基于GIS制图技术的分析

从初唐至晚唐,唐代茶产业迅速发展,茶税、榷茶制度以及贡茶制度随之应运而生,茶叶种植地域亦逐渐扩大,范围涉及甚广。学术界对唐代茶区的研究成果较多,但多有缺漏,且基于唐代茶叶种植地域变化,探究其变化规律的研究尚属空白。本文基于前人学术成果,辨析更新并运用GIS制图技术以探究唐代茶叶种植区域的动态变化过程,认为唐代前后种植区域差异显著,晚唐产茶州较盛唐产茶州分布更为密集且范围更大,种植地域稳步扩张,基本覆盖现今四大茶区,唐代茶叶种植地域呈现聚集到分散、单一长江流域到全国各水系流域、纬度范围逐步扩大、初步形成到全面形成现今四大茶区的变化规律。

园林工程种植土的特性变化及其改良措施

中国进入新时代以来,随着园林景观工程建设的增多和园林景观施工技术的不断创新,绿化的质量得到了人们的重视,标准越来越严苛。种植土壤是园林绿化种植的基本条件,对幼苗的生长和成活率的影响是极其巨大的。在此基础上,文章全面分析了种植土壤在景观工程的变化特征,并进一步提出种植土壤景观工程的改进措施,希望为提高苗木的成活率给予有效参考,实现苗木的健康成长。

园林工程种植土的特性变化及其改良措施

近年来,园林工程建设数量不断增加、园林建设技术不断创新,使绿化质量标准更加严格。种植物是园林工程中绿化种植基础性条件,针对苗木生长和成活率有着不可取代的作用。基于此,本文综合性分析园林工程种植土的特性变化,进一步提出园林工程种植土改良措施,希望为有效增强园林苗木的成活率、实现苗木健康成长等目标提供有效参考。

京津地区近50年来水稻播种面积变化及其对降水变化的响应研究

基于滑动－ｔ突变检验结果，对京津两地近５０年来水稻种植面积的变化进行了阶段划分，并分别讨论了各阶段的变化特点。两地水稻种植面积的阶段性变化均受自然、技术和政策等多方面因素的综合影响。事件相关分析发现，作为人类对降水变化响应的水稻种植面积的变化较降水变化滞后一年，使得年雨量变化与当年水稻种植面积变化之间存在明显的负相关。

海南岛农业绿色发展指标时空变化特征

海南自建省以来农业生产规模、结构及生产方式均发生了很大改变,影响了其农业绿色发展程度。本文借助中国农业绿色发展指标体系,利用NUFER模型(NUtrientflowsinFoodchains,EnvironmentandResources use),选取并定量计算1988—2017年海南岛20项农业绿色发展指标,研究其时空变化特征,探究制约海南岛农业绿色发展的影响因素。研究表明:30年间海南省农业绿色发展水平总体呈下降趋势,较低级别(Ⅲ、Ⅳ级)指标数量由12个增加至15个,较高级别(Ⅰ、Ⅱ级)指标数量由8个减少至5个。随着蔬菜、水果等经济作物种植比例增加,畜禽养殖规模扩大与集约化程度提高,海南农业产值与社会发展水平不断升高,农业产值和农业机械化投入分别从0.62×104$·hm–2和3 kW·hm–2增加至16.1×104$·hm–2和13 kW·hm–2。30年来农业资源(氮素、磷素、农药和农膜)过量投入,其中农药和农膜的使用强度增幅最大,分别从8.0kg·hm–2和0kg·hm–2增加至41.9 kg·hm–2和34.7 kg·hm–2;由于生产力水平较低,导致养分(农田氮素盈余量、农田氮素径流量、农业源氨挥发等)环境排放量大幅增加,农业源氨挥发和单位播种面积农田氮素盈余增幅最大,分别从61.0 kg·hm–2和152.1 kg·hm–2增加至131.4 kg·hm–2和297.9 kg·hm–2。农业资源投入过量、农牧分离导致的环境污染是制约海南岛农业绿色发展的主要原因。在空间上,由于中部为山地林区,是国家重点生态功能保护区,开发力度较小,因此沿海平原的资源投入增长更快、养分环境损失量更多,经济增长、社会发展和农业生产3类指标提升更为迅速。今后海南岛应合理优化沿海地区种植结构,提高生产管理水平,加强农牧结合减少资源损失,实现海南岛农业绿色发展。

疏勒河流域双塔灌区种植结构变化及其原因

基于1996—2010年双塔灌区各乡(镇)农作物类型、种植面积、供水定额、用水定额、作物单产及价格等资料,探讨了气候变化背景下农业种植结构调整原因及其影响。结果表明:研究区2010年作物种植面积较1996年增长2.3倍,其中粮食作物种植面积减少,经济作物和其他作物种植面积增加,农作物总产值和单位产值均明显提高,说明当地种植结构调整优化在产生经济效益方面效果明显。当地种植结构调整主要受自然条件、政策指导、历史根源、农民意愿、市场调节、灌溉供水条件等多方面因素的影响,其中自然条件中的水资源供应状况主要影响作物种植面积,其他因素影响作物种植类型。通过种植结构调整,当地农业产值在增长同时,用水紧张现象较以前有所缓解,地表水基本可以满足农田灌溉需求,减少了对地下水的使用,从而对保护当地生态具有重要意义。

An Econometric Analysis on the Effect of Climate Change on Wheat Cropping Area in China

[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.

关于我国粮食安全与土地资源的研究

根据我国耕地资源态势、流失所引起的变化趋势与粮食生产两者之间的关系,土地资源分布及土地资源退化情况,对历年来影响粮食总产量的因素进行了系统分析研究,总结了加强保护耕地,提高耕地质量,确保粮食稳定增长,仍是我国的一项持久战略。

蒙山县种植结构变化对桑蚕业发展的影响及其建议

蒙山县桑蚕业发展历史悠久,自国家"东桑西移"政策出台之后,桑蚕业得到了极大的发展。但近年来随着蒙山县种植结构发生变化,本地桑蚕业发展受到了阻碍。本文简要阐述了蒙山县种植结构变化对桑蚕业发展的影响机制,为桑蚕业进一步发展提出可行性建议。

CT与增强CT在诊断腹部肿瘤腹腔转移中的临床意义

目的:探讨在腹部肿瘤腹腔转移患者的临床诊断中运用常规CT扫描与增强CT扫描的临床价值。方法:选取南通市通州区人民医院2018年1月—2020年12月收治的107例腹部肿瘤腹腔转移患者,所有患者均经穿刺活检或者手术病理诊断或随访确诊为腹部肿瘤腹腔转移,对患者先后进行常规CT扫描以及增强CT扫描,将两种检查方式的检查结果与病理检查结果进行对比,观察常规CT与增强CT扫描的检查符合率。结果:常规CT扫描与增强CT扫描在种植灶长度、最小种植灶面积与种植灶宽度方面均存在较大的差异,差异有统计学意义(P<0.05);增强CT扫描在诊断总符合率97.20%高于常规CT检查75.00%,差异有统计学意义(P<0.05)。结论:在腹部肿瘤腹腔转移患者的临床诊断中采用增强CT扫描准确率更高,可清晰地观察到患者病灶情况并为临床诊断与对症治疗提供可靠的参考依据。

SPECIES COMPOSITION, HORIZONTAL DISTRIBUTION AND SEASONAL SUCCESSION OF PHYTOPLANKTON IN THE CHANNEL FROM DONGTING LAKE TO THE CHANGJIANG RIVER, CHINA

The species composition, horizontal distribution and seasonal succession of the phytoplankton at five sampling stations in the channel between Dongting Lake and the Changjiang River, China were studied from May 1995 to December 1997. A total of 416 taxa were observed; diatoms comprised the most diverse taxonomic group representing 58.2 % of the total species. The β-mesotrophic indicators were 92 taxa or 22 % of the total, the α-mesotrophic or α,β-eutrophic indicators decreased distinctly to 20 taxa or 4.8 % of the total. The species number and composition of various phyla were approximately similar at Stations 1, 2, 3 and 4, but at Station 5 the number of species was the minimum and the ratio of diatoms to total phytoplankton in the number of species was the highest. In seasonal succession of the phytoplankton species, the number was the highest in May and June, lower in December, January, March and July in the channel. The dominant species were different in different months. The ratio of diatoms species number to blue green algae and green algae species number diminished gradually from winter to summer and autumn, and then increased gradually from autumn to winter and early spring in the annual cycle. Margalef, Simpson and Shannon-Weaver diversity indices changed in different months, their values were higher in winter, lower in summer. Nygaard’s diatoms quotients were lower in winter, then in spring and autumn, higher in summer. These results indicated that the water quality was the best in winter, better in spring and autumn than in summer. The relationship between the structure of the phytoplankton community and the water environmental quality was discussed.

Effect of the Chemical Mutagens Sodium Azide on Plant Regeneration of Two Tomato Cultivars under Salinity Stress Condition in vitro

The study was carried out to induce variations and stimulate callus induction, plant regeneration from different explants of two tomato （Lycopersicon esculentum Mill.） cultivars Trescantos and super Regina by using tissue culture technique and Sodium azide as a chemical mutagens at concentrations （0.0, 2.0 and 4.0） mM under salinity stress condition at the levels（3.0, 6.0 and 9.0） dS/m. Different plant growth regulators were tested for their potentials in callus induction. The results revealed that treated seeds with SA （sodium azide） at concentration （2.0） mM increased seed germination percentage, seedling height and root length as compare to control treatment. While （4.0） mM concentration cause a reduction in all parameters mentioned above. Concerning to callus induction both cultivars showed a different response against different tested media with varying concentrations of plant growth regulators and despite their variable response to all tested media a combination of （2.0） mg from Kinetin （KIN） and lndol acetic acid （IAA） was found to be the most effective as compare to other treatments. Moreover, when callus transferred to a stressed media the variation was observed in explants fresh weight, and high reduction with the increment of salt level were recorded. Similarly the regeneration efficiency from stressed callus were observed at the level 3.0 and 6.0 dS/m while 9.0 dS/m the callus failed to regenerate plants for all three explants of both tomato cultivars.

Greenhouse Farming as Adaptation to Climate Change in Nigeria

The effect of climate change in recent times has disrupted the onset and duration of seasons in Nigeria manifesting in the reduction of both staple and cash crops, and livestock yields. This has transformed the country to a major importer of those agricultural produce she hitherto exported. As a country where over 70% of the population depends on agriculture for survival, the impacts of climate change are a major threat to both food security and the general econoray. Remedial measures which have been suggested including adoption of agronomic and tested practices, reduced burning and afforestation. An option that could be of great potential in ameliorating this situation but which has not been practiced especially in the production of specialty crops is the use of greenhouse farming. This paper discusses the impact of climate change on Nigerian agriculture. The potentials and logistics are required for effective use of greenhouse farming as an adaptation to climate change in Nigeria. It is suggested that research should be carded out to select appropriate glazing materials. The provisions of training and credit facilities for interested farmers are recommended for effective utilization of the system.

“变或不变”:粮食最低收购价下调对稻作大户种植结构调整行为研究

粮食最低收购价是我国粮食宏观调控的重要政策工具,在当前"去库降本"和"提质增效"背景下,下调粮食最低收购价已成为粮食价格体系改革的主要着力点,但农户行为对政策的响应程度决定了其效能作用的空间。因此本文以湖南省为例,以稻作大户种植结构调整行为为切入点,通过61村188户稻作大户的微观调查,研究粮食最低收购价下调的政策影响。实证结果表明,稻谷最低收购价格降低时,稻作大户维持既有水稻种植面积的概率高于改种其他经济作物的概率,即选择"不变"。"不变"的原因是适度规模经营补贴政策能在一定程度上稳定稻作大户的种粮预期,有利于促使农户保持生产的稳定性。因此,这为政府在水稻品种实行的"价补分离"政策提供了经验证据。

Impacts of Climate Change on Growth Period and Planting Boundaries of Spring Wheat in China under RCP4.5 Scenario

This article contributes to research on how climate change will impact crops in China by moving from ex-post empirical analysis to forecasting. We construct a multiple regression model, using agricultural observations and meteorological simulations by GCMs, to simulate the possible planting boundaries and suitable planting re- gions of spring wheat under RCP4.5 scenario for the base period 2040s and 2070s. We find that the south bound- ary of possible planting region for spring wheat spreads along the belt： south Shandong-north Jiangsu-north Anhui-central Henan-north Hubei-southeast Sichuan-north Yunnan provinces, and will likely move northward under RCP4.5 scenario in 2040s and 2070s, resulting in the decrease of possible planting area in China. Moreover, the sowing and harvest date of spring wheat in the base period shows a gradually delayed phenomenon from the belt： south Xinjiang - Gansu, to the Tibet Plateau. As a result, the growth period of spring wheat in China will shorten because of the impacts of climate change. These results imply that a variety of adaptations measures should be set up in response to changing climatic conditions, including developing the planting base for spring wheat, restricting the planting area of spring wheat in sub-suitable areas at risk while expanding the planting area of optimal crops.

Effects of Soil Depth and Season Variation on Community Structure of Arbuscular Mycorrhizal Fungi in Greenhouse Soils Planted with Watermelon

The characteristics of arbuscular mycorrhizal fungal (AMF) community structure in various soil depths and growing seasons of watermelon (Citrullus vulgaris) grown in commercial greenhouses in Daxing of Beijing and Weifang and Laiyang of Shandong, China were investigated using both morphological identification and denaturing gradient gel electrophoresis. The sampled soils had been used for continuous greenhouse production of watermelon for 0, 5, 10, 15, or 20 years. Glomus claroideum was the dominant species in the greenhouse soils planted for 5, 10, and 15 years in Laiyang, while Glomus mosseae and Glomus etunicatum were dominant in the nearby open farmland soil. Sorenson's similarity index of AMF community composition ranged from 0.67 to 0.84 in the soils planted for 5 years, and from 0.29 to 0.33 for 20 years among the three locations. Spore abundance, species richness, and the Shannon index were highest near the soil surface (0-10 cm) and decreased with soil depth, and higher in June and October than in August and December. Canonical correspondence analysis showed that available P and the number of years that soil had been used for greenhouse production were the main factors contributing to the variance of AMF community composition. It was concluded that the community structure of AMF was mainly influenced by soil available P and planting time of watermelon as well as by soil depth and seasonal variation in the commercial greenhouse.

Elucidating Variations in Nitrogen Requirement According to Yield, Variety and Cropping System for Chinese Rice Production

Better understanding of the factors that influence crop nitrogen(N) requirement plays an important role in improving regional N recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-level measurements in different reaches of the Yangtze River, China to determine which factors contributed to variability in N requirement in rice. Yield, variety, and cropping system were significantly related to N requirement. The N requirement remained consistent at about 18.6 kg N Mg^(-1)grain as grain yield increased from 7 to 9 Mg ha^(-1), then decreased to 18.1, 16.9, and 15.9 kg N Mg^(-1)grain as yield increased to 9–10, 10–11, and > 11 Mg ha^(-1), respectively. The decreased requirement for N with increasing yield was attributable to declining N concentrations in grain and straw and increased harvest index. Super rice variety had lower N requirement(17.7 kg N Mg^(-1)grain) than ordinary inbred and hybrid varieties(18.5 and 18.3 kg N Mg^(-1)grain, respectively), which was a result of lower grain and straw N concentrations of super rice. The N requirements were 19.2, 17.8, and 17.5 kg N Mg^(-1)grain for early, middle, and late rice cropping systems, respectively. In conclusion, the rice N requirement was affected by multiple factors, including yield, variety, and cropping system, all of which should be considered when planning for optimal N management.