新疆棉花节水技术灌溉用水效率与影响因素分析

文中以新疆昌吉州呼图壁县军塘湖示范区143户棉农为研究对象,通过实地调研,用随机前沿生产函数模型测算示范区棉花的灌溉用水效率,用线性回归模型分析各因素对棉花灌溉用水效率的影响程度.结果显示:(1)小流量模式灌溉用水技术效率最高,自动化模式次之,低压小流量模式最低,但灌溉用水技术效率整体偏低,不足0.7,还有进一步提升的空间;(2)棉农的年龄、棉农是否为棉花种植典型户、棉农是否参加节水培训3个因素对棉花的灌溉用水技术效率有显著影响,且棉农是否为棉花种植典型户和棉农是否参加节水培训为正面影响;(3)节水技术的普遍推广和制定符合当地实际的农业灌溉水价有利于农业灌溉用水效率的提高.     

干旱区绿洲大田玉米生产效率研究——以张掖市种植户为例

以干旱区绿洲农业典型区张掖市甘州、临泽、高台三县区为例,在投入产出专项调查基础上增补调查内容,利用DEA-Tobit模型分析不同类型农户大田玉米生产效率和影响因素。结果表明:(1)三县区大田玉米综合技术效率存在21.9%的提升空间,其中纯技术效率提升空间大于规模效率,说明种植技术运用程度低是效率不高的主要原因。(2)小规模农户生产效率较高,大规模种植户可通过加大机械化生产、节水灌溉规模等措施,提高生产效率。(3)种植业收入、务工收入、温度与大田玉米生产效率呈显著正相关性;补贴收入、化肥农药用量、种植面积与大田玉米生产效率呈显著负相关性。     

碳排放视角下农户技术效率及影响因素研究——以新疆阿瓦提县为例

以新疆阿瓦提县216户农户调查数据为依据,运用DEA方法测度碳排放视角下的技术效率,并运用Tobit模型对农户技术效率的影响因素进行分析。结果表明:(1)碳排放约束存在改善农业技术效率的内在动力。相较于传统的技术效率而言,碳排放视角下的综合技术效率、纯技术效率和配置效率均有不同程度提高。(2)户主年龄、受教育程度、政府补贴效应、农户环境认知对技术效率具有积极影响,户主从事种植时间对技术效率有负面影响,农户家庭规模和家庭劳动力规模对效率影响不显著。     

渭干河-库车河三角洲绿洲棉花种植面积时空变化特征分析

利用研究区棉花种植面积和产量相关统计数据,探究研究区棉花种植面积和产量的时空变化特征及单产和面积作用对棉花产量的影响。研究结果表明：(1) 近62年来,研究区的棉花种植面积、棉花产量和单产均呈上升趋势,而且表现出明显的阶段性和波动性,1949—1985年间增长缓慢,1986—2011年增长迅速。(2) 就棉花总产波动来看, 单产的作用占42.04%,面积作用占50.96%,在1949—1985年间单产增加对棉花总产量提高的贡献较大,在1986—2011年间棉花种植面积扩大对棉花总产量提高的贡献较大。(3) 1985年前棉花种植面积较稳定,波动不大,主要靠挤占粮食作物面积来扩大,1986年之后棉花种植面积扩大迅速,主要途径为开荒造地。(4) 棉花市场价格的波动、生产成本的上升、产量的徘徊、生产环境的恶化和品种等直接影响着研究区棉花生产的竞争力和棉农增收。     

供给侧改革背景下新疆棉花生产布局空间变化及影响因素分析

棉花目标价格改革政策是新疆农业供给侧改革的重要实现方式,随着该政策的推进,棉花生产逐步由长江流域和黄河流域向新疆转移,同时,在新疆局部也呈现出棉花生产向优势区域集中的发展特征。由于棉花目标价格试点工作主要针对新疆,因此,文中使用空间计量模型对该政策执行后的新疆棉花生产布局空间变化及影响因素进行深入分析。结果显示:棉花的经济效益、非农就业机会是影响棉花生产布局的重要原因;棉花补贴政策、人均耕地面积、单位面积机械拥有量和农业劳动力数量对棉花生产规模有正向影响;县域间空间互动效应在棉花生产布局中发挥了显著作用。     

基于居民意愿调查的新疆棉花生产正外部性价值估计

新疆作为我国最主要产棉区,由于其正外部性未得到矫正,棉花生产的稳定发展受到极大影响。因此,文中以新疆棉花生产为例,运用条件价值法(CVM),通过对新疆棉花生产正外部性补贴的支付意愿调查,估算了棉花生产的生态环境、自然景观及社会保障等正外部性的价值。根据受访居民支付意愿研究表明,新疆棉花生产中未通过市场交易体现出来的外部性非市场价值高达724245.78×104元,每亩棉花294.76元。由于棉花生产的正外部性非市场价值十分巨大,现有较低的补贴水平无法起到鼓励棉花生产的作用;因此,建议以棉花生产外部性价值为依据提高棉花补贴标准,增加棉花补贴项目,从而增强其抗风险能力,保证我国棉花产业安全。     

黄土高原县域农业生产效率时空变化分析

运用DEA模型,以耕地面积、粮食播种面积、乡村从业人员数、农业机械总动力、农用化肥施用折纯量为投入指标,以农业生产总值、粮食产量、油料产量为产出指标,对1987—2014年黄土高原281个县(市)的农业生产效率及时空变化特征进行分析。结果表明:(1)综合效率平均值为0.694,处于中等水平,并且保持了一定的增长态势,但区域差异较大;其变异系数高值(V0.250)出现在黄土高原北部和东部的部分县(市)域;(2)黄土高原纯技术效率主要表现为3种基本类型,其中高效率县(市)数量有所增加,并有向北部扩大的趋势;综合效率受纯技术效率和规模效率二者共同影响,纯技术效率对综合效率的影响大于规模效率;(3)该区农业生产规模效率值大于0.9,平均水平较高,分布也较为均衡。在2005—2014年期间,黄土高原大部分县(市)处于规模报酬递增阶段,可以通过扩大农业生产规模来获得更高的生产效益。     

环境规制约束下新疆棉农生产环境保护意愿与行为的影响因素研究

在农业面源污染较为突出的背景下,环境规制是否对新疆棉农的生产环境保护行为起到了规范作用?环境规制在治理农业面源污染中效果是否显著?这些问题成为全社会关注的问题.在对新疆重点植棉县的棉花种植户问卷调查的基础上,通过将环境规制分析归类为命令控制型、宣传教育型、经济激励型三种类型,运用SPSS17.0软件进行Probit双变...     

新疆棉花产量构成要素分析

本文分析了近 5 0年新疆棉花的种植面积与单产的变化情况 ,以及对新疆棉花产量的相对影响率 ;简要讨论社会因素 (技术中肥料与电力 )和气候因素对棉花单产的影响。分析结果表明 ,近 5 0年来 ,新疆棉花总产中单产的平均作用 (占 45 % )略小于面积的平均作用 (占 5 0 % )。社会经济因素对棉花单产的平均作用为 30 % ,气候因素为 70 % ,但不同时期各因素的相对作用不同。技术进步对单产提高具有明显的促进作用。但 1991年以后 ,化肥和电力的增产作用有所降低 ,即化肥和电力的边际棉花产量逐渐减少。     

棉花早衰的原因分析与预防对策

近年来,由于抗虫杂交棉的推广种植,棉花早衰现象逐年加重,造成棉花减产10%~20%,严重的达30%以上,棉花品质也不同程度下降,影响了棉花价格,降低了棉农效益,严重挫伤了棉农的种棉积极性,成为制约棉花生产的一大障碍因素。因此,认真分析棉花早衰的原因,寻求科学的预防措施,具有十分重要的意义。     

Pesticides in cereal production

A cereal grower will normally attempt to maximise his returns from resources used without prejudicing the future. Historically, for the control of weeds, pests and diseases growers have preferred husbandry methods and the use of ‘resistant’ varieties. Economic pressures, technical developments and subsequent changes in farming systems demand more reliance on pesticides. The adoption of the Common Agricultural Policy and the relatively higher cereal prices improve the cost: benefit ratio from their more extensive use. Additionally, quality standards arising directly or indirectly from EEC legislation, where these can be influenced by pesticide application, will further encourage their routine application. In the longer term, increased fixed costs will encourage the grower to insure against crop losses by the use of prophylactic pesticide applications where appropriate. New systems of production to reduce fixed costs will be adopted, probably involving further use of pesticides. Growers will always wish to contain variable costs as far as is possible: as better forecasting of disease and pest epidemics is developed prophylactic treatments will be discarded. Examples of the economic benefits or penalties of adopting alternatives to pesticides are given.     

Paraquat-induced production of hydrocarbon gases

Paraquat dichloride (1,1′-dimethyI-4,4′-bipyridylium dichloride) induced the production of the hydrocarbon gases propane, ethane and ethylene in the xanthophycean microalga Bumilleriopsis filiformis. Formation of these gases was dependent on the light intensity and photosynthetic electron transport. Diquat dibromide (1,1′- ethylene-2,2′-bipyridylium dibromide), having a higher midpoint potential than paraquat dichloride, induced an even higher evolution of the gases. A total lack of oxygen inhibited the production of gas, while a low oxygen concentration (4–6% by volume) stimulated paraquat-induced gas formation. Culturing algae autotrophically, in a medium with a higher iron content, also increased the production of gases in the presence of the herbicide. Formation of these gases is an indication of the peroxidation of membrane lipids which, according to previous results, is correlated with a decrease of photosynthetic electron-transport activity.     

新疆棉花主产区土地流入对棉花生产的影响

科学测定土地流入对棉花生产的影响,识别棉花适度经营规模范围,对推进土地流转和确保棉花产业安全具有重要意义.文中基于新疆棉花主产区591份棉花种植户的微观数据,利用倾向值匹配法测算了土地流入对棉花生产的影响.结果表明:考虑样本农户自选择和内生性问题后,土地流入使籽棉亩产量平均提升29.20kg;在现有的技术水平下,棉花种...     

双生病毒——一类值得重视的植物病毒

 双生病毒是世界范围内广泛发生的一类植物单链DNA病毒,已在多种作物上引起严重危害。重组是导致双生病毒变异和病害流行的重要原因。近年来,在单组份双生病毒中发现有新型卫星DNA分子——DNAβ,DNAβ是病毒致病所必需的。本文就双生病毒的危害性、病毒的重组、DNAβ的发现及与致病性的关系、双生病毒与伴随的小分子DNA形成病害复合体、双生病毒DNA-A和小分子DNA的进化关系等问题进行了简要评述。     

Seed production by an arable weed community

After cultivation in early April of a sandy loam soil with 9500 apparently viable seeds/m² in 0–10 cm, 295 seedlings/m² emerged of which about half survived to maturity in July. Seeds were dispersed from mid-June to November and 136,460/m² were returned to the soil, representing a 14-fold increase in the seed bank. Application of soil-acting herbicides reduced the numbers of weeds and the total seed output, but that of tolerant species was increased. Maximum numbers of seeds were 59,980/m² for Chenopodium album, 39,430/m² for Sleltaria media and 37,580/m² for Veronica persica.     

Procedures and potentialities in sugar beet production

Cultivation procedures for the sugar beet crop continue to change considerably in England. The average contract per grower has increased from 3.4 in 1936 to 8.2 ha in 1973. Within the last decade the use of genetic monogerm seed has extended to 65% of the area sown, and pelleted seed to 90%. Seed spacing has doubled and the hand work needed to establish the crop drastically decreased. Much of the crop is now sown in March, instead of April or even May. The average yield of sugar has increased since 1936 from less than 3.6 to over 6 t ha^?1. These changes have been associated with routine usage of fungicide and insecticide on seed and chemical weed control on 90% of the crop in recent years; insecticide, mainly organophosphorus, has been used to control aphids and virus on 36 000 to 125 000 ha of crop annually on the basis of spray warnings; sporadic pesticide control has been used against an abundance of seedling, leaf- and root-eating pests and fungi. The changes in cultural practices have been paralleled by changes in the relative importance of the various pests and diseases—for instance, wide seed spacing and the use of herbicide have intensified seedling pest problems. The extent to which crop losses from weeds, pests and diseases have been assessed as a basis for recommendations for control is discussed, as well as the economics of control by pesticides.