棉花调亏灌溉的生理基础研究

以盆栽棉花为材料,通过苗期和现蕾期不同程度的亏水处理(低、中、高三个水平),对调亏灌溉节水效应及生理机制进行了研究。结果表明:适时适度的水分亏缺可使植株旺盛的营养生长得以有效控制,株型和根冠比都更为理想。调亏期间,蒸腾速率和气孔导度都明显下降,而光合速率下降不明显,复水后光合速率和气孔导度明显恢复且接近或高于对照;此外,水分亏缺不仅影响棉桃的数量,而且影响单果重。表明适度的亏水处理可使水分利用效率明显提高,而经济产量接近或高于对照,同时节水20%以上。     

赤峰市松山区土地利用动态变化及其原因分析

以TM遥感资料为信息源 ,利用 3S技术手段 ,对内蒙古自治区赤峰市松山区 1987,1993,2 0 0 0年的土地利用变化进行了分析。结果表明 ,在不同年度内 ,其主要的土地利用类型为耕地、草地和林地。土地利用类型的总量变化也以这 3种土地利用类型和建设用地变化最大。而从年变化速率看 ,1987- 2 0 0 0年 ,以建设用地的增加和未利用土地类型的减少最为快速。从土地利用类型转化的方向看 ,以耕地、草地和林地相互之间的转化最为频繁。从土地利用类型的空间稳定性看 ,耕地的稳定性最高 ,其次为草地 ;而最不稳定的土地利用类型为未利用土地。利用相关分析所作的土地利用变化动因显示 ,该地区土地利用变化的驱动因素主要是社会与经济因素 ,其中以总人口、农业总产值、粮食作物产量总计、农牧民人均纯收入、化肥使用面积和化肥实物量等因子的作用最大 ,而自然因素对该地区土地利用变化的影响极小。     

我国北部农牧交错区城郊土地利用时空变化—以包头市为例

以包头市城郊区为例 ,在地理信息系统支持下 ,以乡镇 (苏木 )为研究单元 ,研究本地区土地利用时空动态变化过程 ,并分析其变化驱动因素。从微观角度分析了北方农牧交错区城郊区土地利用变化特征。农牧交错区是人类活动影响强烈之地带 ,土地利用变化与土地持续研究利用 ,对生态安全和地区持续发展具有十分重要的意义。     

检疫害虫稻水象甲的控制技术研究进展

稻水象甲(Lissorhoptrus。oryzophilus Kuschel)是一种毁灭性的水稻害虫，也是一种重要的检疫害虫。近年来在很多省市发生为害，且发生程度不断加重并呈扩大蔓延趋势。本文概述了近年来稻水象甲大发生危害的情况及原因，深入分析了其发生规律，提出了加强植物检疫、农业防治、化学防治、生物防治、物理防治等综合治理的措施。     

半自然条件下几种赤眼蜂及品系对亚洲玉米螟卵寄生能力比较

在半自然条件(田间网罩)下,将人工饲养的玉米螟卵按4、8、16块/株3个处理分别固定在网罩内的玉米植株中上部叶片上,然后每网罩分别引入供试赤眼蜂20头,24 h后更换玉米螟卵块,连续3 d。7 d后调查供寄生的玉米螟卵被寄生率及羽化率。结果表明:在半自然条件下广赤眼蜂伊朗1-1品系虽寄生能力高于其他供试品系,但到第2、3天明显降低;玉米螟赤眼蜂北京6-2-2品系每天均维持一个较平稳的寄生能力,产卵量在时间上的分配比较分散,并在第2、3天显示出比其他品系较高的寄生潜能。广赤眼蜂伊朗1-1品系的卵块寄生数量可随卵块密度的增加而增加,而其他品系则在各处理密度下,寄生数量基本没有变化;从卵粒寄生率看,广赤眼蜂伊朗1-1和吉林1-2两个品系的寄生数量随卵块密度的增加而大幅度提高,其他品系增加幅度较小。     

采收时间对蜡蚧轮枝菌分生孢子的萌发及致病力的影响

将蜡蚧轮枝菌Vp菌株在PDA培养基上23℃黑暗培养,分别于第5、15、20、25、30天后采收。将不同时间采收的分生孢子置于2％葡萄糖培养液内培养,16 h后检测其萌发率,结果表明,采收于第5天和第15天的分生孢子萌发率分别达到89.76％和94.98％,显著高于采收于第25天(30.27％)和第30天(6.12％)的孢子的萌发率;在PDA培养基培养5 d和15 d的分生孢子在相同浓度下对温室白粉虱的致病力分别达到83.40％和74.44％,显著高于培养了30 d的分生孢子的致病力(8.76％)。     

The value of vegetation cover for ecosystem services in the suburban context

Latin-American cities can be characterized by dynamic processes of urbanization that encroach upon the natural and semi-natural surrounding landscapes. Our study presents the effects of landscape development, transformed from semi-natural conditions into a mostly disperse suburban settlement. We explore the impact that this transformation has had on this context by three ecosystem services that regulate rainwater runoff, enhance microclimate conditions and help to improve air quality by monitoring vegetation cover. We have designed a spatio-temporal hierarchical analysis which employs remote sensing techniques to capture the structural changes of this landscape over long, medium and short term scales on two spatial levels. This methodological approach was tested in the Metropolitan Area of Santiago (MAS) as case study area. Despite of the increase in impervious surfaces due to urban processes, there has also been an increase in vegetation cover, which has led to an improvement in the provision of the above-mentioned ecosystem services. Hence, if diverse urbanization processes continue and they are coupled with an increase in vegetation cover, the provision of ecosystem services could also expand. This phenomenon can be observed in some areas, where public and private green spaces are created and maintained. Our data analyses give evidence that certain types of suburban areas which increase the share of vegetation cover can provide daily ecological benefits for urban neighborhoods, and beyond, for adjacent areas. Moreover, suburban development can successfully provide ecological benefits to citizens. Such processes can only be ecologically sustainable if the composition of vegetation is well-adapted to the regional climatic conditions.     

Response of confection sunflower (Helianthus annuus L.) grown in a semi‐arid environment to planting date and early termination of irrigation

Adjustments on planting date and on the time to terminate irrigation may reduce agricultural water use. However, such management practices in regions with extreme weather conditions have the potential to negatively affect yield. A 3‐year (2012–2014) study was conducted on a clay‐loam soil in a cool, semi‐arid environment to (i) determine the response of confection sunflower to planting date and irrigation termination timing and (ii) identify the relative importance of yield components in irrigated confection sunflower across planting dates. Early May planting had considerable negative effects on all studied variables, except on the percentage of large seeds. The highest yield of total and large seeds was obtained from the late May plantings, averaging 3,777 and 3,379 kg/ha, respectively. None of the irrigation strategies affected the measured variables. However, the interaction between planting date and termination of irrigation significantly affected the 1,000‐seed weight. Our study revealed the last week of May as suitable planting period for confection sunflower in the semi‐arid north‐western region of Wyoming, USA, and that irrigation on heavy soils may be terminated as early as at R5.5 stage without a significant yield reduction. The path‐coefficient analysis indicated head diameter and the number of seeds per head as important traits that significantly influence the yield of confection sunflower across planting dates.     

种植密度对滴灌马铃薯生长、产量的影响

为了了解耕培土滴灌条件下种植密度对马铃薯生长、产量以及水分利用效率的影响.试验共设密度分别为7.28×10⁴ 株/hm²(RS25),6.67×10⁴ 株/hm²(RS35),5.55×10⁴ 株/hm²(CK)3个处理.结果表明:随着种植密度的增加,株高、茎粗、干物质积累量以及商品薯率均有降低的趋势;产量、水分利用效率随种植密度的增加表现出先增大后减少,其中RS35处理产量和水分利用效率均表现最高,分别达到47 325 kg/hm²和12.05 kg/m³;在马铃薯品质方面,种植密度对马铃薯粗蛋白含量的影响不具有统计学意义;淀粉和维生素C随着密度的大幅增加而降低,其中RS25处理的淀粉较CK降低了5.57%,RS25处理的维生素C较CK降低了7.96%,同时RS35与CK处理不具有统计学意义.综上所述,种植密度为6.67×10⁴ 株/hm²的RS35处理马铃薯高产优质,且水分利用效率最高,为黑龙江地区滴灌马铃薯较为适宜的种植密度.     

应用~(15)N示踪探究楸树无性系对氮素的吸收和分配

为探讨楸树无性系对氮素的吸收、分配及利用特性,以2年生楸树无性系015-1、1-3、7080、1-4和004-1组培苗为试验材料,应用15N示踪技术对楸树无性系进行施肥试验。结果表明,5个楸树无性系氮肥的吸收率、利用率及分配率具有较强的一致性,氮肥利用率介于27.14%~31.24%之间。楸树无性系根和叶的肥料氮比例(Ndff)明显大于茎,楸树无性系根和叶对氮肥的竞争力较强,茎对氮肥的竞争力最弱。015-1茎部氮素分配率及无性系7080根部氮素分配率明显高于其他4个无性系;氮素分配率在各个器官中差异显著,叶片氮素的分配率最高,总体趋势为叶根茎。本研究结果为楸树氮肥的合理施用提供了理论依据。