塔里木盆地东南缘绿洲区土壤砷空间分布及农作物砷富集特征

以新疆塔里木盆地东南缘的巴音郭楞蒙古自治州的若羌县、且末县和和田地区的民丰县、于田县的绿洲区为研究区,采集表层土壤3487组、土壤剖面采样点35组,农产品及根系土壤采样点93组,综合采用数理统计方法、地统计学和GIS技术,研究土壤As的空间分布特征,探讨各类农产品对As富集的影响,比较空间自相关性显著区域和空间自相关性无显著区域内农产品和根系土壤中As的含量特征.结果表明土壤As含量较低,农用地和非农用地土壤As含量均值分别为9. 81mg·kg^-1和7. 94 mg·kg^-1.表层土壤As含量超过新疆土壤背景值的采样点个数为568个,占总取样点数的16. 3%;超过风险筛选值的采样点个数为5个.土壤As空间自相关的莫兰指数均大于0,空间聚集类型主要以高-高型和低-低型为主,其中高-高型聚集区主要位于各县农用地范围内.GIS空间分布显示,土壤As含量高值区呈片状集中或岛状零散分布.标准差椭圆显示,若羌县土壤As含量变化趋势方向为南北方向,且末县和民丰县土壤As含量变化趋势方向为西南-东北方向,于田县土壤As含量变化趋势方向为西北-东南方向.若...     

废弃物基水热炭改良对水稻产量及氮素吸收的影响

生物炭农田回用是实现农林废弃物资源化利用和碳封存的有效手段.近年来,水热碳化技术由于在炭产率、能耗及生产过程中的烟气排放等方面显著优于常规热解碳化技术而受到关注.为实现农林废弃物的资源化利用,明确水热炭农田应用对作物生产力的影响,本研究通过原状土柱模拟试验和表征分析,研究了4种不同类型改良水热炭对两种典型土壤的水稻产量和氮素吸收的影响及可能的驱动因素.结果表明,锯末水热炭和秸秆水热炭经物理或生物改良后,在两种类型土壤上均能够增加水稻产量和氮素吸收,减少氮素损失,且其效应不受水热炭添加量影响(5‰,15‰;质量分数).与对照相比,水热炭添加处理的产量和氮素吸收量分别提高9.2%～20.7%和7.7%～17.0%.高C/N比的锯末水热炭更有利于高肥力土壤水稻氮素吸收量的增加;而低肥力土壤由于限制性因子较多,受水热炭类型的影响较小.通过对水热炭的表征分析发现,其表面养分元素丰富;水洗或生物改良后其表面孔隙结构有较大改善,C元素相对含量明显降低,N和O元素相对含量明显增加,这对养分的固持/供应可能产生影响.因此,水热炭改良后孔隙结构的改变和N、O元素含量的增加可能是其施用后水稻产量和氮素吸收增...     

我国作物种质资源保存及其研究的进展

作物种质资源保存在我国已取得迅速发展。近１０年来，种质资源保存体系已初步形成，建成了长期种质库２座，中期种质库１０余座：国家种质库长期贮存上百种作物２４万余份种质，隶属２９科，１６４属，４７０多个种（亚种）；在９３个国家种质圃中，保存多年生和无性繁殖作物２万余份种质。在种质保存技术研究方面也取得重要进展。     

Accumulation of heavy metals in two crop seeds due to soil contamination as determined by neutron activation analysis techniques

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Breeding birds in short-rotation coppices on farmland in central Sweden—the importance of Salix height and adjacent habitats

Plantations of short-rotation coppice (SRC) have a potential for being a useful measure to stop the ongoing impoverishment of farmland biodiversity by increasing structural diversity, and decreasing cultivation intensity and use of pesticides in intensively managed farmland landscapes. The aim of this study was to investigate the relative importance of the structure of the plantation and composition of adjacent habitats for breeding birds in 41 SRCs (meansize±S.E.=9.4±1.6 ha). Mean number of species per ha in the SRCs was 2.8±0.3 species and there were more farmland birds (32 species, 808 territories) than forest birds (22 species, 400 territories). A major result of the present study was the strong influence of adjacent habitats on bird community composition (18 of 22 analysed species affected). There were large differences in bird communities between forest-bordered and open-bordered sites, but occurrence of residual habitats (i.e. other habitats than forest, pastures, shrub areas and arable fields) was also associated with occurrence of several species. The second factor of major importance for the bird fauna was the height of the plantations. Most species (14) were associated with tall plantations (>2 m), seven species were associated with plantations of intermediate (1–2 m) height, and six species were associated with plantations of low height (<1 m). A comparison of ecological traits between species classified as preferring SRC and species classified as avoiding SRC suggests that nest height was the only ecological character associated with a preference for Salix habitats, i.e. species with nests on the ground or in shrubs were more abundant in Salix habitats than in farmland landscapes in general. However, a broad spectrum of species was found in the SRCs and many of these seemed to be dependent on habitat features outside the plantations. Planting of Salix in intensively managed farmland plains will have positive effects on bird diversity by increasing the structural diversity of the landscape. In contrast, plantations on infields in forest-dominated landscapes will have negative effects, since the mosaic structure (i.e. mixture of open and forested habitats) positive for most farmland birds will disappear, and Salix plantations favour relatively few forest species. Additionally, Salix could be planted along sharp edges between coniferous plantations and open farmland in order to increase the complexity of the ecotone in intensively managed forest-farmland landscapes.     

湖南省几种主要菜园土铅的化学行为及其作物效应的初步研究

温度、ｐＨ、有机质及不同价态阳离子对铅吸持－解吸量有明显的影响．土壤中的铅在低浓度范围内（红茶园土为１００μｇ／ｇ，石灰性菜园土为５００μｇ／ｇ）对小白菜生长有刺激作用，超过一定浓度（红菜园土为≥５００μｇ／ｇ，石灰性莱园土为≥１００μｇ／ｇ）则有抑制作用．小白莱的含铅量随土壤铅浓度的增加而增加，两者呈极显著正相关．三种改良剂对铅污染土壤有明显的改良效果，其中以猪粪、石灰两种改良剂的效果为好，钙镁磷肥次之．     

温室气体排放与中国粮食生产

中国用占世界8％的土地养活了世界上1／5的人口，粮食生产已经基本满足了现有人口的需求。但是，生产粮食会向大气释放大最的温室气体。面对全球减少温室气体排放的压力，在粮食生产中，增加农田生态系统的碳固定能力及减少N2O和CH4的排放，直接关系着中国粮食生产的未来发展。文章分析全球和中国温室气体排放清单中粮食生产的作用和意义；利用生物地球化学模型DNDC和中国农业生产数据库，估算中国农田生态系统的土壤碳动态和N2O排放；通过情景分析(Scenario)，预测在不同方案下，中国农田生态系统碳动态和N2O的排放量；提出了我国未来粮食生产应该采取的对策和技术措施。     

农田生态系统中作物—昆虫—杂草的消长与农业环境

通过水旱作物轮换种植，探索与利用作物—昆虫（害虫和益虫）—杂草三大群落的消长与变迁规律，去发展生产，保持农田生态平衡，优化农业生态环境，最大限度地提高作物产量。     

有机无机肥料对土壤肥力和作物产量的影响研究初报

研究有机无机肥料对土壤肥力及作物产量的影响．５年的定位监测结果表明，施无机Ｎ、Ｐ、Ｋ结合冬蔬菜残茎叶还田，不但能增加作物产量和提高经济效益．而且还能培肥土壤．而无机肥料加猪粪或冬绿肥还田的增产效果及土壤培肥效果与全无机肥相近．稻秆还田是增加土壤有机质的一项比较明显的有效措前，这一结论得到了再次验证．施用有机肥料可以增加土壤有效态微量元素的含量．     

油菜根系分泌物对不同作物幼苗生长的化感效应

在实验室采用发芽试验的方法研究了油菜Brassicacampestris根系分泌物对小麦、油菜、蚕豆和玉米种子活力、幼苗生长发育及生理生化特性造成的化感效应。结果表明,油菜根系分泌物的化感累加作用对不同作物种子发芽率、幼苗芽长、芽质量、根长、根质量、根系活力以及幼芽过氧化物酶(POD)活性和丙二醛(MDA)含量均具有显著影响,其化感效应对小麦的影响程度最弱,其中对小麦的种子发芽率、幼苗根长、芽干物质量、POD活性和根系活力以及各作物幼芽细胞膜的毒害程度均表现出促进作用,而对小麦幼苗其它生长特性以及油菜、蚕豆和玉米幼苗的所有生长特性均表现为抑制作用,表明油菜根系分泌物对不同作物及不同生长特性的化感效应具有不同的选择性。因此,合理搭配油菜作物的间、套、轮作是其夺取优质、高产栽培的关键技术。