沙田柚疏花疏果技术的研究

报道了6个处理：A、花蕾直径3～5mm时疏花序；B、第一次生理落果结束后，在果实横径0．5～1．0cm时疏果；C、A＋B；D、第一次生理落果结束后，果实横径2～3cm时疏果；E、不疏蕾不疏花，第二次生理落果结束后、果实横径3～5cm时疏果；CK、不疏蕾和花、不疏果，只疏畸形果、病虫果，对沙田柚坐果率、产量和商品果率的影响。结果表明，除处理B比D、CK显著提高坐果率，处理D、E显著提高商品果率以外，其它各处理间及各处理与CK间的坐果率、株产量与商品果率无显著差异。因此沙田柚的疏果宜在第一次生理落果结束后、果实横径约0．5～1．0cm时进行。     

秸秆全量还田对冬小麦不同小穗位和粒位结实粒数和粒重的影响

 【目的】研究小麦玉米秸秆连续全量还田对小麦穗部不同小穗位和粒位结实粒数及粒重变化的影响。【方法】通过设置3年定位试验研究小麦玉米秸秆全量还田对小麦不同小穗位结实粒数、粒重的小穗位和粒位的影响效应。【结果】小麦玉米秸秆连续全量还田提高了小麦的公顷穗数、穗粒数、千粒重和产量。各处理小麦不同小穗位结实粒数、小穗重、小穗平均单粒重均呈现二次曲线变化趋势,不同粒位的粒重也随小穗位的变化呈二次曲线形式。结实小穗越多、各小穗结实粒数或单粒重差异越小,空间分布模拟曲线的弧度越平缓。秸秆还田提高了小麦主茎穗和分蘖穗的结实小穗数与小穗结实粒数,降低了不孕小穗数,且下部小穗的结实粒数增加幅度较大;秸秆还田还提高了小麦不同粒位的单粒重,以第3、4粒位提高幅度较大。【结论】小麦玉米秸秆连续全量还田提高了小麦不同小穗位的结实粒数和粒重,进而提高了籽粒产量。     

雄性不育和可育亚麻的生殖期形态学与细胞学比较

为了阐明显性雄性核不育亚麻不育株花粉败育的时期及细胞学特点,以雄性不育亚麻和雄性可育亚麻花蕾为材料,采用常规的石蜡切片方法,对花蕾和花粉发育过程进行了解剖学观察研究。结果表明：亚麻雄性不育株和雄性可育株在开花期其花药和花粉的形态学与细胞学差异非常明显。该研究将花药和花粉败育从四分体时期的绒毡层细胞与中层脱离开始划分为4个阶段：败育初期,绒毡层与中层分离;败育中期,小孢子发育停滞;败育后期,绒毡层与小孢子粘连后逐渐消失;败育终期花药干瘪,不能形成花粉。     

Annual-perennial plant relationships and species selection for desert restoration

Exotic plant invasion is a growing concern in the conservation and management of indigenous arid land ecosystems.By creating areas of ameliorated microclimates and fertile soil below their canopies,perennial plants might influence exotic annual plant invasions.We conducted a quantitative literature review of studies that compared exotic annual plant abundance among native perennial plant species and interspace(open areas)microsites in North America's Mojave Desert,where exotic plant invasion has corresponded with increasing extent of wildfire and broad-scale ecosystem transformation.Ten studies compared exotic annual plant abundance between interspaces and below a total of 36 native perennial species.These studies revealed that:(1)With few exceptions,most native perennial species supported a greater abundance of exotic annuals than interspaces,indicating overall facilitation of exotic species by native perennials.(2)Exotic species abundance varied by orders of magnitude among native perennial species,with some perennial species harboring amounts of exotics similar to interspaces.(3)Distributions of dominant exotic species varied,where Bromus rubens displayed a greater affinity for below-perennial microsites than did Schismus spp.and Erodium cicutarium that often were most abundant in interspaces.Results suggest that the degree of facilitation of exotic plants warrants consideration when selecting native perennial species for revegetation and restoration projects.     

Spatial heterogeneity of soil chemical properties between Haloxylon persicum and Haloxylon mmodendron populations

Spatial heterogeneity is a ubiquitous feature in natural ecosystems,especially in arid regions.Different species and their discontinuous distribution,accompanied by varied topographic characteristics,result in soil resources distributed differently in different locations,and present significant spatial heterogeneity in desert ecosystems.In this study,conventional and geostatistical methods were used to identify the heterogeneity of soil chemical properties in two desert populations,Haloxylon persicum Bunge ex Boss.,which dominates on the slopes and tops of sand dunes and Haloxylon ammodendron (C.A.Mey.) Bunge,which inhabits interdunes in the Gurbantunggut Desert of Xinjiang,China.The results showed that soil pH,electrical conductivity (EC),soil organic carbon (SOC),available nitrogen (AN) and available phosphorus (AP) were significantly higher in H.ammodendron populations than that in H.persicum.The coefficient of variation (CV) indicated that (1) most parameters presented a moderate degree of variability (10%＜CV＜100%) except pH in both plots,(2) the variability of soil pH,EC and AP in H.ammodendron populations was higher than that in H.persicum populations,and (3) SOC and AN in H.ammodendron populations were lower than that in H.persicurn populations.Geostatistical analysis revealed a strong spatial dependence (Co/(Co+C)＜25%) within the distance of ranges for all tested parameters in both plots.The Kriging-interpolated figures showed that the soil spatial distribution was correlated with the vegetation distribution,individual size of plants,and the topographic features,especially with the plants nearest to sampling points and the topographic features.In each plot,soil EC,SOC,AN and AP presented similar distributions,and fertile islands and salt islands occurred in both plots but did not affect every individual plant,since the sampling distance was larger than the size of such fertile islands.The results of topographic effects on soil heterogeneity suggested significant differences between the interdunes and dune-tops.Different topographic characteristics (physical factors) between plots result in the differences in SOC,AN and AP,while the heterogeneity of soil pH and EC arise from plant species and their distribution (biotic factor).Such biotic and physical factors did not occur in isolation,but worked together on soil heterogeneity,and played important parts in improving the soil properties.Hence these factors were ecologically valuable in the highly resource-stressed arid study area.     

耕地地力对化肥养分利用的影响机制及其调控研究进展

耕地地力影响了化肥养分的利用效率,是调控养分利用率的基础途径。本文概述了耕地土壤障碍对养分利用的制约机制、耕地地力培育对养分利用的促进机制、提高养分资源利用效率的耕地培肥模式3个方面的研究进展。针对我国主要的耕地土壤–作物系统,提高化肥养分利用率需要解决4个地力调控方面的关键问题:地力与养分利用率关系及其时空变化规律、土壤障碍制约养分高效蓄积转化机制与消减原理、地力培肥促进根系–土壤–微生物互作提高养分耦合利用机制及调控途径、肥沃耕层构建与生物功能提升对养分蓄纳供应的协同驱动增效机制与调控理论。本文提出基于多时空尺度综合研究,建立稳定提升土壤功能–加速养分循环利用的"双核驱动"地力综合管理理论,在不同区域构建并应用化肥减施增效的耕地地力综合管理模式,实现耕地大面积均衡减施化肥的目标。     

甘蓝型油菜生态型细胞质雄性不育两用系的研究Ⅲ. 8-8112AB的温度敏感性及其遗传

8-8112AB是由甘蓝型油菜pol细胞质生态型雄性不育两用系AB1与双低甘蓝型油菜品种杂交选育出的新型双低生态型pol CMS两用系,其在武昌秋播时表现雄性可育,在兰州或秭归高山夏播时表现雄性不育.在相对低温条件下,8-8112AB与正常油菜品系1141B(pol CMS保持系)的花器官形态特征表现相似,而在相对高温条件下,则与pol CMS不育系1141     

基于耕作指数评价东北风沙土肥沃耕层构建周期效果

评价不同肥沃耕层构建模式周期对东北风沙土耕层质量的影响,为该地区合理肥沃耕层构建模式选择提供科学依据,采用系统聚类方法建立了东北风沙土肥沃耕层评价指标的最小数据集(MDS),结合最小数据集的耕作指数(TI-MDS)定量评价了传统耕作、免耕、打破犁底层、传统耕作+有机肥和翻耕+秸秆还田5种不同肥沃耕层构建方式下的东北风沙土耕层构建一个循环周期后的质量,并采用Nash有效系数(E_f)和相对偏差系数(E_r)加以验证。结果表明：全量数据集耕作指数(TI-TDS)均值为0.47,最小数据集耕作指数(TI-MDS)均值为0.48,TI-TDS与TI-MDS相关系数R为0.958^**,二者呈显著正相关。TI-MDS与玉米产量呈显著正相关(R=0.895^**),Nash有效系数(E_f)为0.909,偏差系数(E_r)为0.017,可见TI-MDS合理性较高,可用于定量评价风沙土耕层土壤质量。由耕作评价指数可知,与传统耕作对照相比,传统耕作+有机肥模式的土壤质量提高了一个等级...     

北方泥质海岸盐碱地种植牧草肥土效果研究

采用工程措施为先导、生物措施为核心,在北方泥质海岸盐碱荒地上种植田菁、苜蓿两种牧草对土壤进行培肥效果研究。结果表明,种植田菁、苜蓿一个生长季结束后,土壤盐分和pH值下降;土壤有机质含量有所提高,氮、磷营养状况得到改善;与CK处理相比,两种牧草处理在10～50cm层次的肥土效果好于0～10cm层次;两种牧草相比较,田菁处理好于苜蓿处理。     

玉米秸秆还田对土壤肥力的影响

利用田间微区方法连续3年在沈阳地区草甸土研究玉米秸秆粉碎后直接还田对土壤基本理化性质的影响。结果表明,施用有机物料不仅能够改善土壤的理化性质、培肥地力,还能增加玉米产量,增产效果没有无机肥的增产效果显著。与单施无机肥相比,无机肥配施有机物料能够增加土壤有机质含量,降低土壤容重,提高土壤田间持水量和土壤孔隙度,同时改善土壤的氮、磷、钾养分状况。在等碳量的条件下,玉米秸秆对保持和提高土壤有机质含量的效果好于猪粪肥。