淮河流域中游湿地景观格局指数变化分析

利用淮河流域中游20世纪50年代的地形图和1980、2000年的遥感影像图分别提取、解译得到各时期的土地利用图和基于湿地二级分类的各湿地类型分布图,运用景观指数分析方法对淮河流域中游湿地景观生态变化进行分析评价。分析结果表明：1950~1980年湿地景观格局指数变化大,1980~2000年湿地景观格局指数变化很小。这些湿地景观格局指数的变化总体上说明淮河流域中游湿地格局由多样化、复杂性转为单一化、破碎性,湿地系统组分急剧减少、过渡带大量消失,湿地景观的连通性、异质性大大减弱,湿地系统的完整性、均衡性不复存在,从而导致湿地生态服务功能下降或不能得到充分利用。     

Yield and tuber characteristics of 4x progeny from 2x×2x crosses

Summary Unrelated, unselected 2x haploid-species hybrids that produce 2n eggs, by second division restitution and 2n pollen due to first division restitution were intercrossed to generate 4x progeny. The 19, 4x families were compared with seven cultivars for tuber yield, tuber appearance and tuber set. The mean yield of the 4x families was 30% higher than the mean yield of the cultivars. The best five 4x families outyielded the best five cultivars by 57% and 69% at two locations. Cultivars were superior for tuber appearance and tuber set. The high yields of the 4x families are due to genetic diversity of the 2x parents and their ability to transmit that diversity to the 4x progeny utilizing 2n gametes. The potential of the 2x×2x breeding method is dependent on developing 2x hybrid clones that form 2n eggs and possess desirable tuber types; clones producing 2n pollen and good tuber quality are available.     

利用GGE双标图和综合选择指数划分棉花品种生态区

为提高农作物品种多性状选育和应用的可靠性,本研究基于品种选择指数,应用GGE双标图进行了棉花品种生态区划分。首先依据国家棉花品种审定标准构建通用性强的品种选择指数(SI),即SI=0.40×皮棉产量+0.13×纤维比强度+0.09×(纤维长度+马克隆值)+0.11×枯萎病+0.09×黄萎病+0.10×霜前花率。然后,采用GGE双标图方法对2000—2013年期间39组(含585个单点试验)长江流域国家棉花区域试验中品种选择指数的基因型与环境互作效应及环境间关系进行综合评价与分析。研究结果将长江流域棉区划分为四川盆地生态区、南襄盆地生态区、浙江省沿海生态区和长江中下游生态区。其中,长江中下游生态区为长江流域的主要品种生态区,对长江流域的总体环境代表性最强,涵盖了湖南省环洞庭湖棉区、湖北省江汉平原和鄂东南岗地棉区、江西省环鄱阳湖棉区、安徽省沿江棉区、江苏省宁镇丘陵及沿江和沿海棉区;四川盆地生态区、南襄盆地生态区和浙江省沿海生态区均为特殊生态环境条件下的品种生态区,对总体环境代表性较差。因此,将以长江流域棉区为广谱适应性育种目标环境的棉花品种综合性状选择试验优先安排在长江中下游生态区中,有利于提高育种的总体选择效果,而其余品种生态区不适宜作为以长江流域为目标环境的品种综合性状选择环境,可侧重于特殊适应性品种选育。本研究充分展示了GGE双标图在品种生态区划分方面的应用效果,合理划分了长江流域基于选择指数的棉花品种生态区,可为长江流域棉区的品种多性状选择和推荐策略提供决策依据,也为其他棉区和作物品种生态区划分提供参考。     

冬季东海外海鱼类群落特征及其对拉尼娜事件的响应

根据2004年12月和2008年12月东海区渔业资源底拖网调查资料,利用多元分析[非度量多变量排序(nMDS)、SIMPER],对比分析正常年份(2004年)和拉尼娜(La Ni(n)a)年份(2008年)不同生态属性鱼类的变化特征,探究鱼类群落结构对拉尼娜事件的响应模式.结果表明,2008年冬季与2004年冬季相比,调查水域的种类组成由45种增加至61种,其中,暖水性种类比例减少,暖温性种类比例增加.主要优势种年间变化不大,仍为带鱼(Trichiurus japonicus)和小黄鱼(Larimichthys polyactis),两者资源密度之和分别占总资源密度的59.95％和55.16％.不同生态属性种类的资源密度发生了显著变化,以带鱼(Trichiurus japonicus)为代表的暖水性鱼类资源密度下降,而以小黄鱼(Larimichthys polyactis)为代表的暖温性鱼类资源密度增加.研究水域生物丰富度指数(R)、多样性指数(H')和均匀度指数(J))的均值均有所升高,但独立样本t检验表明,年间3指数间无显著性差异(P＞0.05).在捕捞压力保持相对稳定的情况下,群落组成的变化可能与拉尼娜事件有关,未来需要掌握不同种类对拉尼娜事件的响应模式.     

黄土丘陵区纸坊沟流域农业生态安全预警分析

【目的】为黄土丘陵区生态安全预警及其建设提供科学依据。【方法】以纸坊沟流域近70年代表年份生态安全态势及影响因子的分析为基础,参考压力-状态-响应(PSR)模型建立农业生态安全预警指标体系。运用层次分析法(AHP)和德尔菲法(Delphi)确定指标权重,采用综合指数法计算生态安全质量值,用演化轴解释生态安全预警模式,定量评价该流域1938~2005年的农业生态安全状况,并预测2015年的发展趋势。【结果】纸坊沟流域1938年处于蓝灯区,无需预警;1958年为黑灯区,需作生态安全恶化速度预警;1975和1985年处于红灯区,需作生态安全较差状态预警;1995年处于黄灯区,2005和2015年继续向良好方向演化,均不需预警,但从发展趋势来看,预计人口密度于2020年左右进入警戒状态。【结论】研究结果与该流域的实际情况相符,该指标体系和生态安全预警模型可以应用于黄土丘陵区。     

Genome composition of triploid lily cultivars derived from sexual polyploidization of Longiflorum × Asiatic hybrids (<Emphasis Type="Italic">Lilium</Emphasis>)

About 19 cultivars, which had originated from backcrosses between F1 LA (Longiflorum × Asiatic) hybrids (2n = 2x = 24) as female parents and Asiatic cultivars as male parents (2n = 2x = 24), were analyzed with genomic in situ hybridization. 17 of them were triploid (2n = 3x = 36), and two aneuploid (2n = 3x + 1 = 37). The triploid cultivars had resulted from the functional 2n eggs produced by the female parents (F1 hybrids) because first division restitution (FDR) occurred in their meiosis during megasporogenesis. Similarly, the aneuploid cultivars had originated from viable 2n + 1 eggs. The extra chromosome in cultivar 041555 or 041572 resulted from one univalent or one half-bivalent which might have lagged behind when the sister chromatids of the other univalents and half-bivalents were segregating during the FDR process in their LA hybrid parents, respectively. That the majority of cultivars possessed recombinant chromosomes showed that intergenomic recombination might play an important role during the selection of the cultivars directly from BC1 progenies. That five cultivars of the 15 recombinant cultivars only had reciprocal recombinant chromosomes and 10 cultivars had non-reciprocal recombinant chromosomes indicates that the latter are more important. Because 9 of the 10 non-reciprocal recombinant cultivars possessed substitutions for recombinant segments, it also indicated that such substitutions could be an important source for the genetic variation in the sexual triploid BC1 progenies. In such cases there was a potential for the expression of the recessive genes of the backcross parent in a nulliplex (aaa) condition in the substituted segments. Genetic variation resulting from such nulliplex loci might have played a role in the selection of some of the cultivars.     

甲积峪小流域水沙监测工作做法与思考

甲积峪小流域是英国赠款中国小流域治理管理项目在中国实施水沙监测的惟一一条小流域,该文叙述了监测基础观测内容、观测工程建设以及培训、制度建设和开展监测过程中的要求,以及资料整编分析的内容,并从这些工作中提出了一些成功的经验及对今后发展提出了一些可借鉴的建议。     

珠防工程幼林综合持水能力研究

本文在对珠防工程监测样地调查、测定的基础上,从林冠层、枯落物层和土壤层3个水文层次对珠防二期工程幼林的综合持水能力进行了评价.3 a～4 a生珠防林幼林的综合持水量在2355.25～2457.08 t/hm2之间,比荒山高3.7%～8.2%.其中土壤贮水量、枯落物持水量、植冠层的持水量分别比荒山高3.65%～8.03%、21.4%～61.1%和42.9%-305.3%,而土壤贮水量、枯落物持水量增加不明显,植冠层持水量增加显著.植冠层和枯落物层的持水量比土壤持水量小得多,林分的贮水主体为林地土壤.珠防林幼林的综合持水能力因恢复措施以及林分类型不同而存在差异.人工造林幼林的综合持水能力比封山育林高;4 a生的针叶林的综合持水量最大,针阔混交林、竹林次之;3 a生的阔叶林的综合持水量最大,针阔混交林、针叶林次之.     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

Cycloate,an inhibitor of fatty acid elongase,modulates the metabolism of very‐long‐side‐chain alkylresorcinols in rye seedlings

BACKGROUND: Cycloate inhibits the biosynthesis of very‐long‐chain fatty acids, the essential constituents of plant waxes and suberin. Fatty acids also serve as precursors of aliphatic carbon chains in resorcinolic lipids, which play a fundamental role in the plant defence system against fungal pathogens. In this study, the effect of cycloate on the biosynthesis of 5‐n‐alkylresorcinols in rye seedlings (Secale cereale L.) grown under various light and thermal conditions was examined. RESULTS: The content of alkylresorcinols biosynthesised in rye was generally increased by the herbicide in both green and etiolated plants. The presence of cycloate also affected patterns of alkylresorcinol homologues in plants grown at 15 and 22 °C; very‐long‐side‐chain compounds were less abundant, whereas both short‐chain saturated and unsaturated homologues were generally accumulated. No cycloate‐related effects caused by homologue pattern modifications were observed at elevated temperature. CONCLUSION: This study extends present understanding of the mode of action of thiocarbamate herbicides. Cycloate markedly affected the biosynthesis of very‐long‐side‐chain resorcinolic lipids in rye seedlings, confirming the existence of parallels in both fatty acid and alkylresorcinol biosynthetic pathways. The observed cycloate‐driven accumulation of 5‐n‐alkylresorcinols may improve the resistance of cereals to infections caused by microbial pathogens. Copyright © 2009 Society of Chemical Industry