Soil carbon storage and stratification under different tillage/residue-management practices in double rice cropping system

The importance of soil organic carbon(SOC) sequestration in agricultural soils as climate-change-mitigating strategy has become an area of focus by the scientific community in relation to soil management.This study was conducted to determine the temporal effect of different tillage systems and residue management on distribution, storage and stratification of SOC, and the yield of rice under double rice(Oryza sativa L.) cropping system in the southern China.A tillage experiment was conducted in the southern China during 2005–2011, including plow tillage with residue removed(PT0), plow tillage with residue retention(PT), rotary tillage with residue retention(RT), and no-till with residue retention on the surface(NT).The soil samples were obtained at the harvesting of late rice in October of 2005, 2007 and 2011.Multiple-year residue return application significantly increased rice yields for the two rice-cropping systems; yields of early and late rice were higher under RT than those under other tillage systems in both years in 2011.Compared with PT0, SOC stocks were increased in soil under NT at 0–5, 5–10, 10–20, and 20–30 cm depths by 33.8, 4.1, 6.6, and 53.3%, respectively, in 2011.SOC stocks under RT were higher than these under other tillage treatments at 0–30 cm depth.SOC stocks in soil under PT were higher than those under PT0 in the 0–5 and 20–30 cm soil layers.Therefore, crop residues played an important role in SOC management, and improvement of soil quality.In the 0–20 cm layer, the stratification ratio(SR) of SOC followed the order NTRTPTPT0; when the 0–30 cm layer was considered, NT also had the highest SR of SOC, but the SR of SOC under PT was higher than that under RT with a multiple-year tillage practice.Therefore, the notion that conservation tillage lead to higher SOC stocks and soil quality than plowed systems requires cautious scrutiny.Nevertheless, some benefits associated with RT system present a greater potential for its adoption in view of the multiple-year environmental sustainability under double rice cropping system in the southern China.     

Discrimination of geographical origin of rice (Oryza sativa L.) by multielement analysis using inductively coupled plasma atomic emission spectroscopy and multivariate analysis

This study aims to determine the authenticity of the geographical origin of rice using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and chemometrics. The profiles of 25 elements in brown rice measured by ICP-AES were subjected to data-mining processes, including principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). PLS-DA clearly discriminated the geographical origin of rice samples grown in three countries. Eleven elements (Cu, Ag, Zn, Cr, Ca, Ba, Cd, Bi, K, Pb, and In) significantly contributed to the ability to discriminate the geographical origin of the rice. These results demonstrate the use of multielement profiling combined with chemometrics as a tool for discriminating food origins. This study extends our knowledge about the applications of both multielement profiling and chemometrics for the determination of food authenticity, and thus can be useful for controlling the geographical origin of rice by governmental administration and protecting consumers from improper domestic labeling.     

无芒雀麦-污泥系统中泥/土不同比例对PAHs修复效果的影响

城市污水处理厂污泥中含有较高浓度的有毒有害物质多环芳烃(PAHs),且污泥产量大,如果不经过处理直接农业利用或堆放会导致土壤和作物的污染。本研究利用污泥和土壤不同配比组合(W0%,泥土比0∶1;W25%,泥土比1∶3;W50%,泥土比1∶1;W75%,泥土比3∶1;W100%,泥土比1∶0)的盆栽试验,探讨无芒雀麦-污泥系统对污泥多环芳烃的修复效果。研究结果表明,随污泥含量增加对无芒雀麦株高的影响差异不明显,而生物量却呈现出明显的上升趋势。无芒雀麦对污泥的耐受性表现良好;无芒雀麦对泥/土组合14种PAHs的吸收总量以W100%处理最高,且对3环、4环多环芳烃的吸收量比其他环数优势明显;在不同泥/土组合处理下,无芒雀麦-污泥系统对泥/土14种PAHs总量的去除率在W50%、W75%、W100%处理间没有明显差异,以W75%组合去除率为最高,达85.4%。且含有污泥的所有组合对高环芳烃Pyr、Chry、BaA、BbF、BkF、BaP、InP单体的去除优势表现非常突出,均达到80%或90%以上。综合考虑无芒雀麦的生长状况、吸收量及去除率认为,将耐抗性和去除率高的无芒雀麦作为优选植物资源直接用于城市污泥PAHs的修复是可行的,且以泥土比3∶1为最佳修复组合。     

干旱胁迫下偏关苜蓿显微结构响应特征研究

以山西地方优良种质--偏关苜蓿(Medicago sativa‘Pianguan’)为材料,采用20% PEG模拟干旱胁迫0, 24, 48, 72 h后,观测根、茎、叶各器官显微结构特征参数。利用单位干旱时间内各显微结构参数相对响应关系及干旱时间与干旱指标实测值关系,获取能够在显微结构尺度上定量评价植物体各组织对干旱胁迫响应关系的干旱指数:干旱响应率(RR)和干旱响应度(RD),旨在为干旱胁迫与细胞响应的其他相关研究提供方法学参考。结果表明:叶片海绵组织厚度和栅栏组织厚度、茎韧皮部厚度和筛管直径及髓腔直径、根直径和表皮厚度分别对干旱胁迫有相对较高的响应特征,其中叶片海绵组织厚度、栅栏组织厚度和茎髓腔直径的响应特征最高。综合响应率和响应度分析得出各器官对PEG的耐受性依次为根> 茎> 叶。     

人工增温条件下不同氮素形态比对重齿风毛菊气体交换及其群落生物量的影响

在青藏高原三江源区草地上,以开顶式温棚模拟增温,在其内部施用不同形态氮素(硝态氮和氨态氮)比例的氮肥,对重齿风毛菊(Saussurea katochaete)的光合速率、叶绿素荧光及其群落总生物量进行研究,旨在为人工管理草场施肥提供指导。结果表明:重齿风毛菊的光合速率随硝态氮比例增加而下降,气孔导度则增加。其他气体交换参数没有规律性变化。光系统II(PSII)光化学量子产量(Φ_PSII)在硝态氮比例为0%时最大,非光化学瘁灭(NPQ)则随硝态氮比例增大而增大。重齿风毛菊所在群落的总生物量在硝态氮和氨态氮比例平衡时达到最大。结果表明不同比例氮素施肥会对青藏高原草甸植物的净光合速率和群落总生物量产生影响。     

宝天曼自然保护区森林土壤碳氮储量分布格局分析

森林土壤碳氮储量是森林生态系统物质循环的基础,关系着全球的气候变化。为了认识宝天曼森林土壤碳氮储量的分布格局,以内乡宝天曼自然保护区森林土壤为研究对象,采用土壤剖面调查方法,分析比较了内乡宝天曼土壤碳氮储量和碳氮比与海拔、林龄和土壤类型的关系。结果表明:该区域森林土壤碳储量为14.24～137.97 t/hm²,平均值为82.05 t/hm²,土壤氮储量在0.75～6.89 t/hm²范围,平均值为3.98 t/hm²;土壤碳氮储量与海拔和林龄符合正相关的线性关系,随着海拔的升高和林龄的增大而升高,变化趋势明显,碳氮比保持在20左右;土壤碳氮储量在不同林型间的差异很大;不同土壤类型之间,山地棕壤的碳氮储量极显著高于山地黄棕壤和山地褐土（p<0.01）。该研究揭示了宝天曼自然保护区森林土壤碳氮储量的空间分布规律,对于宝天曼自然保护区森林应对气候变化、森林植被恢复及森林生态系统的管理和保护具有重要的指导意义。     

Leucocyte profile and growth rates as indicators of crowding stress in pejerrey fingerlings (Odontesthes bonariensis)

Crowding is one of the most common stressors found in intensive aquaculture, compromising growth rates and immune function. Plasmatic cortisol is a classic stress biomarker for fish, but its quantification is expensive and demands blood volumes that small individuals do not provide, constraining the usage of this technique to assess stress in fingerlings. The leucocyte profile is an alternative methodology to quantify stress with reduced costs and volumes of blood. Stress conditions promote neutrophilia and lymphocytopenia as response to elevated glucocorticoids levels. Considering the difficulties to assess stress imposed by intensive fish farming using measurement of glucocorticoid hormones, this study aimed to evaluate the stress‐induced changes in leucocyte profiles and growth rates imposed by crowding in fingerlings of Odontesthes bonariensis, a promising South‐American candidate for freshwater aquaculture. To meet these objectives, fingerlings (initial weight 0.05 ± 0.06 g and length 1.68 ± 0.13 cm) were reared for 45 days under three rearing densities (1, 5 and 10 fingerlings L^?1). At the end of this period, fish were anaesthetized and euthanized to obtain the leucocyte profile, neutrophil:lymphocyte ratio (N:L) and growth rate. Increasing density promoted: significant reduction in growth (final length, weight and specific growth rate); neutrophilia and lymphocytopenia; and increased N:L ratio. Concluding, the tested rearing densities imposed distinct levels of stress characterized by different N:L ratio, demonstrating that the leucocyte profile is a reliable alternative to measure stress levels in O. bonariensis fingerlings and probably in other fish species.     

不同铵硝配比对芥蓝品质影响的综合评价

在水培条件下设置等氮量的4个铵硝营养配比处理（CK,0 ∶ 100;T1,10 ∶ 90;T2,25 ∶ 75;T3,50 ∶ 50）,研究其对芥蓝生长和品质的影响。利用模糊数学原理,采用层次分析法确定权重,对芥蓝品质进行综合评价。结果表明：与CK相比,T1处理促进了芥蓝的生长,但对食用品质无显著影响;T2处理芥蓝产量最高,但对食用品质的改善作用较小;T3处理芥蓝食用品质评价值最高,但植株生长受到抑制。芥蓝的综合品质以中量增铵的T2处理最优。基于层次分析法的模糊综合评判对芥蓝品质的综合评价有较好的适用性。     

低盐胁迫对细角螺幼螺呼吸排泄的影响

为了评估细角螺苗种对低盐胁迫的耐受能力,将细角螺(Hemifusus ternatanus)幼螺养殖盐度自27逐渐降低至22、18和14,测定处理后不同时间细角螺幼螺的耗氧率和排氨率。结果显示,盐度27降至22后幼螺耗氧率先显著降低,在第二天升至对照组水平,此后略有波动但均与盐度27无显著差异;盐度降至18与对照组无显著性差异;盐度降至14,细角螺的耗氧率先有显著升高,后与对照组相比无显著差异。盐度从27降至22后,幼螺的排氨率在第一、第二天显著升高,其后逐渐降低,盐度自22降至18和14,排氨率呈先降低后升高的趋势。盐度22处理后幼螺的氧氮比先降低后升高,盐度18和14处理组先升高后逐渐降低,说明低盐胁迫影响细角螺幼螺能量物质分解代谢的比率,胁迫条件下幼螺以脂肪和碳水化合物为主要供能物质。实验结果表明,第一次低盐处理对幼螺呼吸排泄的影响较大,此后再逐渐降低盐度,幼螺具有一定的适应能力。本实验结果可为细角螺养殖和放流前盐度驯化提供参考。     

大菱鲆选育家系抗鳗弧菌性能

基于家系选育技术开展了大菱鲆(Scophthalmus maximus)抗鳗弧菌病选育研究, 从2010年构建的37个选育二代家系中选择成活率高的30个家系进行鳗弧菌(Vibrio anguillarum)感染实验, 开展对鳗弧菌的抗病性研究。结果表明, 不同家系间抗鳗弧菌感染能力存在着显著差异(P＜0.05); 30个家系中, 鳗弧菌感染后, 12个家系的存活率达到65% 以上, 其余家系的存活率则低于65%; 通过bCOX回归分析, 计算各家系的优势比, 优势比最高的5个家系的存活率达到65% 以上; 对各家系的成活率、优势比和死亡历时差4项指标进行聚类分析, 优势比最高且存活率达到65% 以上的5个家系聚为一类。综合感染家系的高成活率、高优势比以及聚类分析的结果, 选育出5个抗病力较强的优良家系。选育出的抗病力较强的家系可做为抗鳗弧菌选育的核心育种群体, 为抗鳗弧菌病的传代选育奠定良好的基础。