Genotype × environment interaction in carbon isotope discrimination and seed yield in cowpea (Vigna unguiculata L. Walp.)

Summary Twenty locally-adapted but genetically diverse cowpea genotypes were grown in 17 replicated trials in a range of sites and seasons in the drylands of eastern Kenya, and the discrimination against the heavy isotope of carbon (with a mass of 13) () was determined in grain and straw samples. Most genotypes gave similar, low grain yields in the environments which subjected the plants to drought stress, but high yielding and low yielding genotypes were clearly distinct in the less stressful environments. The converse pattern was found for : the genotypes were all very similar in the non-stressful (high-) environments, but in the stressful environments, low- (drought susceptible) and high- (drought avoiding) genotypes were clearly distinct. This pattern was clearest for straw , but was also apparent for grain . The early-maturing genotypes, which escaped terminal drought, were generally those with the most stable and highest , but in the case of straw there were statistically significant deviations from this relationship. It is concluded that provides a reliable measure of the specific response of cowpea genotypes to drought, which may be of value in breeding programs provided that carbon isotope discrimination can be measured reasonably economically.     

土壤微生物多样性研究方法综述

Soil microorganisms play a central role in decomposing organic matter, in determining the release of mineral nutrients, and in nutrient cycling. Recently, extensive studies have focused on soil microbial diversity. However, understanding the diversity of this complex microbial community in the soil environment is a challenging task. Thus, it is important to master and comprehend appropriate methods for studying soil microbial diversity. Concepts of soil microbial diversity and major methods of study are briefly introduced in this paper. Then, the application of biochemical-based and molecular-based techniques in this area, and their advantages and disadvantages are evaluated. Based on recent related research, perspectives for studying microbial diversity in soils are presented.     

新疆三工河流域土壤碳库的估算

以土壤生态系统为基本单元,在对土壤有机碳、无机碳及相关资料调查分析的基础上结合GIS技术,对三工河流域土壤碳库进行了估算。结果表明三工河流域总碳储量约为11. 18Pg,其中有机碳占48. 54%,约为5. 43Pg,无机碳约占到51. 46%,约为5. 75Pg。     

采用PLS-DA分析毛火方式对工夫红茶品质的影响

为探究不同毛火方式对工夫红茶品质的影响,明确新型电磁内热式滚筒-热风耦合干燥设备的毛火效果,该研究以一芽一二叶初展嫩度的"福鼎大白"品种为原料进行工夫红茶加工,设定电磁滚筒-热风耦合(Rotary pot-Hot air coupling First-Drying with electromagnetic heat,RHFD)、链板热风(Chain plate Hot air First-Drying,CHFD)、箱式热风(Box Hot air First-Drying,BHFD)、滚筒式滚炒(Rotary pot First-Drying,RFD)等4种毛火方式,比较所制茶样的茶多酚、儿茶素、茶色素、可溶性糖、咖啡碱、氨基酸等29个非挥发性指标,114个气相色谱-质谱技术(GasChromatography-Mass Spectrometry,GC-MS)检测的挥发性香气指标,10个外形和汤色色泽客观评价指标,同时进行了毛火方式的热效率、生产效率、生产成本等性能指标的分析比较,通过偏最小二乘判别统计(PartialLeastSquaresDiscriminationAnalysis,PLS-DA)分析毛火方式对优质工夫红茶品质的影响,并获得标志性差异化合物。结果表明:电磁内热式滚筒-热风耦合毛火处理下茶多酚和儿茶素总量显著最低(P<0.05),简单儿茶素含量较高,茶红素和可溶性糖含量、茶黄素综合指标TDE和茶色素综合指标10TFRB最高(P<0.05),毛火方式对茶黄素总量影响不显著(P>0.05);挥发性化合物总量以RHFD方式最高,RFD方式次之,CHFD方式最低;RHFD毛火方式芳香类、萜烯类等化合物含量最高。电磁内热式滚筒-热风耦合毛火升温快、温度分布均匀且稳定性好,热效率和生产效率高(分别为50.0%、220 kg/h),生产成本较低(仅0.32元/kg),预热时间仅14min;所制红茶在汤色透亮度、香气甜久度、滋味甜醇度等方面均得到提升,感官总分最高(P<0.05),达88.1。PLS-DA分析从挥发性和非挥发性角度均可将工夫红茶4种毛火方式显著区分,并分别获得了43种和18种差异化合物,结合差异性分析获得标志性差异化合物,2,4,6-三(1,1-二甲基乙基)-4-甲基环己-2,5-二烯-1-酮、香叶醇、3-辛酮、水杨酸甲酯、茶黄素、茶褐素、可溶性糖、表儿茶素等,可作为区分工夫红茶毛火方式,以及定向加工甜香、甜醇、高亮等优质工夫红茶的指标物质。该研究为红茶加工基础和品质提升提供技术参考和理论指导。     

黄土高原沟壑区人工植被类型对土壤水分和碳氮的影响

以黄土高原沟壑区人工建造的典型植被油松、侧柏、刺槐、沙棘、苹果为研究对象，研究分析了不同植被类型对土壤水分含量、土壤碳氮累积等的变化影响。研究表明，旱季刺槐林地表现出了强烈的耗水特征，200cm以下土壤含水量具明显减少趋势。200—300cm处水分含量仅为5．8％～7．1％，而油松林地200cm以下与荒草地含水量基本相一致，土壤水分含量保持在15％左右，侧柏、沙棘、苹果土壤水分利用主要在20-200cm范围内。雨季，天然降雨虽对林地水分含量有所补充，但只表现在0-50cm表层，且各个植被类型间表现不明显；与荒草相比，油松群落土壤有机碳氮提高了9．3％，果园土壤有机碳含量显著降低，而沙棘、侧柏和刺槐群落的土壤有机碳含量虽低于荒草群落，但尚未达到显著水平。     

野油菜黄单胞菌中6-磷酸海藻糖合成酶注释基因的功能鉴定

6-磷酸海藻糖在微生物碳代谢调节及抗逆生理中起着极其重要的作用。在野油菜黄单胞菌野油菜致病变种(Xanthomonas campestris pv.campestris,Xcc)8004菌株的基因组中,XC1076注释为6-磷酸海藻糖合成酶。利用突变和表型检测技术,对XC1076进行功能鉴定,结果显示,XC1076的Tn5gusA5插入突变体006B12,在含3%NaCl的NYGB培养基中生长明显缓慢,在含葡萄糖为惟一碳源的NCM培养基中几乎不能生长,反式互补能够基本恢复野生型表型,这说明XC1076与碳代谢调控和抗高渗有关。这些表型实验结果揭示,XC1076的ORF编码的蛋白具有6-磷酸海藻糖合成酶活性。致病生化因子检测显示,XC1076与Xcc胞外酶和胞外多糖的分泌无关。     

Comparative Effects of Organic and Inorganic Fertilizers on Soil Organic Carbon and Wheat Productivity under Arid Region

ABSTRACT

Organic amendments in the soil perform better than synthetic fertilizers in regards to soil fertility and sustainable crop productivity. Experiments were conducted to compare the effects of organic and synthetic fertilizers on soil fertility and wheat (Triticum aestivum L.) productivity. Soil fertility and protein contents of wheat grains (13.2% and 13.3% during 2005–06 and 2006–07, respectively) were improved by organic amendments. However, synthetic fertilizer (at the rate of 150, 100, and 60 kg ha^?1 N, P₂O₅, and K₂O, respectively) applications resulted in the maximum grain yield (4.05 and 4.46 t ha^?1 during 2005–06 and 2006–07, respectively). The observed and simulated soil organic carbon (SOC) reasonably agreed during RothC model validation (R ² = 0.99). Economic analysis showed the maximum net profit and relative increase in income ($729 US ha^?1 and 309%, respectively) from inorganic treatment. Application of synthetic fertilizers increased grain yield and farm profit while organic manure enhanced grain quality. The RothC model had potential for determining the SOC in organic farming under arid environment.     

The sensitivity of water extractable soil organic carbon fractions to land use in three soil types

Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are highly associated with SOC in the silt and clay fraction (<53 µm) and were slightly associated with SOC in the macroaggregate classes. The WEOC fractions were highly and positively correlated with the SOC and mean weight diameter.     

翻埋与覆盖林木枝条改善宁夏沙化土壤性质

土地沙漠化一直是影响宁夏生态建设和农业生产的主要问题之一。为探讨林木枝条对沙化土壤的改良效果,以当地农田防护林所产生的林木枝条为原料,在2011年10月至2013年10月期间研究了土壤翻埋杨树粉碎枝条(chips incorporation,CI)、覆盖杨树粉碎枝条(chips mulch,CM)、翻埋杨树粉碎枝条+覆盖未粉碎的柳树枝条(chips incorporation plus branches mulch,CI+BM)和不做任何处理的对照(control,CK)对宁夏沙化土壤理化性状和生物学特性的影响。结果表明,CI和CI+BM与CK相比,2012年和2013年均增加了土壤总孔隙度、田间持水率、有机碳、有效磷和速效钾含量(P0.05),提高了土壤呼吸强度、微生物数量(细菌、真菌和放线菌)和酶活性(脲酶、过氧化氢酶)(P0.05),降低了土壤密度(P0.05);2013年CI和CI+BM进一步增加了土壤全氮、全磷和水解氮含量(P0.05),但同时也增加了土壤全盐含量(P0.05)。CM与CK相比,2012年和2013年均显著增加了土壤有效磷和速效钾含量(P0.05),提高了土壤呼吸强度和酶活性(P0.05);2013年CM处理的土壤p H值、全氮和水解氮含量亦显著增加(P0.05)。相关分析结果显示,沙化土壤性质的改善与土壤中有机碳含量的增加密切相关,处理间土壤有机碳含量CI+BMCICMCK,表征土壤质量的综合指数表现出同样的趋势:2012年分别为0.907、0.678、0.259和0.105,2013年分别为0.926、0.828、0.258和0.136。该研究为当地及中国北方干旱半干旱地区沙地生态治理及农业生产提供了可借鉴的案例,同时也为促进林木废弃物的资源化利用提供理论基础。     

县域土地利用变化的碳排放效应——以山西省洪洞县为例

[目的]为了分析土地利用变化对碳排放的影响,以洪洞县为例,研究分析县域尺度上土地利用变化的碳排放效应。[方法]选取2000,2010和2013年山西省洪洞县遥感影像,通过解译遥感影像,最终获得洪洞县的土地利用数据。采用碳排放估算模型,估算了洪洞县13a不同土地利用变化导致的碳排放效应。[结果]2000—2013年洪洞县的碳排放量呈现逐年增长的趋势,期间净碳排放放量共增加了6.12×105t。作为主要碳源汇——建设用地和林地,二者的面积不断增长,但建设用地带来的碳排放远超过林地所能吸收的量。洪洞县各个乡镇在这13a中的净碳排放空间差异变化明显。[结论]优化县域土地利用结构,能够有效地减轻碳排放问题。