三峡库区花岗岩母质石英砂土不同经济林模式土壤养分特征研究

为了解三峡库区花岗岩母质不同经济林模式的土壤养分状况,研究了各模式下土壤pH、有机质、全量养分和速效养分的特征,并利用主成分分析法对不同模式的土壤质量进行了综合评价。结果表明,除土壤pH外,经济林土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾等含量的变异较宽,为中等变异。随土壤层次的增加,各模式下土壤有机质、全氮、速效氮、速效磷和速效钾含量呈递减趋势,而全磷和全钾则存在不规律变化。土壤有机质、全氮和速效钾对经济林土壤质量的高低产生着主要作用,土壤养分综合排名表现为柑橘（精细管理）>柑橘（常规管理）>板栗林>茶园。因此,利用生物措施和精细化管理措施,可有效提高该区域经济林的土壤质量。     

The mechanical roles of the clasping leaf sheath in cereals: Two case studies from oat and wheat plants

Stem lodging is a common problem in cereal crop production and a main constraint for grain yield improvement. The leaf sheath that surrounds and protects the hollow internodes of stem could provide the plants with a great physical support. However, this biomechanical function has been ignored for several decades in cereal crops. This study aimed to examine the biomechanical properties of basal stem internodes and lodging susceptibility of the whole plants with or without the clasping leaf sheath in wheat (Triticum aestivum L.) and oat (Avena sativa L.) among different genotypes and agronomic practices (including planting densities and nitrogen application rates). The main objective was to quantify the mechanical role of the leaf sheath in oat and wheat crops by a “safety factor” method. On average, the leaf sheath contributed 40%, 68% and 38% of the overall stem bending strength, flexural rigidity and safety factor, in oat, while it accounted for 11%, 24% and 10%, respectively, in wheat plants. The significant contribution of the leaf sheath is due to its vital role in enlarging the peripheral position (i.e., second moment of area) and stiffness (i.e., Young's modulus). The contribution ratios (%) were found to be higher in oat than in wheat plants, due to the greater mass density of leaf sheath and more proficient/prevailing stay-green capability in oat genotypes. This study emphasizes the important mechanical role of clasping leaf sheath on stem internodes of cereals and indicates that the stay-green trait of the leaf sheath can be exploited to design appropriate varieties with improved lodging resistance and great yield potential.     

免耕和稻草还田对稻田土壤肥力和水稻产量的影响

为了明确稻草还田和免耕等保护性耕作措施对土壤肥力和水稻产量的影响,自2008年于广西大学农学院科研基地进行长期定位试验,设置免耕（NT）、免耕+稻草覆盖还田（NT-SMR）、常规耕作+稻草覆盖还田（CT-SMR）、常规耕作（CT）和常规耕作+稻草翻压还田（CT-SR）5个处理,于2018年水稻成熟期测定产量,水稻收获后分层（0~5、5~10和10~20cm）测定土壤肥力。结果表明,稻田不同土层肥力指标均存在显著性差异,总体上表现为0~5、5~10和10~20cm土层的有机碳、全氮、碱解氮、有效磷和速效钾含量依次下降。NT-SMR处理显著提高了0~5cm土层的有机碳、全氮、碱解氮和有效磷含量,但降低了土壤速效钾含量。在5~10和10~20cm土层,稻草还田处理的有机碳、全氮、碱解氮、有效磷和速效钾含量均优于无稻草还田处理。水稻产量与土壤肥力呈显著正相关。2016年CT-SR处理水稻产量在早季分别比NT和CT处理显著提高了8.52%和7.99%,在晚季分别显著提高了12.12%和7.55%;2018年NT-SMR处理的水稻产量在早季分别比NT和CT处理显著提高了17.78%和10.30%,在晚季分别显著提高了13.88%和19.39%。因此,免耕和稻草还田能明显提高稻田耕作层土壤肥力,增加稻谷产量。     

不同保水处理下苏丹草光合特性研究

为了研究矿区生态修复过程中植物对不同保水措施的生理响应,以常用修复植物苏丹草为研究对象,利用CIRAS-2型(PP-Systems)光合仪测定苏丹草的光合指标,探讨高温下苏丹草对不同保水措施的生理响应,以期为矿区生态修复中的保水措施提供理论依据。结果表明：不同保水处理下苏丹草的光合速率Pn和瞬间水分利用效率WUE日变化均呈“W”型曲线,蒸腾速率Tr日变化呈“M”型曲线。苏丹草的Pn有“午休”现象存在,主要受非气孔因素的影响。影响苏丹草Pn、Tr的主要环境因子为大气CO₂浓度Ca、大气温度Tc、大气相对湿度RH。在土壤上覆盖火烧石和添加粉煤灰均显著增大了苏丹草的Pn和WUE,增强了苏丹草适应高温环境的能力。从Pn的指标来看,土壤表面覆盖火烧石处理比土壤中添加粉煤灰处理的效果好,但两者同时作用效果略低于单独用火烧石处理,原因有待进一步研究。     

沼气池热传递过程研究进展

温度是沼气工程高效运行的关键,沼气发酵不仅要维持适宜的温度,还须保证温度的稳定性。为此,对沼气池热传递过程的相关研究进行分析介绍,主要包括沼气池发酵液温度的影响因素、发酵系统热流损失、增温方式和热传递模型研究,并指出增温方式的选择应建立在正确的热过程分析基础上,建议进一步改进优化热传递模型,更好地指导沼气工程实施。     

阿勒泰羊生长速度与主要血液生化指标含量及尾脂Leptin基因表达关系

试验通过研究不同生长速度阿勒泰羊主要血液生化指标含量和尾脂中瘦素（Leptin）基因的表达水平，探讨阿勒泰羊生长速度与脂肪沉积之间的关系。选取300只出生时间相近的阿勒泰羊公羔，正常饲喂至6月龄，记录日增重，取平均日增重排前10%和后10%的公羔各30只，分为生长快速组（HBW）和生长慢速组（LBW），从生长快速组随机选12只分为抑制生长组（饲喂低能量饲粮以抑制其生长，HBW-75%，n=6）和生长快速对照组（饲喂标准饲粮，HBW-100%，n=6），生长慢速组随机选12只分为促进生长组（饲喂高能量饲粮以促进生长，LBW-125%，n=6）和生长慢速对照组（饲喂标准饲粮，LBW-100%，n=6）；预饲期7 d，正饲期30 d，试验结束后称重并采集血液，屠宰后采集尾部脂肪。检测血液TG、CK、TSH、T3、T4、S.S、GH、INS、PG、Leptin含量或活性及尾部脂肪Leptin mRNA和蛋白表达量，并观察尾部脂肪细胞形态学变化。结果显示，HBW-100%和LBW-100%组初体重与末体重均差异显著（P<0.05），HBW-75%和HBW-100%组初体重与末体重均无显著差异（P>0.05）；LBW-100%和LBW-125%组初体重差异显著（P<0.05），末体重无显著差异（P>0.05）。LBW-100%组的T4、S.S、Leptin、TSH、T3含量显著低于HBW-100%组（P<0.05）；LBW-125%组T3含量显著高于LBW-100%组（P<0.05）；HBW-75%组GH、PG和Leptin含量显著低于HBW-100%组（P<0.05）。LBW-125%组尾部脂肪细胞面积大于LBW-100%组，HBW-75%组小于HBW-100%组（P<0.05）。Leptin mRNA和蛋白表达量检测结果表明，HBW-100%组的Leptin mRNA表达量与LBW-100%组无显著差异（P>0.05），Leptin蛋白表达量极显著高于LBW-100%组（P<0.01）。LBW-125%组Leptin mRNA和蛋白的表达量均显著高于LBW-100%组（P<0.05）。HBW-75%组Leptin mRNA的表达量极显著低于HBW-100%组（P<0.01），Leptin蛋白表达量显著低于HBW-100%组（P<0.05）。综上所述，生长快速组与生长慢速组中，Leptin的表达量与体重和体脂有一定关联；在生长慢速组促进生长后体重和体脂显著增加，Leptin的表达量呈上升趋势；在生长快速组抑制生长后体重和体脂减少，Leptin的表达呈下降趋势。改变生长速度对Leptin的表达量会产生影响，从而改变机体的脂肪沉积状况。     

浅议农业科研单位固定资产如何计提折旧

文章针对农业科研单位固定资产折旧作了初步分析,从固定资产计提折旧的重要性、计提方法、会计核算及存在的问题等方面进行了一些探讨。     

Development and application of a molecular marker for TMV resistance based on <Emphasis Type="Italic">N</Emphasis> gene in tobacco (<Emphasis Type="Italic">Nicotiana tabacum</Emphasis>)

Tobacco mosaic virus (TMV) caused serious loss in yield and quality of tobacco every year. It is a long-term goal to improve the tobacco resistance against TMV by tobacco breeding. N gene was the firstly reported TMV-resistant gene, which showed resistance against all Tobamoviruses except the Ob stain and belonged to the toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat class of plant resistance (R) genes. At present, N gene had already been widely used in tobacco conventional breeding, but there is rare available molecular maker used in marker-assisted selection of TMV resistance. In this study, we designed a pair of primers that specific amplify N gene fragment based on the sequence of N gene intron III, named N-marker. Then, we identified TMV resistance by two selecting methods, PCR with N-marker and inoculated with the TMV-C strain. Results from the two method showed that (1) 13 varieties among 67 tobacco varieties displayed hypersensitive reaction when inoculated with the TMV-C strain, also contained N gene fragments screened by PCR with N-marker; (2) 105 strains of 200 BC1 strains showed resistance against TMV when inoculated with TMV-C strain, meanwhile, 103 of the 105 strains contained N gene fragment verified by PCR with N-marker. Therefore, the N-marker is reliable for high throughput screening of germplasm resources and tobacco breeding materials in selection of N-mediated TMV resistance. Our study not only developed a molecular marker for tobacco breeding, but also identified new germplasm resources that are resistant to TMV.     

氮肥减量条件下间作绿豆压青对甘蔗生长及氮代谢的影响

以甘蔗单作常规施氮量为对照（CK）,设氮化肥减量20%+间作绿豆压青（A）、氮化肥减量40%+间作绿豆压青（B）和氮化肥减量60%+间作绿豆压青（C）3个处理,通过测定甘蔗农艺性状、蔗茎产量和甘蔗叶片氮代谢相关生理生化指标,研究氮肥减量条件下间作绿豆压青对甘蔗生长及氮代谢的影响。结果表明,间作绿豆影响新植蔗分蘖,分蘖率显著低于CK,但对甘蔗有效茎数影响不显著。新植蔗产量表现为A>B>CK>C。氮化肥减量条件下间作绿豆压青对宿根蔗发株率、株高、有效茎数、甘蔗茎径有促进作用。宿根蔗蔗茎产量表现为A>B>C>CK。2年的甘蔗蔗糖分含量表现为C>B>A>CK。氮化肥减少20%条件下间作绿豆压青对提高甘蔗叶片谷氨酰胺合成酶、硝酸还原酶活性和游离氨基酸、可溶性糖含量有促进作用。综合甘蔗农艺性状、蔗茎产量、氮代谢相关指标测定结果和经济效益的表现,试验以氮化肥减量20%+间作绿豆压青的A处理最优。