黑暗和光照处理对马铃薯块茎愈伤效果影响的比较

【目的】愈伤是马铃薯块茎受损后的典型反应,受外界环境因素影响较大。比较黑暗和光照处理对马铃薯块茎愈伤效果的影响,为马铃薯采后愈伤提供理论支持。【方法】本研究选取‘大西洋’马铃薯原原种为试材,人工切半后用酒精对伤口表面消毒,之后分别在黑暗和光照（11 000 lx）条件下进行（20±3）℃常温（（95±5）% RH）愈伤。通过测定愈伤期间损伤块茎的失重率及损伤接种Fusarium sulphureum 7 d后块茎的病情指数来评价愈伤效果,观察伤口处聚酚软木脂（SPP）、聚酯软木脂（SPA）和木质素的积累量以及伤口表面的色度变化,分析伤口处苯丙烷代谢关键酶活性和相关代谢产物含量的变化。此外,研究光照和黑暗对伤口处过氧化物酶（POD）和多酚氧化酶（PPO）活性,以及对过氧化氢（H₂O₂）含量积累的影响。【结果】愈伤期间,黑暗和光照处理的块茎失重率均逐渐升高。黑暗处理显著低于光照处理,愈伤第7天时,分别比光照处理低54.27％和58.96％。愈伤期间,黑暗和光照处理块茎伤口处的SPP和SPA积累量均逐渐增加,黑暗处理促进了软木脂和木质素在块茎伤口处的积累,愈伤第14天时,聚酚软木脂、聚酯软木脂和木质化细胞层厚度分别比光照处理高38.22%、36.76%和14.71%。愈伤期间,黑暗和光照处理块茎伤口表面的L^*值和b^*值均表现为先下降后上升的趋势。黑暗处理显著降低了伤口表面的L^*和a^*值,增加了b^*值,L^*和a^*值在愈伤第5天时分别低于光照处理13.51%、32.74%。b^*值在愈伤第5天时高于光照处理42.11%。愈伤期间,黑暗处理块茎伤口处的苯丙氨酸解氨酶（PAL）活性迅速上升,而光照处理的上升缓慢,两种处理块茎伤口处的肉桂酸-4-羟化酶（C4H）活性先上升后趋于平稳,两种处理块茎伤口处的4-香豆酰辅酶A连接酶（4CL）活性先迅速上升后持续下降。黑暗处理块茎伤口处的苯丙氨酸解氨酶、肉桂酸-4-羟化酶、4-香豆酸CoA连接酶的活性显著高于光照处理,愈伤第7天时,分别比光照处理高79.56%、10.71%和72.48%。黑暗和光照处理块茎伤口处的H₂O₂含量在愈伤第一周均迅速上升,之后趋于平稳。两种处理块茎伤口处的POD活性在愈伤期间均显著上升。黑暗处理块茎伤口处具有较高的过氧化物酶活性和H₂O₂含量,第5天时分别高于光照处理49.8%和49.85%。此外,黑暗处理还提高了伤口处组织的多酚氧化酶活性,在愈伤第3天时显著高于光照处理12.93%（P＜0.05）。【结论】黑暗对马铃薯块茎愈伤具有促进作用,而光照则对块茎愈伤具有一定程度的抑制。黑暗对愈伤的促进作用与激活块茎伤口处的苯丙烷代谢,加速伤口部位多酚氧化酶和过氧化物酶活性以促进软木脂和木质素的积累密切相关。     

外源酶辅助发酵加工藏茶的工艺研究

为解决藏茶加工过程中存在的渥堆时间长及微生物污染导致的安全隐患,探索藏茶加工新工艺,以绿毛茶为试验原料,添加从土豆中制备的外源酶,结合湿热转化加工藏茶,通过响应面分析研究最佳工艺参数,并与传统工艺制成的藏茶进行感官及滋味、色素与香气成分的对比分析。结果表明:以酶添加量80 U·g^-1、茶坯含水量60%、发酵温度34 ℃、发酵时间7 h进行酶促转化,而后在温度80 ℃条件下湿热转化60 h工艺制成的藏茶比传统工艺藏茶的滋味更醇和,汤色更红亮,香气更纯正,无酸馊和风霉味。该工艺制成藏茶比传统藏茶水浸出物增加11.72百分点、茶黄素增加0.05百分点、茶红素增加1.47百分点、茶褐素增加0.28百分点,并产生了较多的花果香型香气物质,其中,具有百合花香、玉兰花香、铃兰香和木香的β-芳樟醇增加1.69百分点,具有木香花香的α-雪松醇增加0.49百分点,具有果香的香叶基丙酮增加2.27百分点,极大地改善了茶叶的风味品质。     

贵州省某地区油菜机械化收获最佳作业条件分析

针对影响油菜机械化收获的油菜成熟度、收割高度、作业天气等因素,项目组通过实地测试,得出1.相同条件下,油菜机械化收获晴天作业平均含杂率及损失率均比阴天低;2.相同条件下,油菜成熟度为8-9成时,机械化收获损失率及含杂率最低;3.相同条件下,收割高度越高,含杂率越低,损失率越大;4.相同条件下,破荚率越高,损失率越小;5.在油菜成熟度为8-9成、收割高度40cm、晴天作业为最佳作业条件,油菜机械化收获破荚率主要范围是99.1%至100%,平均为99.57%,含杂率主要范围是15.31%至19.85%,平均为17.45%;损失率主要范围是0.9%至1.32%,平均为1.11%。     

红外加热对大豆生态系统CO_2排放的影响

通过田间试验,采用静态箱-气相色谱法测定CO2排放通量,研究红外加热增加叶面温度对土壤、大豆-土壤系统CO2排放的影响。结果表明,红外加热叶面增温2℃促进了土壤CO2的排放,在鼓粒-成熟期对照与增温的排放通量分别为202.09±28.75、378.34±156.17mg·m-2·h-1,增温处理使CO2排放通量增加了87.21%,但未达到显著水平;增温使土壤CO2累积排放量显著增加了39.96%。对照和增温的大豆-土壤系统呼吸的气温敏感性系数Q10值分别为0.68和2.54,土壤呼吸的土壤温度Q10值分别为4.22和1.68。研究表明,增温能促进土壤CO2排放,增加大豆-土壤系统呼吸的Q10值,降低土壤呼吸的Q10值。研究结果可为气候变化条件下估算区域农田温室气体排放提供一定的科学依据。     

BREAKING SEED DORMANCY IN THE WHITE SAXAUL TREE (HALOXYLON PERSICUM BOISS. ET BUHSE) AMARANTHACEAE

Seed dormancy is an obstacle to revegetation and reclamation efforts, particularly in arid and semiarid environments. Therefore, the objective of this study was to determine the most effective germination pretreatment for Haloxylon persicum, a tall desert shrub or small tree. The experiment employed a completely randomized block design. Dormancy breaking treatments included scarification with 98% sulfuric acid for 10, 20, 30, and 60 minutes; debracting seeds; debracting + piercing seeds; stratification for 1, 2, 3 and 4 weeks; and leaching seeds in flowing water for 1, 2, 3, and 4 days. Results demonstrated that scarification with 98% sulfuric acid for 10 min was the most effective treatment which increased germination from 23.3% (control) to >82.6%.     

Responses to nitrogen sources and regulatory properties of root phosphoenolpyruvate carboxylase

Time course of changes in extractable root phosphoenolpyruvate carboxylase (PEP C) activity was investigated in wheat, barley, and tomato plants fed with different nitrogen sources. Ammonium-fed plants exhibited a 2–2.5-fold higher PEPC activity than nitrate-fed plants at 7 d after the onset of nitrogen supply. Western blot analysis revealed that the amounts of PEPC subunit proteins increased gradually as reflected in the extractable PEPC activity. These results suggest that the increase in PEPC activity may be due to de novo protein synthesis. PEPC was SO-fold purified from tomato roots after several chromatographic steps. Metabolite effects on the partially purified enzyme were also investigated under optimal or suboptimal conditions in terms of pH and concentrations of phosphoenolpyruvate. Organic acids and acidic amino acids inhibited the enzyme activity, while hexose phosphates stimulated it. Glutamine and asparagine produced in the course of ammonium assimilation hardly affected the activity.     

黑茶对胎牛血清诱导脂肪变性的HepG2细胞的影响

利用含有50%的胎牛血清的培养液处理HepG2细胞48 h,建立非酒精性脂肪变性细胞模型,分别从噻唑兰染色吸光度法(MTT值)、甘油三酯(TG)、胆固醇(TC)3个方面评价茯砖提取物(FZ)、六堡茶提取物(LB)、青砖茶提取物(QZ)、千两茶提取物(QL)清除肝细胞脂肪堆积的作用。结果表明,与模型组相比,加药处理组细胞的脂质堆积有缓解趋势,茯砖茶、六堡茶、千两茶、青砖茶提取物都可显著降低细胞内TG累积(P<0.01);而茯砖、青砖茶提取物对TC的清除效果较好(P<0.01),千两茶与六堡茶效果不明显。以上结果表明,黑茶提取物通过降低细胞内的脂类堆积,可能起到缓解脂肪变性的作用。     

六个油茶优良无性系光响应曲线分析

对岑软2号、岑软3号、岑软24、桂8、赣无1、湘林11这6个油茶(Camellia oleifera)优良无性系光响应曲线进行了分析,了解各无性系的光响应曲线特征参数,所测数据通过二项式回归、直线回归拟舍得出光饱和点(LSP)、光补偿点(LCP)、最大净光合速率(Pmax)等光合特征参数,结果表明,6个油茶无性系LSP为1 165.07～1 373.63 μmol/(m2·s),LCP集中在7.33～50.91 μmol/(m2·s).岑软2号、岑软3号、岑软24和湘林11耐弱光能力较强;桂8 LSP高,LCP也高,较耐强光.岑软2号、岑软3号LSP高,LCP低,对光环境的适应范围较广.Pmax从大到小为岑软2号、岑软3号、岑软24、桂8、赣无1、湘林11,岑软2号、岑软3号具有较大的光合潜力.     

六堡茶、黑茶茶粉和普洱（熟茶）茶粉对Wistar大鼠调节血脂及抗氧化功能的比较研究

 比较六堡茶、黑茶茶粉和普洱（熟茶）茶粉对高脂血症Wistar大鼠的降血脂和抗氧化作用。将Wistar大鼠随机分为正常对照组、高脂模型组、药物组以及六堡茶、普洱（熟茶）茶粉和黑茶茶粉［低、中、高剂量组,即0.5,1.0,2.0g/kg(bw)］。试验大鼠灌胃授试茶样水浸提物30d后采血牺牲,取血分离血清测定血清中总胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白胆固醇（HDLC）等血脂指标,并摘取大鼠肝脏匀浆测定超氧化物歧化酶（SOD）活力、谷胱甘肽过氧化物酶(GSH Px)活力及丙二醛(MDA)含量。六堡茶能够显著降低试验大鼠血清中TC, TG含量（P＜0.05）,普洱（熟茶）茶粉、黑茶茶粉对于控制大鼠血清中TC, TG含量效果不明显（P＞0.05）;普洱（熟茶）茶粉能够显著提高肝组织细胞中GSH Px酶和SOD酶活力,且能够降低MDA含量（P＜0.05）。六堡茶调节血脂水平功效显著优于黑茶茶粉及普洱（熟茶）茶粉,而普洱（熟茶）茶粉抗氧化能力显著好于六堡茶及黑茶茶粉。     

Analysis on stress wave effect during the process ofrock breaking by pulsed jet

A mathematical model of rock breaking under pulsed jet is established by introducing the Johnson-Holmquist-Concrete constitutive relation and the smoothed particle hydrodynamics method. Based on this model, the formation, propagation and attenuation of stress wave during rock breaking by pulsed jet are simulated. The relations between pressure and time at different points on rock surface and the curve of peak stress wave versus distance to action spot are obtained. Destruction behaviors of rock under pulsed jet and effects on stress wave effect from jet velocity and lithology are studied according to the above calculation results, analysis results show that stress wave effect of pulsed jet acts locally and the peak stress wave shrinks sharply as the acting distance increases. The rock breaking mechanism of stress wave is tensile failure during the high speed process of load-unload. Power and effect range of stress wave is in high direct proportion with jet velocity. There is a threshold velocity before the macroscopic failure. Rocks of different lithologies have different destruction types under pulsed stress wave of pulsed jet. Destruction type of low strength rock like sandstone is crack propagation under the tensile stress during the high speed process of load-unload, while the destruction type of high strength brittle rocks like granite and limestone is vertical failure of stress concentration.