采用反相高效液相色谱法同时测定杨梅果实中的有机酸

采用反相高效液相色谱法(RP-HPLC)研究了杨梅果实中有机酸的成分和含量,在C18柱(4.6mmID×250mm,4μm)上,采用紫外检测器(波长214 nm)进行检测,其流动相为0.04 mol/L的KH2PO4-H3PO4缓冲液,pH2.4,流速0.8mL/min,柱温35℃。检测所得7种有机酸标准曲线相关系数达0.999 0以上,平均回收率在88%～101%之间;变异系数RSD<3.06%。     

杨梅铜锌超氧化物歧化酶基因（MrCu／Zn-SOD1）的原核表达及活性鉴定

为获得高表达杨梅（Morellarubra）铜锌超氧化物歧化酶（MrCu／Zn-SOD1）的工程菌,本实验采用RT-PCR技术从杨梅果实中分离扩增了MrCu／Zn．SOD1的cDNA序列（456bp）,将该基因重组到原核表达载体pGEX-2T中,酶切、测序分析表明,重组质粒pGEX-MrCu/Zn-SOD1结构正确。重组质粒转化大肠杆菌BL21（DE3）进行诱导表达。IPTG诱导表达分子量约41kD融合蛋白GST．MrCu／Zn．SOD1。诱导表达后的菌体超声裂解液经谷胱甘肽亲和层析纯化,得到高纯度的GST—MrCu／Zn—SOD1。采用氯化硝基四氮唑蓝法和黄嘌呤氧化法分析其活性。结果表明,GST-MrCu／Zn-SOD1具有特异性SOD酶活性。     

NUTRITIONAL DIAGNOSIS AND CORRECTION OF SHOOT DIEBACK OF RED BAYBERRY (MYRICA RUBRA SIEB. ET ZUCA)

Shoot dieback characterized by leaflet, rosette shoots, and dieback of shoot tips is one of the most important problems in red bayberry production in south China. However, the causes of shoot dieback have not been determined. The results of leaf analysis and correction experiment showed that leaf boron (B) concentrations were highly correlated with leaf area (P < 0.01), spring shoot length (P < 0.01), and spring shoot numbers sprouting from one old shoot (P < 0.05). Foliar application of B at 2.0 g L^–1 of borax was more effective on correcting shoot dieback than foliar application of Zn at 2.0 g L^–1 of zinc sulfate and of molybdenum (Mo) at 2.0 g L^–1 of ammonium molybdate. Boron application increased fruit yields by 1.23–2.15 times compared with the control. Shoot dieback resulted mainly from B deficiency in the red bayberry trees.     

马尾松老头林混交杨梅后叶绿素含量和光合特性分析

通过比较分析紫色土侵蚀区马尾松老头林混交杨梅后混交树种的生长状况、叶绿素含量及光合特性的差异,试图揭示混交的营林模式对混交树种生理生态的影响。结果表明：马尾松老头林混交杨梅后,马尾松的胸径和树高分别增加45.55%和35.90%,其叶片叶绿素 a、b 和叶绿素 a+b 表现为略有增加,而叶绿素 a/b 比值从2.246减少到2.181;马尾松老头林混交杨梅后,马尾松的最大净光合速率和量子效率均表现为显著增加,光的补偿点表现为略为减少,而光的饱和点表现为略为增加,表明混交杨梅后增强了马尾松的光合能力。     

丁岙杨梅上应用防虫帏与避雨棚结合技术对果实品质的影响

丁岙杨梅果实成熟期恰逢夏季梅雨季节,高温高湿导致采前落果严重,果蝇数量大量发生,果实品质差,针对此情况采用防虫帏与避雨棚相结合技术对丁岙杨梅单树进行避雨栽培试验。通过测定露地栽培和避雨栽培丁岙杨梅果实的单果重、可溶性固形物、可滴定酸的含量、各糖成分积累量、果蝇数量等指标,探讨防虫帏与避雨棚结合技术对丁岙杨梅单树果实品质的影响和防虫效果。试验结果表明:经过防虫帏与避雨棚结合技术栽培的单树杨梅果实单果重与对照差异并不明显,但是可溶性固形物、可滴定酸含量、各糖成分积累、果蝇数量防御上均优于对照果实,生产上值得推广。     

轻度遮荫对紫羊茅生长和叶绿素含量的影响

研究了20%,40%轻度遮荫处理对紫羊茅叶片叶绿素含量和生长的影响。结果表明：遮荫60d,随光强的减弱,叶片中叶绿素a、叶绿素b和总叶绿素含量显著增加,20%和40%遮荫处理叶绿素总量分别比自然光照增加了8.80%和10.87%。紫羊茅分蘖能力和各部分植物量增量明显提高,20%和40%遮荫处理总干重增量分别比自然光照提高15.46%和35.00%。随遮荫强度增加,植株高度增加。遮荫能显著提高植株的含水量,40%遮荫处理植株含水量达到76.39%。     

1-MCP处理对杨梅果实贮藏期间品质及活性氧代谢的影响

为研究1-甲基环丙烯(l-MCP)对杨梅果实贮藏期间衰老的影响,本试验以"东魁"杨梅为试材,以常规冷藏为对照,研究不同1-MCP处理浓度与处理时间对杨梅果实品质和活性氧代谢的影响.结果表明:l-MCP处理可有效降低杨梅果实采后腐烂率,抑制H2O2累积,缓解VC和GSH的降解,诱导SOD、CAT和POD活性的升高,且1.0μL/L 1-MCP处理24 h的效果最佳;贮藏15 d时,1.0μL/L 1-MCP熏蒸24 h组的果实腐烂率与H2O2含量较对照组分别下降了48.25个百分点和128.58 mmol/mg Pro,SOD、CAT、POD活性较对照组分别提高了56.89、3.04、195.00 U/mg Pro,GSH和VC含量分别升高了18.67 mg/mg Pro和7.71 mg/100 g.由此可见,1-MCP处理可通过提高杨梅果实的SOD、CAT、POD等抗氧化酶活性及GSH和VC含量以有效清除活性氧自由基,从而延缓杨梅果实采后衰老,延长其保鲜时间.     

云南杨梅中多酚类物质的提取与活性研究

以云南富民杨梅为原料,提取其中的多酚类活性物质进行总酚含量测定,并进一步研究其抗氧化、抑制亚硝胺能力。试验结果表明:杨梅总酚含量140.43mg/100g样品。DPPH自由基法显示,杨梅多酚提取物具有一定的清除DPPH自由基能力,其清除能力与多酚提取物浓度之间存在明显的剂量效应关系,随着杨梅多酚提取物浓度的增大,其清除二苯代苦味酰自由基(DPPH)的能力增强。在与2,6-二叔丁基对甲酚(BHT)的抗氧化性比较中,杨梅多酚提取物的抗氧化性明显要高于合成的抗氧化剂BHT,当杨梅多酚提取物的浓度0.20mg/ml时,清除羟自由基的清除率为91.60%,同等条件下,杨梅多酚提取物清除羟自由基的清除率是常用抗氧化剂BHT的1.52倍。杨梅中多酚类物质具有良好的阻断亚硝胺合成能力,有一定的清除亚硝胺能力,当杨梅多酚提取物含量为0.60mg/ml时,清除率最高。     

光照强度和温度对紫羊茅分蘖的影响

秋冬季节在贵阳通过塑料大棚内外不同温度和光照水平生产紫羊茅（ＦｅｓｔｕｃａｒｕｂｒａＬ．Ｐｅｎｎｌａｗｎ）地毯式草坪的协相关分析得出：光照强度（ｘ）与分蘖数（ｙ）有直线回归关系，棚内分蘖数极显著高于棚外（Ｐ＜００１），温度对分蘖数影响最大。     

Effects of the infection by the fungal endophyte Epichloë festucae in the growth and nutrient content of Festuca rubra

Festuca rubra, a commercially important turfgrass, is a common species in natural semiarid grasslands of western Spain. In natural populations of this grass, about 70% of the individuals are infected by the fungal endophyte Epichloë festucae. In most cases, infected plants are asymptomatic. To test if there were differences in growth or nutrient content between infected (E+) and uninfected (E−) plants, five half-sib lines of F. rubra were used. Each line consisted of E+ and E− individuals. These plants were used for a 5 years long field experiment in conditions typical of the surrounding semiarid grasslands. The soil was poor in nutrients, and rainfall was scarce in the spring and summer. No differences in biomass production or number of stems were observed between E+ and E− plants. Regarding nutrient content, E+ plants in vegetative state contained more phosphorus than E− plants. This effect was consistently observed in the 3 years that this type of tissue was analyzed. In one of these 3 years Mn content was lower in E+ plants than in their E− counterparts. In plants in a reproductive stage, differences between E+ and E− plants were found with respect to Ca, Mg, and Cu content. In this developmental stage, the contents of neutral detergent fiber and lignin were lower in infected plants, and their organic matter digestibility was greater. The evidence presented in this study shows that in field conditions, the content of certain nutrients, P in particular, and fiber constituents of F. rubra are altered when the plants are infected by the endophyte E. festucae. Since most nutrients were found in concentrations below the adequate range for plant growth, increased P content is a beneficial effect of E. festucae infection. This fact helps to explain why endophyte infection incidence is high in natural populations of F. rubra, and why the development of endophyte infected turfgrass cultivars may be useful for low maintenance lawns.