贝莱斯芽胞杆菌HN-2的鉴定及对杧果炭疽菌的抑菌活性研究

菌株HN-2为本实验室分离得到的一株生防细菌，通过采用形态学观察结合现代分子生物学的手段鉴定生防菌HN-2为贝莱斯芽胞杆菌Bacillus velezensis，以杧果炭疽菌Colletotrichum gloeosporioides Penz作为靶标，其发酵上清液的正丁醇萃取粗提物的活性最好，抑菌圈大小为20.93 mm，半最大效应浓度（EC₅₀）为70.62 μg/mL。通过飞行时间质谱（MALDI-TOF-MS）数据结合基因检测的结果分析发现，正丁醇提取物中主要活性成分为脂肽类物质，其中含有表面活性素（surfactin）、伊枯草菌素（iturins）和泛革素（fengycin）等。通过显微观察发现正丁醇粗提物可以造成杧果炭疽病菌菌丝扭曲、膨大、畸形，从而抑制杧果炭疽病菌的生长，菌株HN-2正丁醇提取物处理后的杧果15 d内未出现杧果炭疽病病状，对杧果果实具有较好的保护作用。贝莱斯芽胞杆菌HN-2的主要活性物质为脂肽类物质，其对植物病原真菌有较好的防治效果，具有进一步深入研究和开发应用的潜力。     

油茶内生拮抗细菌的筛选、鉴定及防效

为筛选出对油茶炭疽菌有拮抗效果的生防菌株，以油茶健康叶为对象，平板对峙法筛选，利用形态和生理生化特征以及16S rDNA基因和gyrA基因序列对菌株进行鉴定，测定其抑菌活性，并将该菌株与枯草芽胞杆菌Y13复配进行林间防效试验。结果表明，对油茶炭疽病菌拮抗作用效果较强的内生菌株为HBMC—B05；菌落为乳白色，不透明，边缘不整齐，中间有凸起；分子鉴定结果显示菌株HBMC—B05为贝莱斯芽胞杆菌Bacillus velezensis，其对果生炭疽菌Collectotrichum fructicola，抑菌率可达到81.31%，对另外3种油茶炭疽病病原菌抑菌率可达到70%以上，对其他4种致病菌也有抑制作用；复合菌剂对油茶病害的田间防治效果达到59%以上。该菌株的抑菌具有广谱性，可为油茶病害的生物防治扩充菌种资源，具有广泛的应用前景。     

内蒙古锡林郭勒盟典型草原固碳量及固碳潜力估算

为了评价不同放牧强度对草原固碳量及固碳潜力的影响，本研究采用系统动力学建模方法耦合CASA光合利用率模型、Shiyomi放牧模型、Raich土壤呼吸模型等模型，建立了基于系统动力学库-流思路的碳循环模型，该模型包含3个子系统、4个碳库。结果表明：1998至2015年，在内蒙古锡林郭勒盟的温度降低、降水量增加的背景下，净初级生产力呈现升高的趋势，典型草原土壤固碳量呈现下降趋势；放牧强度在3羊·公顷^-1下净生态系统初级生产力最低，固碳潜力最大，分别为-16.2 gC·m^-2和24.84 TgC。因此，建议内蒙古锡林郭勒盟典型草原西部（阿巴嘎旗、那仁宝力格站）的放牧强度不宜超过1.5羊·公顷^-1；东部（多伦县、东乌珠穆沁、西乌珠穆沁、锡林浩特站）不宜超过4.5羊·公顷^-1。     

生长调节物质对小豆豆芽营养成分影响和功能性评价

为筛选最适合芽菜培养的小豆品种,以‘白红8号’为试材,设置3种生长调节物质(乙酰水杨酸、乙烯利和6-苄氨基腺嘌呤(6-BA))的各6个浓度(0.0、0.1、0.2、0.3、0.4、0.5 mmol/L;0、20、30、40、50、60 mg/L和0、2、3、4、5、6 mg/L)喷施处理,测定其生物特性(上胚轴长度、上胚轴直径、萌发率、鲜重、干重和产出比)、营养成分(可溶性蛋白和可溶性糖)及抗氧化等特性。结果表明:3种生长调节物质喷施处理都能够提升其营养价值,在乙烯利喷施浓度为50 mg/L,‘白红8号’小豆芽苗菜中各营养成分、酶活性及抗氧化性等均可达到最大值,显著提高了其营养价值。因此,为提高生产中小豆芽苗菜的产量和营养价值,最终确定乙烯利喷施浓度为50 mg/L效果最佳。     

Prevalence,intensity and histopathology of Zeylanicobdella arugamensis infestation on groupers reared on different aquaculture systems

The marine leech, Zeylanicobdella arugamensis, is a major threat to aquaculture in grouper-producing countries including Indonesia. This study aimed at investigating prevalence, intensity and histopathology of the ectoparasite in humpback and hybrid groupers cultured in different rearing systems. A total of 260 groupers (60 humpback groupers and 200 hybrid groupers) were used for samples. The marine leech was observed on skin, fins, gills and mouth, followed by histopathological assay on the skin tissue. The results showed that prevalence of the leech in both groupers was higher when they were cultured in the floating net cages compared with the hatchery, p < .05. Furthermore, humpback grouper had a higher prevalence than hybrid grouper when they were cultured in a similar system, p < .05. Meanwhile, there was no significant difference in intensity between the two groupers, p > .05. Within the hybrid groupers, the highest prevalence was obtained from hybrid groupers reared in the earthen ponds. Histopathological studies showed that the infected groupers exhibited inflammation, congestion and erosion of the epidermis layer. Hybrid grouper had more severe histopathological lesions in the skin tissues. These results suggested that species and type of aquaculture system had significantly determined the prevalence, intensity and severity of lesion in Z. arugamensis infestation.     

Crude garlic extract significantly inhibits replication of grapevine viruses

Efforts to control viral diseases of grapevine include the production of certified material and development of virus-resistant transgenic grapevines. However, effective antiviral agents, once the viruses have infected the plants, are still lacking. This study shows that a crude garlic extract has significant antiviral activity against grapevine viruses. Replication of grapevine leafroll-associated virus 2 (GLRaV-2) was obviously inhibited in grapevine cv. Cabernet Sauvignon calli treated with diluted (1:100) garlic extract. The relative RNA levels of GLRaV-2 and grapevine fleck virus (GFkV) in cv. Summer Black grapevine in in vitro-grown plantlets 10 days after treatment with diluted (1:100) garlic extract were about 22% and 20%, respectively, of that in controls. The viral RNA accumulation of GLRaV-2, GFkV, grapevine virus A (GVA), grapevine fanleaf virus (GFLV) and grapevine rupestris stem pitting-associated virus (GRSPaV) in field-grown grapevine cv. Centennial Seedless plants sprayed with diluted (1:100) garlic extract were about 31–40%, 26–38%, 18–31%, 17–42% and 15–18%, respectively, of that in controls. Moreover, the garlic extract treatment led to a significant decrease in viral RNA accumulation of GLRaV-3, GLRaV-2, GVA, GFkV, GFLV, GRSPaV and grapevine Pinot Gris virus in pot-grown grapevine cv. Shine Muscat plants, and viral disease symptoms in these plants were obviously attenuated. In addition, this extract significantly induced expression of pathogenesis-related protein genes and stimulated activity of antioxidant enzymes in grapevines. Taken together, these results indicate that the crude garlic extract acts as a significant inhibitor against a broad range of grapevine viruses.     

1976—2017年青海湖东北部地区极端降水事件变化特征分析

为进一步了解高寒牧区气候变化,依据1976—2017年青海湖东北部海晏站逐日降水资料,采用百分位法确定冬、夏半年极端降雨（雪）阈值并统计极端降水事件,运用线性趋势、R/S和小波分析法分析极端降水事件变化特征、未来演变趋势及周期。结果表明：青海湖东北部地区冬、夏半年极端降水日数和极端降水量呈不显著增加趋势;冬半年极端降水强度和日最大降水量不显著增加,而夏半年不显著减小;极端降水对年降水的贡献率均以不同的速率增加,其中夏半年的极端降水对年降水的影响较大;冬半年降水日数不显著减小,而降水量显著增加,表明冬半年发生短时强降水的几率增大,夏半年的降水日数和降水量增加不明显;未来,冬半年极端降水日数增加趋势将发生转变,极端降水量与之前的变化趋势无关将继续呈现震荡性,其他各要素将持续前期的变化趋势;冬（夏）半年极端降水日数和降水量分别存在明显的周期变化特征。高寒牧区的极端降水研究对于预防短时强降水带来的雪灾、洪涝事件的发生意义重大。     

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.     

龙须藤茎皮甲醇提取物生物活性初探

龙须藤Bauhinia championii在医用方面已证实具有良好的抗菌、消炎作用,但其在农用方面的活性研究还鲜有报道。本研究分别采用菌丝生长速率法和种子生物测定法,首次测定龙须藤茎皮甲醇提取物及分离组分对6种农业有害真菌和单、双子叶两种植物的生物活性。结果表明,龙须藤甲醇浸提物对水稻稻瘟病菌Magnaporthe oryzae有一定的抑制效果,对油菜Brassica napus和稗草Echinochloa crusgalli的根芽均没有抑制作用。但其甲醇浸提物中分离的大部分组分对供试病原菌和植物的根芽都表现出一定抑制作用。杀菌活性方面:10号组分对西瓜枯萎病菌Fusarium oxysporum和番茄早疫病菌Alternaria solani的抑制效果最好,抑制率分别达到80.0%和78.0%,除草活性方面:1～3号组分对油菜根的抑制率较高,达到50%以上,2号组分对稗草根的抑制效果最好,达到68%。可见,龙须藤茎皮提取物中含有具有良好杀菌活性和除草活性的物质。     

具有除草活性的生防菌株GD-9发酵条件优化及菌剂制备

为了明确具有除草活性的生防菌株GD-9发酵过程中各因子的配比和最优条件,采用单因素试验对菌株最适碳源、氮源、载体、固态发酵基质进行了筛选,应用正交试验设计研究了碳源、氮源、初始含水量、接种量、初始pH、培养时间、培养温度7种因素对菌株活菌数的影响。试验结果表明菌株GD-9最佳固态发酵条件为:氮源NaNO_3 58.4 mg/g,碳源葡萄糖48.4 mg/g,培养基质最适初始含水量为258 mg/g,最适接种量为0.26 mL/g,初始pH 7.6,最佳培养时间147.8 h,最佳培养温度30.7℃,最适宜的载体为黏土,分散剂为聚乙烯醇,稳定剂为膨润土,润湿剂为糊精。通过发酵试验结果制备生防菌株GD-9的固体菌剂,该研究为菌剂的商品化生产奠定基础。