Differential responses of red clover cultivars to Sclerotinia trifoliorum under diverse natural climatic conditions

The susceptibility of 15 red clover ( Trifolium pratense ) cultivars to Sclerotinia trifoliorum under natural conditions in field experiments was investigated at sites in Sweden located at latitudes ranging from 60 to 64°N, with corresponding ranges of climatic regimes and lengths of vegetative growth and winter periods. At each site, 10 red clover cultivars were included: five were common, and five were selected according to the regional climate. Clover rot caused by S. trifoliorum from natural sources occurred in all geographical areas studied, and all cultivars included were affected. The numbers of plants of each cultivar killed by the pathogen was estimated at five sites over 2 years. Severe effects were observed in the first winter at these sites, but while incidence of clover rot increased and diseased areas expanded substantially in the second winter in northern Sweden, this pattern was not observed in southern regions. Tetraploidy, late flowering type and previous selection for resistance among cultivars positively influenced survival rates in the field. Estimates of susceptibility of cultivars obtained under field conditions after 2 years showed strong correlation when compared with rankings of susceptibility caused by an aggressive isolate of S. trifoliorum in previously conducted controlled environment laboratory tests. Yields were correlated to the proportion of gaps caused by the pathogen, indicating its economic importance.     

释放丽蚜小蜂防治越冬番茄温室白粉虱技术研究

研究和利用以生物防治为核心的绿色防控技术替代化学防治十分必要。丽蚜小蜂是温室白粉虱的专性寄生天敌,对温室白粉虱控制效果突出。为明确越冬番茄温室利用丽蚜小蜂防治白粉虱的关键技术,以普通的化学农药防治为对照,比较了不同益害比（2∶1、4∶1和6∶1）放蜂对白粉虱的控制效果,以及3月5次放蜂与11月2次放蜂＋翌年3月5次放蜂（放蜂益害比均为6∶1）对白粉虱数量增长的影响。结果表明：不同益害比放蜂处理的温室白粉虱数量均低于对照,尤以6∶1处理控制白粉虱效果最好;3月放蜂处理能将温室白粉虱数量持续控制在较低水平,且效果与11月放蜂＋翌年3月放蜂处理差异不显著。在衡水越冬番茄温室内使用丽蚜小蜂防治白粉虱时,应将释放天敌集中在年后温室温度刚开始回升、害虫发生数量较少时进行。     

倒春寒与杨树烂皮病发病的关系

对辽宁省1997-2010年倒春寒分为轻度、中度偏轻、中度和重度等4级,并对不同等级倒春寒与辽宁省杨树烂皮病Valsa sordida发病的关系进行了分析。结果表明：倒春寒与杨树烂皮病年发生总面积呈正相关（P〈0.05）,与中、重度发病面积呈正相关（P〈0.01）,与轻度发病面积关系未达到显著水平（P〉0.05）;与轻度病害所占比率呈负相关（P〈0.01）,与中、重度病害所占比率呈正相关（P〈0.01）。倒春寒发生越严重的年份,相应的杨树烂皮病发病面积越大。倒春寒发生程度越重,中、重度病害发生的面积和比率增加越明显。     

应用Verhulst模型测报松针褐斑病发病率

依据瑞金市１９９２～１９９８年松针褐斑病逐年发病率的时间数据序列,尝试应用Ｖｅｒｈｕｌｓｔ模型进行预测预报。     

梨锈病田间发病规律及相关性分析

[目的]研究梨锈病田间发病规律及发病影响因素,为梨锈病抗病性鉴定提供科学依据.[方法]以翠冠×金星杂交梨苗为试材,采用田间发病和人工接种鉴定方法,对梨锈病发病规律及抗性进行相关性分析.[结果]梨杂交实生苗对梨锈病的抗性表现出广泛的分离,不同年份梨杂交实生苗锈病病情指数概率分布差别较大;田间发病条件下,病害分布呈多峰型,人工接种呈单峰型;同一年份不同时期杂交实生苗对梨锈病的抗病性不一致;梨锈病病情指数与桧柏和梨树间的距离呈极显著负相关,相关性逐年增强.[结论]梨树杂交苗单株对梨锈病抗性年份间有差异,同一年内不同时期也不一致;对锈病人工接种鉴定,应进行多次接种,才能筛选出综合抗性较强的单株;进行田间抗性鉴定时应考虑梨树与桧柏距离对病害的影响.     

关中麦田产壳玉米秸秆密度与小麦赤霉病穗率的关系

为了准确预测关中地区小麦赤霉病的病穗率,采用田间模拟试验和田间调查相结合的方法,建立了麦田产壳玉米秸秆密度与穗表赤霉菌孢子数的关系模型y=1.115+2.506x,并在实验室前期关中小麦赤霉病病穗率预测模型的基础上,建立了基于麦田产壳玉米秸秆密度的小麦赤霉病预测模型。预测模型中产壳玉米秸秆密度参数的灵敏度变化范围为0.09~0.13,为中等灵敏参数。利用2014年关中15个代表县以及杨凌1986-1992年的实测数据对预测模型进行了评价,该模型的预测准确度在75%以上。综合来看,此预测模型使用简单,预测准确度高。     

温室非洲菊组培苗灰霉病发生规律与防治技术

通过研究温室非洲菊组培苗灰霉病的症状特点和温湿度、光照、通风状况、栽植密度、施肥、虫害对该病的影响,提出相应的防治措施。结果表明:灰霉病可侵害移栽后的非洲菊组培苗的叶片、根颈和花,引起叶片、花出现坏死病斑或枯死,根颈腐烂等症状。温度低、湿度高、光照强度小于2 000 lx、栽植密度过大、通气不良、室内不清洁、偏施氮肥、虫害较多均有利于发病。防治该病的方法是以农业防治为基础,如室内清洁卫生,穴盘消毒,合理浇水,定时通风,合理施肥,控制光照,治虫防病等;化学防治为辅;提倡使用生物防治手段。该研究为温室非洲菊组培苗移栽后灰霉病的防治提供了依据。     

Control of postharvest anthracnose of banana using a new edible composite coating

Anthracnose is a postharvest disease of banana caused by the fungus Colletotrichum musae that results in major economic losses during transportation and storage. For the management of banana anthracnose, antifungal effects of Arabic gum (AG) (5, 10, 15 and 20%), chitosan (CH) (1.0%), and the combination of AG with CH were investigated in vitro as well as in vivo. CH at 1.0% and 1.5% had fungicidal effects on C. musae. AG alone did not show any fungicidal effects while the combination of 1.0% CH with all tested AG concentrations had fungicidal effects. However, the potato dextrose agar (PDA) medium amended with 10% AG incorporated with 1.0% CH showed the most promising results among all treatments in suppressing the mycelial growth (100%) and conidial germination inhibition (92.5%). In vivo analysis also revealed that 10% AG incorporated with 1.0% CH was the optimal concentration in controlling decay (80%), showing a synergistic effect in the reduction of C. musae in artificially inoculated bananas. The 10% AG incorporated with 1.0% CH coatings significantly delayed ripening as in terms of percentage weight loss, fruit firmness, soluble solids concentration and titratable acidity. The results showed the possibility of using 10% Arabic gum incorporated with 1.0% chitosan as a biofungicide for controlling postharvest anthracnose in banana.     

贵州省贫困发生率与生态系统服务价值相关性分析

为探究贫困水平与生态系统服务价值(ESV)的相关性。基于2010年贵州省土地利用和贫困发生率数据,利用GoeDa模型和ArcGIS软件探究了贫困发生率与ESV的空间相关性。结果表明:贫困发生率与ESV之间存在正相关性,贫困发生率较大的地区ESV越高。贫困发生率与地均ESV的Moran指数大于贫困发生率与生态系统服务总价值(TESV)的Moran指数。贵州省东南部呈高—高相关,中部呈低—低相关,西部呈高—低相关。社会经济发展水平与土地利用结构空间格局的差异是造成贫困发生率与ESV空间关系不同的主要原因。     

二氢吡啶在奶牛养殖中的应用研究

将二氢吡啶添加到奶牛日粮中，进行饲养试验。结果表明，试验期末，试验组奶牛产奶量与对照组相比提高5．65％，未达显著水平；奶料比、乳脂率、乳蛋白含量与对照组相比无变化。试验组奶牛乳房炎的发生率与对照组相比降低61．95％。