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361.
Marcel Wenneker Peter F. de Jong Nina N. Joosten Paul W. Goedhart Bart P. H. J. Thomma 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(3):631-635
Fruit tree canker caused by Neonectria ditissima is a serious problem in apple-producing regions with moderate temperatures and high rainfall throughout the year; especially in northwestern Europe, Chile, and New Zealand. Control measures are applied to protect primary infection sites, mainly leaf scars, from invasion by external inoculum. However, latent infections may occur when young apple trees are infected symptomlessly during propagation. This study aimed to develop a method for detection of latent fruit tree canker infections. Inoculations with conidiospore suspensions of N. ditissima were carried out in tree nurseries on the main stems of two-year-old trees of three apple cultivars and one pear cultivar. The inoculations were carried out during the natural abscission period in the autumn. No visible lesion or canker formations were present at the time when the inoculated trees were uprooted. It appeared that the infections may remain latent during the period from infection to uprooting (2 months) and during the subsequent 4 months of cold storage of the trees. Nevertheless, symptoms were generally induced within 8 weeks after transfer of infecting planting material from the nursery field into a climate chamber with high temperature and high relative humidity. The methodology presented is developed to detect latent infections of N. ditissima in nursery trees, prior to planting in the orchards, and it may contribute in reducing the problem with European fruit tree canker in commercial production. 相似文献
362.
Karl H. Mellert Jonathan Lenoir Susanne Winter Christian Kölling Andraž Čarni Isabel Dorado-Liñán Jean-Claude Gégout Axel Göttlein Daniel Hornstein Matthias Jantsch Nina Juvan Eckart Kolb Eduardo López-Senespleda Annette Menzel Dejan Stojanović Steffen Täger Ioannis Tsiripidis Thomas Wohlgemuth Joerg Ewald 《European Journal of Forest Research》2018,137(1):79-92
Based on macroecological data, we test the hypothesis whether European tree species of temperate and boreal distribution maintain their water and nutrient supply in the more arid southern margin of their distribution range by shifting to more fertile soils with higher water storage than in their humid core distribution range (cf. soil compensatory effects). To answer this question, we gathered a large dataset with more than 200,000 plots that we related to summer aridity (SA), derived from WorldClim data, as well as soil available water capacity (AWC) and soil nutrient status, derived from the European soil database. The soil compensatory effects on tree species distribution were tested through generalized additive models. The hypothesis of soil compensatory effects on tree species distribution under limiting aridity was supported in terms of statistical significance and plausibility. Compared to a bioclimatic baseline model, inclusion of soil variables systematically improved the models’ goodness of fit. However, the relevance measured as the gain in predictive performance was small, with largest improvements for P. sylvestris, Q. petraea and A. alba. All studied species, except P. sylvestris, preferred high AWC under high SA. For F. sylvatica, P. abies and Q. petraea, the compensatory effect of soil AWC under high SA was even more pronounced on acidic soils. Soil compensatory effects might have decisive implications for tree species redistribution and forest management strategies under anthropogenic climate change. Therefore, soil compensatory effects deserve more intensive investigation, ideally, in studies combining different spatial scales to reduce the uncertainty associated with the precision of soil information. 相似文献
363.
为探究多鳞白甲鱼幼鱼日粮中最佳碳水化合物添加类型,以葡萄糖、麦芽糖、糊精、玉米淀粉及纤维素5种碳水化合物为糖源,分别配制5种日粮,对多鳞白甲鱼幼鱼进行了为期56 d的养殖实验。结果显示,(1)生长及饲料利用率方面,麦芽糖组的终末体重、特定生长率、饵料系数以及蛋白质效率等指标最佳,纤维素组最差。(2)体成分方面,纤维素组全鱼粗脂肪水平最低,粗灰分水平显著高于麦芽糖组,麦芽糖组及纤维素组肌糖原含量最低,糊精组肝糖原含量最低。(3)主成分分析表明,C16:0、SFA、MUFA和PUFA比例对肝胰脏脂肪酸比例产生主要影响,其中,C16:0和SFA比例在麦芽糖组显著提高,MUFA比例在糊精组显著提高,而PUFA在纤维素组显著提高;C18:1n-9和MUFA比例对肌肉和脂肪组织总体脂肪酸组成产生主要影响,二者比例在麦芽糖组显著提高。(4)血清生化指标方面,麦芽糖组及纤维素组谷丙转氨酶活性、麦芽糖组谷草转氨酶活性显著较高,葡萄糖组及纤维素组碱性磷酸酶活性、球蛋白含量较高,而血糖含量反之。(5)抗氧化能力方面,麦芽糖组肝胰脏过氧化氢酶、总超氧化物歧化酶、谷胱甘肽过氧化物酶活性最高,纤维素组丙二醛含量最... 相似文献
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365.