小麦慢锈品种‘平原50’上条锈菌侵染的超微结构观察初报

用光镜和电镜观察以条中２８号小种接种的慢锈品种“平原５０”和感病品种“铭贤１６９”的病理组织和超微结构。光镜观察发现两品种在侵入阶段无明显差异。在接种５天后，两品种中的菌落大小，吸器个数上出现较明显差异。     

早熟禾锈病的研究

人工接种实验结果证明，哈尔滨市早熟禾锈病是由冠锈菌引起的，其转主寄主为：小叶鼠李、金刚鼠李和东北鼠李。该病菌主要以冬孢子越冬，也有少量夏孢子可以越冬。用夏孢子人工接种潜育期为９￣１４ｄ，用锈孢子人工接种在２０℃时潜育期为８￣１２ｄ。早熟禾锈病的发病高峰期一般在８月上旬￣９月上旬，病情的轻重与降雨量关系较大。防治试验结果表明：用火烧去草坪上的干枯叶能推迟和降低发病率１０％；定期合理修剪草坪，茬高８ｃ     

Determining reference values for stem water potential and maximum daily trunk shrinkage in young apple trees based on plant responses to water deficit

The use of plant water status indicators such as midday stem water potential (Ψ_stem) and maximum daily trunk shrinkage (MDS) in irrigation scheduling requires the definition of a reference or threshold value, beyond which irrigation is necessary. These reference values are generally obtained by comparing the seasonal variation of plant water status with the environmental conditions under non-limiting soil water availability. In the present study an alternative approach is presented based on the plant’s response to water deficit. A drought experiment was carried out on two apple cultivars (Malus domestica Borkh. ‘Mutsu’ and ‘Cox Orange’) in which both indicators (Ψ_stem and MDS) were related to several plant physiological responses. Sap flow rates, maximum net photosynthesis rates and daily radial stem growth (DRSG) (derived from continuous stem diameter variation measurements) were considered in the assessment of the approach. Depending on the chosen plant response in relationship with Ψ_stem or MDS, the obtained reference values varied between −1.04 and −1.46 MPa for Ψ_stem and between 0.17 and 0.28 mm for MDS. In both cultivars, the approach based on maximum photosynthesis rates resulted in less negative Ψ_stem values and smaller MDS values, compared to the approaches with sap flow and daily radial stem growth. In the well-irrigated apple trees, day-to-day variations in midday Ψ_stem and MDS were related to the evaporative demand. These variations were more substantial for MDS than for midday Ψ_stem.     

红皮云杉叶锈病病原菌的研究

红皮云杉叶锈病发生在小兴安岭林区,该林区的地理位置是48°～48°43′N,12°23′～130°19′E,总面积 51.8万 ha(包括东风、新青林业局)。此病害过去仅危害过伐林下层的幼龄林木,不引起人们的重视。但近年来已扩展到5～10年生的人工林木及林间苗圃的苗木上,严重地影响云杉人工林的生长量和苗木产量,给林业生产造成较大的损失(图版Ⅰ-1)。为此从1984～1986年开展了本项试验,现将有关病原菌接种试验和生活史部分的研究结果报道如下。     

桥梁钢筋锈蚀检测

本文通过对桥梁结构物中钢筋锈蚀的分析，来评定桥梁结构中钢筋的使用状态，为准确鉴定旧桥的质量与可靠度提供技术数据。     

Growth responses, physiology and decay associated with pruning plantation-grown Eucalyptus globulus Labill. and E. nitens (Deane and Maiden) Maiden

Detailed studies have been undertaken to define pruning regimes for Eucalyptus nitens, but little is known of E. globulus responses to pruning although this is a more commonly planted species. This paper describes experiments that aimed to identify (a) levels of pruning that reduce E. globulus growth, (b) physiological processes contributing to those growth responses, (c) the incidence of decay and factors influencing decay incidence following pruning of E. globulus, and (d) comparative responses of E. nitens and E. globulus to live branch pruning. Results of a field experiment indicated that removal of between 30 and 50% of the crown length was appropriate for E. globulus plantations verging on canopy closure. The significant reduction in height growth associated with removal of 50 or 70% of crown length suggested pruning should remain below 50% of crown length if reduced stem growth of pruned trees was to be avoided. Stem volume was only significantly reduced over the period of the experiment by 70% pruning, but it was estimated that standing volume following removal of 50% of crown length would be reduced by 82 m³ ha⁻¹ over a 20-year rotation if there were no other silvicultural interventions. The growth responses observed were probably related to large reductions in leaf area following 50 or 70% removal of crown length. Trees responded to pruning by changing patterns of biomass partitioning to favour stem growth at the expense of branch growth. A glasshouse study determined that light-saturated net CO₂ uptake (A_max) increased following pruning. E. nitens seedlings had both a higher baseline A_max and higher A_max following pruning than did E. globulus, which could partially explain the greater effect of pruning on E. globulus growth than has been observed for E. nitens in other studies. This result, as well as apparently different patterns of foliage distribution through the crowns of E. globulus and E. nitens, suggested that models of pruning responses need to be parameterised for both species. In addition, a more conservative pruning regime may be appropriate for E. globulus than E. nitens. Pruning increased the frequency of branch traces with decay infection, and there was a trend towards increasing decay outbreaks with increasing pruning severity. Decay outbreaks were more likely to occur following pruning of high angle or larger diameter branches.     

Effect of drought on diameter increment of Quercus ilex, Phillyrea latifolia, and Arbutus unedo in a holm oak forest of NE Spain

The present study was carried out to elucidate the drought growth responses of Quercus ilex L., Phillyrea latifolia L., Arbutus unedo L., and other accompanying woody species of the Mediterranean holm oak forest. We submitted holm oak forest stands in Prades mountains (NE Spain) to a 2-year experimental drought. We reduced soil water availability about 15% by plastic strips and funnels that partially excluded rain throughfall and by ditch interception of water runoff. Mean stem diameter increment showed a great variation depending on the species. A. unedo had larger growth rates than Q. ilex and P. latifolia, but it was also the species that experimented the highest growth reduction in the drought plots (77%), suggesting a higher drought sensitivity than Q. ilex (55%) and P. latifolia (no drought effect). The growth reduction was specially marked in the larger trees. Aboveground stand biomass increment, estimated from stem diameter by allometric relationships, was 1.9 Mg ha⁻¹ per year in the control plots. The 15% reduction in the upper soil moisture produced 42% reduction in this biomass increment. In the drier conditions predicted in this Mediterranean area in the frame of climate change, an important reduction of growth rates can be hence expected, accompanied by a gain of dominance of drought-tolerant species such as P. latifolia in detriment of more mesic species such as Q. ilex.     

涨南红豆红锈病的发生与危害

海南省尖峰岭地区营造的5－6年生海南红豆行道树，严重发生了由红锈藻引起的红锈病，在500株幼树中，发病株率高达97.5%，Ⅲ-Ⅳ级病株率80％，病情指数75.5，导致部分叶片干枯或脱落，嫩枝枯死，树势衰弱，生长严重受阻。文章对该病的症状、病原、危害及发生规律进行了报道。     

RELATIONSHIP BETWEEN SCOTCH PINE NEEDLE RUST AND HOST CHLOROPHYLL CONTENT

PhotoSynthe3isisaprocessofaccumulat-ingorganicmaterialsinthylakoidmembranesofgreenplantchloroplast.Whentheleavesofgreenplantaredestroyedbysomefactor,chlo-rophyllcontentwillchange,whichcanaffeetorganicmaterialsaccumulatonandharmtreegrowth.TherearesomerePortsonrelationshipbetWeentreechlorophyllcontentanddifferentstandsmictUre,differentsiteconditionanddifferentgrowthperiod,buttherePOrtsontreedisease,especiallytheeffectsofneedlesrustonchlorophyllcontCnthavenotbeenseen.lntl1isstUd3,thechlorophyl…