南亚热带主要果树冻(寒)害低温指标的确定

根据历史气候和冻(寒)害灾情资料、2007/2008、2008/2009年冬季盆栽移放试验和典型年考察资料,以及冻(寒)害形态学标准,采用数理统计和对比印证方法,对南亚热带主要果树冻(寒)害低温指标进行研究。确定了几种主要南亚热带果树的轻、中、重、严重冻(寒)害低温指标,结果分别为龙眼:-1.5～0℃、-2.5～-1.5℃、-3.5～-2.5℃、<-3.5℃;荔枝:-2.0～0℃、-3.0～-2.0℃、-4.0～-3.0℃、<-4.0℃;香蕉:3.0～5.0℃、1.0～3.0℃、-1.0～1.0℃、<-1.0℃。结果可为果树冻害监测预警及避冻区划提供参考。     

‘富士’苹果不套袋与套袋密度对树体光合特性的影响

为进一步探讨不套袋与套袋对苹果品质影响的机理,以8年生‘富士’苹果（‘天红2号’/‘M26’/八棱海棠）为试验材料,共设5个套袋密度处理（不套袋、套袋1/3的果实、套袋1/2的果实、套袋2/3的果实、套袋所有果实）,所用果袋为小林果袋（双层纸袋,内红外棕）,研究不同套袋密度对果实套袋前（6月19日）、套袋后2天（6月21日）、套袋中（8月22日和9月27日）、摘袋后2天（10月9日）和采收后1天（11月3日）苹果叶片光合特性的影响。结果表明,套袋不仅降低了苹果树冠层内的光照强度,而且显著降低了叶片的光合速率,而随着套袋密度的增加,苹果树冠层内的净光合速率显著降低,尤其是在8月和9月。5个处理的冠层光强、气孔导度、叶绿素含量、类胡萝卜素含量和叶片比重的变化与净光合速率的变化基本一致,说明果实套袋导致叶片光合性能下降。套袋苹果光合速率的降低是由气孔导度的降低引起的,这可能与光照强度降低有关;而在9月光合速率的降低还可能与高温弱光,套袋苹果叶片出现非气孔限制有关。     

青海蔷薇科野生果树种质资源的研究

通过调查并结合有关文献和植物标本研究表明,青海省蔷薇科野生果树有60种（含2个变种、1个变型）,隶属于10属,占全省野生果树总数的53.6%。其中以蔷薇属（Rosa）和栒子属（Cotoneaster）最为丰富,分别有13种、12种,其次悬钩子属（Rubus）和李属（Prunus）分别有9种、8种,这4个属的种类占青海蔷薇科野生果树的70%;果实类型有梨果、聚合果、核果3种类型,其中梨果类、聚合果类占有较大比例,分别占总种数的45%和40%。青海省蔷薇科野生果树不少种类具有抗寒耐旱等特性,可作为砧木或抗性育种材料,一些种类果实营养较为丰富。青海蔷薇科野生果树主要分布于东部的黄河、湟水河及大通河流域,并划分为西倾山区、祁连山区和青南高原区3个分布区域,分析了各区的种类和分布情况;垂直分布在海拔1800~4000 m之间。另外,对几种重要野生果树资源进行了评价,并提出了开发利用的建议。     

Recent advances in molecular genetics of forest trees

The use of molecular markers has greatly enhanced our understanding of the genome structure of forest trees. Conifers, in particular, have a relatively large genome, containing a very high proportion of repeated DNA, consisting of tandemly repetitive and dispersed repetitive DNA sequences. The nature of highly conserved tandemly repetitive rRNA genes has been investigated in a number of tree species, and their sites mapped on specific chromosomes by fluorescent in situ hybridization (FISH). Different families of retrotransposons (IFG, and TPE1) have been isolated and characterized from the dispersed repetitive DNA of pines. Genome maps have been constructed in a number of forest tree genera: Pinus, Picea, Pseudotsuga, Cryptomeria, Taxus, Populus, and Eucalyptus. EST databases have been established from cDNA clones of pines and poplars. The structure and maternal or paternal modes of inheritance of organelle genomes have been investigated in forest trees. Comparative mapping in conifers has shown that gene families are conserved across genera. Due to lack of polyploidy in conifers, the evolution of this group of trees may have occurred primarily by duplication and dispersal of genes, probably by retrotranspositions, to form complex gene families. The evolution of angiosperm tree species has presumably involved both gene duplication as well as genome duplication (polyploidy). Application of genetic engineering has shown that genes from phylogenetically unrelated organisms can be introduced and expressed in trees, thus offering prospects of genetic improvement of forest trees. This revised version was published online in August 2006 with corrections to the Cover Date.     

Drying half of the root-zone from mid fruit growth to maturity in ‘Hass’ avocado (Persea americana Mill.) trees for one season reduced fruit production in two years

We tested the effect of extended drying of half the root system on fruit yield and fruit Ca concentration, an indirect measure of fruit quality, in avocado (Persea americana Mill. cv Hass). In a field experiment on a sandy soil, withholding irrigation and plastic sheeting was used to dry the root-zone beneath the whole canopy (DD) or half the canopy (WD), compared with well-watered trees (WW). The irrigation water contained added nutrients and was slightly saline. Yield, shoot growth, leaf conductance, leaf and fruit water status and mineral concentrations of leaves and fruit were studied. The responses of treated trees were assessed in the following season during which normal irrigation practices were restored. With respect to yield, the WD treatment behaved the same as the DD treatment. It reduced yield by more than half and proportionately more than the reduction in water supply thus reducing irrigation efficiency. Re-watering did not restore yield of WD or DD-trees in the next season. The WD and DD treatments had no effect on the concentration of Ca in the fruit mesocarp and so are unlikely to affect fruit quality. The main impact of reduced water supply on the trees was fruit abscission and this was linked to dry soil around the roots rather than the water status of the leaves or fruits. We conclude that extended drying of half of the root-zone in one season reduced irrigation efficiency for two seasons by promoting the abscission of developing fruit to the same extent as occurred when the whole root system was exposed to extended drying.     

热带观赏水草日本荷根的组织培养

以日本荷根的根状茎为外植体,对日本荷根组织培养技术进行简要报道.     

聚类分析在我国果树研究中的应用及问题分析

对近１０年来聚类分析在我国果树研究中的应用情况进行了简要总结。涉及十余种果树及系统聚类和模糊聚类两种聚类分析方法。文中对有关问题进行了分析和讨论。     

果树花药采集机的设计

果树有自花授粉不结实或结实率低的特点,严重影响北京地区果树生产。若实施果树人工辅助授粉需要进行花粉的制作,其中一个重要环节是花药的采集。为提高花药采集工作效率,节约采集成本,设计出一种构造简单、操作方便、花药采集率高和机械性能稳定的花药采集机。经过样机试验表明,机具可使花药的采集相对手工操作节省成本9 6.3%,工作效率提高9 5.8%。     

观赏植物诱变育种的研究现状和展望

本文综述了观赏植物辐射诱变育种的研究现状,并对花卉辐照诱变的手段、方法、处理材料和适宜辐照剂量、辐照机理与方法及应用作了总结,同时对观赏植物辐射诱变育种存在的问题及发展方向进行了探讨。     

成熟期苹果树冠层器官异源图像配准

为精确构建果树冠层彩色三维空间结构,以成熟期苹果树冠层为研究对象,将PMD摄像机及彩色摄像机相结合获取冠层器官异源图像,开展异源信息配准技术研究。将SIFT算法应用于异源图像特征点提取研究中,并应用目标函数优化RANSAC算法完成同名点提纯以保证特征点匹配的有效性,避免了异源图像尺度变化及果园自然光照的影响;在分析异源图像成像效果基础上,确定了应用双线性映射模型求解异源图像空间映射关系,有效克服了应用仿射变换模型求解异源图像空间映射关系的不精确性。果园不同自然环境下的配准实验表明:提出的混合算法适用于苹果树冠层器官异源图像的配准,晴天顺光环境下的正确配准率为88.2%,晴天逆光环境下的正确配准率为84.2%,阴天环境下的正确配准率为72.7%。