Diversity of the coat protein-coding region among Ilarvirus isolates infecting hop in Australia

Coat protein (CP) sequences of 17 Ilarvirus isolates were obtained from hops at three farms in Tasmania, Australia. Phylogenetic analysis of these sequences and additional database sequences indicated several Apple mosaic virus (ApMV) isolate clusters distinct from Prunus necrotic ringspot virus (PNRSV): one containing isolates from apple; one containing a single isolate from almond; a third containing Australian hop isolates of the 'apple' serotype and a German isolate of unknown origin; and a fourth containing Australian hop isolates of the 'intermediate' serotype. Isolates from hop, pear and prune from the Czech Republic either formed a fifth grouping, or were divergent members of the 'intermediate' serotype group. Deduced amino acid (aa) residue differences between the coat proteins of the two hop isolate serotype groups were highlighted as possible regions of serological differentiation. No evidence for coinfection of plants with both serotypes was found. Tests of ApMV-infected hop buds using the Shirofugen flowering cherry assay revealed a possible differentiation of the two strains based on hypersensitivity. Because of serological similarities to PNRSV, these viruses have commonly been reported as strains of PNRSV. However, this study shows ilarviruses from Australian hops are strains of ApMV, but distinct from those infecting Malus spp.     

果梅幼树对春施~(15)N-硫铵的吸收与分配

以盆栽3年生细叶青梅/毛桃为试材,研究了早春施用~(15)N-(NH_4)_2SO_4条件下,果梅对~(15)N的吸收分配规律。结果表明:由于春季土温较低,限制了植株对肥料氮的利用率。在新梢旺长期,植株从肥料氮中吸收的氮素营养主要用于新生器官的建造,且新梢成为~(15)N的主要分配中心,其次即为果实,再其次为细根。至花芽分化期,植株的生长中心已发生转移和分散,但春施氮对促进当年生枝的花芽分化和维持叶片正常光合功能仍有重要作用,此期亦是根系生长的关键时期之一,且与贮氮相比,春施氮更有利于当年新根的萌发和根系的扩大。     

山杏幼苗水分生理生态特性及凋萎湿度的研究

对山杏幼苗进行 3种施水量的水分培养和干旱处理。结果表明 :随施水量的减少 ,叶片的净光合速率、蒸腾速率、气孔导度和水分利用效率等指标都随之下降 ,叶片温度提高。 40 9.2和 1 89.2 mm施水量对山杏幼苗各项指标的影响呈显著差异 ,而 40 9.2和 32 1 .2 mm之间与 32 1 .2和 1 89.2 mm之间均无差异。随土壤干旱的加剧 ,山杏幼苗叶片的蒸腾速率和水势与土壤含水量呈规律性变化 ;当干旱持续 39天时 ,1 .44%的土壤含水量可视为山杏幼苗的凋萎湿度     

马哈利樱桃离体茎尖超低温保存的研究

用玻璃化法超低温保存马哈利樱桃;切取经５℃低温驯化３０d的离体茎尖置于固体培养基 （ＭＳ＋０．７mol/Ｌ蔗糖）预培养２４h,在含１mＬ５０％甘油＋５０％蔗糖的保护液中处理８０min后浸入液氮。２５℃水浴快速化冻２min,然后接种到标准培养基上。２１d后调查,茎尖存活率达８４．６％。     

Penetration, Development and Emigration of Juveniles of the Nematode Meloidogyne arenaria in Myrobalan Plum (Prunus cerasifera) Clones Bearing the Ma Resistance Genes

Penetration, development and emigration of M. arenaria in the roots of three Myrobalan plum (Prunus cerasifera) clones genetically characterized for their resistance to root-knot nematodes (RKN) were studied during the 10 (penetration) and 15 (emigration) days following the date of inoculation (D) of 2500 juveniles (J2s) per plant into the soil. Miniaturized tests were conducted on the two resistant clones P.2175 (Ma1 gene) and P.1079 (Ma2 gene) and the susceptible clone P.2032 (recessive for both genes), obtained from micropropagated plantlets and grown in mini-containers under controlled conditions at 25°C in a growth chamber. For penetration and development studies, nematodes in the roots were recovered by the acid fuchsin-lactophenol staining technique. Equivalent numbers of J2s were recovered in all the clones at D+1 and D+2. Subsequently, the numbers increased rapidly in P.2032 and were significantly different from those in P.1079 and P.2175 that remained at a low level. No swollen larvae were observed in the resistant clones. In P.2032, the first swollen larvae were observed at D+4, the first females were observed at D+12, whereas the first females with attached egg sacs and the first new-generation J2s were obtained between D+21 and D+28. Our data suggest that the resistance phenomenon does not act on the very early nematode penetration but acts later by preventing feeding-site induction and development into the third-stage. For emigration studies, plants in which J2s had been allowed to penetrate for two days (from D to D+2) were washed free of soil, repotted and then, after various periods of growth, soil-free roots were placed under a mistifier to evaluate the numbers of emigrating individuals. Emigration of J2s from the roots occured mainly from D+2 to D+4 in all the genotypes and was very limited from D+4 to D+10. There was no significant differences in the number of emigrated juveniles between the resistant and susceptible clones, indicating that emigration cannot explain the difference in the numbers of nematodes recovered in the roots.     

桃树不同生长型及其研究进展

生长型是桃树重要的树体特征,是控制树体大小的遗传因素,与栽培关系密切。综合有关文献介绍了桃树的紧凑型、半矮化型、矮化型、柱型、直立型、短枝型、垂枝型等生长型资源及不同生长型在遗传、形态特征、生理、栽培等方面的研究进展。紧凑型受单位点显性基因控制,树体开张,分枝角度大,萌芽率及成枝力均高,光透过率较低;半矮化型树体介于普通型和紧凑型之间;矮化型为单基因隐性性状,节间极短,树体矮小,叶片密度大,光透过率低;柱型枝条分枝角度小,冠幅小,叶面积指数大;直立型介于柱型和普通型之间;短枝型能形成较多的短果枝,并以短果枝结果为主;垂枝型枝条披散下垂,枝条弯曲。不同生长型之间在氮素、干物质分配和内源激素水平上也存在一定的差异。紧凑型、矮化型由于树冠密度大,光透过率低而在应用上受到限制,直立型和柱型因适应了高密度栽培而更受人们的重视。针对目前存在的生长型分类与命名问题,作者认为应首先考虑节间长度,其次为萌芽率、成枝力等,然后考虑的是枝条的分枝角度。     

甘肃桃(Prunus kansuensis)雌雄配子体发育规律及遗传特性的研究

为了了解甘肃桃的早花性与其花芽分化的关系及早花性的遗传能力,以甘肃桃1号(甘肃桃)(Prunus kan-suensis)、96-7(普通桃)(P.persica)、甘肃桃1号×96-7的杂种一代群体(20株)为试材,对材料的生物学特性和花芽分化解剖结构进行了研究。结果表明,1)通过对叶、花、果形态特征观察发现,甘肃桃1号×96-7杂种群体的表现性状趋向甘肃桃1号。2)甘肃桃1号在落叶前形成雄配子体,具有花粉的早熟性。3)杂种群体花芽分化始期及花芽分化特性也趋向于母本甘肃桃1号。     

青梅主要病虫害的发生及防治

近年来随着广东青梅种植规模扩大和商品化生产深入,病虫害问题逐渐突出。通过对青梅果园病虫害的调查研究以及防治试验,初步掌握了广东省青梅主要病虫害的发生与流行规律,并总结出有效的防治技术,为青梅种植业的健康发展提供参考。     

我国美国杏李栽培现状及发展对策

介绍美国杏李生物学特性、分布及在我国引种概况、栽培表现,阐述了制约我国美国杏李发展的主要因素,从提高认识、完善机制、加强科研与技术推广和转变经营理念等方面提出了促进产业发展的对策.     

油初始坐果机制研究

以成年油木奈树为材料,对其初始坐果进行了研究。结果表明,盛花后2周内,油木奈出现大量的落花落果;幼果(子房)低水平的GA1 3与油木奈的落花落果高峰关系密切,而内源细胞分裂素ZRs和[diH]ZRs以及ABA与幼果(子房)的生长呈显著的正相关;初始坐果期,油木奈的雌配子体发育缓慢,且有相当数量的胚囊中途退化、败育,无法正常受精,从而导致其大量的落花落果。文中就油木奈的初始坐果机制进行了讨论。