弱光对三年生油桃源叶韧皮组织超微结构的影响

以日光温室内栽培的三年生油桃“早红艳”(Prunus persica L．var．nectarine Ait“Zao Hong Yan”)为试材,利透射电子显微镜(TEM)技术首次对处于正常光照条件和弱光条件下的源叶的韧皮组织进行了超微结构观察,重研究了叶片超微结构对弱光的响应。结果表明：在正常光照条件下,油桃源叶各级叶脉的筛管和伴胞的平均直均比弱光条件下的大,表明光能影响细胞的发育,而弱光抑制了细胞的生长。在正常光照下的伴胞具有致密的胞质,内含丰富的线粒体、内质网、多泡体、囊泡和质体,而弱光下的伴胞明显液泡化,同时含有少量的线粒体和质网。在弱光条件下也观察到叶绿体基粒片层边缘紊乱,筛孔处于阻塞状态。在弱光下,邻近维管束鞘细胞的肉细胞内积累了大量的淀粉粒和少量的线粒体。淀粉粒的积累可能是由于光合同化产物的生产与输出之间的平衡,这一观察结果有力地支持了大部分叶片是在光照条件下输出其大部分同化产物的观点。在筛管／伴胞、伴／韧皮薄壁细胞、韧皮薄壁细胞／韧皮薄壁细胞和韧皮薄壁细胞／维管束鞘细胞之间的胞间连丝密度都在弱光条下下降,在正常光照强度下支脉筛管／伴胞和韧皮薄壁细胞／维管束鞘细胞之间可以观察到胞间连丝,而在弱光几乎观察不到胞间连丝的存在,所以同化物的运输在弱光条件下可能以质外体运输为主,而在正常光照强度下,质体运输可能是主要的运输方式。这些研究结果证明,日光温室内油桃通过源叶韧皮组织超微结构的变化对弱．做出适应性响应。     

西北高寒植物长果婆婆纳的化学成分

利用柱层析、薄层层析、重结晶等分离手段,从玄参科婆婆纳属长果婆婆纳的脂溶性成分中,分离得到8个化合物,经^1HNMR、^14CNMR、DEPT等现代波谱技术鉴定它们为5个单萜环烯醚苷,3个苯甲酸衍生物。该植物采自青海互助县海拔3700～3800m山坡上,为高海拔、高寒植物,其化学成分为首次报道。     

我国境内常春藤叶婆婆纳染色体计数及其生态学意义

常春藤叶婆婆纳 ( Veronica hederaefolia L.)是地中海周缘国家的重要农田杂草 ,近期由境外传入我国江苏、浙江地区。对该种的染色体计数表明 ,我国境内的这一新外来杂草染色体数目从 1 8、36、54、32和 2 2均有 ,分别占总计数的 2 3.91 %、1 .0 9%、2 .1 7%、69.57%和 3.2 6%。新传入我国境内的常春藤叶婆婆纳是一种具有潜在危害的农田杂草。     

The effects of phosphorus nutrition and soil pH on the growth of some ancient woodland indicator plants and their interaction with competitor species

The forest under-storey herbs Anemone nemorosa, Lamiastrum galeobdolon and Veronica montana are generally considered indicator species of old, broadleaved woodland sites where the soil fertility is often low. In a glasshouse bioassay, however, all three species not only showed large positive growth responses to supplied P concentrations (0–10mgL ^–1) solutions, but also tolerated high P concentrations (20–40mgL ^–1), well above those normally found in their natural habitat. Plants responded by raising the concentrations of P in their shoot and root tissues and increasing their biomass, resulting in an increased P uptake. A shade-tolerant competitor species, Urtica dioica, also grew vigorously across the full range of P concentrations, restricting the growth of the woodland species. This emphasises the difficulty of establishing semi-natural woodland vegetation in the presence of competitor species, for example in situations where new woodlands are planted on fertile ex-agricultural soils containing large residual concentrations of P. The influence of soil pH on the growth and nutrient relations of A. nemorosa, L. galeobdolon, V. montana, Poa trivialisandU. dioicawas determined in a separate experiment using an ex-arable soil as the growing medium with pH levels adjusted from 7.4 to 5.8 and 4.3 respectively. Acidifying the soil enhanced growth, but reduced the concentrations of N, P and K in the leaves of all three woodland species, probably due to dilution of these minerals in the increased dry matter production. The competitor species (P. trivialis and U. dioica) responded in similar manner to the woodland indicator species. These results suggest that manipulating soil pH as a means of facilitating the establishment of woodland indicator species in new farm woods is unlikely, in the short term, to be effective where competitor species are present.     

青桃利用单、复花芽结果对盛果期生长结实的影响

青桃盛果期,特别中庸偏旺的植株,单、复花芽果枝数大体均等,复花芽果枝以其复芽个体较大,枝条较粗而往往表现为优势。然而笔者于1974—1979年观察了青桃树以单、复花芽结果对盛果初期的影响,结果表明:利用单花芽结果,控制了强旺枝和结果部位,使果枝分布均匀,树势稳定,尤其果枝数、花芽数、单株产量等的变动趋势与年度增加无关,r为:-0.2899、0.0620(单、复花芽果枝数分别占总果枝数的35.1％和16.7％),-0.3830、-0.1804(单、复花芽朵数分别占总花芽朵数的44.5％和13.4％),0.4093(单株年产量为179.4公斤,从而延长了盛果期;利用复花芽结果却相反,促进树势极性生长,旺枝增强,果枝外移,内膛空虚,尤其果枝数、花芽数、单株产量等的变动趋势随年度增加而呈显著与极显著负相关,r为:-0.8938~(**)、-0.9818~(**)(单、复花芽果枝数分别占总果枝数的27.1％和21.1％),-0.953~(**)、-0.8908~(**)(单、复花芽朵数占总花芽朵数的35.3％和6.8％).-0.8853~(**)(单株产量较单花芽结果减产19.4％),从而明显缩短盛果期。     

中国境内睫毛婆婆纳生态特征研究

睫毛婆婆纳是地中海周缘地区的重要农田杂草 ,对其个体生理生态学和种群生态位研究表明 ,睫毛婆婆纳种子在通气性良好的土壤中具有高的萌发率 ;含水量为 1 0～2 0 %的土壤 ,有利于其种子萌发 ;种子萌发对 pH值要求并不严格 ;低温能促进其种子萌发 ;光合作用特征与波斯婆婆纳比较接近 ,属于耐阴植物 ;种子呼吸强度比同属其它杂草略低 ;种群在南京地区的实际生态位宽度比同属的波斯婆婆纳、婆婆纳要小 .生态位重叠值计测表明 ,睫毛婆婆纳与同属的两种杂草有最为相似的生态要求 .     

Construction of a saturated linkage map for Prunus using an almond×peach F2 progeny

 A map with 246 markers (11 isozymes and 235 RFLPs) was constructed using an interspecific F₂ population between almond (cv Texas) and peach (cv Earlygold). RFLPs were obtained using 213 probes from the genomic and cDNA libraries of different species (almond, peach, P. ferganensis, cherry, plum and apple), including 16 almond probes which correspond to known genes. All markers were distributed in eight linkage groups, the same as the basic chromosome number of the genus, covering a total distance of 491 cM. The average map density was 2.0 cM/marker and only four gaps of 10 cM or more were found; the two largest gaps were 12cM each. This map was compared with one constructed previously with an intraspecific almond population sharing 67 anchor loci. Locus order was nearly identical and distances were not significantly different. A large proportion of the mapped loci (46%) had skewed segregations; in approximately half of them, the distortion was due to an excess of heterozygotes. One of the distorted regions could be associated with the position of the self-incompatibility gene of almond. Received: 6 November 1997 / Accepted: 26 May 1998     

Developmental changes of enzymes of malate metabolism in relation to respiration, photosynthesis and nitrate assimilation in peach leaves

The developmental profile of the activities of some enzymes involved in malate metabolism, namely phosphoenolpyruvate carboxylase (PEPC; EC 4. 1. 1. 31), NAD⁺-linked (EC 1. 1. 1. 37) and NADP⁺-linked (EC 1. 1. 1. 82) malate dehydrosenase (MDH), NAD⁺linked (EC 1. 1. 1. 39) and NADP⁺-linked (EC 1. 1. 1. 40) malic enzyme (ME), has been determined in leaves of peach [ Prunus persica (L.) Batsch cv. Maycrest], a woody C₃ species. In order to study the role of these enzymes, their activities were related to developmental changes of photosynthesis, respiration, and capacity for N assimilation. Activities of PEPC, NAD(P)⁺-MDH and NADP⁺-ME were high in young expanding leaves and decreased 2- to 3-fold in mature ones, suggesting that such enzymes play some role during the early stages of leaf expansion. In leaves of peach, such a role did not seem to be linked to C₃ photosynthesis or nitrate assimilation, in that photosynthetic O₂ evolution and activities of nitrate reductase (EC 1. 6. 6. 1) and glutamine synthetase (EC 6. 3. 1. 2) increased during leaf development. In contrast, leaf respiration strongly decreased with increasing leaf age. We suggest that in expanding leaves of this woody species the enzymes associated with malate metabolism have anaplerotic functions, and that PEPC may also contribute to the recapture of respiratory CO₂.     

Changes in carbohydrate and enzyme levels during development of leaves of Prunus persica, a sorbitol synthesizing species

Carbohydrate levels and activities of enzymes associated with starch, sucrose and sorbitol metabolism were assayed in leaves of peach [ Prunus persica (L.) Batsch cv. Redhaven] of different ages, in order to examine developmental changes in leaf carbohydrate metabolism. Dry matter, soluble protein, chlorophyll and the activities of key enzymes of the reductive pentose phosphate pathway increased during leaf development. The levels of leaf carbohydrates, especially sorbitol and starch, also increased. Changes of starch levels were related to increases in the activities of enzymes associated to starch metabolism, such as ADPglucose-pyrophosphorylase (E.C. 2.7.7.27) and amylase (E.C. 3.2.1.1. plus E.C. 3.2.1.2). The activities of enzymes involved in sucrose and sorbitol degradation decreased during leaf development, whereas the activities of aldose-6-phosphate reductase (E.C. 1.1.1.200) and cytosolic fructase-1,6-bisphosphatase (E.C. 3.1.3.11) increased. In contrast, the activity of sucrose-phosphate synthase (E.C. 2.4.1.14) did not vary in a significant manner. The results suggest that the ability to synthesize and utilize both sucrose and sorbitol changes as peach leaves mature, and also that there are differences in metabolism of these two transport sugars during leaf development.