植物的根营养

植物根营养的范围是极其广阔的。它包括着有关於吸收和同化土壤中礦物物质和有机物质的问题,有关於水分的吸收和用水分供应地上器官的问题,有关於根系活动的和根系同周围环境条件相互作用的许多其他表现的问题。在本概述中,我们只谈论属於植物对矿物质的吸收和同化的问题以及属於阐明各个器官在这个过程中的作用的问题。同时,我们将用主要的注意来阐明根系在同化营养物质中的作用。植物同化土壤中的营养物质是极其复杂的过     

名词解释

[42]代谢源(metabolic source) 植物制造及产生同化产物的部位或器官,如进行光合作用的长成的叶片,进行矿质吸收和转化的根系,以及转化、输出养料的萌发种子等。同一器官在植物生长发育的过程中,可以由库转变为源;例如幼小的叶子需要从成长的叶片获得同化产物,这时是库;等到长大进行光合作用以后,就会转变为制造及输出同     

水稻秧苗根系活力的初步研究

水稻秧苗的地上部与根系是有机的统一整体。根系不仅是稻苗吸收水份、矿质营养及支持地上部的重要器官,周时也是植物体内物质代谢循环里许多重要物质的合成器官;而根系的生长所需要的养分也要地上部制造的养料来供给,所以秧苗地上部的生长状况好坏可通过根系的活动能力反映出来。所谓根系活力是指秧苗吸收、合成、生长的综合表现。它与     

温度对小麦成熟期间叶片光合能力衰退的影响

引言许多工作先后指出,稻麦等禾谷类作物结实器官中干物质的大部分,一般是开花后的同化器官所制造的。从这一点出发,应该注意这段时间内执行同化功能的叶器官的光合作用。叶片的同化能力是受一系列的外界条件所影响的。诸如光照之强弱,土湿、气湿之大小和土温、气温之高低……等,都会对这段时间内叶片活动发生作用,影响光合器官的寿命、结构和功能,从而也影响了物质     

植物根系的分泌生理及其在农业上的意义

植物根系不仅是一个强大的吸收器官,也是一个活跃的代谢、合成器官,而且还是一个积极的分泌器官。植物根系分泌物的成分植物根系能分泌各种物质,其中不仅有矿质营养元素,而且有各种有机物质。这些分泌物有     

植物根系的分泌生理及其在农业上的意义

植物根系不仅是一个强大的吸收器官和活跃的代谢器官,而且也是一个分泌器官。植物根系能分泌各种物质,其中不仅有矿质营养元素,而且还有各种有机物质,如糖、氨基酸、有机酸、生长素、生物碱、维生素、核苷酸和酶等。     

叶子的光合作用和同化物质消耗的关系

一系列的研究者确定在抑制同化物质外运时,葉子的光合作用强度降低。因为同化物质的外运是和它的消耗联系着的,所以正如所证明的,我们可以看到光合作用对同化物质被植物消耗的依赖性。我们的工作中,这种关系是应用C~(14)O_2同位素的方法对茶豆植物进行研究的。这植物在温室内用含有微量元素的一半濃度的溶液培养。     

五种C4荒漠植物光合器官中含晶细胞的比较分析

为了探讨荒漠植物适应干旱环境的机理,选择光合器官发生很大变化的5种C4荒漠植物进行了解剖结构的对比研究。结果表明,这5种植物中含晶细胞的数量、大小、形态和分布位置等存在差异。白梭梭（Haloxylon persicum）和梭梭（H.ammodendron）的同化枝普遍具有含晶细胞;沙拐枣（Calligonum mongolicum）的含晶细胞很少,一般只分布在贮水组织或靠近栅栏组织处;木本猪毛菜（Salsola arbuscula）的含晶细胞也不多,主要分布在栅栏组织和表皮细胞之间;猪毛菜（S.collina）的含晶细胞更少,仅在贮水组织中偶尔可见晶簇。比较梭梭、白梭梭和沙拐枣同化枝不同部位的解剖结构发现,梭梭同化枝基部含晶细胞最多,中部次之,顶部最少;白梭梭同化枝项部的含晶细胞数量较多,中部及基部较少;沙拐枣同化枝顶部与基部的粘液细胞较多,中部较少,基部几乎没有栅栏组织,而其维管组织较为发达。综合晶体的酸碱溶解性及硝酸银组化分析结果,并参照能谱仪的分析结果得知,梭梭、白梭梭、沙拐枣和木本猪毛菜的叶片或同化枝中所含晶体的主要成分为草酸钙。通过比较解剖结构发现,梭梭和白梭梭的同化枝中含晶细胞最多,其它3种植物的同化器官中含晶细胞较少,而沙拐枣同化枝中有粘液细胞存在。     

CaM拮抗剂对麦苗氮素同化酶及干物重的影响

钙调蛋白拮抗剂ＣＰＺ（Ｃｈｌｏｒｐｒｏｍａｚｉｎｅ,氯丙嗪,简称ＣＰＺ）抑制小麦幼苗对外源硝态氮的吸收及其向有机氮的转化,对根器官的影响明显大于叶片,这与ＣＰＺ处理后不同器官中ＮＲ、ＧＳ活性受影响的程度相一致;根和茎叶干物质累积量下降。但ＣＰＺ处理后小麦幼苗不同器官中全钙含量增加,说明作为植物第二信使系统的钙调蛋白受拮抗影响植物的氮同化过程。     

为什么要保护生物多样性

生物多样性是生态系统的主要组成部分,绿色植物吸收太阳的光能和土壤中的水分和养分,制造有机物质,而微生物又分解有机残落物为矿质养分,供应植物生长的需要,这个过程使生物多样性得以生存和不断发展。它是人类赖以生存的物质基础,没有植物,人类就无法生存。但是,在世界已知的265000种高等植物中,只有大约 150种被作为食物的主要来源,只     

Rhythm assimilation in the isolated canine heart under isovolumic conditions

Isolated canine heart has an expressed ability for autoregulation of bioelectrical and contractile functions irrespective of the neurohumoral factors influence on the work of the heart, and Frank-Starling law. Under the change of stimulation frequency, the autoregulation of heart functions is carried out as rhythm assimilation at organ (cell) level. The heart has a higher ability to bioelectrical rhythm assimilation rather than the mechanical rhythm assimilation. Incomplete rhythm assimilation is characterised by the alternation of contractions. The "Everything or nothing" law has no applicability to the work of the heart.     

CO2浓度倍增对几种植物叶片的叶绿素蛋白质复合物的影响

研究了CO_2浓度倍增对大豆(Glycine max L.,C_3植物)、黄瓜(Cucumis sativus L.,C_3植物)、谷子(Setaria italica (L.) Beauv.,一种不很典型的C_4植物)和玉米(Zea mays L.,C_4植物)叶片的叶绿素蛋白质复合物的影响。实验植物盆栽于聚乙烯薄膜(或玻璃)的开顶式培养室中。播种后对照室的CO_2浓度立即保持在大气浓度(350±10)×10~(-6)中,CO_2浓度倍增处理室则保持在(700±10)×10~(-6)下。研究结果表明,对于大豆、黄瓜和谷子,CO_2浓度倍增均使其PSⅡ捕光叶绿素a/b-蛋白质复合物(LHCⅡ)的聚合体态的量增多,单体态的量减少。但C_4植物玉米对CO_2浓度倍增没有这样的反应。作者认为在大豆等植物中,LHCⅡ的上述状态变化可能是植物的光合机构对长期高CO_2浓度的一种适应效应,这样能提高光合作用中光能的吸收、传递和转换的效率,并支持高效的光合碳素同化作用。     

The phenology of leaf quality and its within‐canopy variation is essential for accurate modeling of photosynthesis in tropical evergreen forests

Leaf quantity (i.e., canopy leaf area index, LAI), quality (i.e., per‐area photosynthetic capacity), and longevity all influence the photosynthetic seasonality of tropical evergreen forests. However, these components of tropical leaf phenology are poorly represented in most terrestrial biosphere models (TBMs). Here, we explored alternative options for the representation of leaf phenology effects in TBMs that employ the Farquahar, von Caemmerer & Berry (FvCB) representation of CO₂ assimilation. We developed a two‐fraction leaf (sun and shade), two‐layer canopy (upper and lower) photosynthesis model to evaluate different modeling approaches and assessed three components of phenological variations (i.e., leaf quantity, quality, and within‐canopy variation in leaf longevity). Our model was driven by the prescribed seasonality of leaf quantity and quality derived from ground‐based measurements within an Amazonian evergreen forest. Modeled photosynthetic seasonality was not sensitive to leaf quantity, but was highly sensitive to leaf quality and its vertical distribution within the canopy, with markedly more sensitivity to upper canopy leaf quality. This is because light absorption in tropical canopies is near maximal for the entire year, implying that seasonal changes in LAI have little impact on total canopy light absorption; and because leaf quality has a greater effect on photosynthesis of sunlit leaves than light limited, shade leaves and sunlit foliage are more abundant in the upper canopy. Our two‐fraction leaf, two‐layer canopy model, which accounted for all three phenological components, was able to simulate photosynthetic seasonality, explaining ~90% of the average seasonal variation in eddy covariance‐derived CO₂ assimilation. This work identifies a parsimonious approach for representing tropical evergreen forest photosynthetic seasonality in TBMs that utilize the FvCB model of CO₂ assimilation and highlights the importance of incorporating more realistic phenological mechanisms in models that seek to improve the projection of future carbon dynamics in tropical evergreen forests.     

半干旱生态条件下植物个体的综合生态效应的空间距离分布规律

通过对有关生态因子的空间距离变化规律的测定和引入相应的生态效应系数综合分析,得到在半干旱生态条件下植物个体的综合生态效应的空间距离分布规律为: E=α_1E_(1o)[1 (x/hc)~2]-3/2 (α_NE_(NO) α_WE_(WO))[1 (x/hr)~2]-3/2 (α_cE_(co) α_hE_(ho))[1 (x/hc)~2]-1/2由于具抑制效应的因子的生态效应随相对空间距离增加而减弱的速度大于其互惠效应的因子,在一定相对空间距离处(w/h=6.8)综合生态效应由干扰转变为互惠。定义了生态场的概念。     

SHORT‐TERM MEASUREMENT OF CARBON STABLE ISOTOPE DISCRIMINATION IN PHOTOSYNTHESIS AND RESPIRATION BY AQUATIC MACROPHYTES,WITH MARINE MACROALGAL EXAMPLES1

Progress in the study of stable isotope discrimination in carbon assimilation by aquatic macrophytes has been slower than for other groups of primary producers, such as phytoplankton and terrestrial plants. A probable reason has been the methodologies employed for such a study: field collections or long‐term incubations, both relying on the observation of changes in carbon isotope composition of plant tissue. Here, we present a short‐term incubation method based on the change in carbon stable isotope composition in water. Its fundamental advantage over the other approaches is that the change in stable isotope composition in water in a closed system is much faster than in the plant tissue. We applied the method to investigate the relationship between carbon assimilation intensity and isotope discrimination. The results included a relatively small discrimination in respiration, a significant influence of carbon assimilation rate on discrimination, and the suggestion of HCO₃^? or CO₂ uptake in photosynthesis. The information gathered using this method would be difficult to obtain in other ways, and so we believe that it should contribute to a better understanding of the physiology and ecology of aquatic macrophytes.     

毛乌素沙地根际土壤微生物数量与植物盖度相关性的初步研究

对毛乌素沙地不同生境下根际土壤微生物细菌、真菌、放线菌的数量进行了研究,结果表明：根际不同菌种菌落总量表现为细菌最多,放线菌次之,真菌最少;地貌部位、植物类型等不同生境条件下,微生物菌落总量和垂直分布上均存在明显差异;固定沙丘迎风坡及荒草地的生物多样性指数高于其他地方,各微生物类群间分布比例较均匀。植物盖度与微生物的数量并不存在直接的相关性。因此,在改善毛乌素沙地生态环境时,应关注不同生境条件下植被演替的递续性和植物类型的配置。     

Catchment land cover influences macroinvertebrate food‐web structure and energy flow pathways in mountain streams

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How does a legume nodule work?

Nitrogen fixation in legume root nodules requires biochemical cooperation between the plant and Rhizobium cells. Bacteroids contribute the N₂-fixing system and haem for leghaemoglobin, but apart from the production of the globin moiety of leghaemoglobin and the assimilation and export of the NH₃ produced, little is known about the contributions of the plant. It now appears that the plant cell may regulate the type and/or quantity of carbon compounds supplied to the Rhizobium bacteroids.     

SEASONAL PATTERN OF NET PHOTOSYNTHESIS OF ARTEMISIA TRIDENTATA

Gas exchange studies were carried out on Artemisia tridentata during the course of a growing season using microclimatically controlled cuvettes and infrared gas analysis. A definite seasonal pattern of net photosynthesis emerged. This pattern was influenced by the interaction of four major factors: plant water potential, leaf temperature, irradiation, and stage of phenological development. In spring and early summer, when plant water stress was minimal, photosynthesis rate was mainly correlated with leaf temperature and irradiation. During mid and late summer, increased plant water stress and phenological changes assumed at least equal importance with temperature and irradiation in limiting net photosynthesis. Indeed, plant water potential, mainly through its influence on stomatal aperture, r_s‘, was probably the single most important factor influencing assimilation rate of this species on a seasonal basis. However, variations in mesophyll resistance to CO₂ flux, r_m‘, in response to temperature, water stress, or phenological changes also were involved. Sagebrush photosynthesis under field conditions was highest in late May and early June, and declined thereafter, minimum rates occurring in August during the driest period. Optimal temperatures for net photosynthesis were higher later in the season, indicating a change in gas exchange capacity more suitable to the warmer temperatures later in the season.