气孔限制在植物叶片光合诱导中的作用

用三种不同的气体交换分析方法研究了玉米、大豆等叶片光合诱导期间的气孔限制作用。发现有利于气孔开放的因素如良好的土壤水分状况、较高的空气湿度等,能够缩短叶片的光合诱导期;CO_2饱和条件下,叶片的光合诱导期比在普通空气条件下的诱导期短得多;在光合诱导后期细胞间隙CO_2度达到稳态值以后,气孔导度的增加伴随着光合速率的提高和气孔限制值的下降。而气孔导度的降低则会引起光合速率的降低和气孔限制值的上升。诱导期存在气孔限制,并在后期占优势。     

小麦和大豆叶片的气孔不均匀关闭现象

用14CO2放射自显影的方法研究了田间小麦和大豆叶片在水分胁迫下的气孔关闭状况。正常浇水的小麦和大豆叶片呈现出对14CO2的均匀吸收。在小麦与大豆"片水势分别降至-1．75和-1．32MPa的土壤干旱条件下,两种作物叶片都发生气孔不均匀关闭。离休叶片在空气中快速脱水易引起气孔不均匀关闭。正常供水小麦叶片在晴天中午明显的光合午休时,无CO2的不均匀吸收。某些晴天中午,在大豆光合午休低谷时段观察到较明显的气孔不均匀关闭,用气体交换资料计算出的细胞间隙CO2浓度并不随气孔年度的降低而下降,反而略有回升。     

水分胁迫条件下气孔与非气孔因素对小麦光合的限制

较长时间、中度以上土壤干旱条件下,盆栽小麦叶片光合下降,气孔导度虽然降低,但叶内部CO_2浓度升高,叶肉CO_2导度下降,电子传递和羧化反应受到抑制,表明叶片光合的下降并非气孔部分关闭所致,叶肉细胞光合能力降低是干旱下小麦光合下降的原因。     

影响水稻光合午休的因素分析与响应曲面分析

当光强达到1700μmolphotonm~-2s~-1,叶温超过35℃的晴天中午,水稻可产生明显的午休．通过光合午休过程中各因素与光合速率的相关性分析,采用R～2（决定系数）决定最佳回归分析所建立的复合回归模式,以此数学模型绘制响应曲面图．本文由数学分析,证实了午休过程中光合速率下降的主要限制因子是气孔导度;并分析了光合午休过程中,气孔导度与其它各因素的交互作用对光合速率的影响,揭示午休是在干热条件下,气孔导度减小,胞间CO_2浓度明显降低,光合原料短缺导致的光合速率下降．     

田间小麦叶片光合效率日变化与光合“午睡”的关系

小麦灌浆初期叶片(旗叶)晴天中午光合速率下降(“午睡”)伴随了气孔导度、胞间CO_2浓度下降,而气孔限制值中午升高,进一步证实气孑L中午关闭是光合“午睡”的一个重要原因。叶片光合效率的中午下降并非都伴随着光合“午睡”现象。当两者同时发生时,胞间CO_2浓度降低,而光合速率与气孔导度、胞间CO_2浓度之间的相关性高于光合速率与光合效率之间的相关性。这些事实表明。即使光合效率中午下降是光合“午睡”的部分原因,但较之气孔中午关闭只是一个次要原因。     

大豆光合日变化与内生节奏的关系(简报)

在光照、温度、温度和CO_2浓度都相对恒定的条件下,大豆的光合速率、气孔导度和蒸腾速率都显现出早晚低,中午高的周期性变化。这是由大豆内生节奏造成的,能为环境因素所调整,与光合作用的午休并没有关系。     

田间冬小麦叶片光合午休过程中的非气孔限制

1　引　　言作物的光合午休是近几年作物栽培生理研究的热点之一 ,研究大都从生态、生理的各个方面阐述光合午休的成因与机理 ,如土壤水分降低 ,ＣＯ2 浓度下降 ,ＶＰＤ过高 ,气孔限制与非气孔限制 ,羧化效率降低等[4 ,6,10 ] .其中有关作物光合午休过程中的非气孔限制问题 ,多数研究仅根据Ｆａｒｑｕｈａｒ判据[2 ] 判断发生了非气孔限制即止 ,至于非气孔限制的具体内容 ,多见于讨论 ,缺乏直接的实验证据 .本文对大田生态条件下 ,冬小麦生育后期旗叶光合午休过程中的非气孔限制问题进行了较深入的研究 .2　材料与方法2 1　供试材料选用冬…     

烤烟旺长期气孔和非气孔限制对水分胁迫的反应

烤烟NC89、LJ851、LJ911在旺长期生长迅速,耗水量大。烟株生长的最适宜土壤相对含水量应保持在75%~85%,此土壤水分条件下的中午光合速率的下降是气孔限制所致。当土壤相对含水量低于75%,光合非气孔限制因素开始出现。当土壤相对含水量低于65%时,非气孔限制逐渐成为光合下降主导因子,并可能导致光合器官受到损伤。     

自然条件下中熟籼稻初穗期剑叶光合的气孔和非气孔限制特征

为探究自然条件下中熟籼稻初穗期剑叶光合作用的气孔与非气孔限制特征,利用LI-6400光合仪测定了4个水稻品种(恢复系R7-35,不育系井大3S,杂交F_1代井大3S/R7-35和对照品种9311)的气体交换数据,获得了它们的净光合速率、气孔导度、胞间CO_2浓度和气孔限制值对光的响应曲线。结果表明:与最大净光合速率相对应的饱和光强(I_(sat))分别为1500、1800、1200和1200μmol·m~(-2)·s~(-1);除井大3S/R7-35外,其他3个水稻品种的气孔导度随光强的增加而非线性增加,由此可知,在较高光强处限制这4个水稻叶片光合作用的因素是非气孔限制。与最小胞间CO_2浓度(C_i)相对应的光强分别为1600、1600、1400和1600μmol·m~(-2)·s~(-1),与最大气孔限制值(L_s)相对应的饱和光强分别为1400、1200、1400和600μmol·m~(-2)·s~(-1)。根据Ci降低和Ls升高作为判断叶片光合速率降低的主要原因是气孔因素的判据标准,品种9311则在光强小于1600μmol·m~(-2)·s~(-1)时,Ci随光强的增加而降低,在光强小于600μmol·m~(-2)·s~(-1)时,Ls随光强的增加而升高,但该品种在光强小于1200μmol·m~(-2)·s~(-1)时,其光合能力随光强的增加而非线性增加。这个结果与以Ci降低和Ls升高作为判断准则相互矛盾。为此,提出用植物叶片是否存在I_(sat)作为判断光合速率下降的非气孔限制因素准则,用气孔导度是否存在最大值作为植物叶片的气孔限制因素准则。     

水分胁迫对小麦叶片光合作用的影响及其与抗旱性的关系

在水分胁迫初期,两个小麦品种叶片光合速率,气孔导度和细胞间隙CO_2浓度降低,气孔限制值增加,光合速率的降低主要是气孔因素的限制。中度到严重水分胁迫使叶片光合速率、气孔导度和气孔限制值降低,细胞间隙CO_2浓度明显增加,且叶圆片放氧能力,叶绿体Hill反应、叶绿素荧光强度和表观量子产额降低,此时光合速率的降低主要是叶肉细胞光合活性的下降引起的。抗旱性弱的郑引一号叶肉细胞光合活性比抗旱性强的丰抗13更容易受到水分胁迫的影响。     

田间大豆光合午休原因的综合研究

本研究利用主成分分析构造同归模型,利用典型相关分析等方法,对自变量的重要程度进行排序,确定了光合午休的主要原因是气孔因素限制所致.光抑光合也是一个值得注意的因素,但不是主要因素.空气相对湿度、叶片与大气间水汽压差是诱发气孔限制的重要因素.当空气相对湿度较为适中时,叶温的影响较小,在空气相对湿度变坏的情况下,叶温才对光合午休有重要影响.     

我国1950s～1990s推广的玉米品种叶片光合特性演进规律研究

自1950s以来,我国玉米（Zea mays L.）产量以年递增幅度为126kg     

小麦籽粒发育初期土壤水分亏缺对植株各部位光合作用的影响

小麦开花后5～16天内给予不同程度的土壤干旱处理。无论轻、中或重度干旱均不同程度地释低了植株的净光合率,但不同器官或部位对干旱的反应不同,上部器官的光合受影响较小,故随着干旱的加重在全株光合中所占比例逐渐增加。恢复灌水后,曾受轻度及中度干旱的植株,中、上部器官的光合有补偿性增强,因而可能减轻产量的损失。     

PHOTOSYNTHESIS IN THE SNOW: THE ALGA CHLAMYDOMONAS NIVALIS (CHLOROPHYCEAE)1

Red blooms of snow algae consisting almost exclusively of large spherical red cells of Chlamydomonas nivalis (Bauer) Wille are widespread during the summer in the Beartooth Mountains in Montana and Wyoming. Field studies designed to examine the effects of temperature, light, and water potential on algal activity were performed with natural populations using photosynthetic ¹⁴C-HCO₃- or ¹⁴CO₂ incorporation as a measure of activity. The algae photo-synthesized optimally at 5.4 × 10⁴ lx, but were not inhibited by increased light intensity up to 8.6 × 10⁴ lx, the maximum observed in the field. Photosynthesis was sensitive to a reduction in water potential, and since low water potentials develop in snow at temperatures below 0 C, it is unlikely that significant algal activity occurs at the sub-0 temperatures which occur throughout winter. Photosynthesis was much lower following melting of the snow, but this was probably due to decreased diffusion of CO₂. The optimal temperatures varied considerably among the different algal populations. Most samples photo-synthesized optimally at 10 or 20 C but retained substantial activity at temperatures as low as 0 or -3 C. Exceptional samples photosynthesized optimally at 0 or -3 C. It is proposed that the varied temperature responses reflect the presence of different temperature strains. Taken together, the data suggest that development of the snow algae can occur only during the summer months.     

UNIQUE LOCATION OF THE PHYCOBILIPROTEIN LIGHT-HARVESTING PIGMENT IN THE CRYPTOPHYCEAE1

The cryptophyte algae, or cryptomonads, comprise a small algal group with a unique photosynthetic apparatus. Both a chlorophyll a/c₂ light-harvesting complex and a phycobiliprotein antenna (which can be either phycoerythrin or phycocyanin) are present, with the phycobiliprotein playing the major role in harvesting light for photosynthesis. Longstanding circumstantial evidence suggested that, in cryptophytes, the phycobiliprotein is located in the intrathylakoid space (thylakoid lumen) rather than on the outer surface of the thylakoid as part of a phycobilisome as in other algae. We used immunogold labeling to show conclusively that 1) the phycoerythrin (PE) of the cryptophyte Rhodomonas lens Pascher and Ruttner is located within the intrathylakoid space, 2) the PE is not exclusively bound to the thylakoid membrane but instead is distributed across the thylakoid lumen and 3) a fraction of this PE is tightly associated with the thylakoid membrane. The thylakoids are not everted to compensate for this unusual arrangement. The location of the major light-harvesting pigment on the “wrong” side of the otherwise very normal photo-synthetic membrane is unexpected, unique to the cryptophytes, and, remarkably, does not impair the photosynthetic abilities of this organism. A model is presented which incorporates these results -with previous information to give a complete structural picture of the cryptophyte light-harvesting apparatus.     

鼎湖山森林群落的光能利用效率

本文研究了鼎湖山自然保护区,亚热带季风常绿阔叶林和针叶阔叶混交林的光能利用效率。根据群落的垂直结构和成层现象,应用红外线CO_2气体分析法,分层测定了主要植物22种58株的光合速率.计算了群落的生产力;用量子传感器分层测定了两个群落的光合有效辐射,并计算其光能利用效率。结果表明:阔叶林总生产力的光能利用效率为14.28%,混交林为12.01%,说明了不同森林类型对光能资源的利用效率。     

银杏光合与蒸腾特性的研究

通过测定银杏净光合速率、蒸腾速度、气孔阻力等生理指标和观测银杏叶片形态、解剖特征,结果表明：１．银杏光补偿点为７６μｍｏｌ．ｍ＾－１．ｓ＾－１,光饱和点为１０４０μｍｏｌ．ｍ＾－２．ｓ＾－１。超过光饱和点后,随光照强度增加光合强度反而下降。２．银杏光合最佳温度为２６℃。３．净光 速率的日变化呈“午休”型的双峰曲线变化,最高峰出现在１０：００Ａ．Ｍ．前后,次峰出现在６：００Ｐ．Ｍ．前后。４．蒸腾速度     

PHYSIOLOGICAL AND PHOTOSYNTHETIC CHANGES DURING THE FORMATION OF RED APLANOSPORES IN THE CHILOROPHYTE HAEMATOCOCCUS PLUVIALIS1

Changes in physiological and photosynthetic parameters were followed in the freshwater chorophyte Haematococcus pluvialis Flotow (Volvocales) during the transformation of green vegetative cells to red aplanospores.Formation of aplanospores was induced by exposure to a nitrogen-deficient medium. In spite of an increase in cellular volume (from 6.6 to 41 pL) and amassive accumulation of astaxanthin, chlorophyll content of the mature aplanospore decreased only slightly (from 16 to 14.8 pg'cell^?1)as compared to the vegetative cell. Aplanospore formation was characterized by a gradual reduction in the maximal photosynthetic rate and increases in the photosynthetic quantum requirement and minimal turnover time for photosynthetic O₂ evolution.Respiration rate increased (4.2 times)and excretion rate decreased (up to 8.8 times) during aplanospore formation. Measurements of photosynthetic unit “size” and estimation of the cellular content of photosystem II reaction centers suggest that the photosynthetic complex remains relatively centers stable during the formation process and in the mature aplanospore.A functional relationship between the describe changes in the physiology of the cells and their photosynthetic parameters is proposed.     

光下无CO_2气体处理对叶片光合强度的影响

小麦等C_3植物的叶片在光下经无CO_2或低CO_2气体处理后,通入高CO_2气体,光合强度出现“升、降、升”的波动,而玉米等C_4植物无此现象。不同植物的光合波动幅度不同。强光、高CO_2、低O_2等能缩短第一次光合上升时间,增大光合下降幅度;而低CO_2、高O_2等则减少光合下降幅度。此现象与RuBP及ATP的含量变化有关。