施肥对旱地冬小麦近轴和远轴叶面气孔敏感性的影响

 施肥降低旱地冬小麦的叶片水势。当作物体内出现水分胁迫时,冬小麦叶片两面气孔对施肥的反应有明显差异。远轴叶面气孔对施肥的反应比近轴叶面气孔敏感。旱地施肥以后,冬小麦远轴叶面气孔首先收缩,且收缩的程度比近轴叶面大,从而使远轴叶面气孔阻力与近轴叶面气孔阻力的比值(Rab／Rad)增大。旱地施肥以后,远轴和近轴叶面气孔阻力均急剧增大,并且随肥力水平的提高(施肥量增加)而缓慢增大,二者呈直线关系发展趋势。旱地施肥对土壤水势有影响,但不论是提高还是降低土壤水势,均增大Rab／Rad。说明施肥确有增强旱地冬小麦远轴叶面气孔对环境因素变化敏感性的作用。     

冬小麦近轴和远轴叶面气孔对土壤水分胁迫反应的敏感性

当根层土壤水分含量不足,作物体内出现水分胁迫时,小麦叶片两面气孔的反应有明显差异。远轴叶面气孔对水分胁迫的反应比近轴叶面气孔敏感。当出现水分胁迫时,远轴叶面气孔首先收缩,且收缩的程度比近轴叶面气孔大。远轴与近轴叶面气孔阻力的比值(r_(ab)/r_(ab))与根层平均土壤水势(Ψ_s)有关,当Ψ_s大于-50 kPa时,r_(ab)/r_(ad)基本稳定在1.5左右,而当Ψ_s小于-50 kPa时,r_(ab )/r_(ab)随Ψ_s降低而明显增加。     

淡黄香青叶面气孔对不同海拔高度的适应表现

对比分析了分布于马衔山不同海拔高度的淡黄香青气孔复体的适应表现。结果表明：随海拔升高,植株叶片上气孔分布区域增大,叶两面气孔数量增加,气孔向外突起程度增加,孔下室及气孔张度增大。同时气孔每天的开放时间缩短。研究认为气孔复体的变化是淡黄香青适应高山低氧低二氧化碳分压的表现,同时也是植株因海拔升高造成的光合物质分配改变的结果。     

作物干旱指标对西北半干旱区春小麦缺水特征的反映

针对作物水分胁迫较为严重的西北半干旱区,应用CI301-PS光合作用仪对春小麦开花到乳熟期间的生理特征和环境因子进行了近1个月的观测, 并研究分析了3种作物干旱指标叶水势、作物水分胁迫指数以及气孔导度随时间变化和对气象因子的响应.发现干旱胁迫增加时,叶片水分减少,作物水分胁迫指数增大,叶水势降低,气孔导度有所减小.因此,气孔下腔的CO2浓度降低,作物净光合速率有所减小,不利于半干旱区小麦生物量的累积;三者相比,叶水势是反应西北半干旱区作物干旱最敏感的指标;受半干旱区逆湿现象的影响,9:00或之后一段时间观测叶水势和气孔导度对小麦等作物缺水状况反映得更客观.     

农田小麦在土壤湿润条件下的气孔活动

1984年在北京大屯农业生态系统试验站用MK 3型自动气孔计对土壤湿润、睛朗天气条件下冬小麦气孔传导力的日变化,季节变化、以及叶龄和梯度变化进行了观测。发现叶片传导力(gl)的日变化为双峰曲线,正午gl的降低可能是强光和高的饱和差作用的结果,从而限制了光合潜力的发挥。近轴面传导力(gd)和远轴面传导力(gb)的比(α)不是一个常数,这是因为两面气孔对环境条件的反应不同。gl和冠层传导力(g(?))都以孕穗期为最高。灌浆时期gl和gc有所降低,反映了叶片的过早衰老。这是影响本地区小麦产量的重要因素之一,其原因不仅与土壤水分有关,还与大气条件和病虫害有关。本文还讨论了gl随时龄的变化。观测表明,气孔计可以迅速准确地掌握作物群体的生理动态,有可能用于指导农田灌灌和管理。     

4种作物部分非叶器官气孔频度及其在光合作用中的意义（英文

通过对小麦（Triticum aestivum L.）、大豆 (Glycine max (L.) Merrill)、 油菜（Brassica napus L.）和玉米（Zea mays L.）等4种作物部分非叶器官(油菜和大豆的豆荚;小麦的外稃和玉米的苞叶)的气孔频度、气孔大小和气孔指数进行了比较研究。结果发现,上述作物非叶器官的气孔频度均较对应叶低;而气孔大小和气孔指数则变化较大。其中油菜和大豆非叶器官气孔的直径通常比对应叶大,小麦和玉米非叶器官的气孔直径则较小;大豆和油菜的非叶器官气孔指数比对应叶小,     

4种作物部分非叶器官气孔频度及其在光合作用中的意义（英文

 通过对小麦（Triticum aestivum L.）、大豆 (Glycine max (L.) Merrill)、 油菜（Brassica napus L.）和玉米（Zea mays L.）等4种作物部分非叶器官(油菜和大豆的豆荚;小麦的外稃和玉米的苞叶)的气孔频度、气孔大小和气孔指数进行了比较研究。结果发现,上述作物非叶器官的气孔频度均较对应叶低;而气孔大小和气孔指数则变化较大。其中油菜和大豆非叶器官气孔的直径通常比对应叶大,小麦和玉米非叶器官的气孔直径则较小;大豆和油菜的非叶器官气孔指数比对应叶小,     

水稻叶切片在光合反应液中气孔状态的扫描电镜观察

用溶氧电极测定水稻叶片光合放氧速率,其叶切片浸沉在光合反应液中,切面能与溶液进行气体交换。由于水稻叶切片用的是2.5mm~2,背腹两面气孔数总共有1400—1900多个,因此通过气孔进行气体交换,应该也是一个重要的途径。这方面未见     

不同类型作物对干湿交替环境的反应

通过对干湿交替环境下春小麦、马铃薯、大豆和玉米等作物的产量,水分利用效率及光合作用、蒸腾作用、气孔导度等生理变化的研究表明：（１）春小麦和马铃薯在干湿交替环境下可获得与充分供水相当的产量而它们的水分利用效率却显著提高,大豆减产幅度较大,玉米减产严重,其水分利用效率显著低于全湿处理;（２）浇水后各作物的光合速率、蒸腾速率和气孔导度都有所增加,但不同作物增加的幅度不同,就是同一作物各指标的增幅也不同;     

三种国产阴地蕨科植物叶的表皮构造

运用光学显微镜和扫描电镜对三种国产阴地蕨科植物 :劲直蕨萁 (Botrypusstrictus)、小阴地蕨(Botrychiumlunaria)和薄叶阴地蕨 (Sceptridiumdaucifolium)叶的成熟表皮构造进行了详细观察和研究。它们具有共同的特征 :气孔散生 ,气孔类型无规则型 ,气孔长轴方向多与叶脉延伸方向一致。但也存在明显区别 ,特别是劲直蕨萁与另外二个种的区别更为明显 :前者表皮细胞垂周壁直 ,相邻气孔不接触 ,保卫细胞平周壁具细条纹。但后二者之间亦有一定区别 :薄叶阴地蕨的气孔为下生式 ,不下陷 ,而小阴地蕨的气孔为两面气孔型 ,气孔下陷。本文是国内首次对阴地蕨科叶的表皮构造进行研究 ,其研究结果表明 ,表皮构造在阴地蕨科植物的鉴定上具有重要意义 ,并且在研究阴地蕨科的分类以及起源和演化上也有一定参考价值。     

Physical features of grass leaves influence the placement of eggs within the plant by the Hessian fly

Hessian fly eggs are more likely to be found on adaxial rather than abaxial surfaces of wheat leaves. These leaf surfaces differ in their physical features: the adaxial side of the leaf has parallel grooves and ridges while the abaxial side is relatively smooth. We used leaf models to investigate the relationship between Hessian fly egglaying and these physical features. When both sides of a green paper leaf model were treated with a wheat leaf extract, but only one side of the model was scored with parallel grooves, the grooved side received more eggs than the smooth side. As the number of grooves per surface increased from 0 to 10, eggs per model increased. When grooves and the wheat leaf extract were tested together and separately, the grooves significantly increased egg numbers in the presence, but not the absence, of wheat extract. In contrast, wheat extract increased egg numbers both in the absence and presence of grooves. Molding techniques were used to recreate the physical features of the adaxial and abaxial leaf surfaces of five grasses. For four of the grass genotypes (a triticale, two common wheats, and a durum wheat), patterns of egglaying on real leaves and molded models were similar, i.e., adaxial leaf surfaces and adaxial molded models were preferred over abaxial leaf surfaces and abaxial models. On the fifth grass, oat, preferences for the adaxial side of real leaves and for adaxial models were not as obvious. We conclude that the adult female Hessian fly obtains information about the leaf surface through her tactile and/or kinesthetic senses and uses this information when making egglaying decisions.     

Characterization of juvenile and adult leaves of Eucalyptus globulus showing distinct heteroblastic development: photosynthesis and volatile isoprenoids

Heteroblastic Eucalyptus (Eucalyptus globulus L.) leaves were characterized for their functional diversity examining photosynthesis and photosynthesis limitations, transpiration, and the emission of isoprene and monoterpenes. In vivo and combined analyses of gas-exchange, chlorophyll fluorescence, and light absorbance at 830 nm were made on the adaxial and abaxial sides of juvenile and adult leaves. When adult leaves were reversed to illuminate the abaxial side, photosynthesis and isoprene emission were significantly lower than when the adaxial side was illuminated. Monoterpene emission, however, was independent on the side illuminated and similarly partitioned between the two leaf sides. The abaxial side of adult leaves showed less diffusive resistance to CO(2) acquisition by chloroplasts, but also lower ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, than the adaxial leaf side. In juvenile leaves, photosynthesis, isoprene, and monoterpene emissions were similar when the adaxial or abaxial side was directly illuminated. In the abaxial side of juvenile leaves, photosynthesis did not match the rates attained by the other leaf types when exposed to elevated CO(2), which suggests the occurrence of a limitation of photosynthesis by ribulose bisphosphate (RuBP) regeneration. Accordingly, a reduced efficiency of both photosystems and a high non-radiative dissipation of energy was observed in the abaxial side of juvenile leaves. During light induction, the adaxial side of juvenile leaves also showed a reduced efficiency of photosystem II and a large non-radiative energy dissipation. Our report reveals distinct functional properties in Eucalyptus leaves. Juvenile leaves invest more carbon in isoprene, but not in monoterpenes, and have a lower water use efficiency than adult leaves. Under steady-state conditions, in adult leaves the isobilateral anatomy does not correspond to an equal functionality of the two sides, while in juvenile leaves the dorsiventral anatomy does not result in functional differences in primary or secondary metabolism in the two sides. However, photochemical limitations may reduce the efficiency of carbon fixation in the light, especially in the abaxial side of juvenile leaves.     

Variations in the dorso-ventral organization of leaf structure and Kranz anatomy coordinate the control of photosynthesis and associated signalling at the whole leaf level in monocotyledonous species

Photosynthesis and associated signalling are influenced by the dorso-ventral properties of leaves. The degree of adaxial/abaxial symmetry in stomatal numbers, photosynthetic regulation with respect to light orientation and the total section areas of the bundle sheath (BS) cells and the surrounding mesophyll (M) cells on the adaxial and abaxial sides of the vascular bundles were compared in two C₄[ Zea mays (maize) and Paspalum dilatatum ] and one C₃[ Triticum turgidum (Durum wheat)] monocotyledonous species. The C₃ leaves had a higher degree of dorso-ventral symmetry than the C₄ leaves. Photosynthetic regulation was the same on each side of the wheat leaves, as were stomatal numbers and the section area of the BS relative to that of the M cells (BS/M section area ratio). In contrast, photosynthetic regulation in maize and P. dilatatum leaves showed a marked surface-specific response to light orientation. Compared to the adaxial sides of the C₄ monocotyledonous leaves, the abaxial surfaces had more stomata and the BS/M section area ratio was significantly higher. Differences in dorso-ventral structure, particularly in Kranz anatomy, serve not only to maximize photosynthetic capacity with respect light orientation in C₄ monocotyledonous leaves but also allow adaxial and abaxial-specific signalling from the respective M cells.     

The higher resistance to chilling stress in adaxial side of <Emphasis Type="Italic">Rumex</Emphasis> K-1 leaves is accompanied with higher photochemical and non-photochemical quenching

Responses of two sides of Rumex K-1 leaves to chilling stress (5 °C, photon flux density of 100 μmol m⁻² s⁻¹) were studied by using gas exchange, chlorophyll (Chl) fluorescence, and spectrum reflectance techniques. The Chl and carotenoid contents in the two sides were not affected by chilling treatment, and both were higher in the adaxial side. The maximum quantum yield of photosystem (PS) 2 and fraction of functional PS1 in the abaxial side decreased more markedly than those in the adaxial side during the chilling treatment, indicating that the abaxial side was damaged more significantly than the adaxial side. Before chilling, there were no obvious differences in actual photochemical efficiency of PS2, photosynthesis, and photorespiration between two sides of the leaves. Under chilling stress, the actual photochemical efficiency of PS2, photosynthesis, and photorespiration all declined more significantly in the abaxial side, which was partly attributed to lower carboxylation efficiency in the abaxial side than that in the adaxial side. Non-photochemical quenching was higher in the adaxial side, though the de-epoxidation of xanthophyll cycle pigments’ pool on basis of Chl was higher in the abaxial side. Both the slower decrease in the photochemical quenching and the higher non-photochemical quenching may account for the higher resistance to chilling stress in the adaxial side of Rumex K-1 leaves.     

Dorsoventral variations in dark chilling effects on photosynthesis and stomatal function in Paspalum dilatatum leaves

The effects of dark chilling on the leaf-side-specific regulation of photosynthesis were characterized in the C(4) grass Paspalum dilatatum. CO(2)- and light-response curves for photosynthesis and associated parameters were measured on whole leaves and on each leaf side independently under adaxial and abaxial illumination before and after plants were exposed to dark chilling for one or two consecutive nights. The stomata closed on the adaxial sides of the leaves under abaxial illumination and no CO(2) uptake could be detected on this surface. However, high rates of whole leaf photosynthesis were still observed because CO(2) assimilation rates were increased on the abaxial sides of the leaves under abaxial illumination. Under adaxial illumination both leaf surfaces contributed to the inhibition of whole leaf photosynthesis observed after one night of chilling. After two nights of chilling photosynthesis remained inhibited on the abaxial side of the leaf but the adaxial side had recovered, an effect related to increased maximal ribulose-1,5-bisphosphate carboxylation rates (V(cmax)) and enhanced maximal electron transport rates (J(max)). Under abaxial illumination, whole leaf photosynthesis was decreased only after the second night of chilling. The chilling-dependent inhibition of photosynthesis was located largely on the abaxial side of the leaf and was related to decreased V(cmax) and J(max), but not to the maximal phosphoenolpyruvate carboxylase carboxylation rate (V(pmax)). Each side of the leaf therefore exhibits a unique sensitivity to stress and recovery. Side-specific responses to stress are related to differences in the control of enzyme and photosynthetic electron transport activities.     

Dorsoventral asymmetry of photosynthesis and photoinhibition in flag leaves of two rice cultivars that differ in nitrogen response and leaf angle

Rice is believed to show photosynthetic symmetry between adaxial and abaxial leaf sides. To verify this, we re‐examined dorsoventral asymmetry in photosynthesis, chlorophyll fluorescence and anatomical traits in flag leaves of two Oryza sativa cultivars that differ in nitrogen (N) response and in leaf angle: ‘Akenohoshi’, a cultivar that can adapt to low‐N (LN), with low leaf angle (more erect leaves), and ‘Shirobeniya’, a cultivar that is unable to adapt to LN, with higher leaf angle. Plants were grown under standard‐N (SN) and LN conditions. LN leaves of both cultivars became more erect than SN, but LN Akenohoshi still had more erect ones than Shirobeniya. Contrary to results of previous studies, leaves of both cultivars showed an asymmetry in photosynthetic rate between adaxial and abaxial sides (higher on the adaxial side) under SN. SN leaves of both cultivars showed lower susceptibility to photoinhibition on the adaxial side than on the abaxial side. However, leaves of Akenohoshi showed less asymmetry in these traits under LN than under SN, whereas leaves of Shirobeniya had similar degrees of asymmetry in these traits under both SN and LN. Both cultivars also showed dorsoventral asymmetry in anatomical traits of mesophyll tissue regardless of N level, but the degree of asymmetry was lower in LN Akenohoshi. These data reveal that rice leaves exhibit dorsoventral asymmetry in photosynthetic and anatomical features, and that the degree of asymmetry varies with cultivar and N level. It is suggested that lower leaf angles (particularly in Akenohoshi) in the presence of LN represent a light acclimation to prevent photoinhibition.     

Distinct light responses of the adaxial and abaxial stomata in intact leaves of Helianthus annuus L

Using a laboratory-constructed system that can measure the gas exchange rates of two leaf surfaces separately, the light responses of the adaxial and abaxial stomata in intact leaves of sunflower ( Helianthus annuus L.) were investigated, keeping the intercellular CO₂ concentration ( C _i) at 300  µ L L⁻¹. When evenly illuminating both sides of the leaf, the stomatal conductance ( g _s) of the abaxial surface was higher than that of the adaxial surface at any light intensity. When each surface of the leaf was illuminated separately, both the adaxial and abaxial stomata were more sensitive to the light transmitted through the leaf (self-transmitted light) than to direct illumination. Relationships between the whole leaf photosynthetic rate ( A _n) and the g _s for each side highlighted a strong dependence of stomatal opening on mesophyll photosynthesis. Light transmitted through another leaf was more effective than the direct white light for the abaxial stomata, but not for the adaxial stomata. Moreover, green monochromatic light induced an opening of the abaxial stomata, but not of the adaxial stomata. As the proportion of blue light in the transmitted light is less than that in the white light, there may be some uncharacterized light responses, which are responsible for the opening of the abaxial stomata by the transmitted, green light.     

Variation of Leaf Stomatal Conductance in Winter Wheat Canopy

Leaf stomatal conductance measured and analysed in the canopies of two winter wheat varieties in the field revealed that the probability of adaxial to abaxial conductance ratio followed an approximately normal distribution with a peake value of about 1.5. The ratio changed with the developmental stages being maximium at the heading stage. Leaf stomata in wheat of the upper part of the canopy were more active and showed more pronounced diurnal change of conductance than those of the lower part. Stomatal conductance decreased from top to bottom in canopy as a negative exponential function. By comparing adaxial and abaxial conductances in the apical, middle and basal parts of a leaf, the distribution of the stomatal conductances of a wheat leaf was as follows: a steady decrease from the basal part of adaxial, through the middle and apical parts of the adaxial surface turning to the apical part of abaxial, and then the middle and lastly, the basal part of abaxial. Based on values of the correlation coefficients among the various stomatal conductance and average stomatal conductance, the authors suggested that optimal apical measurement of stomatal conductance would be at the middle and apical parts and that of abaxial would be at middle and basal parts.     

An apparent anomaly in peanut leaf conductance

Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO₂ through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C₃ species is associated with the greater conductance of CO₂ through their upper leaf surfaces.     

冬小麦群体叶片气孔导度差异性分析

对冬小麦 (Triticum aestivum L.)两个品种 3个生育期测定和分析了群体叶片的气孔导度。结果表明 ,近轴面气孔导度比远轴面的大 ,二者之比呈近似正态分布 ,最大概率出现约为 1 .5,该比值在冠层垂直方向变化不显著 ,但随季节而变 ,抽穗期最大。叶片气孔导度从冠层顶部向下迅速递减 ,递减系数约为 0 .57,且各层日变化大致平行。冠层上部气孔活跃 ,导度日变化明显 ,下部日变化不大。同一叶片的气孔导度由近轴面的叶基 ,经由其叶中、叶尖 ,翻过尖点 ,再从远轴面的叶尖经叶中向叶基递减。对近轴面叶中、叶尖气孔导度与该面平均气孔导度相关系数较大 ,而对远轴面叶中、叶基气孔导度与该面气孔导度相关系数较大 ,据此建议测定近轴面气孔导度时 ,应以叶中、叶尖部位为最佳点 ,而测定远轴面气孔导度时 ,应以叶中、叶基部位为最佳点