大田和旱棚环境下小麦旗叶气孔性状变异及其与光合参数的关系

为了明确小麦旗叶与气孔性状的变异及其对干旱胁迫的响应,在大田和旱棚环境下种植204个小麦品种,测定其旗叶和气孔性状,并对10份气孔性状极端的材料的光合参数进行测定分析。结果表明,小麦品种间旗叶和气孔性状存在显著差异,在旱棚环境下旗叶长度、旗叶面积、气孔长度和气孔面积较大田分别降低了6.6%、7.0%、1.4%和3.0%,气孔密度增加了12.0%。旗叶长度与气孔长度、旗叶宽度与气孔宽度和旗叶面积与气孔面积的相关系数在大田环境下分别为0.18、0.15和0.18,在旱棚环境下分别为0.31、0.18和0.25。极端材料中,与气孔密度大的材料相比,气孔密度小的材料的净光合速率在大田环境下增大了9.67%,蒸腾速率增加27.57%,瞬时水分利用效率减少26.04%。在大田环境下气孔长度与蒸腾速率和气孔导度均呈正相关(相关系数均为0.37),气孔面积与蒸腾速率呈正相关(相关系数为0.39),气孔密度与蒸腾速率和净光合速率均呈负相关(相关系数均为-0.38);在旱棚环境下气孔长度与蒸腾速率和净光合速率均呈正相关(相关系数分别为0.36和0.42)。这说明,环境条件对小麦旗叶性状之间的相关性影响较大,较大的旗叶面积和较低的气孔密度会促进小麦光合作用,有利于提高小麦的产量及抗旱性。

Comparison of Stomatal Characteristics between Dendrobium loddigesii and Dendrobium candidum

[Objective]This study was to reveal the physiological and ecological mechanism of growth and development of test-tube seedlings.[Methods]Leaf stomata of test-tube seedlings of D.loddigesii and D.candidum at different growth and development stages were observed under scanning electron microscope,and their fluorescence induction response curve was assayed by using modulate fluorometer.[Results] At each growth and development stage,D.loddigesii test-tube seedling has a higher leaf stomatal density over D.candidum,while a lower stomata opening rate.Along with the growth,the size of stomata of both D.loddigesii and D.candidum did not change obviously,but their stoma density increased by 83% and 17.6% respectively.Leaf stomata opening rate reached the highest at the age of 240-day-old.Under the conditions of three settled light intensities,stomatal opening degree of D.loddigesii was increased by the intensity of illumination,the maximum aperture occurred at the light intensity of 54 μmol/m2·s.Given the same culture condition,both the maximum electron transport rate（14 μmol/m2·s）and light saturation point（318 μmol/m2·s）of D.loddigesii test-tube seedling are lower than that of D.candidum（20 μmol/m2·s,483 μmol/m2·s）.Moreover,the potential photosynthetic capacity of D.loddigesii is relatively poor.[Conclusion]The photosynthetic rate varies among different species of Dendrobium,which could be attributed to their different stomatal characteristics.Usually,the light intensity of tissue culture chamber is set up as 27 μmol/（m2·s）,where both D.loddigesii and D.candidum do not acquire an optimal state for their leaf stomatal opening.Considering the characteristics to select suitable culture condition,the stomatal aperture and photosynthetic rate could be enhanced,which can promote the growth and development of test-tube seedlings.

基于叶片形态及显微特征评价12个猕猴桃栽培品种的抗旱性

【目的】探讨不同猕猴桃品种的叶片宏观形态和微观结构特征的差异,筛选抗旱性评价关键指标并进行抗旱性综合评价。【方法】采用多功能图像分析法、石蜡切片法和扫描电镜技术,选取12个猕猴桃栽培品种为材料,对叶片形态、气孔器和表皮毛微特征、解剖结构等24项指标进行观测、记录。通过方差分析明确不同品种的叶片形态和解剖结构的差异,以主成分分析筛选综合指标,运用隶属函数法进行抗旱性综合评价。【结果】不同猕猴桃品种的叶片形态、解剖结构、气孔器及表皮毛特征具有显著差异,相关性分析表明不同指标间具有显著或极显著的相关性,运用主成分分析从24个抗旱相关指标中筛选了叶片宽度、叶形指数、气孔长轴、单簇茸毛数、上表皮细胞厚度、下表皮细胞厚度、栅海比、组织结构紧密度共8项关键性指标。通过隶属函数法比较不同品种间的抗旱能力,抗旱性强弱为:徐香>金美>金霞>海沃德>金艳>金魁>金梅>东红>翠玉>金桃>桂海4号>Hort16A。使用聚类分析将12个猕猴桃品种按抗旱能力聚为5类。【结论】通过对叶片形态及显微结构的分析,评价并筛选到抗旱性相对较强的猕猴桃品种,研究结果为猕猴桃品种改良、品种选择及生产管理等提供了基础理论依据。

山桐子雌、雄株叶片表皮微形态特征比较

【目的】探究山桐子叶片表皮微形态特征及其雌、雄株差异,为该种质资源的挖掘利用提供参考。【方法】利用扫描电镜对40份山桐子(雌、雄株各半)叶片进行微形态观察,测定12个气孔相关性状,并分析样品间的异同。【结果】(1)山桐子雌、雄株叶片的表皮毛、细胞形态、气孔特征及蜡质式样相似,其下表皮密布的类锥形纤维体型蜡质纹饰,鲜见于其他植物类群。(2)山桐子雌株叶片的气孔大小(长度、宽度、面积及周长)及密度相关参数均略大于雄株;雄株叶片的气孔开口相关参数(孔隙宽度、开口面积及气孔开度)均略高于雌株;但所有差异均未达到统计学显著水平(P>0.05)。(3)多数气孔性状彼此显著相关,而气孔密度与其他性状关联较弱,可能受到相对独立的遗传调控。【结论】研究明确了山桐子叶片表皮的微形态特征,其类锥形纤维体型蜡质式样可作为种质评鉴的关键依据,其气孔性状参数可为童期种苗的性别判定提供重要参考。

CO_(2)辐射效应与生理效应对气候系统影响异同的模拟研究

基于CESM地球系统模式,模拟研究不同CO_(2)浓度变化情景下,在快响应阶段和平衡阶段,CO_(2)通过影响大气辐射传输过程的辐射效应和通过影响植被气孔的生理效应对气候系统的影响和作用机制异同。试验结果表明,在CO_(2)倍增的情况下,CO_(2)辐射效应和生理效应都会引起全球地表的增温。辐射效应在两个阶段的地表增温中均起主导作用,而在快响应阶段,生理效应在全球陆表增温中贡献率达到了(27.5±0.9)%。CO_(2)辐射效应和生理效应对全球水循环的影响有明显差异。在平衡阶段,CO_(2)辐射效应使全球地表蒸散增加(5.2±0.1)%,径流量增加(8.0±0.4)%;而CO_(2)生理效应使全球地表蒸散量下降(3.9±0.1)%,径流量增加(10.1±0.4)%。在快响应阶段,生理效应在蒸散量的变化中占据主导作用。在CO_(2)倍增试验基础上,又进行了大气CO_(2)浓度分别为400×10^(-6)、600×10^(-6)、800×10^(-6)、1000×10^(-6)的模拟试验。随着CO_(2)浓度的增加,受辐射效应影响,地表温度、蒸散量和降水量出现持续增加,但增幅有所放缓;受CO_(2)生理效应影响,地表蒸散量持续减少,下降幅度并未出现明显变化。CO_(2)辐射效应和生理效应的协同作用具有非线性。对于地表温度、降水和蒸散等变量,CO_(2)辐射效应和生理效应共同作用引起的变化与两者单独作用时引起的变化之和存在差异,且这种差异随着CO_(2)浓度的增加越来越显著。

A polygalacturonase gene OsPG1 modulates water homeostasis in rice

A dynamic plant architecture is the basis of plant adaptation to changing environments.Although many genes regulating leaf rolling have been identified,genes directly associated with water homeostasis are largely unknown.Here,we isolated a rice mutant,dynamic leaf rolling 1(dlr1),characterized by‘leaf unfolding in the morning-leaf rolling at noon-leaf unfolding in the evening’during a sunny day.Water content was decreased in rolled leaves and water sprayed on leaves caused reopening,indicating that in vivo water deficiency induced the leaf rolling.Map-based cloning and expression tests demonstrated that an A1400G single base mutation in Oryza sativa Polygalacturonase 1(OsPG1)/PHOTO-SENSITIVE LEAF ROLLING 1(PSL1)was responsible for the dynamic leaf rolling phenotype in the dlr1 mutant.OsPG1 encodes a polygalacturonase,one of the main enzymes that degrade demethylesterified homogalacturonans in plant cell walls.OsPG1 was constitutively expressed in various tissues and was enriched in stomata.Mutants of the OsPG1 gene exhibited defects in stomatal closure and decreased stomatal density,leading to reduced transpiration and excessive water loss under specific conditions,but had normal root development.Further analysis revealed that mutation of OsPG1 led to reduced pectinase activity in the leaves and increased demethylesterified homogalacturonans in guard cells.Our findings reveal a mechanism by which OsPG1 modulates water homeostasis to control dynamic leaf rolling,providing insights for plants to adapt to environmental variation.

The evolution and diurnal expression patterns of photosynthetic pathway genes of the invasive alien weed,Mikania micrantha

Mikania micrantha is a fast-growing global invasive weed species that causes severe damage to natural ecosystems and very large economic losses of forest and crop production.It has advantages in photosynthesis,including a similar net photosynthetic rate as C4 plants and a higher carbon fixation capacity.We used a combination of genomics and transcriptomics approaches to study the evolutionary mechanisms and circadian expression patterns of M.micrantha.In M.micrantha,16 positive selection genes focused on photoreaction and utilization of photoassimilates.In different tissues,98.1%of the genes associated with photoresponse had high expression in stems,and more than half of the genes of the C4 cycle had higher expression in stems than in leaves.In stomatal opening and closing,2 genes of carbonic anhydrase(CAs)had higher expression at 18:00 than at 8:00,and the slow anion channel 1(SLAC1)and high-leaf-temperature 1 kinase(HT1)genes were expressed at low levels at 18:00.In addition,genes associated with photosynthesis had higher expression levels at 7:00 and 17:00.We hypothesized that M.micrantha may undergo photosynthesis in the stem and flower organs and that some stomata of the leaves were opening at night by CO_(2)signals.In addition,its evolution may attenuate photoinhibition at high light intensities,and enhance more efficient of photosynthesis during low light intensity.And the tissue-specific photosynthetic types and different diurnal pattern of photosynthetic-related genes may contribute to its rapid colonization of new habitats of M.micrantha.

Effects of Paclobutrazol Seed Priming on Seedlings Quality,Physiological and Bakanae Disease Index Characteristics of Rice(Oryza sativa L.)

Rice(Oryza sativa L.)is one of the most important cereal crops in the world.Bakanae disease is a significant rice disease widely distributed in rice-growing regions worldwide.Therefore,the present investigation aimed to assess the optimal concentrations of paclobutrazol(PBZ)as a treatment for rice grains(cv.Sakha 108)to control bakanae disease,also evaluating its impact on grain germination,seedling growth parameters as well as disease index.Paclobutrazol concentrations had no significant impact on seed germination,regardless of whether the seeds were incubated with Fusarium fujikuroi or not.Application of PBZ,either alone or in combination with fungal pathogens,negatively impacted the rice seedlings’height.Paclobutrazol at 25,50 and 100 mg/L,combined with the fungal pathogen positively impacted root length.Paclobutrazol at 3 and 6 mg/L mitigated the adverse impact on chlorophyll pigments content in infected seedlings.The highest proline contents were achieved by 100 mg/L PBZ alone or in combination with fungal pathogens.It has been observed that the application of PBZ,either alone or in combination with a fungal pathogen,leads to the enhancement of catalase,peroxidase,and polyphenol oxidase activities.The median lethal concentration of PBZ was 0.874 mg/L;applying low concentrations of paclobutrazol effectively increased the percentage of fungal growth suppression.Application of PBZ,at higher concentrations(50 and 100 mg/L),decreased infection percentage and disease severity index(DSI)significantly.These findings suggest that PBZ can be an effective treatment for controlling bakanae disease and enhancing resistance in rice plants.

基于改进boxlevelset的叶片显微图像气孔分割方法

深度学习技术已被用于气孔分割任务。然而,训练数据的标注是机械且耗时的人工过程,特别是在数据集比较大的时候。为了减少标注时的工作量,研究提出一种基于弱监督模型Boxlevelset的气孔分割方法。将原模型的特征提取网络ResNet50替换为ResNest50,并且在特征提取过程中引入CBAM模块。以黑杨气孔为研究对象,该方法可有效分割出气孔,F1得分为79.89。所提出的方法减少了标注训练数据所需的时间,同时保证了分割精度,从而显著减少了训练气孔分割网络所需的工作量。

参与气孔脱落酸信号转导的离子通道与转运蛋白研究进展

干旱胁迫条件下,脱落酸会诱导植物气孔的快速关闭。定位在保卫细胞质膜与液泡膜上的特定离子通道和转运蛋白是脱落酸信号转导途径下游的关键效应分子,其活性变化参与对气孔开度的渗透调节。本文梳理了参与气孔脱落酸信号转导的主要离子通道和转运蛋白,探讨了这些跨膜孔道蛋白的分子表征及活性调控模式,并对其作为遗传靶标在改良作物水分利用效率层面的潜力进行了展望。

甜瓜CmEPF基因家族的鉴定及表达分析

【目的】表皮模式因子(epidermal patterning factor,EPF)是一类植物特有的分泌蛋白,在植物生长发育特别是气孔形态建成过程中发挥着重要作用,旨为揭示甜瓜EPF基因的特性和功能。【方法】对甜瓜CmEPF基因家族进行基因组鉴定,利用生物信息学手段对其基因结构、系统进化以及组织表达特性进行分析。【结果】甜瓜基因组存在11个可分为3个亚家族的CmEPF成员,它们的基因结构相对保守,含有1-3个内含子,且大都分布于甜瓜的叶绿体上;基于系统进化分析将其分为3个亚家族。不同器官RT-qPCR分析发现,CmEPFs基因在甜瓜器官中广泛表达,但不同家族成员在不同器官中的表达模式存在差异,其在第二片叶表达量较高,且气孔密度、光合速率和蒸腾速率最高,其表达量与光合参数和气孔密度显著相关。【结论】CmEPFs基因通过影响甜瓜的气孔密度,影响其光合作用,从而调控甜瓜叶片气孔对外界环境的响应。

挤压型银石墨焊料层气孔形成原因及改善对策

采用挤压法制备垂直纤维强化型银石墨产品,按常规混粉-等静压-烧结-挤压-切片-脱碳-切分覆焊料工艺,产品背覆焊料近银层区域有明显的气孔。比较增加3种不同温度的烧结以及增加脱碳层厚度对焊料层气孔的影响,研究结果表明,脱碳后增加烧结,烧结后银层内气孔孔径变小,覆焊料时,排入焊料层单个孔气量相对变少,不同温度对银点尺寸影响不同;增加脱碳层厚度,对焊料层气孔大小和数量无明显改善。

Disruption of the 1-deoxy-D-xylulose-5-phosphate reductoisomerase （DXR） gene results in albino, dwarf and defects in trichome initiation and stomata closure in Arabidopsis

1-Deoxy-D-xylulose-5-phosphate reductoisomerase （DXR） is an important enzyme involved in the 2-C-methyi-D- erythritol-4-phosphate （MEP） pathway which provides the basic five-carbon units for isoprenoid biosynthesis. To investigate the role of the MEP pathway in plant development and metabolism, we carried out detailed analyses on a dxr mutant （GK_215C01） and two DXR transgenic co-suppression fines, OX-DXR-L2 and OX-DXR-L7. We found that the dxr mutant was albino and dwarf. It never bolted, had significantly reduced number of trichomes and most of the stomata could not close normally in the leaves. The two co-suppression lines produced more yellow inflorescences and albino sepals with no trichomes. The transcription levels of genes involved in tricbome initiation were found to be strongly affected, including GLABRA1, TRANSPARENT TESTA GLABROUS 1, TRIPTYCHON and SPINDLY, expression of which is regulated by gibberellic acids （GAs）. Exogenous application of GA3 could partially rescue the dwarf phenotype and the trichome initiation of dxr, whereas exogenous application of abscisic acid （ABA） could rescue the stomata closure defect, suggesting that lower levels of both GA and ABA contribute to the phenotype in the dxr mutants. We further found that genes involved in the biosynthetic pathways of GA and ABA were coordinately regulated. These results indicate that disruption of the plastidial MEP pathway leads to biosynthetic deficiency of photosynthetic pigments, GAs and ABA, and thus the developmental abnormalities, and that the flux from the cytoplasmic mevalonate pathway is not sufficient to rescue the deficiency caused by the blockage of the plastidial MEP pathway. These results reveal a critical role for the MEP biosynthetic pathway in controlling the biosynthesis of isoprenoids.

REGULATING EFFECTS OF VASCULAR ENDOTHELIAL GROWTH FACTOR AND ANG Ⅱ ON FROG'S PERICARDIAL STOMATA, MESOTHELIUM AND ANGIOGENESIS

To observe the regulating effects of vascular endothelial growth factor (VEGF) and angiotensinⅡ (ANG II) on the frog’s pericardium, lymphatic stomata and angiogenesis so as to reveal their effects and mechanism on the mesothelial permeability, lymphatic stoma regulation and myocardial hypertrophy. Methods. VEGF and ANGⅡ were injected into the frog’s peritoneal cavity so as to examine the changes of the pericardial stromata by using transmission electron microscopy, scanning electron microscopy and computerized imaging analysis. Results. Scattered distributed pericardial stomata were found on the parietal pericardium of the frog with a few sinusoid mesothelial cells, whose blood supply was directly from the cardiac chambers flowing into the trabecular spaces of the myocardium (because there are no blood vessels in the myocardium of the frog). The average diameters of the pericardial stomata in VEGF and ANGⅡ groups were 1.50μ m and 1.79μ m respectively, which were much larger than those in the control group (0.72μ m, P Conclusions. VEGF and ANGⅡ could strongly regulate the pericardial stomata by increasing their numbers and openings with larger diameters and higher distribution density. They could also increase the sinusoid areas with the result of the higher permeability of the pericardium, which clearly indicated that VEGF and ANGⅡ could speed up the material transfer of the pericardial cavity and play an important role in preventing myocardial interstitial edema. Yet there was no strong evidence to show the angiogenesis in the myocardium.

Investigation of Different Characters of Stomata on Three Cocoa Clones with Resistance Level Difference to VSD （Vascular Streak dieback） Disease

The development of the science of cytology and genetics, particularly on cell structure and function provided a breakthrough for breeders and allowed for early selection. Character of stomata density on some commodities was reported as important factor to determine the disease resistance. The research was done for getting information about the differences in the stomata characters influenced on the level of Vascular Streak dieback （VSD） resistance on cocoa. The research was conducted in the Laboratory of Genetics, Gadjah Mada University and leaves samples were conducted in Kendeng Lembu Gardens, PTPN XII. The research used a split plot design with three factors included the type of clones with different levels of VSD disease resistance （PA 191, BL 703 and GS 29）, leaf position （top, middle and base） and leaf age （young and old）. Stomata characters included number of stomata, stomata opening width, stomata wide and stomata diameter were observed. The results showed that the stomata characters in three cacao genotypes with different resistance levels indicated a difference in number of stomata, stomata size, stomata opening width, stomata wide and stomata diameter. Stomata number, stomata opening width and stomata diameter on PA 191 （resistance clone） were lower than the susceptible clones （BL 703 dan GS 29）. The lowest of number and diameter stomata on the base position on the old leaves tissues. Number of stomata, stomata opening width and stomata diameter were estimated role in mechanism of VSD resistance and that were expected could be used as criteria selection to VSD resistance.

Relation of Leaf Stomatal Traits to Yield and Drought Resistance of Wheat

[ Objective] The study aimed to discuss the relation of leaf stomatal traits to yield and drought resistance of wheat. [ Method] Using the DH population of wheat cultivar Hanxuanl0/Lumai14 as the test object, the relation of leaf stomatal density （SD）, length （SL） and width （ SW）, stomatal conductance （g,）, photosynthetic rate （ Pn ）, transpiration rate （ Tr） to grain yield per plant and index of drought resistance （IDR） on the 10th and 20t＂ day after anthesis under the conditions of drought stress and normal irrigation were discussed by the methods of correlation analysis and path analysis. [ Result] Under the two water conditions, the correlations of these stomatal traits with yield components and IDR were mostly not significant on the 10t＂ day after anthesis, but there were significantly positive correlations between thousand kernel weight （TKW） and these traits on the 20^th day after anthesis. Path analysis showed that g,, Pn and Tt, were main factors affecting yield per plant （YPP） and IDR, and they had stron- ger direct effects on YPP and IDR, while their indirect interaction was also strong. The direct effects of SD, SL and SW on YPP and IDR were small, as well as their indirect action among SD, SL and SW. On the other hand, the correlations between SD and SL were significant, and the correlations of SL with SW, gn, P, and Tt, were extremely significant on the 10th and 20th day after anthesis under the two water conditions. However, the correlations of SD and SL with g,, P,, and Tr changed with water conditions or growth stages, showing that water conditions or growth stages had great effects on the correlations between two traits. Therefore, it is not always a good means to improve stomatal conductance, photosynthetic rate and transpiration rate and hence promote wheat yield by selecting stomatal density and size. [ Conclusion] The research could provide scientific references for revealing the roles of leaf stomatal traits in wheat breeding for drought resistance.

基于改进YOLO v3的玉米叶片气孔自动识别与测量方法

气孔是植物叶片与外界环境交换气体和水分的重要结构。针对现有气孔性状分析主要采用人工测量,过程繁琐、效率低下、容易出现人为误差的问题,本文采用YOLO(You only look once)深度学习模型完成了玉米叶片气孔的自动识别与自动测量工作。结合玉米叶片气孔数据集的特点,对YOLO深度学习模型进行了改进,有效地提高了气孔识别和测量的精确率。对YOLO深度学习模型中的预测端进行了优化,降低了误检率;同时,结合气孔特征对16倍、32倍下采样层进行简化,提高了识别效率。实验结果表明,改进后的YOLO深度学习模型在玉米叶片气孔数据集上识别精确率达到95%,参数测量的平均精确率达到90%以上。本文方法能够自动完成玉米叶片气孔的识别、计数与测量,解决了传统气孔分析方法的低效率问题,为农业科学家、植物学家开展植物气孔分析研究提供了技术支撑。

国产柿属(Diospyros)的叶表皮形态研究及其分类学意义

为了解柿属(Diospyros)植物的叶表皮特征,在光学显微镜下观察了46种2变种植物的叶表皮微形态特征,并进行了主成分分析。结果表明,柿属植物的叶表皮微形态可分为2组:A组的表皮细胞为不规则形,垂周壁浅波状或深波状;B组的表皮细胞为多边形,垂周壁平直或弓形。气孔全部位于下表皮,以无规则型为主,但同时有辐射型、环列型和十字型气孔存在。大多数种具有表皮毛,表皮毛有非腺毛和头状腺毛的区别。柿属植物的叶表皮微形态特征类型多样,能够为部分类群的分类提供较好的形态学证据。

Effect of Genetic and Altitude Differences on Stomata Characters as Resistance Indicators to Vascular Streak-Dieback （VSD） in COCOA （Theobroma cacao L.）

Preliminary research results indicated that the stomata is one important trait that can be used as an indicator of resistance to vascular streak dieback （VSD） disease. The influence of genotype and environment on the stomatal characters is expected to provide information for specificlocations （habitats） suitable for planting cocoa in particular to avoid VSD attack. The research was conducted at KendengLembu, PTPNXII, East Java. Experimental design used a splitplot design testing： location （altitude） and genotype factors. The location factors, distinguished on the basis of the altitude, were labelled highlands and lowlands. The genotype factors consisted of three clones with different levels of resistance to VSD diseases： PA 191 （tolerant）, BL 703 and GC 29 （susceptible）. The cocoa clones observed were top grafted onto locally available rootstock seedling and planted in 2006-2007. The maintenance of the plants was conducted in accordance with the standards of cocoa cultivation in the PTPN XII. Parameters measured were leaf stomata traits at different positions of the leaf （tip, middle and base）. Characters observed were the number of stomata, opening width of stomata, and diameter of the stomata. The results of the research showed that PA 191 in the lowlands had the lowest number, diameter and opening width of stomata. In contrast, GC 29 in the lowlands showed the highest number of stomata PA 191 and BL 703 in the highlands had a number, diameter and openings width of stomata that was relatively low compared with GC 29. However, the characters of the stomata （number, diameter and openings width of stomata） of the three genotypes in the highland showed a smaller value in each case than in the lowlands. The severity level of VSD attack was greater in the lowlands than in the highlands and PA 191 showed the lowest level of VSD attack at both altitudes.

镉胁迫对刺槐幼苗生长与光合生理特性的影响

[目的]探究镉胁迫对刺槐生长与光合生理特性的影响。[方法]以刺槐幼苗为研究对象,测定不同浓度镉处理下刺槐生长、叶绿素含量、叶绿素荧光参数、呼吸速率和气孔特性等。[结果]在镉胁迫下,刺槐幼苗地径、株高受到明显抑制;高浓度处理植株的鲜质量、干质量下降,低浓度处理植株则略微上升,但均与对照差异不显著。随着镉浓度增加,刺槐叶绿素a、叶绿素总量呈下降趋势,而叶绿素b、类胡萝卜素变化无规则,但与对照差异不显著;初始荧光(F0)与最大荧光产量(Fm)先升后降,最大光化学效率(Fv/Fm)逐步下降,非光化学淬灭系数(qN)逐步上升,实际光化学量子效率(ΦPSII)均低于对照值,但差异不显著;胁迫植株气孔宽度、气孔面积降低,气孔逐步闭合,呼吸效率受到显著抑制;通过相关分析显示,多数指标之间显著性相关;经随机森林回归分析,初始荧光(F0)、根系镉含量、气孔宽度和叶绿素a的重要性分别在叶绿素荧光参数、植株富集镉含量、气孔特性、光合色素中最强,成为影响刺槐光合功能的最关键因子。[结论]刺槐幼苗生长与光合生理受到一定影响,但仍表现出较强的镉胁迫耐受性,可为镉污染地区的园林应用提供参考。