毛乌素沙地10种重要沙生植物叶的形态结构与环境的关系

10种重要沙生植物叶器官的比较解剖学研究表明其普遍特征是;叶片的表面积与体积比值小;叶表具表皮毛和厚的角质膜;气孔下陷、具孔下室;叶肉中栅栏组织发达;叶各类组织中普遍有含晶细胞和粘液细胞,具有发达的机械组织和输导组织。个别植物叶退化而由同比枝行使光合作用;部分植物具皮下层和异细胞层,以及具异常结构,以上特征是适应沙漠干旱环境的结果,反映出植物形态结构与环境的统一性。     

杂交水稻开花结实期间叶片衰老

在杂交水稻开花期间,通过剪去穗部部分枝梗和叶片等处理,形成不同的库源比,叶片衰老的生理生化指标变化和结实率的测定表明,杂交水稻组合的库源矛盾大,叶片衰老快;但谷粒数与旗叶面积比不一定高,降低库源比,能明显减缓杂交水稻叶片中蛋白质、叶绿素含量及倒3、4、5片叶叶绿素含量的平均值与旗叶叶绿素含量的比率的下降和丙二醇含量的升高。这些都说明杂交水稻叶片功能早衰与其库源矛盾较大有关。     

银缕梅叶器官的宏观与微观结构及系统意义

银缕梅〔Ｓｈａｎｉｏｄｅｎｄｒｏｎｓｕｂａｅｑｕａｌｅ（Ｃｈａｎｇ）Ｄｅｎｇ,ＷｅｉｅｔＷａｎｇ〕叶表皮毛为星状毛,气孔器为平列式中周缘型,叶缘齿型为弗特吉型,叶肉栅栏组织一层细胞厚,三叶隙三叶迹的节,从茎节到叶之间的维管束呈分离合并分离的变化格局,并且呈续次合并和续次分离发育模式。这些结果进而说明银缕梅属的独立性,也从一个侧面证明它应属于狭义的弗特吉族（Ｆｏｔｈｅｒｇｉｌｅａｅ）。     

Variation in Nickel Content in the Nickel-Hyperaccumulating Shrub Psychotria douarrei (Rubiaceae) from New Caledonia1

Plants that hyperaccumulate Ni contain > 1000 ppm (dry wt.) in their tissues. Variation of Ni content within hyperaccumulating plant species is poorly explored. Using the Ni-hyperaccumulating shrub Psychotria douarrei, we documented variation of leaf Ni levels within individual shrubs, and variation with respect to plant size and leaf age. Plant size did not correlate significantly with leaf Ni content, and leaf Ni content did not correlate significantly with soil Ni content. Older leaves contained twice as much Ni as younger leaves. Older leaves also contained greater concentrations of Ca, Fe, and Cr but less K, P, and Cu. Five elements (Zn, Pb, Co, Mn, Mg) showed no significant variation due to leaf age. We also examined the effect of leaf age on epiphyll cover, finding increased epiphyll cover on the upper surface of older leaves. The dominant leafy liverwort epiphyll had a relatively high Ni content (400 ppm), suggesting that epiphylls of Ni hyperaccumulators obtain some Ni from host leaves. Individual shrubs differed in mean leaf Ni content almost two-fold (14,900-27,700 ppm). Variation among branches within individuals also ranged widely; however, this intraplant variability was not strongly correlated with the mean leaf Ni content of an individual shrub. We concluded that Ni contents in leaves of P. douarrei vary considerably due to leaf age, among individual shrubs, and among branches within a shrub.     

Differentiation of Xanthomonas campestris pvs. pelargonii and hederae by Polymerase Chain Reaction

Geranium isolates of Xanthomonas campestris pv. pelargonii ( Xcp ) and English ivy isolates of X. campestris pv. hederae ( Xch ) were tested by polymerase chain reaction (PCR) to determine whether the two pathovars could be discriminated using amplification conditions developed to identify and detect Xcp in infected geraniums. Using PCR, other workers reported that the genomes of Xcp and Xch were indistinguishable. The objective of this study was to determine whether the two pathovars have sufficient sequence diversity to allow them to be distinguished by molecular means. Three primer pairs were used for PCR amplification. Two of the primer pairs (REP and XcpM1/XcpM2) were able to distinguish between Xch and Xcp , whereas amplification with the third primer pair (ERIC) did not allow discrimination between the two pathovars. Based on PCR amplification, Xcp and Xch are distinctly different pathovars. Additionally, all three primer pairs showed discrimination between Xcp and Acidovorax , a bacterial pathogen that induces leaf spot on geranium.     

Epidermal structures and stomatal parameters of Chinese endemic Glyptostrobus pensilis (Taxodiaceae)

Glyptostrobus pensilis K. Koch, the only living species, is endemic to southern China. Epidermal structures of G .  pensilis have been studied on leaves collected from Guangzhou, southern China, the native locality of the species, and from Hangzhou, eastern China, the cultivated locality. Leaves are linear, linear-subulate and scale-like. Epidermal cells are rectangular and elongate parallel to the mid-vein on areas lacking stomata, and short, with rounded corners, on intrastomatal areas. Stomatal bands lie parallel to the mid-vein on both surfaces of leaves. Commonly the stomata have five or six subsidiary cells. Stomatal parameters (density and index) of the same surfaces of linear leaves from Guangzhou and Hangzhou show no statistically significant differences ( P  > 0.05). Considering the stomatal parameters of the same surfaces of linear-subulate leaves between the two localities, the stomatal index of the abaxial surfaces reveals no significant differences ( P  > 0.05), while the stomatal index of the adaxial surfaces and the stomatal density of both surfaces exhibit significant differences ( P  < 0.05). Intra-individual variation in stomatal index is smaller than that in stomatal density based on the coefficient of variability of stomatal parameters of the same areas of leaves. When studying the correlation between stomatal parameters of G. pensilis and atmospheric CO₂ concentrations, the stomatal parameters of linear leaves are mostly significant, and stomatal index is more useful than stomatal density.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 153–162.     

Influence of atmospheric oxygen on leaf structure and starch deposition in Arabidopsis thaliana

Plant culture in oxygen concentrations below ambient is known to stimulate vegetative growth, but apart from reports on increased leaf number and weight, little is known about development at subambient oxygen concentrations. Arabidopsis thaliana (L.) Heynh. (cv. Columbia) plants were grown full term in pre-mixed atmospheres with oxygen partial pressures of 2·5, 5·1, 10·1, 16·2, and 21·3 kPa O₂, 0·035 kPa CO₂ and the balance nitrogen under continuous light. Fully expanded leaves were harvested and processed for light and transmission electron microscopy or for starch quantification. Growth in subambient oxygen concentrations caused changes in leaf anatomy (increased thickness, stomatal density and starch content) that have also been described for plants grown under carbon dioxide enrichment. However, at the lowest oxygen treatment (2·5 kPa), developmental changes occurred that could not be explained by changes in carbon budget caused by suppressed photorespiration, resulting in very thick leaves and a dwarf morphology. This study establishes the leaf parameters that change during growth under low O₂, and identifies the lower concentration at which O₂ limitation on transport and biosynthetic pathways detrimentally affects leaf development.