Abstract:To quantify the emission of greenhouse gases methane （CH₄） and nitrous oxide （N₂O） from paddy field of an agroforestry ecosystem in the hilly area in Guangdong, measurements were made with closed static chamber and a modified gas chromatograph （HP5890 Ⅱ） in situ. In this paper, gas samples were taken simultaneously from plot with rice and plot without rice. The seasonal emission of CH₄ from plot with rice in the second crop season was significantly correlated to soil temperature at 5 cm depth. Rice plants played a key role in CH₄ emission from paddy field. Mean seasonal emission of CH₄ and N₂O from plot with rice in the second crop season were 1.16±0.38 mg m^-2h^-1 and 42.33±20.00 μg m^-2h^-1, respectively. Mean seasonal emission of CH₄ and N₂0 for plot without rice in the second crop season were 0.15±0.11 mg m^-2h^-1 and 51.69±15.87μg m^-2h^-1, respectively. The results showed that the average seasonal emission of CH₄ in plot with rice was significantly higher than that in plot without rice, while no difference in average seasonal emission of N₂0 was found.

Abstract:Stand spatial structure of Pinus massoniana and broadleaved mixed forest in Fujian was investigated using three structure parameters （mingling, neighborhood comparison, and uniform angle index-neighboring tree distribution pattern）. The results showed that P. massoniana was the dominant species in the mixed forest, which exhibited aggregation of single species, and the rest tree species were more or most intensive in mingling. When using neighborhood comparison method to characterize the size differentiation of trees, P. massoniana had an advantage over other species which differentiated seriously both in dominant species and suppressed species. Considering tree distribution pattern using uniform angle index, the stands in this community was found to be a clumped distribution.

Abstract:The community of Liriodendron chinense in Sandaokeng Nature Reserve in Hunan Province was investigated using several species diversity indices. Floristic composition, physiognomy, species diversity and the possible succession of the community were analyzed. The results indicated that the vertical structure of the com- munity was obvious, which composed of tree, shrub, herb and ground layers. There were 76 vascular plant species in the community belonging to 48 families and 57 genera. Phanerophytes （accounted for 68.42%） were dominant in the life-form spectrum, which was similar to that in subtropical evergreen and deciduous broad-leaved forest. The community had very high species diversity. Species diversity indices in shrub layer were higher than that in tree layer and herb layer. Richness index of the community was 76. Simpson index D was 0.9516, which was close to the maximum of D; Shannon-Weiner index H was 3.3247. Evenness index based on Simpson index J_s was 0.5843, and that based on the Shannon-Weiner index J_sw was 0.8826. Because of the decline of growth potential and quantitative decrease in population, as well as deficiency in young seedlings, the community of Liriodendron chinense is now at the senescence phase.

Abstract:The life form spectrum, leaf size spectrum, light and water eco-forms were investigated in understory plants of artificial Cupressus lusitanica forest, Acacia dealbata forest and Alnus ferdinandi-coburgii forest as well as secondary shrub community in karst mountain area in Yunnan. The results showed that phanerophytes was the dominant life form in the three forests, followed by hemicryptophytes. Micro-phanerophytes comprised highest percentage. The dominant leaf size of the three kinds in forests was mesophyl 1. The life form spectrum and leaf size spectrum in the forests were similar to those in subtropical evergreen broad-leaved forest in Middle Yunnan. Among the three plantations, A lnus ferdinandi-coburgii forest is shown to have good hydrothermal condition and species diversity, which is beneficial for vegetation restoration.

Abstract:Laticifers of Jatropha curcas L. （Euphorbiaceae） are cells which secret latices with medicinal components. The types, distribution and sizes of laticifers in all organs of this species were observed under light-microscope by the means of paraffin sectioning, freeze-sectioning and semi-thin sectioning. The results showed that there were four types of laticifers in Jatropha curcas, i.e. articulated anastomosing and nonanastomosing laticifers, non-articulated branched and unbranched laticifers. The laticifers were commonly distributed in the cortex and phloem, whereas a few laticifers in xylem of stem and vein, as well as in pith of stem, petiole, pedicel and fruit stalk. The diameters in laticifers near vascular tissues were wider than those near the epidermis. In stem, the diameters of laticifers near vascular tissues and near epidermis were 40-60 μm and 5-18 μm, respectively.

Abstract:The leaves of three mangrove species, Kandelia candel （L.） Druce, Bruguiera gymnorrhiza （L.） Blume and Rhizophora stylosa Griff., collected from the access to Jiulong River, Fujian, were studied anatomically. Results showed that the three species were adapt to aquatic environment in structure：having thicker cuticle, epidermis with hypodermis as aquiferous tissue, stomata sunk in and distributed in lower epidermis, with large substomatal chambers, developed vascular bundles with enlarged vessels in mid rib. Cross section views indicated that leaves of K. candel was isolateral with symmetric structure, whereas those of B. gymnorrhiza and R. stylosa were dorsi-ventral and asymmetric. Leaves of all the 3 species were abundant in tannin that was richest in K. candel, followed by R. stylosa and B. gymnorrhiza. The differences in leaf structure could help specific identification in taxonomy．

Abstract:Anther wall browning in variety Taichung 65 of japonica rice （Oryza sativa L.） was studied through cold pretreatment of anthers at late uninucleate stage. Some microstructural and ultrastructural changes in the anther wall were found during anther culture. Anatomical observation showed that anther wall browning took place mainly in epidermis and endothecium. Cold pretreatment of anthers at 10℃ could effectively reduce the browning rate during the early culture period and delay degradation of the membrane structures of epidermis and endothecium, and thus postpone browning in anther wall. Meanwhile, cold pretreatment contributed to stimulating cell enlargement in the middle layer and delaying tapetum degradation, which produced positive effects on the microspore dedifferentiation. Although anther wall browning favored microspore in vigor and development, it was not the key factor in reducing the ability of pollen callus induction.

Abstract:Proteomatic analysis is a new powerful tool for revealing the changes in protein level. Two-dimensional polyacrylamide gel electrophoresis （2DE） and computer image analyses were employed to compare the global protein patterns between normal and aborted embryo of litchi （Litchi chinensis Sonn.）. Totally, 129 and 130 protein spots were obtained from normal and aborted embryos, respectively, of which 24 spots in both kind of embryos showed no significant difference, but 35 spots exhibited obvious differences in quantity, Furthermore, some spots were missing and some new spots emerged in aborted embryo compared with normal embryo. The differences in expressing the proteins between normal and aborted embryos of litchi are useful for regulating and controlling the embryo abortion.

Abstract:Viability of pollen of Magnolia soulangeana was tested at different storage temperatures and methods. Culture solution of 5% sucrose supplemented with 0.01% or 0.1% boric acid gave good results for pollen germination, the germination rate reaching to above 70%. Pollen viability declined with the increased preservation time. The decrease of pollen viability was slowered in the order of room temperature, 5℃, and -20℃. Cryogenic storage at -196℃ had no significant changes, even though the pollen stored for 2 years, the germination rate being 79.3%. Pollen samples exhibited high tolerance to re-freezing and thawing.

Abstract:Microspore culture of twenty F1 hybrids between cabbage （Brassica oleracea var. capitata） and broccoli （Brassica oleracea var. italica） and their corresponding parents were carried out, and the major factors affecting microspore embryogenesis was investigated. Liquid medium 1/2NLN was used for microspore culture, which contained 0.5 mg L^-1 NAA, 0.05 mg L^-1 BA, 5 mg L^-1 AgNO₃, 0.2 mg L^-1 2,4-D and 0.1 mg L^-1 active carbon. Results showed that fourteen F1 hybrids could produce embryoids, the induced frequency being 70%. The highest embryo producing rate appeared in＇ Luzhou808×Xiabao＇ with averaging 16.2 embryos developed per flower bud. The optimum period of microspores for embryoid development was from late uninucleate （late anaphase I） stage to binucleate （anaphase II） stage. The heat-shock treatment at 34℃ for 2 days was beneficial for stimulating symmetric unclean division of microspore cells. The embryo production was significantly increased in liquid medium containing 170 g L^-1 sucrose for 3 days and then by adding low sucrose content （110 g L^-1）.

Abstract:Activity and cytochemical localization of polyamine oxidase （PAO, EC 1.4.3.4 ） were studied in the young seedlings ofKennong 4 of Glycine max （L.） Merrill. PAO activity was undetected in the seeds until 24 h after imbibition, and increased during seed germination. However, the activity in various organs was significantly different in distribution between the germinating seeds （after 72 h of imbibition） and the young seedlings （after 120 h of imbibition）. In the germinating seeds, PAO had the highest activity in radicles （5.17±0.91 U g^-1 FW）, followed by embryonal axis, embryonic bud, and lowest in cotyledons （0.12±0.03 U g^-1 FW）. In the young seedlings, PAO showed the maximum activity in hypocotyls （5.47±0.66 U g^-1 FW）, followed by juvenile root, apical bud, and lowest in cotyledons （0.10±0.03 U g^-1 FW）. The differences of PAO activity in distribution presumably had positive effects on seed germination as well as seedling morphogenesis. PAO localization was determined in various parts of the young seedlings by using a cytochemical technique and transmission electron microscope. PAO was present mainly on vacuole membrane in apical bud cells, cell wall of both cotyledons and hypocotyls as well as on its surface. In hypocotyls, PAO closely attached to the surface of cell wall, while in root cells, it appeared in cell wall, intercellular space, on cell membrane, and especially on vacuole membrane. The results confirmed that PAO widely spread in cell wall and intercellular space. Moreover, to the author＇s best knowledge, PAO was found on cell membrane and vacuole membrane for the first time.

Abstract:An invasive species A lterrumthera philoxeroides and its indigenous congener A. sessilis were compared in the vegetative growth, photosynthesis and chlorophyll fluorescence. Stem tip cuttings of the herbs were cultivated for 28 d in 5 light growth chambers at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, respectively. Results showed that the main stems ofA. philoxeroides developed with lower accumulated effective temperature （AET）（11.6 d ℃） than that ofA. sessilis （27.0 d ℃）, but the new leaves ofA. philoxeroides emerged with more AET （12.1 d ℃） than that ofA. sessilis （6.7 d ℃）. Main stems and leaves ofA. philoxeroides started to grow at lower temperatures, 10.4 ℃ and 11.0 ℃, respectively, than A. sessilis which needed 12.8 ℃ and 14.9 ℃, respectively, indicating that A. philoxeroides was less sensitive to low temperature than A. sessilis. Data of photosynthesis and chlorophyll fluorescence revealed that the maximum net photosynthetic rate （NPR） in A. philoxeroides was higher than that inA. sessilis, so was light saturation point （LSP）, esp. at 25 ℃. The maximal photochemical efficiency （F_v/F_m） varied slightly for A. philoxeroides in the range of 10-30℃, which, however, rapidly declined for A. sessilis at 10 ℃. It might be concluded that high growth rate in main stems, wide range of temperature adaptation and strong capacity for photosynthesis would be important factors for the invasion of A. philoxeroides.

Abstract:Cut flowers of Gerberajamesonii Bolus were kept in basal preservative solution （BP, 20 g L^-1 sucrose ＋ 200 mg L^-1 citric acid ＋ 150 mg L^-1 8-hydroxyquinoline citrate） and basal preservative in addition of 30 mg L^-1 uniconazole （S-3307）. Those kept in distilled water were used as the control. Floral appearance and several physiological and biochemical indexes were determined during the senescence process of cut flowers. The results showed that S-3307 could extend the vase life of cut flowers for 4.3 days and 2.3 days as compared to the control and BP, respectively. However, the pedicel-bending rate was only 9.8% of the control and 28.8% of BP. Further studies showed that S-3307 could increase the ability of absorption water and fresh weight, which inhibit the reduction of protein content, and superoxide dismutase and catalase activities, reduce the accumulation of proline and malondialdehyde, and maintain stability of membrane in petals of the cut flowers. S-3307 could retard the senescence of the cut flowers, and improve the decoration quality of the cut flowers during vase-holding period.

Abstract:Strobilanthes adpressa J. R. I. Wood of Acanthaceae is reported as a new record from China.

Abstract:Recent researches on basic chromosome numbers of 601 taxa including 72 genera of the subfamily Chloridoideae are reviewed. Two main basic chromosome numbers occur in the majority of chloridoid genera, i.e. 9 and 10. Evidence indicates that x=9 and 10 are palepolyploid and aneuploid deviation basic chromosome numbers. Cytological characters have significant systematic value in recognizing supra-generic group in the Chloridoideae. An evolutionary trend of basic chromosome numbers is proposed： x=6→x=5→x=10→x=9. The primitive diploid group with 2n=2x=lO might have been extinct in the early, evolution.

Abstract:Flow cytometry （FCM） is a current technique for sorting certain cell subset from various cellular associations based on differences in cell＇ s physical and chemical properties, by which the selected cell subset could be further studied in function and morphology. The advantages of this technique include rapidity, sensitivity and synchronization of multi-parameter detection. The principles of FCM are briefly described, and its applications in plant cytoplast, protoplast and chromosome are reviewed.