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Table of Content
    Volume 36 Issue 8
    01 August 2012

    Upper left: Eremosparton songoricum community (photographed by YIN Ke-Lin); Upper right: Fruits growing in the plants (photographed by YIN Ke-Lin); Lower left: Fruits dispersing in root of plants (photographed by HUANG Zhen-Ying); Lower right: Soil seed bank of E. songoricum away from mother plants (photographed by HUANG Zhen-Ying). Eremosparton songoricum (Fabaceae) is a leafless perennial clonal semi-shrub. It is a rare and endangered endemic species in Central Asi

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    Review on Special Issue of Seed Ecology
    Carol C. Baskin, Jerry M. Baskin
    Chin J Plan Ecolo. 2012, 36 (8):  0-0.  doi:1
    Abstract ( 690 )   PDF (173KB) ( 1590 )   Save
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    Editorial
    Seed ecology: roles of seeds in communities
    HUANG Zhen-Ying, CAO Min, LIU Zhi-Min, and WANG Lei
    Chin J Plan Ecolo. 2012, 36 (8):  705-707.  doi:10.3724/SP.J.1258.2012.00705
    Abstract ( 962 )   PDF (252KB) ( 1853 )   Save
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    Research Articles
    Ten years’ observation of seed rain in a Fagus lucida community in Dalaoling Nature Reserve in the Three Gorges: seed rain density, species composition and their correlation with the community
    XU Yue, SHEN Ze-Hao, Lü Nan, TANG Yuan-Yuan, LI Dao-Xin, WANG Gong-Fang, TAN Jia-Lin, and LIU Yi-Ping
    Chin J Plan Ecolo. 2012, 36 (8):  708-716.  doi:10.3724/SP.J.1258.2012.00708
    Abstract ( 1102 )   PDF (467KB) ( 1711 )   Save
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    Aims Our objective was to analyze the temporal dynamics of the number and species composition of the seed rain of a Fagus lucida community and determine the relationship of species composition between seed rain and the community.
    Methods For ten years, we studied the seed rain in a 1.3 hm2 plot in the Dalaoling Nature Reserve of the Three Gorges Region, using 100 seed traps at ten different topographic positions.
    Important findings A total of 60 926 seeds from 48 woody species fell into the traps, the average seed rain density was (82.9 ± 61.5) seeds·m–2·a–1 (mean ± SD) and the average species number was 16.7 ± 5.5 (mean ± SD) per year. The interspecific difference of seed production was striking, with the top three species having contributed 70% of the total seeds. The interannual variation of seed rain density and species richness was synchronic, both revealed periodic fluctuations including three mast years. There was no correlation of seed rain density between trees and shrubs, but a significant positive correlation was found in species richness of these two life forms. There were 23 woody species shared by the seed rain and the community, accounting for 47.92% of the species richness in seeds and 54.76% in the community. However, the 23 species contributed 96.22% of the total seed rain, indicating that dispersal limitation occurred in this community. Compared with other forest community types in China, the seed rain density of this community is significantly lower.

    Temporal and spatial variation of seedfall in a broad-leaved evergreen forest in Gutianshan Nature Reserve of Zhejiang Province, China
    DU Yan-Jun and MA Ke-Ping
    Chin J Plan Ecolo. 2012, 36 (8):  717-728.  doi:10.3724/SP.J.1258.2012.00717
    Abstract ( 914 )   PDF (1040KB) ( 1423 )   Save
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    Aims Seedfall of woody plants often fluctuates considerably from year to year and from site to site. These variations may have strong effects not only on the recruitment of the plant populations themselves, but also on the community composition and structure. Our objective was to elucidate seasonal, annual and spatial variations of seedfall in broad-leaved evergreen forest in Gutianshan Nature Reserve of Zhejiang Province over four years.
    Methods Seed rain was censused weekly since June 2006, using 130 seed traps set along 2.3 km of trails within the Gutianshan 24 hm2 subtropical evergreen forest plot. Each seed trap consisted of a square, 0.5 m2 Poly Vinyl Chloride (PVC) frame supporting a shallow, open-topped, 1-mm nylon mesh bag suspended 0.8 m above the ground. Because of heavy snowfall in February 2008, seed traps were damaged, and all seed traps were reset. Therefore, seed rain data were absent from February to April 2008. We summarized four years of seed rain data from June 2006 to August 2010.
    Important findings There were a total of 124 227 seeds over the four years, belonging to 63 species, 51 genera and 29 families, and the Pearson correlation between adult tree basal area and seed production was significant. There was a marked peak in the number of seeds and species in each year in the dry season (autumn), but there were also ten species that dispersed their seeds in the wet season. Different species had different fruiting dates. Based on four years of seed rain data, annual variation in seedfall (CVyears) on Gutianshan was substantial (CVyears > 75% for almost all species), and the median coefficient of variation of annual seedfall was 1.72. Spatial variation was also great, and the median coefficient of spatial variation in seedfall among traps was 8.06. Spatial variation in seedfall density was greater than annual variation for almost all species. The rarity of seed-bearing adults, variation in seed deposition with distance, and different topography might be the most important sources of this spatial variation. Comparing with Barro Colorado Island tropical forest seed rain, Gutianshan data supported the hypothesis that annual variation in seedfall is lower in the tropics than at higher latitudes.

    Spatiotemporal dynamics of seed rain in natural forest of Betula alnoides in Jingxi County, Guangxi, China
    GUO Jun-Jie, ZHAO Zhi-Gang, OU Jing-Li, SHA Er, LIN Kai-Qin, ZENG Jie, and XU Da-Ping
    Chin J Plan Ecolo. 2012, 36 (8):  729-738.  doi:10.3724/SP.J.1258.2012.00729
    Abstract ( 892 )   PDF (593KB) ( 1255 )   Save
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    Aims Our objective was to study spatiotemporal dynamics of seed dispersal of Betula alnoides and analyze its correlation with wind speed and wind direction at community and individual levels.
    Methods Seed dispersal was investigated for a natural forest and an isolated tree of B. alnoides. We set seven sample lines 100 to 355 m long in or around the natural forest. One seed trap was placed every 5 m, and seeds were collected every two days. We set eight sample lines (east, southeast, south, southwest, west, northwest, north, northeast) around the isolated tree. Three seed traps were placed every 5 m from 0 to 50 m and every 10 m from 60 to 150 m, and seeds were collected each day. Wind speed and wind directions were measured at two sites. Seed rain density was calculated.
    Important findings The seed rain lasted 83 and 60 days at the community and individual levels, respectively. The starting, fastigium and subsiding stages of seed dispersal lasted 11, 32 and 40 days for the community and 9, 25 and 26 days for the isolated individual. Seeds dispersed at the fastigium stage accounted for 83.1% and 68.7% of all seeds collected at the community and individual levels, respectively. Seed rain density was higher during the day than at night, and the highest seed rain density by day occurred at 12:00–16:00. At the individual level, seed rain density decreased with increasing distance from the maternal tree, and 79.6% of seeds were collected in the area of 0–30 m around the maternal tree. Seed rain density at the community level also decreased with longer distance from the forest edge, and 79.6% of seeds were collected in the area of 0–45 m around the forest edge. The seed rain density was significantly different among directions (p < 0.01), which was affected by wind direction. Seed rain density was also positively affected by wind speed (p < 0.05).

    Seed mass variation in common plant species in Wanfoshan Natural Reservation Region, Anhui, China
    CHEN Yan-Song, ZHOU Shou-Biao, OU Zu-Lan, XU Zhong-Dong, and HONG Xin
    Chin J Plan Ecolo. 2012, 36 (8):  739-746.  doi:10.3724/SP.J.1258.2012.00739
    Abstract ( 1054 )   PDF (428KB) ( 1690 )   Save
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    Aims Our objective was to investigate seed mass variation within species, genera and families, as well as its relationships with life form and plant phylogeny.
    Methods Seeds were collected at the Wanfoshan Natural Reservation Region from July to October 2011. Air-dried weight of 100 diaspores, including seeds and indehiscent and single-seeded fruit, was measured for each of three replicates. Seed mass variation and ecological significance were analyzed.
    Important findings Seed mass varied greatly from 10–3 g to 103 g. The seed mass distribution of various species was normal, as checked by the Kolmogorov-Smirnov Test. The mean weight of 1 000 diaspores was 21.487 g. The seed mass of Momordica cochinchinensis (1 775.192 g) and Aeginetia indica (0.006 g) were the heaviest and lightest, respectively. More than 60% of the species had a mean seed mass between 0.1 and 10.0 g. The seed mass of 105 species was < 1.0 g. There were significant differences of seed mass among 68 families and eight life forms, as determined by one-way analysis of variance (p < 0.001). Pearson’s relative analysis showed a negative relationship between seed mass and phylogeny (r = –0.079, p = 0.048) and a positive relationship between seed mass and life forms (r = 0.220, p < 0.001). A significant difference was also detected at the generic level (p < 0.001) in some families, including Compositae, Poaceae, Cyperaceae and Rosaceae.

    Spatial difference and regularity of seed dispersal of Ulmus macrocarpa in Horqin Sandy Land, China
    YANG Yun-Fei, BAI Yun-Peng, and LI Jian-Dong
    Chin J Plan Ecolo. 2012, 36 (8):  747-753.  doi:10.3724/SP.J.1258.2012.00747
    Abstract ( 772 )   PDF (427KB) ( 1444 )   Save
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    Aims Ulmus macrocarpa is a typical anemochorous plant. It can form mono-dominant woodland in Keerqin Sandy Land, China. Our objectives were to investigate seed-fall characteristics of U. macrocarpa in the understory and away from both the woodland edges and isolated trees at different distances in different compass directions, and to illustrate the underlying mechanisms of seed dispersal in U. macrocarpa.
    Methods In mid June 2011, we investigated seed dispersal after seeds fall in a nature reserve of U. macrocarpa woodland in Tongyu County in western Jilin Province. The woodland is about 50 km2 in area which has nearly primitive landscape appearance. The seed density of U. macrocarpa was randomly sampled in the understory and orderly sampled at 1 m intervals from the tree bases away from the woodland edges and isolated trees along vertical sections of different directions. The quadrat was 50 cm × 50 cm in area. Differences in the seed density among the understory and parallel sections of different distance away from the woodland edges were tested by one-way ANOVA. Two types of density functions of theoretical distribution were used to reflect the patterns of seed dispersal away from seed sources along vertical sections of different directions.
    Important findings The understory of U. macrocarpa had the highest mean seed density. The mean seed density was significantly reduced at 3 m away from the woodland edges, and it decreased exponentially with increasing in distance away from the woodland edges. We observed the highest cumulative seeds per unit area in the northeast direction; whereas the lowest numbers in the southwest and west directions, which may attribute to a high frequency of southerly winds. The pattern of seed dispersal matched the Weibull and Log-normal distributions (χ2 (α) < 0.900). In conclusion, U. macrocarpa has the same long-distance seed dispersal mechanism in different directions under natural conditions in Horqin Sandy Land.

    Will competitiveness of resulting plants of persistent soil seed bank decline? Example from Eupatorium adenophorum
    SHEN You-Xin, and ZHAO Chun-Yan
    Chin J Plan Ecolo. 2012, 36 (8):  754-762.  doi:10.3724/SP.J.1258.2012.00754
    Abstract ( 904 )   PDF (496KB) ( 1100 )   Save
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    Aims It has been assumed that plants grown from persistent soil seed bank (PSSB) are not less competitive because of soil storage. Our objective was to determine whether the competitiveness of plants of PSSB will decrease.
    Methods We compared heights and biomass of Eupatorium adenophorum plants grown from fresh seeds and grown from one-year-old buried PSSB seeds with no competition (control) and competition with density of 0.25, 1, 4 and 8 plants·cm–2. We also compared plants grown from fresh seeds and three-year-old buried PSSB seeds with no competition (control) and competition with density of 0.10, 0.17, 0.60 and 2.17 plants·cm–2. The PSSB seeds and fresh seeds were germinated simultaneously, and seedlings were grown in garden pots up to 175 days. Plant height was measured every 15 days and biomass was measured every 30 days (3 replicates).
    Important findings The height and biomass of plants of one- and three-year-old buried PSSB seeds were lower than for plants germinated from fresh seeds in the control (no competition) and with competition at most measuring times. However, most differences were not statistically significant.

    Characteristics of the soil seed banks and relationships with the vegetation in restored wetlands in Sanjiang Plain, northeast of China
    WANG Guo-Dong, Lü Xian-Guo, JIANG Ming, WANG Ming, ZHAO Kui-Yi, and LOU Yan-Jing
    Chin J Plan Ecolo. 2012, 36 (8):  763-773.  doi:10.3724/SP.J.1258.2012.00763
    Abstract ( 850 )   PDF (485KB) ( 1682 )   Save
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    Aims Seed banks are an important source of regenerative material in wetlands. Our objective was to study characteristics of the soil seed banks and relationships with the vegetation in different restoration successional stages.
    Methods We collected soil seed banks from different depths (0–5 cm, 5–10 cm and rhizomes) from farmed wetland, restored wetland in different successional stages and natural wetland and germinated them under two water regimes (flooded and non-flooded) in a greenhouse. We used quadrats to survey vegetation structure in natural wetland and restored wetlands of different successional stages.
    Important findings With increased the restoration time, seed bank composition and size increased, and the vegetation community showed succession from a xerophyte-dominated community to a wetland community dominated by Calamagrostis angustifolia. Number of species germinated from the seed banks was 24, 29 and 39, while 21, 25 and 14 species were recorded in the vegetation of in 7-year restored wetland, 14-year restored wetland and natural wetland, respectively. Wetland type, water regime, depth of burial significantly influenced both the species richness and seedling emergence (p < 0.01). Seed density varied with depth so that seed density was higher in 0–5 cm than in 5–10 cm. The seed density in 0–5 cm was four times as that in 5–10 cm in natural wetland while it was just 1.3 times in restored wetland. The similarity between layers was low. More species germinated under non-flooded condition than flooded and the life forms differed. Because the restoration time was short, the similarity between seed bank and vegetation in different restoration successional stages was always <30%. Many wetland species germinated from rhizome fragments, especially C. angustifolia and other wetland species. Our research suggests that the seed bank could retain and restore several wetland species in different restoration successional stages, which can be valuable for vegetation succession and wetland restoration.

    Seed dormancy release and soil seed bank of three arid desert plants under burial conditions
    WANG Yan-Rong, YANG Lei, and HU Xiao-Wen
    Chin J Plan Ecolo. 2012, 36 (8):  774-780.  doi:10.3724/SP.J.1258.2012.00774
    Abstract ( 834 )   PDF (749KB) ( 1444 )   Save
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    Aims Our objective was to study the effects of depth and duration of seed burial in the field on seed dormancy release and soil seed bank dynamics of three desert plants.
    Methods The field burial experiment was conducted during an 18-month period at the site of the original seed collection at Alax Desert of Nei Mongol, China during April 2008 to October 2009. The species included Lespedeza potaninii, Nitraria tangutorum and Peganum nigellastrum with the dormancy of 98%, 95% and 3%, respectively, at the beginning of burial (stored 6 months at 5 °C since harvested). Four burial depths were used: 0, 2, 5 and 10 cm.
    Important findings Dormancy release patterns were different among the three species. The dormancy percentage of L. potaninii seeds decreased from 98% at date of burial to 64% after 18-month burial on the soil surface (0 cm); lower decreases were observed when buried at 2, 5 and 10 cm (82% to 87%). Dormancy in N.
    tangutorum
    dropped from 95% to 1% after 6-month burial in the field. In contrast to these species, P. nigellastrum seeds exhibited seasonal pattern (dormancy cycle) during the experimental period. The maximum points of dormancy were observed in October in each of the two years, decreasing thereafter with dormancy of
    3% when buried. The speed of dormancy release increased in N. tangutorum as the soil burial depth increased, but decreased in P. nigellastrum. At the end of 18-month burial, the field-germinated seeds on average of different buried depths were 11%, 12% and 8% for L. potaninii, N. tangutorum and P. nigellastrum, respectively; the average laboratory germinations were 3%, 74% and 42%, and dead seeds averaged 3%, 15% and 10%, respectively. According to the soil seed bank classification proposed by Thompson and Grime (1979), L. potaninii, N. tangutorum and P. nigellastrum had persistent seed banks.

    Adaptive strategies of dimorphic seeds of the desert halophyte Suaeda corniculata in saline habitat
    YANG Fan, CAO De-Chang, YANG Xue-Jun, GAO Rui-Ru, and HUANG Zhen-Ying
    Chin J Plan Ecolo. 2012, 36 (8):  781-790.  doi:10.3724/SP.J.1258.2012.00781
    Abstract ( 1143 )   PDF (534KB) ( 1407 )   Save
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    Aims Suaeda corniculata (Chenopodiaceae) is an annual halophyte in salt marshes and saline deserts of northern China. It produces two distinct types of seeds (brown and black). The primary aims of our study were to compare the morphology, dormancy and germination characteristics of dimorphic seeds of S. corniculata in order to elucidate adaptive strategies of the desert halophyte in stressful saline habitat.
    Methods Seeds were collected in saline habitats in Otog, Nei Mongol. The dimorphic seeds were incubated in different temperature regimes, light and salinity (NaCl) conditions to determine their germination responses. The effects of cold stratification and seed coat scarification on dormancy breaking of black seeds were also tested.
    Important findings Dimorphic seeds were different in seed mass and testa morphology. Brown seeds were bigger and more permeable to water than black seeds. Seed ratio was 5.6 : 1 (black seeds : brown seeds). Freshly matured brown seeds had a high germination percentage (84%–100%) in all temperature regimes and under either light or dark conditions. By contrast, black seeds had a lower germination percentage (8%–78%) than brown seeds in all temperature regimes, and germination was increased in light. Seed coat scarification, GA3 treatments and cold stratification significantly increased the germination of black seeds, suggesting that black seeds had non-deep physiological dormancy. Responses of dimorphic seeds to saline stress were different. Brown seeds were more salt-tolerant than black seeds and germinated at a high germination percentage in high salt concentrations. Cold stratification reduced the sensitivity of black seeds to salt stress and increased the initial germination percentage, recovery and final germination in salt solutions. The differences in morphology, dormancy and germination characteristics between dimorphic seeds of S. corniculata increased the species’ fitness to heterogeneous habitats and formed an ecological adaptive strategy that may allow S. corniculata to successfully adapt to the harsh desert habitat.

    Effects of cold stratification and dry storage at room temperature on seed germination of eight desert species from the Hexi Corridor of China
    WANG Ju-Hong, MA Rui-Jun, and CHEN Wen
    Chin J Plan Ecolo. 2012, 36 (8):  791-801.  doi:10.3724/SP.J.1258.2012.00791
    Abstract ( 1050 )   PDF (481KB) ( 1380 )   Save
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    Aims We investigated seed germination of eight desert plant species of the Hexi Corridor of China following cold-wet stratification and dry storage at room temperature to better understand seed germination and dormancy characteristics and how these species are adapted to their habitat.
    Methods Seed viability and initial germination percentage of Glycyrrhiza uralensis, Sphaerophysa salsula, Peganum multisectum, Zygophyllum fabago, Nitraria tangutorum, Lycium ruthenicum, Salsola ruthenica and Asterothamnus centrali-asiaticus were determined. Then seeds of these species were divided into four groups (I, II, III and IV) and stored in a refrigerator ((4 ± 1) °C, moist), cold room in winter ((–5 ± 1) °C, moist), outdoor in winter ((–26 – 10) °C, moist) and room temperature ((20 ± 1) °C, dry) for 60 d. Germination was determined under a constant (20 °C) and an alternating temperature regime (25 °C / 10 °C) with 12 h photoperiod (light/dark) for 30 d. Two main germination indices including germination percentage and T50 (half germination time) were recorded. Data were analyzed by one-way ANOVA and the least significant difference test (LSD) at 5% level.
    Important findings There were three types of seed responses to cold-wet stratification: germination percentage increased, no change, or decreased. Germination percentage of seeds of P. multisectum and Z. fabago significantly increased following cold-wet stratification of 4 °C and –5 °C, and partially increased following –26 –10 °C. Germination percentage of seeds of L. ruthenicum significantly increased following 4 °C, –5 °C, –26 – 10 °C and dry storage at room temperature, with germination of 90%–100%. Seeds of P. multisectum, Z. fabago and L. ruthenicum have slight physiological dormancy. Germination of seeds of N. tangutorum, G. uralensis and Sphaerophysa salsula slightly changed following three cold-wet stratification. Seeds of Salsola ruthenica with non-dormancy (germinated to 84% before storage) decreased their germination following cold-wet stratification of 4 °C, whereas no change occurred at –5 °C, –26 – 10 °C. In addition, the response of germination to incubation temperature varied with species.

    Variation in fruit and seed traits and seed germination among different populations of Eremosparton songoricum
    LIU Hui-Liang, ZHANG Yong-Kuan, ZHANG Dao-Yuan, YIN Lin-Ke, and ZHANG Yuan-Ming
    Chin J Plan Ecolo. 2012, 36 (8):  802-811.  doi:10.3724/SP.J.1258.2012.00802
    Abstract ( 885 )   PDF (649KB) ( 1229 )   Save
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    Aims Eremosparton songoricum is a rare and endangered endemic species in Central Asia. In China, it occurs in severely wind-eroded mobile and semi-mobile sand dunes of the Gurbantünggüt Desert. It has low fruit set, low seed set and rare seedling establishment. Our objectives were to determine the characteristics of populations, i.e., the variation of fruit or seed traits and seed germination among populations, to explain mechanisms of ecological adaptations of E. songoricum in different heterogeneous environments.
    Methods We determined the density and distance of plants and differences of shape, mass and proportion of multi-seed in six populations. Temperatures simulating those in the natural habitat of E. songoricum were used to determine the type of seed dormancy.
    Important findings The distance (F = 2.34, p = 0.03) and crown size (F = 8.49, p < 0.01) of plants were significantly different among populations and were highest in site C that was severely disturbed by humans. The distance and crown size located in the northeastern Gurbantünggüt Desert with abundant soil moisture (E and F) were higher than populations located in the hinterland of desert (A, B, D) except population C. The characteristics of fruit and seed (length, width, thickness and mass of fruits and seeds) in the populations were significantly different but seed length and width were not. The majority of traits values were higher in populations E, F and C. The proportion of multi-seed per fruit was significantly different (F = 6.96, p < 0.01) and was highest in population C (32.50% ± 4.79%). Freshly matured E. songoricum seeds were dormant since germination percentages were <15% in all the tested temperature regimes in the populations. Scarified seeds germinated to a significantly higher percentage than non-scarified ones in all temperature regimes, indicating freshly matured E. songoricum seeds were physically dormant. A significantly lower germination percentage was recorded at 15/5 °C than at the higher-temperature regimes, indicating that low temperature inhibited seed germination. Large-seeded populations (C, E and F) had higher germination percentages (<70%) than small-seeded populations (A, B and D; <50%) after
    scarified treatments (F = 30.77, p < 0.01), indicating that seeds from all populations had physical and physiology dormancy (PY + PD). The varying degree of PY + PD of E. songoricum seeds in different populations may be an important survival strategy for E. songoricum in the heterogeneous environments in the Gurbantünggüt Desert.

    Responses of seed germination of Leymus chinensis to environmental factors in degraded grassland on Songnen Plain in China
    MA Hong-Yuan, Lü Bing-Sheng, YANG Hao-Yu, YAN Chao, and LIANG Zheng-Wei
    Chin J Plan Ecolo. 2012, 36 (8):  812-818.  doi:10.3724/SP.J.1258.2012.00812
    Abstract ( 906 )   PDF (442KB) ( 1519 )   Save
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    Aims Our objective is to study the seed germination of Leymus chinensis in response to critical environmental factors, including temperature, water content and drought stress, type of soils and the saline-alkali stress, in order to explain the mechanisms of degradation of L. chinensis grassland on Songnen Plain in China.
    Methods We investigated seed germination of L. chinensis under four temperature regimes (two constant 28 °C and 35 °C and three fluctuating 5/28 °C, 5/35 °C and 16/28 °C), 2.5%–40.0% water content and 0–30% polyethylene glycol 6000 (PEG) solution simulating drought stresses, two types of soils (saline-alkali and non-saline-alkali) and two kinds of salts (NaCl with concentrations from 0 to 500 mmol·L–1 and Na2CO3 from 0 to 100 mmol·L–1).
    Important findings Fluctuating temperature is a necessary condition for high seed germination of L. chinensis. One of the reasons for grassland degradation in this area is the degraded soil environment where seeds of L. chinensis could not regenerate.

    Effects of simulated warming and precipitation change on seedling emergence and growth of Quercus mongolica in Dongling Mountain, Beijing, China
    DONG Li-Jia, and SANG Wei-Guo
    Chin J Plan Ecolo. 2012, 36 (8):  819-830.  doi:10.3724/SP.J.1258.2012.00819
    Abstract ( 841 )   PDF (578KB) ( 1466 )   Save
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    Aims Temperature and water supply are crucial drivers for plant seedling regeneration. Dongling Mountain is one of the temperate areas most sensitive to climate change in China, and Quercus mongolica is the dominant species. Our objective was to investigate how climate change (warming and precipitation change) affects the physiological and ecological processes of seeds and seedlings of Q. mongolica to determine the regeneration mechanisms and change in patterns of this key species.
    Methods We used a controlled, growth-chamber experiment for rising temperature and changing water supply. There were three levels for both temperature and water supply: monthly mean temperature (control) over past the 18 years and increased by 2 °C and 6 °C and monthly mean precipitation (control) and +30% and -30%. Seeds of Q. mongolica were collected in fall of 2010, planted in May 2011, and grown in pots under the treatments. We periodically measured traits of seedling emergence and growth during the first growing season.
    Important findings Seedling emergence percentage was affected by precipitation and its interaction with temperature, while seedling growth and biomass were affected by temperature and precipitation alone, rather than by their interaction. Increased temperature by 2 °C and water addition shortened the seedling emergence time; increased temperature by 6 °C combined with reduction of water increased seed mortality and reduced seedling emergence percentage, yet with water addition promoted seedling dynamics. Increased temperature by 2 °C had no significant effects on seedling growth, while increased by 6 °C significantly increased the specific leaf area, restricted the seedling growth and biomass, and reduced the ratio of root and shoot. In addition, water reduction reduced only root biomass but not shoot, total biomass and root:shoot. Water addition significantly promoted growth of leaf length, increased leaf numbers and increased aboveground biomass, especially leaf biomass. Therefore, proper temperature elevation or water addition may benefit the potential regeneration ability of Q. mongolica, but highly elevated temperature with reduced precipitation may be deleterious under future climate change.

    Cotyledon loss and its effects on survival and growth of Quercus wutaishanica seedlings under different densities
    YAN Xing-Fu, ZHOU Li-Biao, ZHANG Kao-Wen, and ZHOU Yun-Feng
    Chin J Plan Ecolo. 2012, 36 (8):  831-840.  doi:10.3724/SP.J.1258.2012.00831
    Abstract ( 820 )   PDF (713KB) ( 1292 )   Save
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    Aims Our objective are to explore cotyledon predation by rodents and its effects on survival and growth of Quercus wutaishanica seedlings under different densities, and to disclose the potential bottlenecks limiting seedling recruitment and natural regeneration of populations.
    Methods We transplanted Q. wutaishanica seedlings at six densities of 3.24, 2.56, 1.96, 1.44, 1.00 and 0.64 individuals·m–2 in a Larix principis-rupprechtii plantation of China’s Dadaogou forest region, Liupan Mountains. We surveyed retention rate of seedling cotyledon (RRC), retention rates of taproot (RRT) and apical bud (RRA) after cotyledon predation by rodents and retention rates of cotyledon- and apical bud-predated (RRCP, RRAP) and cotyledon- and apical bud-remained seedlings (RRCR, RRAR). At the end of the experiments, we harvested all surviving seedlings and determined seedling height (SH), basal stem diameter (BSD), leaf number (LN), taproot length, leaf area per seedling (LAPS), total dry mass, root shoot ratio and specific leaf area.
    Important findings Density effect of cotyledon predation on Q. wutaishanica seedlings was observed and the RRC decreased with increase of seedling density. Six and five weeks after transplanting, the RRCs of two higher densities (3.24 and 2.56 individual·m–2) stabilized at their minimums (8.64% and 7.81%), while those of two lower densities (1.44 and 0.64 individual·m–2) were still higher at the last cotyledon survey and were signifycantly higher than those of all other density treatments (p < 0.05). The RRA was the highest (25.23%) in 1.44 individual· m–2 density and was higher (4.19%) than that in 3.24 individual·m–2 density (p < 0.05), and all other densities resulted in < 20% of RRA. Significant difference between RRCP and RRCR was detected only on certain survey dates of individual density. RRAP was slightly lower than RRAR, and individual density exhibited the inverse. The fluctuation of retention rate of different seedling types may have be resulted from new germinated sprouts after apical buds were gnawed. SH, BSD, LN and LAPS all increased slightly with density decrease. The maxima of all parameters except SH were detected under the density of 1.44 individual·m–2 and, to some extent, were related to whether cotyledon was predated by rodents or not, indicating that more seedlings grown at higher density lost their cotyledons and thus exerted influence on seedling growth.

    Thermal time model analysis for seed germination of four Vicia species
    HU Xiao-Wen, WANG Juan, and WANG Yan-Rong
    Chin J Plan Ecolo. 2012, 36 (8):  841-848.  doi:10.3724/SP.J.1258.2012.00841
    Abstract ( 983 )   PDF (475KB) ( 1513 )   Save
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    Aims The study aimed to: 1) investigate the accuracy of thermal time model in predicating seed germination response to temperature for different legume species after dormancy release; 2) compare temperature requirements for seed germination of different legume species from the Qingzang Gaoyuan.
    Methods The seeds of four Vicia species were germinated over the constant temperature range of 5–30 °C at 5 °C interval. The effects of temperature on seed germination were summarized in terms of the thermal time model for germination.
    Important findings The base temperature (Tb) did not differ significantly within each sub-population by regressing germination rate on sub-optimal temperatures. In contrast with Tb, the ceiling temperature (Tc) differed significantly within each sub-population by regressing germination rate on supra-optimal temperature in all species except Vicia sativa. These imply the base temperature for all individual seeds in the populations were relative constant, but the ceiling temperatures may vary within the sub-populations. Tb value estimated by repeated probit analysis was quite close to the value estimated by regressing germination rate within sub-optimal temperatures; however, Tc value estimated by this method was close to the value estimated with T50. Compared to two perennial legume species, annual legume species had lower Tb and Tc. The thermal model was accurate to predict the germination time course under different temperatures.

    Research on modeling germination response to salinity of barley seeds
    ZHANG Hong-Xiang, TIAN Yu, ZHOU Dao-Wei, ZHENG Wei, and WANG Min-Ling
    Chin J Plan Ecolo. 2012, 36 (8):  849-858.  doi:10.3724/SP.J.1258.2012.00849
    Abstract ( 921 )   PDF (563KB) ( 1314 )   Save
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    Aims Salinization is a worldwide problem, and some researchers focus on the effect of salt on seed germination. The results are variable, and quantifying germination response to salt is significant. Furthermore, seed germination is affected by salinity, as a result of both osmotic and ion effects. How the two effects act together is unclear. Thus our objectives are to propose a model to accurately describe the effect of salt on seed germination and to clarify the role of the osmotic and the ion effect act under different salinities.
    Methods Two varieties of barley (Hordeum vulgare) seeds (‘Cask’ and ‘County’) were cultured in five binate iso-osmotic polyethylene glycol (PEG) and NaCl solutions (–0.45, –0.88, –1.32, –1.76 and –2.20 MPa, distilled water as the control) at four constant temperatures of 5, 12, 20 and 27 °C. Germination time courses were recorded and germination rates (the reciprocal of germination time) were calculated. The hydrotime model and the new salinity model were used to calculate the parameters and test which was the better fit.
    Important findings Results indicated that not only were seeds in saline conditions able to germinate at lower osmotic potentials than seeds germinating in an isotonic PEG-6000 solution, but that they were also able to do so faster. The hydrotime parameters of the NaCl treatments had great differences with the isotonic PEG treatments, which indicated the hydrotime model cannot describe salt effects on seed germination well. Barley seed germination rates in salt solutions were negatively linear with salinity. We proposed a salinity model to quantify germination response to salt. The germination time calculated from the salinity model approached the real data, compared to that calculated from the hydrotime model. Differences of germination rates in NaCl and the isotonic PEG treatments increased and then decreased with decreasing water potential. We suggest three situations of function mode by the osmotic and ion effects of salt. First, at low salinities the osmotic effect acts as the main negative role. Second, at medium salinities the two effects act together, with the positive ion effect stronger than the negative osmotic effect. Third, at high salinities the ion effect begins to harm the germination process.

    Ex situ symbiotic seed germination, isolation and identification of effective symbiotic fungus in Cymbidium mannii (Orchidaceae)
    SHENG Chun-Ling, LEE Yung-I, and GAO Jiang-Yun
    Chin J Plan Ecolo. 2012, 36 (8):  859-869.  doi:10.3724/SP.J.1258.2012.00859
    Abstract ( 899 )   PDF (1027KB) ( 1442 )   Save
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    Aims The in situ and ex situ seed baiting techniques, which have been developed in recent years, are effective methods to study the compatible mycorrhizal fungi of orchids. Our aim was to obtain the compatible mycorrhizal fungi of epiphytic Cymbidium mannii using the ex situ seed baiting technique.
    Methods Bark, moss, litter and humus around the roots of adult plants of C. mannii were collected as substrate to cultivate C. mannii seeds in the laboratory. The fungi were isolated from developed protocorms and identified by morphological and molecular characteristics. The effects of different mycorrhizal fungi and light on seed germination were examined by in vitro symbiotic germination.
    Important findings The isolated fungus was identified as a species of the genus Epulorhiza and was named as FCb4. After 58 days cultivation, seeds inoculated with FCb4 strain and FDaI7 strain (Tulasnella, isolated from Dendrobium aphyllum) had a high germination ratio, whereas seeds without the fungus failed to germinate. There was no significant difference between the germination ratios of seeds inoculated with FCb4 and FDaI7 strains, but FCb4 was significantly superior for seedling formation and development compared with FDaI7 in light. This indicated a lower degree of symbiotic fungal specificity on seed germination than the protocorm development stage in C. mannii. The fungus we obtained was effective for seed germination, and protocorm and seedling development for C. mannii. Germination and protocorm production were higher in the dark (0/24 h light/dark) than the light condition (12/12 h light/dark), whereas the subsequent protocorm development was better with light. These findings will aid in seedling production and reintroduction of C. mannii.

    Response of respiratory rate and reactive oxygen species scavenging enzyme activity in seed mitochondria of Clausena lansium dehydration and its ecological significance
    WANG Wei-Qing, CHENG Hong-Yan, LIU Shu-Jun, and SONG Song-Quan
    Chin J Plan Ecolo. 2012, 36 (8):  870-879.  doi:10.3724/SP.J.1258.2012.00870
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    Aims Recalcitrant seeds shed at relatively high water contents and metabolism activities are sensitive to dehydration. However, the mechanism for desiccation sensitivity of recalcitrant seeds is unclear. Here, we used the recalcitrant Chinese wampee (Clausena lansium) seeds as materials to investigate the relationship between desiccation sensitivity and the change in respiratory rate and reactive oxygen species (ROS) scavenging enzyme activity of mitochondria.
    Methods We dehydrated Chinese wampee seeds at 25–28 °C and 72%–80% relative humidity for 0, 4, 7 and 10 days then assayed the survival of seeds and axes, changes in respiratory rate of axes and cotyledons, activity of cytochrome c oxidase (CCO), integrity of outer mitochondrial membrane, pathways of CCO and alternative oxidase (AOX) and activities of ROS scavenging enzymes in mitochondria of axis and cotyledon.
    Important findings With the loss of water content, survival of seeds and axes gradually decreased, and desiccation sensitivity of seeds was greater than that of axes. Respiratory rate and integrity of outer mitochondrial membrane of axes and cotyledons decreased with dehydration. Respiratory rate of CCO pathway in mitochondria of axis and cotyledon and of AOX pathway in mitochondria of cotyledon increased in the initial phase of dehydration and then decreased, and that of AOX pathway in mitochondria of axis significantly decreased with dehydration. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) in axis mitochondria and those of APX in cotyledon mitochondria decreased with dehydration, and those of dehydroascorbate reductase (DHAR) in axis mitochondria and of SOD, DHAR and GR in cotyledon mitochondria increased in the initial phase and then decreased. Our data indicate that desiccation sensitivity of Chinese wampee seeds is closely related to decreases in respiratory rate and reactive oxygen species (ROS) scavenging enzyme activity of mitochondria and also to long-term adaptation to the tropical/subtropical habitat.

    Diversity of indigenous bacterial communities in Oryza sativa seeds of different varieties
    ZOU Yuan-Yuan, LIU Lin, LIU Yang, ZHAO Liang, DENG Qi-Yun, WU Jun, ZHUANG Wen, and SONG Wei
    Chin J Plan Ecolo. 2012, 36 (8):  880-890.  doi:10.3724/SP.J.1258.2012.00880
    Abstract ( 765 )   PDF (646KB) ( 1579 )   Save
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    Aims Our purpose is to study the bacterial community structures in rice (Oryza sativa) seeds, and to compare and analyze community structures in different varieties in different hybrid combinations.
    Methods Primers 799f and 1492r were used to amplify the bacterial 16S rDNA genes in the rice seeds. The community structure and diversity of indigenous bacteria in the rice seeds of hybrid progenies and their parental lines in three hybrid rice combinations, including ‘Fengyou 611’ (‘Fengyuan A’ × ‘Yuanhui 611’), ‘Jinyou 611’ (‘Jin 23A’ × ‘Yuanhui 611’) and ‘Jin 23A/09H013’ (‘Jin 23A’ × ‘09H013’), were analyzed by the 16S rDNA clone library technique and amplified by ribosomal DNA restriction analysis (ARDRA).
    Important findings In seven clone libraries, each library had 200–300 positive clones and 30–40 operational taxonomic units (OTUs). Analysis for the representative sequences identified by ARDRA revealed diverse phyla of bacteria in the 16S rDNA libraries, which consisted of alpha, beta, and gamma subclasses of Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. The dominant genera were Pantoea and Bacillus. Indigenous bacterial communities in the rice seeds of different varieties were different. The dominant bacteria in the hybrid progeny seeds had some relationship with that of their parental seeds in both variety and quantity. When the most abundant bacterial genera of both parental seeds were the same, such as Pantoea, the most abundant bacterial genus in the hybrid progeny seeds was also Pantoea, but with higher contents than that in the parents, as in the combination of ‘Fengyou 611’. When the most abundant bacterial genera in the two parental seeds were different and the abundance of the dominant bacterial genus in the male parent was < 50%, the dominant bacterial genus in the hybrid progeny seeds was the same as its female parental seeds, but with greater abundance, such as the combination ‘Jinyou 611’. However, when the abundance of the first dominant bacterial genus in the male parental seeds was > 50%, the most abundant bacterial genus in the hybrid progeny seeds was the same, and the abundance was lower than that in the male parental seeds, such as the combination ‘Jin 23A/09H013’.

    Review
    Advances, trends and challenges in seed bank research for sand dune ecosystems
    TANG Yi and LIU Zhi-Min
    Chin J Plan Ecolo. 2012, 36 (8):  891-898.  doi:10.3724/SP.J.1258.2012.00891
    Abstract ( 820 )   PDF (348KB) ( 1607 )   Save
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    Sand dunes, characterized by wind erosion and sand burial, are a unique habitat with particular physical and biological processes. The study of sand dune seed banks is vital to biodiversity conservation and vegetation restoration. However, spatial-temporal patterns, mechanism of formation and ecological function of seed banks in the dune habitat are not fully understood. In recent years, much attention has been paid to these seed banks. Seed bank size and composition are dependent on dune type, position and soil depth. Seasonal and annual patterns of the seed bank are regulated by wind and the rainy season. The seed bank is shaped by diverse disturbances and habitat types. The structure and composition of the seed bank are highly related to plant reproductive strategies of colonizers. Contribution of the seed bank to vegetation restoration varies with dune type. Further studies are needed on 1) regional differences in seed banks, 2) relationship to stages of plant life history, 3) consequences of various disturbances, 4) contribution to vegetation restoration and 5) linkages to sand burial and erosion.

    Review on influence mechanisms of light in seed germination
    ZHANG Min, ZHU Jiao-Jun, and YAN Qiao-Ling
    Chin J Plan Ecolo. 2012, 36 (8):  899-908.  doi:10.3724/SP.J.1258.2012.00899
    Abstract ( 1656 )   PDF (407KB) ( 2973 )   Save
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    Seed germination is a key process in the natural regeneration of plant populations and is mainly controlled by favorable temperature, water or light conditions. Light plays a critical role in determining the ability and rate of germination of photoblastic seeds. Furthermore, the regulation of seed germination by light involves not only
    complicated physiological processes but also rigorous signal transductions and gene expression pathways. We summarized available data on the relationships between seed germination and other factors (i.e., light attributes, coupling of light and water/heat and phytochromes in seeds). To assess the effects of light on seed germination, we also comprehensively summarized the physiological reaction and light signal transduction mechanisms regulated by phytochromes in seed germination.

    Characteristics of seagrass seed and restoration of seagrass bed
    HAN Hou-Wei, JIANG Xin, PAN Jin-Hua, CONG Wei, SUN Juan, ZHANG Zhuang-Zhi, SONG Shao-Feng, SHENG Bao-Li, WANG Qing-Yan, and LI Xiao-Jie
    Chin J Plan Ecolo. 2012, 36 (8):  909-917.  doi:10.3724/SP.J.1258.2012.00909
    Abstract ( 921 )   PDF (358KB) ( 1899 )   Save
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    Reported seagrass bed losses have led to increased awareness of the need for seagrass bed restoration, and seeds have potential for this restoration. In this paper, we systematically review the research and application of seagrass seeds in recent years. The morphology, development, dispersal, dormancy and germination of seagrass seeds are summarized and compared from the viewpoint of seed biology and seed ecology. We propose that when natural seagrass seed banks are researched, it is also necessary to establish artificial seagrass seed banks based on research of seed biology and seed ecology, which will guide seed collection and preservation. Seeding method and the approach of restoration using seeds are discussed, and we also point out problems existing in current research and application. In conclusion, we project expectations of the future in the research and application of seagrass seeds, and we forecast that seagrass seed ecology research will be an emphasis in the future. In the application area, research should focus on increasing the seed germination rate and seedling rate, and the problem of low seedling survival rate must be solved if artificial seedlings grown from seeds are to be utilized to restore seagrass beds.

    New advances in seed geography
    YU Shun-Li and FANG Wei-Wei
    Chin J Plan Ecolo. 2012, 36 (8):  918-922.  doi:10.3724/SP.J.1258.2012.00918
    Abstract ( 926 )   PDF (287KB) ( 2162 )   Save
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    We add research content and several hypotheses and also amend some scientific questions in the field of seed geography. Three research areas that we expound upon are the geographies of soil seed banks, seed rain and seed dispersal syndromes. We summarize two hypotheses: 3-dimensional (latitude, longitude and altitude) variation hypotheses on soil seed banks and on seed dispersion modes. We also supplement the geography of seed chemical elements with seed isotope content. In the geography of seed mass, we mention elaiosomes. In the geography of seed morphology, we reaffirm use of length and width of seed and their ratio, absence or presence of seed (or fruit) wings, length and width of seed wings and their ratio, etc. In the geography of fruits and flowers, we add length and width of flower sepal and petal, as well as length, width and height of fruits and also percentage of fruit ripe in summer and autumn. In the geography of seed genetic characteristics, we add seed DNA content. In the geography of seed cell characteristics, we include seed starch grain. Overall, seed geography is a constantly developing field that should incorporate additional research from seed science and technology.


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