Table of Content

20 August 2010, Volume 19 Issue 4

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Analysis on the landscape changes of the Xiaoxiangling Mountains in Sichuan Province during approximately 30 years

HUANG You-you, LIU Shou-jiang, WANG Qiong, MA Yong-hong, TIAN Mao-jie, XU Xiao

2010, 19(4):  1-9. 

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Based on remote sensing data of 1974, 1994 and 2002, the landscape changes of giant panda habitat in the Xiaoxiangling Mountains was quantitatively analyzed by combining 3S technology with quantitative analysis of the landscape ecology in this paper, and the mutual-transformational phenomena and dynamically changed characteristics which took place in the landscape of the Mountains in approximately 30 years were summarized by comparative analysis. At last, the concretely variation trend, the changing amplitude were determined. To analyze the Mountains landscape pattern, we identified 9 vegetation types using “optimize supervised classification method”, on field investigations, and a selected group of landscape metrics at the class and landscape level was used to quantify the changing pattern of vegetation landscape in the study region. All of the analyses were performed using a geographic information system and the landscape pattern analysis software Fragstats. The conclusions are as follows: 1) The diversity and uniformity of the vegetation landscape has reduced, but connectivity has enhanced, and every vegetation type has no more deposited in the whole landscape and created ascendancy vegetation type gradually, the cracked extent of landscape has relieved in the district in nearly 30 years. 2) Coniferous and broad-leaved mixed forest and coniferous forest have unceasingly increased.And coniferous and broad-leaved mixed forest was the background of the area, while it has had the biggest amplification in the first 20 years, increased 14.27%. Sub alpine shrub and sub alpine meadow have variation tendency that change from “increasing at first” to “decreasing at last”, while alpine shrub with the contrary variation tendency, and has had the largest damping in the first 20 years, decreased 11.05%. But alpine shrub basically unchanged in approximately 30 years. The research results could not only reveal the distribution structure and change law of its landscape, but also provide referenced datum for macroscopically protection of local ecosystem environment.

Effect on species diversity of plant communities caused by invasion of Alternanthera philoxeroides in different habitats

ZHANG Zhen, XU Li, ZHU Xiao-min

2010, 19(4):  10-15. 

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Alternanthera philoxeroides is one of the most notorious invasive weeds and has been introduced to regions with warm to subtropical humid climates worldwide. To ascertain the effect of the invasive species on plant communities in different habitats, field surveys of species diversity of plant communities and morphological traits associated with the host plant were investigated. 1) The species had good growth in wetlands where the morphological traits (including stem length, leaf area and node length) of A. philoxeroides, showed a significant difference from that in other habitats (namely, road sides, cultivated land and lawn). However, there were significant differences in leaf area and node length between the disturbed habitats (road sides and cultivated land) and other habitats. The two morphological characteristics were related to adaption of the host plants to human activities and heat-drought stresses. 2) Based on the sample plot survey, the variation in relative coverage, frequency and densities, showed a certain pattern in the different invaded habitats. As the important value of the species was over 60.96%, plant species diversity was reduced in communities severely invaded by A. philoxeroides. The alien invasion plant could have huge impacts on native plant communities, and management supervision should be strengthened and managed through target-oriented procedures.

Niche characteristics of main herbage populations in Eucalyptus grandis plantation

ZHONG Yu, ZHANG Jian, LIU Quan-bo, YANG Wan-qin, WU Fu-zhong, FENG Mao-song

2010, 19(4):  16-21. 

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Based on the data of 60 plots obtained from investigation, the niche breadth and niche overlapping of 13 main herbage populations in Eucalyptus grandis plantation were studied by using Levins and Shannon-Wiener niche breadth index and Levins niche overlapping index. The niche breadths of Hicriopteris glauca and Miscanthus sinensis were bigger than that of the others because these two species had extensive adaptation to environment. The species with big niche breadth didn’t always have big niche overlapping, and the niche breadth and niche overlapping did not have a positive direct liner relation. In conclusion, relatively lower niche overlapping between species were apparent in herb layer of E. grandis plantation. From the eco-response rate, aggression of H. glauca was strongest, and few species would monopolize the herb layer of E. grandis.

The mutual allelopathic effect between invasive plant Flaveria bidentis and four forgage species

HUANGFU Chao-he, CHEN Dong-qing, WANG Nan-nan, YANG Dian-lin

2010, 19(4):  22-32. 

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Efforts to control exotic invasive allelopathic plants and reclamation of invaded areas may require establishing species that are tolerant to allelochemicals. Mutual allelopathy between invasive plant Flaveria bidentis and four forage species, Cichorium intybus, Trifolium pratense, Medicago sativa and Lolium multiflorum, was investigated through Petri dishes assay in the laboratory. The results showed that allelopathic activity depended on both the concentration levels of the extracts and plant tissues from which the extract was derived. The synthetic effect of both types of aqueous extract across the concentration range from F. bidentis on M. sativa was less zero, thus the growth of this forage species was actually stimulated while other three forage species inhibited at most concentrations, even to different degree. At same time, this forage species shows higher phytotoxic activity on the germination and seedling growth of seed of F. bidentis, respectively, with the synthetic effect of 65% and 93% with leaf and stems and roots extract, respectively. Based on these results, we assigned the species M. sativa as promising native species for restoration of sites infested with F. bidentis.

Allelopathic effects of Neotyphodium endophytes of Elymus dahuricus on seeds and seedlings of three turf grass species

YANG Song, LI Chun-jie, CHAI Qing, HUANG Xi, NAN Zhi-biao

2010, 19(4):  33-40. 

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Allelopathic effects of Neotyphodium infected Elymus dahuricus were tested on seeds and seedlings of Lolium perenne, Festuca arundinacea, and Poa pratensis found to affect all three grasses. The seed germination experiment showed that extracts from E. dahuricus inhibited seed germination and seedling growth of all three grasses under germination conditions. The Neotyphodium endophyte considerably enhanced the inhibition of E. dahuricus on seed weights of L. perenne, seed germination of P. pratensis and seed germination, root length, seedling length, and seed weight of F. arundinacea (P<0.05). However, the endophyte considerably reduced inhibition of E. dahuricus on root length and seedling length of L. perenne, seedling length of P. pratensis, and seed weight of F. arundinacea (P<0.05). In a pot experiment, extracts from E. dahuricus accelerated plant growth of all 3 grasses, thus while the Neotyphodium endophyte reduced seed germination of L. perenne, and seed length of P. pratensis (P<0.05), it enhanced the seed germination of F. arundinacea (P<0.05).

A study on soaking and germination characteristics of Fritillaria przewalskii seeds

CHANG Yan-li, CHEN Yuan, GUO Feng-xia, LIN Yu-hong, LI Tian

2010, 19(4):  41-46. 

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The effect of soaking Fritillaria przewalskii seeds following after-ripening, and the seed germination characteristics at different temperatures (10, 15, 20, 25, 10/20℃ change), were measured in order to provide a theoretical basis for their artificially domesticated cultivation. The 1000-grain weight ranged from 0.72 to 0.82 g. The seeds completed morphologic after-ripening following storage for 45 d at 20℃ and physiological after-ripening after seeds were mixed with sand (sand∶seed ratio of 4∶1) for 150 d at 5-10℃. The soaking process fitted a Logistic curve, which included sharp soaking, stable soaking and saturated soaking stages. Under dark conditions, the seed germination quality improved with increased temperature and reached an optimum at 15℃ with a germination rate of 90.67% and germination power of 89.33%. However, when the temperature exceeded 15℃, seed germination was significantly reduced and sprout growth was restrained. Temperature was the key condition for seed germination following after-ripening. This suggests that the best time to sow F. przewalskii seeds is under humid and adumbral conditions when the soil temperature is 15℃.

Effects of N dressing ratio on carbon and nitrogen transport and on grain yield of Lolium multiflorum

ZHOU Qin, ZHAO Chao-peng, CAO Chun-xin, JIANG Qiao-jun, JIANG Hai-dong

2010, 19(4):  47-53. 

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The effects of the same total amount of nitrogen fertilizer, applied as different ratios of base, jointing and heading fertilizer, on stem and tiller dynamics, dry matter accumulation and yield of annual Lolium multiflorum was studied in a field trial. Grain yield was significantly influenced by the nitrogen application strategy. Increasing the ratio of base fertilizer increased stem and tiller numbers at the greening stage and promoted dry matter accumulation at the over-wintering and greening stages. Increasing the ratio of jointing fertilizer effectively increased stem and tiller numbers and dry matter accumulation at the jointing stage. Increasing the ratio of heading fertilizer increased the spike rate and grain yield. The effective spike rate, grains per spike, spike numbers and theoretical yield of applying heading fertilizer treatments (N6-N10) were higher than for treatments of non-heading fertilizer (N1-N5). Dry matter accumulation after anthesis was curvedly related with grain yield (r=0.961 7^**), while the nitrogen transfer amount of vegetative organs after anthesis was linearly related with grain yield (r=0.921 5^**). The appropriate ratio of heading fertilizer could increase dry matter and nitrogen accumulation after anthesis, and promote nitrogen transfer, which in turn, could increase the yield of annual L. multiflorum. Too high a ratio of heading fertilizer inhibited the transfer of organic matter, reduced nitrogen transfer amount and nitrogen transfer efficiency. In this study the most appropriate N ratio of base, jointing and heading fertilizer was 4∶5∶1 and this produced the highest grain yield.

Effect of nitrogen and phosphorus fertilizer on yield and quality of Notopterygium franchetii

FANG Zi-sen, GAO Ling-hua, ZHANG En-he, ZHANG Xin-hui, CHEN Hong-yu

2010, 19(4):  54-60. 

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During 2004-2006, a field experiment in the Huichuan domestication and cultivation base of Notopterygium franchetii was conducted to study effects of nitrogen and phosphorus fertilizers on yield of N. franchetii, extract content, and essential oil content. The yield of N. franchetii gradually increased with an increase of N or P fertilization. The extract content increased initially but then decreased as N fertilization increased while the opposite happened with an increase of P fertilization. Essential oil contents increased with an increase of N fertilization; initially, it gradually increased but then it decreased with a further increase of P fertilization. The highest yield was with a treatment of N 375 kg/hm² and P₂O₅ 600 kg/hm², an increase of 20.39% compared with the N₀P₀ treatment. The highest extract content was obtained with N 300 kg/hm² and P₂O₅ 0 kg/hm², and of essential oil with N 375 kg/hm² and P₂O₅ 450 kg/hm², increases of 12.32% and 22.73% respectively compared with the N₀P₀ treatment. GC-MS analysis of rhizomes and roots of N. incisum gave 89 peaks from which 80 compounds were identified, accounting for 95.74%-99.32% of total essential oils, most of which were terpenoids and their derivatives, mainly dutrex cluster, enols, ketones and esters. The peak of essential oil relative content was after 21-22 min, but the essential oil contents were different in all treatments. Some of the high content compounds in this plant have not previously been reported in the literature.

Response and drought resistance of four leguminous pastures to drought during seed germination

QIN Wen-jing, LIANG Zong-suo

2010, 19(4):  61-70. 

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The biological and germination characteristics of four Leguminous pasture plants (Vicia villosa, Astragalus adsurgens, Melilotus albus, Lespedeza hedysaroides) on the Loess Plateau were studied when under water stress. 1) The four species had different biological seed characteristics. Seed water content and seed imbibition rates of A. adsurgens and V. villosa were higher than those of the other two species while seed vitality of L. hedysaroides and V. villosa were higher than the others. 2) As the drought intensified, total seed germination rate, seedling fresh weights, drought resistance index, growth of radical and plumule of the four species declined with M. albus showing the largest decline. 3) The low content PEG-6000 improved seed germination of L. hedysaroides, seedling growth of A. adsurgens, and those of the drought resistance index. 4) The comprehensive evaluation of the four species by the membership function method indicated that the drought resistances decreased in the order V. villosa, L. hedysaroides, A. adsurgens, and M. albus.

Effects of salt stress on germination and seedling growth of Medicago falcata

QIN Feng-mei, ZHANG Hong-xiang, WU Yi, ZHOU Dao-wei

2010, 19(4):  71-78. 

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Developing high quality legumes with saline and alkaline tolerance is a key to improving the low protein content of forage and to select forage adapted to the low salinization and alkalinization habitats of the Songnen region. Seed germination and seedling growth are crucial stages in the life history of a plant and determine its subsequent growth potential. The effects of salt stress on germination and seedling growth of Medicago falcata, were compared in two cultivars of M. sativa (CW₄₀₀ and Gongnong No.2). Seeds were germinated under conditions of 0, 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 mmol/L NaCl and percentage seed germination, germination index, seedling growth, and proline, Na⁺, and K⁺ contents of three materials were measured. Germination percentage and index of all three materials were suppressed to different extents as salt concentration increased with the suppression more obvious in higher salt concentrations. By comparison with two cultivars of CW₄₀₀ and Gongnong No.2, M. falcata had significantly lower germination percentage and index, but growth of the radicle was not affected by the salt solution and there were no significant differences between the treatments and the control. The recovery test showed that seeds of the three materials could remain viabile in salt solutions. The total germination of M. falcata and CW₄₀₀ reached 100% in 60 mmol/L NaCl, but only the total germination of M. falcata reached above 90% in all the solutions and it had the highest recovery percentage although there were no significant differences between treatments. As an osmotic regulator, proline quickly accumulated in M. falcata seedlings. The proline content of M. falcate, M. sativa CW₄₀₀ and Gongnong No.2, in 100 mmol/L were 3.1, 2.3 and 1.4 times respectively that of the control. In conclusion salt tolerance of M. falcata was stronger than that of M. sativa, and M. falcate and it is thus more applicable for growth in Songnen grasslands.

A comprehensive evaluation of salt-tolerance and the physiological response of Medicago sativa at the seedling stage

LI Yuan, LIU Gui-bo, GAO Hong-wen, SUN Gui-zhi, ZHAO Hai-ming, XIE Nan

2010, 19(4):  79-86. 

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A comprehensive evaluation of salt tolerance and the physiological response of 18 Medicago sativa. germplasms from Russia was studied under different NaCl concentrations (0.3%, 0.4%, 0.5% and 0.6%) in the green house at the seedling stage. They were compared with Zhongmu 1. The standard deviation coefficient allocation weighted method not only considered different indexes allocation weight, but also evaluated drought resistance of all the materials. Four strong salt tolerant germplasms, M7, M9, M15, and 810, were screened using this method. Free proline content, soluble sugar content, relative electrical conductivity, MDA content and water saturation deficit were considerably increased by an increase of salt concentration, while leaf water potential decreased. The soluble sugar content, relative electrical conductivity, MDA content, water saturation deficit and water potential in the leaf at the seedling stage responded sensitively to the level of salt stress and this can be used as an identification index of salt tolerance.

Diurnal change of photosynthetic characteristics and response to light intensity of seven ornamental grasses

GAO He, ZONG Jun-qin, CHEN Jing-bo, GUO Ai-gui, LIU Jian-xiu

2010, 19(4):  87-93. 

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The diurnal variations of photosynthetic rate (Pn), stomatal conductance (Cond), transpiration rate (Tr), intercellular CO₂ concentration (Ci), water using efficiency (WUE), solar radiation (PAR) of Miscanthus sinensis ‘Strictus’, Panicum virgatum ‘Rehbraun’, Phalaris arundinacea ‘Picta’, M. sinensis ‘Cabaret’, Cortaderia selloana ‘Pumila’, M. sinensis ‘Cosmopolitan’ and M. sinensis ‘Morning light’ were determined by Li-6400 portable photosynthetic system, and the light saturation point (LSP) and the light compensation point (LCP) were calculated at the same time. Among the 7 ornamental grasses, the LSP,Pn and WUE of P. virgatum ‘Rehbraun’ were the highest. Both M. sinensis ‘Morning light’ and P. arundinacea ‘Picta’ have higher Cond,the Pn and Tr of M. sinensis ‘Morning light’ were the higher and P. arundinacea ‘Picta’ was the lower. WUE of P. arundinacea ‘Picta’ was lowest with low dry tolerance and good performance at wet site which was a shade tolerance plant of C₃ plant characters with appearing noon-rest phenomenon dued to the decrease of Cond. Shade tolerance from strong to weak were ranked as follows: C. selloana ‘Pumila’＞P. arundinacea ‘Picta’＞M. sinensis ‘Cabaret’＞M. sinensis ‘Cosmopolitan’＞ M. sinensis ‘Strictus’＞P. virgatum ‘Rehbraun’＞M. sinensis ‘Morning light’.

Effects of lactobacillus on fermentation quality of mixed silage of Medicago sativa and Elymus dahuricus

WANG Kun-kun, YU Zhu, SHAO Tao, LIU Ping-du

2010, 19(4):  94-100. 

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Fresh Medicago sativa and Elymus dahuricus in different ratios were made into silages to study the effects of lactobacillus on fermentation quality of mixed silages after 45 days. The fermentation quality of M. sativa and E. dahuricus silages were significantly (P<0.05) affected by additives. All bi-crop ratios except the 70∶30 ratio improved the fermentation quality of silages with a 30∶70 ratio the best treatment. There were interactions between the additives and bi-crop rations. For the lowest pH and ammonia-N contents and the highest V-score, the treatment with 0.025% lactobacillus was the best in all crop ratios.

Effects of temperature and moisture on soil nitrogen mineralization of lucerne stands

ZOU Ya-li, HAN Fang-hu, GEN Li-ying, SHEN Yu-ying

2010, 19(4):  101-107. 

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The effects of temperature and moisture on nitrogen mineralization in the 0-10 cm soil layer from four years (4 a) and eight years(8 a) old lucerne stands in the Loess Plateau were determined by an incubation experiment with combinations of three temperature levels (5℃, 15℃, and 25℃) and three moistures levels (30%, 50%, and 70% of field capacity). Temperature was the dominant factor affecting net mineralization in the 0-10 cm soil layer from lucerne stands in the Loess Plateau. The highest net nitrification rates were 0.481 μg/(g·d)(4 a), 0.942 μg/(g·d)(8 a) with net mineralization rates of 0.293 μg/(g·d)(4 a), 0.632 μg/(g·d)(8 a), which were in the 25℃/70FC treatment after 14 days incubation. The highest nitrogen immobilization rate (0.232 μg/g·d) in soil from 4 a lucerne stands was in the 5℃/30FC treatment while it was 0.127 μg/(g·d) in the 5℃/70FC treatment for the 8 a stands. Microbial biomass carbon content in the 0-10 cm soil layer from 8 a lucerne stands was 1.44 times higher than that in the 4 a stands under 25℃/70FC condition. The differences of nitrogen mineralization rate and organic microbial C between two ages of lucerne soil are due to the difference of soil organic C content from the two soils.

Physical and chemical properties of the soil in Chongqing Qinglong golf course greens

WENG Ling-fei, HAN Lie-bao, CHANG Zhi-hui, KONG Wei-cai

2010, 19(4):  108-114. 

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Soil particle distribution, pH, total nitrogen, available phosphorus, available potassium, available iron, available sulfur and organic matter of the putting greens at the Qinglong golf course were analysed. In the golf course soil beside individual greens, the organic matter concentration was about 5-10 g/kg, the proportion of nitrogen, phosphorus and potassium was not in balance, and the pH of the greens soil were all alkaline (pH>7.8). Moreover, the microelement concentrations were low, the distribution of soil particles was fine, which affected aeration and drainage. The article suggests that the managers should increase organic fertility and phosphorus fertility, and regulate soil pH in order to benefit grass growth. In addition, soil testing is needed for rational application of fertilizer to ensure the turf is healthy.

Effects of elk grazing on soil physical and chemical properties of grassland on Tiane Island

ZHOU Cun-yu, FEI Yong-jun, WU Lei, YANG Chao-dong

2010, 19(4):  115-121. 

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Grassland soil was sampled twice in the Tiane Island Nature Reserve and the physical and chemical properties had changed with different intensities of elk disturbance. In winter, soil bulk density in the heavy disturbance plot was reduced due to its lower organic matter, but in spring, soil bulk densities were not significantly affected by elk disturbance. In spring, soil moisture in the heavy disturbance plot, which had the least vegetation cover and litter layer, was the lowest of the five plots. However, the differences in soil organic matter between the five plots with different disturbance intensities were not significant, except for a few soil layers. In winter, soil total N, P, and K contents in three layers significantly increased in the heavy disturbance plot, but in spring (with more rainfall), soil total N, P, and K contents in the three layers decreased in that plot.

Genetic diversity of native Elymus sibiricus populations in the Southeastern Margin of Qinghai-Tibetan Plateau as detected by SRAP and SSR markers

YAN Jia-jun, BAI Shi-qie, ZHANG Xin-quan, CHANG Dan, YOU Ming-hong, ZHANG Chang-bing, LI Da-xu

2010, 19(4):  122-134. 

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The objectives of the study were to quantify the genetic variability in eight natural populations of Elymus sibiricus collected from Southeastern Margin of Qinghai-Tibetan Plateau, and to explore its genetic variation distribution pattern. Sequence-related amplified polymorphism (SRAP) markers and simple sequence repeat (SSR) markers were employed. The follow results were obtained: 1) A total of 384 fragments were identified with 16 SRAP primers sets, of which 86.98% were polymorphic. Meanwhile, a total of 221 alleles were detected at 16 SSR loci, with 192 (86.88%) being polymorphic, indicating considerable genetic variation at the species level. 2) The mean gene diversity (H_e) was estimated to be 0.109 2 and 0.129 6 within populations detected by SRAP and SSR markers respectively, and 0.243 4 and 0.373 2 at the species level. 3) A high level of genetic differentiation among populations was detected based on Nei’s genetic diversity analysis both in SRAP (G_st=0.552 5) and SSR (G_st=0.515 8) markers, and an indirect estimate of the number of migrants per generation (0.405 0 by SRAP markers, 0.469 4 by SSR markers) showed that gene flow was low among populations. 4) Shannon’s index analysis and AMOVA analysis displayed the same result that mainly genetic variation of E. sibiricus existed among the populations. In addition, a geographical pattern of population differentiation, where the populations from south, north and middle area of sampling sites were clearly separated from each other, was revealed by cluster analysis. Based on the genetic information available for the native E. sibiricus, some conservation strategies were proposed.

Sequence analysis of the rDNA ITS region of Pennisetum species (Poaceae)

CHEN Zhi-tong, HUANG Qin-lou, PAN Wei-bin, HUANG Yi-bin

2010, 19(4):  135-141. 

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The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from 15 species of Pennisetum (Poaceae) from areas such as Fujian, Jiangsu, Hainan were sequenced and the sequences submitted to the Genbank database. The phylogenetic relationship of the 15 species were studied by CLUSTAL X and MEGA software. Their length of nrDNA ITS region ranged from 573 to 586 bp. P. americanum×P. purpureum and P. americanum×P. purpureum cv. slimstem may be the same variety with different names. The phylogram tree indicated that sequence analysis of nrDNA ITS regions is a good technique for studying the genetic diversity of Pennisetum.

Identification of QTLs for nutrient contents of rice as forage

FAN Chuan-guang, ZHANG Xiang-qian, ZHANG Jian-guo, LIAN Zi-xian

2010, 19(4):  142-148. 

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A genetic linkage map of 85 SSR markers was constructed based on an F₂ population derived from a cross between a cultivated rice “Taichung 65” (Oryza sativa) (♀) and a common wild rice (O. rufipogon) (♂). The markers in the linkage map were distributed on 12 rice chromosomes. The statistic software of Mapmaker/QTL 1.0 was used to detect QTLs for crude protein, crude fiber, ether extract, crude ash, silica, and water soluble carbohydrate contents. There were 3 QTLs for crude protein, 1 QTL for ether extract, 2 QTLs for silica, and 3 QTLs for water soluble carbohydrate. They were identified on chromosomes 1, 2, 4, 7, 8, 9, 10 and 11. Interval mapping identified 4 major QTLs and 5 minor QTLs. Major QTLs were qCEE-1 (explained 56.8% of variation) for the ether extract content, qCWSC-4 (explained 23.1% of variation) and qCWSC-7 (explained 25.0% of variation) for WSC content and qCS-9 (explained 15.9% of variation) for silica content. QTLs for crude fiber and crude ash contents were not detected.

A comparative study on the anatomical structure of leaves from different populations of bermudagrass

LI Ya-nan, LUO Li-juan

2010, 19(4):  149-158. 

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A study of the anatomical structure of leaves from 20 populations of bermudagras growing in different environments found that there were significant differences in cuticular thickness, epidermal cells thickness, leaf epidermal cell lengths and widths, stomata size and density, leaf thickness, number and diameter of vascular bundles, and strengthening tissue thickness. The coefficients of variability were greater in stomatal density and in strengthening tissue thickness than in vascular bundles of midribs and the abaxial epidermis. Stomatal density ranged from 77.49 to 335.46 per mm², with a coefficient of variability up to 36.93%. Strengthening tissue thickness ranged from 7.50 to 45.00 μm, with a coefficient of variability up to 64.20%. Using the indexes measured, the 20 populations of bermudagrass could be divided into four categories by cluster analysis. The results of cluster analysis were identical with the population distributions of the bermudagrass.

Lemma micro-morphological characteristics of MT-1 elephantgrass and its closely related varieties

ZHANG Xiang-qian, ZHOU Feng, XIE Xin-ming

2010, 19(4):  159-165. 

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Micro-morphological characteristics of lemmas of Pennisetum purpureum cv. MT-1 and its closely related varieties were investigated using scanning electron microscopy. An abundant polymorphism of micro-morphological characteristics of lemma was revealed among the elephantgrass varieties. The results showed that there were seven different kinds of epidermal cell, three of which, cross-shaped, dumb-bell-shaped, moniliform cell, were widespread. Eleven different types of indumentums were mainly seen in the middle of the elephantgrass lemma and two of them, microhairs with short basal cell and prickle-hairs were in common. Five elephantgrass varieties were divided into four groups according to different kinds of tubercles. Based on the differences of micro-morphological characteristics of lemma surfaces, MT-1 elephantgrass and its closely related varieties can be identified and distinguished.

Studies on growth and wind-resistance traits of Casuarina and Acacia stands from coastal protection forest

WU Zhi-hua, LI Tian-hui, ZHANG Hua-lin, XIE Yao-jian

2010, 19(4):  166-175. 

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Trees from plots (22) of 2 clones of 4 and 6-8 year old Casuarina and from two species of 8 year old Acacia stands, were measured for growth and wind-resistance traits such as wood density and pilodyn penetration in a site at the Nansan coastal protection forest in Zhanjiang. Diameter at breast height (DBH), pilodyn data, wood base density (WBD) and bark thickness (BT) were made at a height of 1.3 m while WBD was measured on whole wood cores from 1.3 m height taken by increment borer. In general, growth traits such as DBH, tree height, bark thickness, crown width, and WBD increased with forest age but there were significant differences in stand growth between species. There were also significant differences in all traits between forest ages. All traits except for branch angle and DBH were significantly correlated. The traits were divided into three categories and examined by principal-component factor analysis. The results of hierarchical cluster analysis in which Euclidean distance was taken as a similarity measure and the average linkage cluster method was used as a clustering algorithm showed that there were significant differences in traits between plots: Two plots of A. mangiums and A. confuse stands were classified in a category, and No.5 and No.6 Casuarina stands were classified as the same cluster and were significantly different from the others because their plots were located in front of the protection forest belt. The stands were hit by Typhoon Kammuri and the strong Typhoon Hagupit in 2008. They were located 120-130 km from the eyes of the two storms. Almost all Casuarina stands had low grade wind damage (e.g. branch-breakage) only, but there was considerable wind damage to the Acacia stands where damage to A. mangiums and A. confuse plots was level six and five respectively. A regression model of stand wind damage with growth and wind-resistance traits was developed. The statistic R² was 0.861 and showed the linear regression was a good fit to the data. For categorical traits, acoustic velocity (AV), WBD and pilodyn penetration value (PPV) were major while branch angle, tree height, and stem strength were minor in determining the meaning of wind damage grade. An increase in tree height, crown width, PPV, and GSV resulted in an increase in predicted wind damage grade. In terms of the regression, the plot with the worst fit was Acacia mangium, the second was Acacia confuse, and the best was Casuarina clone 701, whereas stands of two Casuarina clones were not significantly different.

Effect of Selenomonas ruminantium alone, or in combination with yeast cultures, on in vitro rumen bacterial fermentation

MAO Sheng-yong, LONG Li-ming, ZHU Wei-yun

2010, 19(4):  176-186. 

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In vitro batch culture techniques were used to investigate the effect of S. ruminantium alone and in combination with yeast cultures on rumen bacterial fermentation. When Leymus chinensis was used as a substrate, yeast culture addition increased the acetate, propionate, butyrate, valeric acid, isovaleric acid and TVFA contents (P<0.05), and reduced lactic acid content, but had no significant effects on pH value, isobutyrate or ratio of acetate to propionate (P<0.05). The ratio of acetate to propionate and the lactate concentration were reduced (P<0.05), and acetate, propionate, n-butyrate, isobutyrate, isovaleric acid, TVFA content and pH value were improved by S. ruminantium supplementation (P<0.05). There was no significant interaction between pH value, acetate, propionate, butyrate, isovaleric acid or TVFA content between S. ruminantium and yeast cultures (P>0.10). When maize was used as a substrate, live-yeast culture addition increased pH value, acetate, propionate, n-butyrate, isobutyrate, isovaleric acid and TVFA content (P<0.05), and reduced lactate concentration and the ratio of acetate to propionate (P<0.05), but there was no significant effect on isobutyrate content (P>0.10). pH value, acetate, propionate, butyrate, isovaleric acid and TVFA content were improved by S. ruminantium, and S. ruminantium supplements lowered lactate content and the ratio of acetate to propionate (P<0.05). There was a significant interaction effect on pH value, lactate, acetate, propionate butyrate, TVFA content and the ratio of acetate to propionate between S. ruminantium L9 and yeast cultures (P<0.05). When starch was used as a substrate, S. ruminantium had an increase in pH value and acetate, propionate, butyrate and TVFA content (P<0.05), but a decrease in lactate concentration and the ratio of acetate to propionate (P<0.05). Yeast culture supplement increased pH value and acetate, propionate, butyrate and TVFA content (P<0.05), but had no effect on valeric acid, isobutyrate content or the ratio of acetate to propionate (P>0.10). A significant interaction effect was observed on pH value, acetate, propionate, butyrate, TVFA, lactate content and the ratio of acetate to propionate between S. ruminantium and yeast cultures (P<0.05). S. cerevisiae L9 can be considered a good strain which might tolerate the adverse conditions in the gastrointestinal tract when used as a live microbial feed supplement in the diet of the animals. Compared with the addition of yeast or S. cerevisiae alone, the live-yeast cultures combined with S. cerevisiae L9 more effectively to reduce lactate and maintain a stable ruminal pH.

Dynamics of the ecological footprint and ecological capacity of Qingyang, Gansu

ZHANG Zhi-quan, YU Ai-zhong, LUO Zhu-zhu, CHEN Nian-lai, HUANG Gao-bao

2010, 19(4):  187-193. 

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The ecological footprint (EF) and ecological capacity (EC) of Qingyang from 2001 to 2005 were calculated, and the historical change pattern and causes of EF and EC during this period were analyzed. A forecast model for sustainable development trends of Qingyang was developed. The average personal EF gradually increased from 1.12 to 1.34 hm² from 2001 to 2005, whereas the average personal EC declined from 1.13 to 1.11 hm², thus the EF and EC in Qingyang developed in opposite directions. In 2001 there was an ecological surplus of 0.02 hm², but in 2002 it became a deficit which rose to 0.23 hm² in 2005. Over the same period, the EF per ten thousand yuan GDP decreased, while the ecological occupation rate increased, indicating that the biologically productive area, the resource utilization rates, and the ecological pressure were all increasing. The model forecasts that in 2010, the average personal EF and EC would be 1.33 and 1.03 hm² respectively, and the average personal ecological deficit would reach 0.30 hm². Overall, the results indicate that the ecological environment in Qingyang is not safe and that the present development model is not sustainable.

Status, degraded causes and comprehensive treatment of Dunhuang Xihu wetland ecosystem

QI Deng-chen, CHEN Wen-ye, ZHANG Ji-qiang, WU San-xiong, YUAN Hai-feng

2010, 19(4):  194-203. 

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The Dunhuang Xihu wetland ecosystem in the survey found that due to natural and man-made factors, such as multiple other complex effects of wetland ecosystems is deteriorating. In the degradation of wetland ecosystems causes of in-depth analysis and research, based on the adjustment of industrial structure, construction and development of water-saving cities, and strengthen scientific research and improve the wetland ecosystem monitoring system to control the population quantity and improving the population quality, and strengthen environmental legislation and related policies building measures, put forward a comprehensive wetland ecosystem restoration measures to achieve the Dunhuang Xihu wetland ecosystem for sustainable development.

Research progress on effects of grazing on physical and chemical characteristics of grassland soil

ZHANG Cheng-xia, NAN Zhi-biao

2010, 19(4):  204-211. 

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The published literature was reviewed for effects of grazing on soil physical properties (bulk density, water infiltration) and chemical properties (soil organic matter, total nitrogen, and total phosphorus). The effects on soil properties were inconsistent because of the complexity and resilience of grassland soil ecosystems to perturbation. In general, because the impact of livestock trampling led to increased soil bulk density as grazing intensities increased, and to reduced soil infiltration and water holding capacity, although this phenomenon decreased as soil layers increased. Soil bulk density may decrease in sandy soil with lower organic matter content, because overgrazing reduces soil organic matter thus influencing the stability of soil aggregates and resulting in a collapsed soil structure. The transformation process of organic matter is very complicated because the effects of grazing on soil organic matter are affected by many factors, such as temperature, precipitation, vegetation, soil and management measures (e.g. continuous grazing, rotation grazing, and enclosure). The effects of grazing on soil organic matter is not consistent in the published literature: It may increase, decrease, or have no-effect. Livestock interacts with soil nitrogen content of grassland by feeding, trampling and excreting. Based on reported literature, total nitrogen may be increased and decreased or show no change as grazing intensity is increased. The effect of grazing on soil phosphorus is different. Soil total phosphorus is reduced while available phosphorus is increased as grazing intensity is increased. However, some researchers report that soil total phosphorus and available phosphorus of grasslands have little change under long-term grazing conditions. Overgrazing is the most common cause of soil degradation. The awareness of this process and mechanism of overgrazing is of great significance for curbing grassland degradation and achieving sustainable development of grassland animal husbandry.

Research progress on ragweed (Ambrosia)

ZENG Ke, ZHU Yu-qiong, LIU Jia-xi

2010, 19(4):  212-219. 

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The invasion of exotic plants has caused tremendous economic losses in agriculture, forestry and animal husbandry in China, and seriously destroyed ecological balance and biodiversity. In addition, ragweed plants can induce serious allergies, and harm to our health. In this paper, ragweed is reviewed in terms of biological features, ecological features, and adaptability for environmental factors, control measures and pharmaceutical values.

Research progress on Oncidium in tissue culture and transgenes

CUI Guang-rong

2010, 19(4):  220-229. 

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This article reviews the main research progress on Oncidium tissue culture and genetic transformation. There are important effects of explants, medium and its supplements [including organic compounds and plant growth regulators (PGRs)], and culture methods for protocorm-like bodies (PLB) or crown bud induction in Oncidium in vitro culture. Flower-stalk, flower bud, apical bud and root-tip of field plants can all be used as explants in primary culture, but flower-stalks and flower buds are the best commonly used explants for Oncidium in vitro culture. All of the tissues or organs of test-tube plants are good explants for Oncidium in vitro culture. Oncidium is mainly cultured on solid media and 1/2MS or MS is the commonly used basic medium for in vitro culture. The types, concentrations of PGRs, and their combinations in the medium are key factors in Oncidium in vitro culture. The process of PLB formation in Oncidium is a typical somatic embryogenesis which is greatly influenced by PGRs, genotype and culture condition. Research on genetic transformation of Oncidium is in a primary stage.

A study on seasonal dynamics of qualititive characters of five plant species in Kubqi sandy land

YU Feng, WANG Ming-jiu, GAO Li, YAN Zhi-jian, NIE Su-mei

2010, 19(4):  230-235. 

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The nutrition of Astragalus adsurgens, Hedysarum laeve, Astragalus melilotoides, Lespedeza davurica and Artemisia desertorum were measured. The nutrition of the five species of sandy plants showed obvious seasonal dynamic changes. As the growing season progressed, crude protein, crude fat and phosphorus content in the leaves and stems gradually declined, whereas ADF, NDF, and calcium content increased. Nitrogen free extract content at the beginning of July was higher than at other times, e.g. it reached 53.5% (P＜0.05) in leaves of A. adsurgens. At the beginning of August, fibre showed an upward trend, e.g. NDF and ADF contents of A. adsurgens and H. laeve reached 55.3% and 50.5%, respectively, a significant (P＜0.05) increase. Therefore, to obtain high-quality forage, the best harvest time would be from the end of June to the middle of July. Although crude protein content in leaves of A. desertorum was low, crude fat and calcium content were relatively high, 3.3% and 4.1% (P＜0.05) respectively. High-quality forage can be produced with timely mowing and processing modulation.

The pattern of seed reproduction and its response to resources in Pedicularis semitorta individuals

WANG Xiao-juan, ZHANG Long-chong, ZHAO Zhi-gang

2010, 19(4):  236-242. 

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There is a common phenomenon that a discrepancy in female productive success exists in the inflorescence of many plants, especially alpine plants. The non-uniform pollination hypothesis, the architecture effect hypothesis, and the resource competition hypothesis are three hypotheses to explain such patterns of within-inflorescence variation in female reproductive success. However, experiments to evaluate the influence of outside environmental factors on female reproductive success are rare. In this experiment, the effects of population density and defoliation on the female productive success of P. semitorta were investigated. The parameters tested include seed number, seed mass, ovule number per fruit, and individual seed weight. We also choose twenty natural groups of P. semitorta to find whether this plant’s reproduction allocation is restricted by pollen resources. There was no significant discrepancy in the rate of fruit set and the rate of seed set between natural pollinated and artificial supplement pollinated plants. However, population density had a significant effect on seed number per fruit and individual seed weight, while defoliation affected seed numbers, seed mass, and ovule number per fruit. In density and defoliation treatments, fruit position had a marked relationship to all the above parameters, indicating that architecture effects play a role in this plant’s female reproductive success. All the parameters of defoliated individual plants were less than those of the non-defoliated ones. The interaction effect of defoliation and fruit position had a significant influence on seed numbers and ovules per fruit, indicating that defoliation had a negative effect on female reproductive success. We suggest that the architecture effect and resource competition both affect female reproductive success of P. semitorta and that they are the results of plant plasticity.

A study on the variations of pivotal photosynthetic active radiation parameters of a Leymus chinensis meadow-steppe in Hulunber

LI Jin, ZHANG De-gang, ZHANG Hong-bin, LI Gang, YANG Gui-xia, LI Lin-zhi, XIN Xiao-ping

2010, 19(4):  243-250. 

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The diurnal and seasonal variations of photosynthetic active radiation (PAR) parameters, the calculation of reflectance of canopy and transmittance of soil in a Leymus chinensis meadow-steppe in Hulunber were studied. The seasonal variations of both PAR and absorbed photosynthesis active radiation (APAR) tended to decrease in the growth period from early June to late September. PAR fluctuated over a wider range (25 and 58 mol/m²) than APAR (17 and 34 mol/m²). However, the fraction of photosynthetic active radiation (FPAR) tended to increase during the season. It fluctuated between 0.46 and 0.77 with the highest FPAR value of 0.77 in the last ten days of August. Changes of incident PAR, reflectance PAR, and transmittance PAR of the canopy and the soil reflectance PAR during clear days were standard sine curves. The diurnal variation of canopy reflectance ratio was highest in the morning and evening but lowest around 12:00 noon. The diurnal change (0.4) of the reflectance ratio of soil varied over a wider range in June than in July and September (0.08). The diurnal variation of APAR was identical with the incident PAR. The diurnal FPAR variation was a curve of cosine on clear days in June, July, and the middle of August, with a variation of 0.60, compared with a variation of only 0.13 in September. The relative correct PAR data were obtained by measuring on the ground as well as FPAR and it provided a reference for the evaluation of precision and validation of FPAR in grassland.

Effect of spraying uniconazole on soybean yield and quality

YAN Yan-hong, YANG Wen-yu, ZHANG Jing, WAN Yan, LUO Qing-ming

2010, 19(4):  251-254. 

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Differences of soybean yield and quality between treatments was studied by spraying different concentrations of uniconazole at the V₅ and R₁ stages. Spraying 25-100 mg/L uniconazole reduced plant height, enhanced stem diameter, and increased branch number and yield. The protein content, protein yield, and fat yield of all treatments were higher than those of the control (except A2B1). They were highest in the 75 mg/kg uniconazole treatment at the V₅ stage where they higher than the controls by 5.05%, 56.59%, and 59.15%, respectively. Spraying 75 mg/L uniconazole at the V₅ stage mainly increased yield, protein, and fat accumulation.

A study of germination characteristics and morphology of wild Urtica angustifolia seed

JIANG Yi-bao, ZHANG Fang, CUI Guo-wen, WANG Cheng-zhang

2010, 19(4):  255-258. 

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The aim of this research was to observe external morphology of Urtica angustifolia seed and detect seed vitality under different conditions. The wild U. angustifolia seeds were incubated at 15℃, 20℃, 25℃, 30℃, or 35℃, with 50, 100, 300, or 500 mg/L gibberellin, and with seed soaking in 98% concentrated sulfuric acid and 35% sodium hydroxide for different times. The length and width of U. angustifolia seeds were 958.72 and 534.85 μm. U. angustifolia seed vitality of those harvested in 2008 was 83.25%. U. angustifolia seed was yellow-gray, and the 1 000-seed weight was 0.104 5 g. The optimum germination temperature for U. angustifolia seeds was 25℃, which gave a germination rate of 42.67%. The seed germination rate was enhanced by soaking in 98% concentrated sulfuric acid for 5 min and 35% sodium hydroxide for 15 min, but gibberellin had no effect on germination rate.

Karyotype studies on three Ligularia of Changbai Mountain

DONG Ran, QU Xiao-jie, WANG Li-qing, LIU Hong-zhang

2010, 19(4):  259-263. 

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Karyotypes of three Ligularia species (L. jaluensis, L. Mongolia, and L. intermedia) from Changbai Mountain were studied using the conventional pressed disc method. The chromosome numbers of the three species were all 2n=58 and the karyotype of L. mongolia was 2A while those of the other two species were 2B. Their indices of karyotypic asymmetry were between 59.22% and 62.89%. Their karyotype formulas were 2n=2x=58=42m+16sm,2n=2x=58=44m+12sm+2st and 2n=2x=58=32m+26sm, respectively. The composition of relative chromosome length was: L. jaluensis - 2n=58=2L+20M₂+30M₁+6S, L. mongolia - 2n=58=28M₂+28M₁+2S, and L. intermedia - 2n=58=2L+28M₂+26M₁+2S. The chromosome numbers and karyotypes of the three Ligularia species tested are reported for the first time.