Table of Content

20 June 2009, Volume 18 Issue 3

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View of the curriculum convention of vocational education in pratacultural science

REN Ji-zhou

2009, 18(3):  1-5. 

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Base on characters and significance of vocational education in pratacultural science, and analysis on current states of vocational education in pratacultural science, this paper demonstrates that the theories of the three factor groups, the three interfaces and the four production levels are the foundation bed for construction of curriculum framework of pratacultural science. The structure and specialized subject setting of pratacultural vocational education was put forward. As higher level of vocational education for example, the tentative curriculum framework and courses which could be available were listed. At the end of the paper, it points out that there are a lot of vacancies in vocational education of pratacultural science in most of providences of China, hence these situations must be remedied duly, otherwise it will restrict the development of pratacultural science in China.

Effects of different disturbances on species diversity and biomass of community in the typical steppe

Hugejiletu, YANG Jie, Baoyintaogetao, BAO Qing-hai

2009, 18(3):  6-11. 

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Abstract: Effect of different disturbances on species diversity, community height, community density, aboveground biomass of the typical steppe was investigated by quadrant method. Four treatment plots were devised in the study area, including moderately grazed (G), mowing once a year (M), exclosure for 7 year (E7) and exclosure for 27 year (E27) plots. The richness index, diversity index and evenness index in the E27 and G were significantly higher than those in the E7 and M, but there is no significantly difference between E27 and G. So, E27 and G might maintain community species diversity. The important values of the indicator plant of degradation (Cleistogenes squarrosa) in M and G plots were significantly higher than that of the exclosure plots. The above ground biomass of E7 was 454.06 g/m2,and significantly higher than that of the other plots. Thus, E7 could significantly increase the steppe productivity, but there would be no help for the steppe productivity if exclosure lasts too long.

Effects of enclosure on the community characteristics of Leymus chinensis in degenerated steppe

ZUO Wan-qing, WANG Yu-hui, WANG Feng-yu, SHI Guang-xu

2009, 18(3):  12-19. 

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Enclosure is widely used in steppe restoration as a brief and effective treatment in China but the effects on structures and functions of the steppe ecosystem by the increase in fencing time during this restoration requires further study. The vegetation composition and dynamic productivity characteristics were studied in both fenced and freely grazed plots during a five-year vegetation investigation on degraded Leymus chinensis steppe in Inner Mongolia. 1) The species diversity and community evenness were improved in the enclosure treatment compared with the freely grazed treatment, but the ecological dominance if the community decreased although the differences were not statistically significant (P＞0.05). 2) Dominant species were changed by the enclosure treatment. The dominant species were L. chinensis and Stipa grandis in the fenced plots, showing the characteristics of the typical steppe while L. chinensis and S. grandis were not always the dominant species in the freely grazed plots. 3) The average height of the community vegetation, the aboveground biomass and litter fall were initially increased under the enclosure treatment, but with time, the aboveground biomass gradually decreased and the litter fall increased. 4) The restoration of the structures and functions in the steppe was not isochronous in the enclosure treatment: Community biomass reached a peak only after two years but by four years the dominant species were restored to the typical steppe level. Community diversity was not improved even after a seven-year enclosure compared to the freely grazed treatment. In conclusion, the restoration purpose should be considered when planning enclosure treatment and a timetable established in order to improve sustainability and reduce the costs of restoring the steppe.

A study on population and community structure of Tamarix elongata growing
in heavy saline soils in the Middle Reaches of the Shule River

FANG Min-yan, ZHANG Ming, DING Pin, ZHANG De-gang

2009, 18(3):  20-27. 

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The aboveground parts of Tamarix elongata and other plants, together with population structure and community structure composition of heavy saline soil and salt dunes in the Middle Reaches of the Shule River are described. 1) Tamariaceae are more suitable for two of the habitats than other species and T. elongata was the dominant species in these two habitats. 2) The spacial pattern of T. elongata was a binomial distribution in heavy saline soil, but a Poisson distribution in sand dunes. 3) The importance values of the dominant species in heavy saline soil are T. elongata 0.323, Alhagi sparsifolia 0.215, Phragmites australis 0.037, Agriophyllum splendens 0.029, Asparagus persicus 0.018 4, Poacynum hendersonii 0.014 and in salt dunes is T. elongata 0.902, A. sparsifolia 0.193, L. ruthenicum 0.081 4, P. australis 0.020, Karelinia caspica 0.006, and Reaumuria soongorica 0.001. 4) There are dominant negative inter-specific ecological associations between T. elongata and A. sparsifolia in heavy saline soil but no obvious direct specific ecological association in salt dunes.

Effects of interseeding on plant diversity and productivity in Maqu alpine desertified meadow

ZHENG Hua-ping, CHEN Zi-xuan, NIU Jun-yi, GAO Yu-hong

2009, 18(3):  28-33. 

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The effects of interseeding on species richness, species diversity, and productivity in Maqu alpine desertified meadow is discussed. Interseeding markedly increased species richness and groups density. Species density was increased 8.08％ by interseeding with Poa pratensis, and by 39.65％ with mixed interseeding with Festuca sinensis and Elymus nutans. The Pielou, Simpson, and Shannon-Weiner indexes were all reduced after interseeding, with F. sinensis alone or in a mixture with F. sinensis and E. nutans. Above-ground biomass increased significantly after interseeding and reached about 55.74％ more than the control after mixed interseeding with E. nutans, F. sinensis and P. pratensis. Grasses accounted for more than 50％ of the total biomass and are the main yield components in grasslands and can contribute most to the improved economic value of meadows. Interseeding is therefore beneficial to recovering desertified meadow and protecting ecological environments.

Exotic plants in the Jinfo Mountain Nature Reserve: Species ascertain and their distribution

SUN Juan, YANG Guo-feng, CHEN Yu-cheng, TENG Yong-qing, YAN Di, YI Si-rong

2009, 18(3):  34-42. 

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Abstract: Invasion of natural ecosystems by exotic plant species is a major threat to biodiversity. The nature reserve contains a diversity of plant species. However, many exotic plant species have become established, potentially damaging the structure and function of native plant communities. The exotic plant species were investigated at selected sites and by walking through the Reserve (JFM), 1) Fifty six exotic plant species found in the JFM. They were mainly herbaceous plant species sporadically distributed in the park. The distribution of most of the alien plants (except Miscanthus floridulus) was consistent with human disturbance and together with the native plant species could be used as an available resource since they were not in competition with each other. 2) the exotic plants became established in four ways: introduced intentionally (31 species), natural invasion (15 species), uncertain, probably invasion (9 species), and introduced accidentally (1 species): the percentages were 55%, 27%, 16%, and 2%, respectively. 3) the frequency of invasive plants was positively correlated with human disturbance

The character and dynamics with season of soil seed banks in abandoned croplands of loess gully region

WANG Ning, JIA Yan-feng, BAI Wen-juan, ZHANG Zhen-guo, JIAO Ju-ying

2009, 18(3):  43-52. 

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Samples were collected along two 10 m sections and a germination experiment was carried out in the laboratory to investigate the composition, density, type, and distribution at different times and spaces of the seed bank. There were 50 species belonging to 39 genera and 15 families in the soil seed bank. The density and composition of the main species in the bank were not significantly different between seasons. During the succession, the number of species and the density of the bank initially increased, then declined, and finally increased again. However, the seed bank density changed more acutely during the year, ranging from 1 067 to 14 717 seed/m², with the maximum value in summer, the medium in autumn, and the minimum in spring. The soil seed bank in the study field was persistent with Artemisia scoparia the main species coexisting with other annual vegetation, perennials and shrubs. Additionally, in the field, the soil seed bank did not change notably with the season. There is some potential for vegetation restoration using the soil seed bank.

Genetic analysis of cold tolerance of zoysia grass

GUO Hai-lin, GAO Ya-dan, XUE Dan-dan, CHEN Xuan, LIU Jian-xiu

2009, 18(3):  53-58. 

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Abstract: The aims of this study were to find the genetic mechanism of cold tolerance in zoysia grass, and to provide an experimental basis for analysis of molecular markers related to cold tolerance for Molecular Marker-Assisted Breeding of zoysia grass. Two Zoysia F₁ segregating populations of the reciprocal crosses of Z136 (cold tolerant) and Z039 ( non-cold tolerant) were obtained, and the cold tolerance of F₁ populations were identified by leaf electrolyte leakage rate. The heredity of cold tolerance in the two F₁ populations of Z136×Z039 and Z039×Z136 were analyzed by major gene and polygene mixed genetic models. Both crosses had a high variation range of cold tolerance: -11.6 to -0.3℃ (Z136×Z039) and -10.9 to -1.7℃ (Z039×Z13), ranges far beyond those of their two parents (-9.1 and -3.3℃). The average LT₅₀ of reciprocal crosses were -6.0 and -6.3℃, both intermediate between the two parents. No obvious maternal genetic phenomenon for cold tolerance were observed in zoysia grass. The frequency distribution of cold tolerance in F₁ populations of the two crosses showed characteristics of a mixed normal distribution, which indicated that the inheritance of cold tolerance was based on a major gene plus poly-genes model. The results of genetic analysis showed that genetic model B-4 was the most suitable for the trait, i.e. the cold tolerance of zoysia was controlled by two equal additive major genes and the heritability of the major genes were 77.27% and 79.60% in the two crosses.

Genetic diversity of Gliadin in worldwide germplasm collections of Elymus sibiricus

MA Xiao, CHEN Shi-yong, ZHANG Xin-quan, ZHOU Yong-hong, BAI Shi-qie, LIU Wei

2009, 18(3):  59-66. 

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Gliadin markers based on A-PAGE were used to analyze genetic diversity and genetic relationships among eighty-six Elymus sibiricus accessions from Asia and North America. A total of 52 gliadin bands were scored, of which 47 were polymorphic (90.4%). The generated similarity matrix showed that the genetic diversity within the accessions was fairly high (average similarity index=0.373). Similarity values among the accessions ranged from 0.108 and 0.952. Similar results were obtained when genetic diversity was estimated using the Shannon index of diversity. The total genetic diversity across all accessions was 0.460. The proportion of variation explained by within geographic groups and between geographic groups diversity was 0.559 and 0.442, respectively. Cluster analysis showed a clear demarcation between accessions from the Qinghai-Tibetan Plateau, China and the others as separate groups. The extent of genetic diversity and genetic relationship among accessions is discussed. The clustering pattern probably depended on geographic origin and ecological adaptability of the accessions.

Genetic diversity identification based on ISSR analysis of Agrostis stolonifera
germplasm resources in Guizhou

SHANG Yi-shun, YANG Chun-yan, ZHONG Li

2009, 18(3):  67-73. 

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Agrostis stolonifera is a widely grown, cool season turf grass in China. To determine genetic diversity and relationships of A. stolonifera resources, 285 plants from three wild populations and a cultivated population in Guizhou were screened by inter-simple sequence repeat(ISSR)markers. Nine of 60 primer pairs produced a total of 81 bands, of which 66 were polymorphic. Statistic analysis showed a rich genetic diversity of A. stolonifera resources in Guizhou province. The genetic differentiation coefficient (Gst) and the gene flow (Nm)among three wild populations were 0.492 0 and 0.516 4 .The genetic differentiation was considerable in the three wild populations. The genetic distance GD)of the subpopulations ranged from 0.087 7 to 0.592 6. The subpopulations could be clustered into three groups based on GD. Correlation analysis found a significant positive correlation between geographical distance and genetic distance (r=0.494), and this is persuasive evidence that there is a significant correlation between genetic component and the geographic distribution of A. stolonifera resources. Further genetic relationship analysis discovered a high genetic similarity among wild populations, ranged from 0.700 3 to 0.940 9 while the cultivated population (KROMI) had an obvious genetic differentiation from wild populations.

The phylogenetic relationships between nine Elymus taxa from China based on three genetic markers

YAN Xue-bing, ZHOU He, WANG Kun, WANG Cheng-zhang, GUO Yu-xia

2009, 18(3):  74-85. 

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Genetic markers are commonly used to construct systematic trees in studies of phylogenetic relationships among plant taxa. In this study, nine native Elymus species were sampled to analyze their phylogenetic relationships using three genetic markers. Nine Elymus species were separated into two groups: Sect. Turczaninovia(Nevski) Tzvel. and Sect. Elymus. Allozyme markers did not show clear groupings, but Elymus species belonging to the same section or with the same genomic constitution indicated a close relationship. Microsatellite markers did not indicate clear groupings or relationships among the nine Elymus taxa. A significant relationship was found between three genetic markers. A morphological marker was the most significant and gave similar results to the actual relationship of individual species. The second was the allozyme marker and the third a microsatellite marker. Therefore, we suggest that morphological traits are the most direct and efficient genetic markers of Elymus taxa, while allozyme markers are a valuable predictor of the relationship among populations or species, and microsatellites are more suitable for studying inter-population rather than inter-species relationship of Elymus.

Cytogenetic studies of the intergeneric and interspecific hybrids among the
Pseudoroegneria, Roegneria and Elymus (Poaceae: Triticeae)

ZHANG Chun, WANG Xiao-li, YU Hai-qing, ZHANG Hai-qin, ZHOU Yong-hong

2009, 18(3):  86-93. 

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The differentiation and phylogeny of the St genome was investigated in the interspecific hybrids of three diploid species of Pseudoroegneria. Intergeneric hybridizations of P. libanotica and P. tauri were carried out with 4 tetraploid species of Roegneria (StY) and with 3 species of Elymus (StH, StYW). The fertility and chromosome pairing behavior in meiosis of the parents and their hybrids F₁ were investigated. 1) The St genome in P. libanotica and P. tauri (from Iran) may differt from that of P. spicata in North America; 2) Differentiation of the St genome was found in allopolyploid species with the StY, StH, and StYW genome combinations; 3) The Y genome is distinct from the H genome but is closely related to the St genome, with which some homology has been observed.

Dynamic analysis of autumn color changes based on digital imaging technique in zoysiagrass

JIA Yun-qi, CAO Zhi-zhong, WANG Yun-wen, SUN Jie-feng, HE Yong

2009, 18(3):  94-102. 

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The dynamics of autumn color changes in four zoysiagrass accessions was analyzed by Sigmascan Pro 5.0 image analysis software using the photos of individual plants taken at intervals by a digital camera. The appropriate settings for selecting the green pixels were hue (H) 32-107, saturation level (S) 10-100, and for yellow pixels was H 10-32, The ranking order of the four accessions for dormancy date (from early to late) was Z. japonica cv. Liaoning,H₂ strain, cv. Qingdao and Z. japonica var. pollida Nakai ex Honda cv. Jiaodong. It was concluded that there was a correlation between the date of autumn dormancy and the latitude of origin of the four accessions. Compared with traditional visual rating, the advantages of digital image analysis are greater repeatability and more accuracy.

Transformation of Cichorium intybus with the AtNHX1
gene and salinity tolerance of the transformants

ZHAO Yu-wei, WANG Ying-juan, BU Huai-yu, HAO Jian-guo, JIA Jing-fen

2009, 18(3):  103-109. 

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The AtNHX1 gene was transferred into Cichorium intybus using Agrobacterium and 42 regenerated plants resistant to Kanamycin (Kan) were obtained. Incorporation and expression of the AtNHX1 gene in the transformants were confirmed by PCR, Southern blot, and RT-PCR. Under the same salt stress conditions, the transgenic calli with NaCl resistance, that were induced from transgenic plants, had considerably higher relative growth rates than the wild-type calli. Under the stress of different concentrations of NaCl, the K⁺/Na⁺ ratio in the transgenic plant cells was always higher than that in the wild-type, whereas the relative conductivity was the opposite. The transformation of the AtNHX1 gene not only enhanced the salt tolerance of transgenic C. intybus, but also reduced cell membrane damage induced by salinity.

Protoplast culture and plant regeneration of Zygophyllum xanthoxylum

WANG Ying-hua, CHEN Gang, JIA Jing-fen, HAO Jian-guo

2009, 18(3):  110-116. 

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An efficient protocol for plant regeneration from protoplasts of Zygophyllum xanthoxylum was established. The friable calli induced from segments of cotyledon were used for protoplast isolation through enzyme digestion. The effects of different media and plating densities on protoplast divisions and plant regeneration were studied. Sustained cell divisions and colony formation from the protoplasts of Z. xanthoxylum were obtained by a DPD medium containing 1.0 mg/L 2, 4-dichlorophenoxyacetic acid (2, 4-D), 0.2 mg/L 6-benzylaminopurine (6-BA), 0.2 mg/L kinetin (KT), 0.5 mol/L mannitol, 500 mg/L casein hydrolysate, and 2% (W/V) sucrose at a plating density of 2×10⁵ /mL. The division frequency was 28.4%. Regenerated plantlets were obtained when these calli were transferred to MS medium containing 1.0 mg/L 6-BA and 0.5 mg/L (NAA).

Cloning of PA1 gene from Pisum sativum and genetic transformation on Medicago sativa

ZHANG Gai-na, JIA Jing-fen

2009, 18(3):  117-125. 

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A gene, a sulphur-rich and insect-toxic seed albumin-PA1 gene, was cloned by PCR method from Pisum sativum (cultivar shijiadacaiwan). In order to characterize the function of this gene, a plant expression vector, pCAMBIA1301-PA1, was constructed. This vector was transformed into M. sativa via Agrobacterium-mediated method. The conditions for transformation were optimized. The several transgenic embryogenic calli and regenerated plantlets were obtained. PCR and Southern blotting identification confirmed that PA1 gene and hygromycin-B phosphotransferase-resistant gene has been integrated into the genome of M. sativa, SDS-PAGE analysis indicated that PA1 gene expressed in the transgenic lines. Free amino acid analysis showed that the levels of methionine and cysteine in tansgenic M. sativa. Plantlets improved from 0.1% to 0.4%.

Isolation, identification, and sequence analysis of rDNA-ITS of
Pythium species sampled from rhizosphere soil of corn

CHAI Zhao-xiang, LI Jin-hua, LOU Bing-gan, LI Wei, GAN Hui-lin1,
GUO Cheng, ZHAO Ling, DONG Di

2009, 18(3):  126-135. 

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Pythium spp. were isolated from the rhizosphere soils of corn sampled from Honggu and Qilihe districts of Lanzhou using a baiting method. Twenty three isolates were obtained after subculture and purification. Based on the morphology, culture characteristics, growth rate, adaptation to temperatures and sequence analysis of rDNA-ITS, the 23 isolates were all identified as P. scleroteichum, P. ultimum or Pythium sp. This is the first report of P. scleroteichum in China and of P. ultimum from corn in Gansu. P. ultimum was the dominant population of the three species (60.9% of the isolations), while Pythium sp. (26.1%) was second, and, P. scleroteichum (13.0%) was third.

Effects of phosphate fertilizer on utilization of non-structural carbohydrate
in resident tissue of Medicago sativa during the early regrowth stage

JIANG Hui-xin, SHEN Yi-xin, ZHAI Gui-yu, LIU Xin-bao, YUAN Pei-xun

2009, 18(3):  136-141. 

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A field experiment was conducted to study the effects of phosphate fertilizer on utilization of non-structural carbohydrate (NSC) stored in the main root, crown, and stubble of alfalfa (Medicago sativa) during early regrowth after defoliation. NSC is mainly stored in the root and crown. A great deal of starch, the major component of stored NSC, was utilized during early regrowth. With increasing rates of phosphate fertilizer, starch reserves increased in the main root and crown and at 270 kg P₂O₅/ha starch reserves were 73.5% and 31.1% higher respectively than those in the control. Phosphate fertilizer improved the activity of α-amylase and accelerated the hydrolyzis of starch in the main root and crown, thus promoting regrowth by enhancing mobilization of starch reserves for emergence of dormant buds and new shoots after defoliation. The dry weight of plants treated with 270 kg P₂O₅/ha was significantly (P＜0.01) greater than the control 13 days after defoliation. NSC in the main root and crown of alfalfa is the main source of nutrients during early regrowth and phosphate fertilizer improved the storage and conversion efficiency of NSC thus accelerated regrowth of alfalfa after defolition.

The long-term effects of returning straw and applying organic fertilizer on weed
communities in a paddy field with a double rice cropping system

LI Chang-xin, ZHAO Feng, RUI Wen-yi, HUANG Qian-ru, YU Xi-chu, ZHANG Wei-jian

2009, 18(3):  142-147. 

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In 2007, the results of a long-term fertilizer experiment were used to study the characteristics of weed communities in a paddy field, where crop straw was returned and organic fertilizer applied since 1985 (Jinxian County, Jiangxi Province). Weed species biodiversity was significantly reduced under long-term straw return and organic fertilizer application. Long-term straw return through mulching reduced weed density and biomass, but they were increased during the field fallow by organic fertilizer application. The positive effects of organic fertilizer application on weed growth were greater in early planted rice plots than in late planted ones. The negative effects of straw return on weed growth were greater in winter with mulching after application than in summer when straw was mixed into the soil. Alopecurus japonicus was the dominant population with a relative density of more than 90% in all plots and the next common weed populations were Lapsana apogonoides and Aneilema keisak. This suggests that straw return and organic fertilizer application can effectively control weed communities in the paddy field during fallow.

Effects of different varieties and levels of fertilizer application on the economic benefit
of forage rye and fertilization management

LI Zhi-jian, ZHU Ting-cheng, QIN Ming

2009, 18(3):  148-153. 

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The experiment was carried out in the Wuqiao experiment fields of China Agricultural University from Oct. 1997 to Apr. 1998, to study the effects of nitrogen, phosphate, and potassium fertilizer applications on the economic benefit of forage rye and to optimize the fertilizing scheme. Mathematical models were established for the economic benefit of rye production with the treatments of N, P, and K fertilizer in this study. To gain more economic benefit, it was necessary to reduce fertilizer doses to control the cost of rye production when the price of rye hay was low and increase fertilizer doses to improve the yield of forage rye when the price of rye hay was high. The amount of fertilizer application should be determined by the integration of several targets, including the maximum yield, economical considerations, and quality. Higher fertilizer application is best for obtaining maximum yield but strategies to use moderate amounts of fertilizer are more economical. For obtaining higher quality, more nitrogen fertilizer is required. These three targets were compromised only by the price of forage rye. In general, the optimum combination of N, P, and K was 225 kg/ha N, 75 kg/ha P₂O₅, 30 kg/ha K₂O.

Influence of urea application on aboveground biomass and important value of the species in the degraded grassland

HE Dan, LI Xiang-lin, WAN Li-qiang, HE Feng, LI Chun-rong

2009, 18(3):  154-158. 

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When different amounts of urea were applied to improve the degraded grassland, different species responded differently to the different concentrations. Fifty kg/ha of urea was the best concentration for increasing productivity and importance of Leymus chinensis in the grassland community, while 75 kg/ha was optimum for Phlomis tuberosa and 100 kg/ha for Potentilla acaulis. This shows that different concentrations of urea may be used to give some limited control of the structure of the degraded grassland plant community.

Effect of nitrogen on growth and total alkaloids of Sophora flavescens

JI Ying, ZHANG Qing-xia, LIN Hai-ming, CAI Wei

2009, 18(3):  159-164. 

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The effect of nitrogen on growth, total alkaloids concentration and total alkaloids yield of Sophora flavescens was studied. Four levels of N (50, 100, 150, 200 mg/kg) were applied using urea (N 46%) in a pot experiment. The control was no N. Plant height, root diameter, root dry weight, aerial dry weight, Chl concentration and total alkaloids concentration increased relative to the amount of N applied. The root dry weight was 26.7 g/plant at 150 mg/kg N applied, an increase of 42% compared with the control. Root dry weight/root fresh weight and root dry weight/total plant dry weight decreased with amount of N applied. Nitrogen application had significant positive effect on root diameter. The root diameter was highest at 150 mg/kg N applied, an increase of 21.1% compared with the control. The percentage of xylem diameter increased with N applied while the percentage of root bark depth decreased. Chl concentration and total alkaloids concentration increased with N applied. Chl concentration was highest at 100 mg/kg N applied, an increase of 33.8% compared with the control. Total alkaloids concentration (4.4%) was also highest at 100 mg/kg N applied, an increase of 35.7% compared with the control. Total alkaloids concentration increased by improving Chl concentration. The total alkaloids yield per plant (1.18 g/plant) was highest at 150 mg/kg N applied, an increase of 90.5% compared with the control.

Effect of fertilization on the grass yield, water utilizing and nutrition
uptake of Sudangrass and Ryegrass rotation regime

LI Wen-xi, LU Jian-wei, YANG Juan

2009, 18(3):  165-170. 

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The effect of different fertilization strategies on the grass yield, water utilizing and nutrition uptake of a Sudangrass and Ryegrass rotation regime was studied in a two-year pot experiment. Application of NPK combinations improved the yield of Sudangrass and Ryegrass, and total yield for the two seasons of 2005 and 2006 was 1 690.0 g/pot, which was 700.7%, 426.4%, and 15.9% higher than that of the PK, NK, NP treatments respectively. In 2006 and 2007, total yield of the two seasons was 2 091.3 g/pot, which was 1 260%, 384.5% and 4.4% higher than that of the PK, NK, NP treatment respectively. The NPK combination promoted nutrient uptake of N, P₂O₅, K₂O by the forage grasses of 6.36, 1.83, 13.91 g/pot in 2005 and 2006 respectively, and of 4.91, 2.31, 7.64 g/pot in 2006 and 2007. Similarly, fertilizer utilization efficiencies of N, P, K were 59.4%, 33.9%, 96.0% in the first rotation and 47.4%, 39.8%, 43.1% in the second rotation giving an average fertilizer utilizing efficiency of 53.4%, 36.8%, 69.5%.

Germination responses of three desert plants to temperature and water potential

HUANG Wen-da, WANG Yan-rong, HU Xiao-wen

2009, 18(3):  171-177. 

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The hydrothermal model that quantifies seed germination progress affected by temperature and water potential, is one of the important methods in the physiological and ecological researches of seed. Seed germination percentage and germination rates (1/t₅₀) of three desert plants Cleistogenes songorica,Peganum multisectum and Bassia dasyphylla collected from Alashan desert grassland, Inner Mongolia were estimated under the water potential ranging from -2.1 to 0 MPa at 15, 20, 25, and 30℃. The hydrotime (θ_H) and thermaltime (θ_T) were estimated by using the hydrothermal model. Significant positive correlations were observed between the germination percentages of three desert plants and the osmotic potentials (r²=0.54-0.96, P＜0.01), and between the germination rates (1/t₅₀) and the osmotic potentials (r²=0.66-0.95, P＜0.01) except P. multisectum ( of which the germination percentage was less than 50% from -2.1 to 0 MPa at 15, 20, and 25℃). θ_H varied with temperature change (P＜0.05) from 15 to 25℃ appearing P. multisectum＜B. dasyphylla＜C. songorica. And θ_T varied with osmotic potential change from -1.5 to 0 MPa, showing similar order.

Studies on filling dynamic and germination characteristics of Rheum palmatum seeds

SHI You-tai, CHEN Yuan, GUO Feng-xia, LIU Ya-ya, TU Cai-yun

2009, 18(3):  178-183. 

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Cards were hung as a flower sign in triennium Rheum palmatum plants cultivated in Li county of Gansu during blossom. The 1 000-grain weight, water content and seed germination in the plants were measured in period time after 10 d following the blossom day. Filling dynamic and germination characteristics of R. palmatum seeds were studied in order to provide theoretic basis for its seed standard production. The results showed that the 1 000-grain fresh weight increased and got at the highest value on the 36th day following blossom, and then rapidly decreased to the level near its dry weight, which fitted to Logistic equation with a rapid increase during 13-36 d after blossom. The grain filling rate showed ‘fast-slow-fast-slow’ pattern and went to bottom two times because of raining. The grains dehydrated grown fast with filling duration prolong and the water content decreased to the end. The seed germination vigor, germination rate and germination index were significantly improved with filling duration prolong within 36 d after blossom but showed difference further long, which were positively and significantly related with grain dry weight while negatively and significantly related with water concentration. All above revealed that the seed filling is affected by weather. The fast dehydrating rate in seeds is an important indication for seed maturation and the maturity affects its seed germination quality. The best harvest time should be during 46-52 d following blossom (at the beginning of July) during which the water content in the seeds should be 12%-16% with still non-perishing stems.

A regional test of alfalfa varieties in the Longdong area

CAO Hong, ZHANG Hui-ling, MA Yong-xiang, CHEN Hong,
FANG Gang, HAN Ji-guang, ZHANG Fu-zhong

2009, 18(3):  184-191. 

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A regional test and quality analysis of 15 alfalfa varieties was carried out in the Longdong area (Xifeng District, Ningxian County, and Huanxian County of the Qingyang area) during 2003-2006. Gannong No.1 and Alfaking were varieties with very good characteristics such as higher and more stable yield, better quality and wider adaptability than the control variety (Longdong alfalfa). The two alfalfa varieties could therefore be planted on a large scale in the whole of the Longdong area. The six varieties, Golden empress, Sanditi, AmeriStand, Xinjiang, Millionaire, and Phabulous, grew faster than the control variety and had better quality and higher, more stable yield, so they could be grown in some suitable local areas. This suggests that selecting superior varieties overseas may rapidly enhance the economic efficiency of developing the crop within a short period, while selecting domestic superior varieties could improve the resistance of alfalfa, prolong the production life, and enhance the ecological benefits of growing the crop.

Salinity stress responses and tolerance thresholds in four warm-season turfgrasses

LIU Yi-ming, CHENG Feng-zhi, WANG Qi, HU Yu-yong, WANG Zhao-long

2009, 18(3):  192-199. 

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Four warm-season turfgrass species ]Bermudagrass ‘Tifdwarf’ (Cynodon dactylon×C. transadlensis), Centipedegrass (Eremochloa ophiuroides), Seashore Paspalum ‘Salam’ (Paspalum vaginatum), and Zoysiagrass (Zoysia matrella)] were grown in PVC pots under a series of NaCl concentrations to study the salinity stress responses of turfgrass growth and physiological parameters. Seashore Paspalum showed the best salinity tolerance. The visual quality, relative growth rate, relative water content, chlorophyll index, and Fv/Fm decreased 52.2%, 76.2%, 62.1%, 59.4%, and 72.9%, respectively after 36 d at 600 mmol/L NaCl, but the electrolyte leakage increased to 71.5%. The cell membrane damage in Seashore Paspalum was the lowest of the three species. Zoysiagrass also showed good salinity tolerance, with decreases in visual quality, relative growth rate, relative water content, chlorophyll index, and Fv/Fm of 85.2%, 85.3%, 70.5%, 73.9%, and 49.3%, respectively after 36 d at 600 mmol/L NaCl, and with an increase in electrolyte leakage of 81.8%. Bermudagrass and Centipedegrass showed the lowest salinity tolerance with treatment of 600 mmol/L NaCl and both species were dead after 36 d. The salinity tolerance thresholds of four turfgrass species were determined using linear regression of plant growth rate against NaCl concentration. After 36 d treatment plant growth rate was reduced to 50% of the control. The tolerance thresholds are Centipedegrass 222.4 mmol/L, Bermudagrass 232.4 mmol/L, Zoysiagrass 374.8 mmol/L, and Seashore paspalum 474.0 mmol/L.

The relationship between electrolyte leak and light energy dissipation of PSⅡ
in the leaves of Puccinellia tenuiflora seedlings under Na₂CO₃ stress

ZHANG Jun, WANG Jian-bo, CHEN Gang, DU Kun, LIU Juan, SUN Guo-rong

2009, 18(3):  200-206. 

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Fluorescence induction kinetics was used to investigate the relationship between electrolyte leakage and light energy dissipation of PSII in the leaves of Puccinellia tenuiflora seedlings under Na₂CO₃ stress. The maximal photochemical efficiency of PSII (Fv/Fm) and potential photochemical efficiency (Fv/Fo) decreased as electrolyte leakage increased. Actual photochemical efficiency of PSII in the light (ΦPSII), electron transfer rate (ETR), the photochemical quenching coefficient(qP), photochemical efficiency (PR), heat dissipation (HD) and heat dissipation rate (HDR) increased when electrolyte leakage was less than 0.2. However, ΦPSII, ETR, qP and PR decreased when electrolyte leakage was more than 0.2. The dividing line for effectual control of P. tenuiflora appeared to be an electrolyte leakage of 0.2. The non-photochemical quenching coefficient (qNP) increased when electrolyte leakage was less than 0.15, while qNP decreased when electrolyte leak was over 0.15. Thus the inflexion of qNP appeared to be an electrolyte leakage of 0.15, whereas that for ΦPSII, ETR, qP and PR was 0.2. This could explain the regulation ability of effectual heat dissipation when electrolyte leakage was less than 0.15 and why the ability of heat dissipation reduced when electrolyte leakage was over 0.15. The results showed that P. tenuiflora improved the function of PSII by increased heat dissipation and light energy absorbion by light-harvesting pigment, resulting in the augmentation of active oxygen elimination by antioxidant enzyme systems when electrolyte leak was in a certain range. However, when electrolyte leakage exceeded this range, the functioning of PSII was inhibited or the PSII system suffered from irreversible damage.

The responses and mechanisms of water use efficiency to different water stresses of three alfalfa varieties

LIU Guo-li, HE Shu-bin, YANG Hui-min

2009, 18(3):  207-213. 

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Water use efficiency (WUE) of alfalfa was investigated under water stress. The physiological changes in leaf net photosynthetic rate (Pn), transpiration rate (Tr), intercellular CO₂ concentration (Ci), stomatal density, and carbon isotope composition (δ¹³C) of three alfalfa varieties were measured at three soil water levels in a greenhouse pot experiment. WUE of Longdong and Xinjiangdaye varieties was the greatest at 50% field water capacity (FWC) and the least at 75%FWC but the opposite for Algonquin. At 25%FWC, WUE of all varieties was the best in the daytime, but for 75%FWC and 50%FWC, the results were not consistent. Pn/Ci declined as water stress became more severe, while both stomatal density and δ¹³C increased. This suggests that water stress could to some extent enhance WUE of alfalfa, but responses differed between varieties. In addition, stomatal regulation and leaf carboxylation efficiency could both play roles in modulating WUE of alfalfa.

Weed species and their chemical control in Paspalum vaginatum cv.
“Salam” at the Kingswan Countryside Club

XUE Guang, SHEN Zheng-gao, DU Jin-rong, GAO Xiang

2009, 18(3):  214-223. 

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This study was conducted at the Kingswan Countryside Club between 2006 and 2008 to determine the weed species, their growth habits and life cycles. The 95 weed species found included 19 grasses, 3 sedges, and 73 broadleaved species from 29 families. Among them, 50 species only germinated in spring, 36 in the fall and the remainder in both spring and fall. During the first year of course establishment there were remnant traces of the original weed community present although more mat-forming weeds were present due to the regular cultivation practices such as mowing. Field trials showed that 65.4%-94.8% of grasses and broadleaved weeds were controlled with fall applications of Shadeout at 0.045-0.03 kg ai/ha mixed with chlosulfuron at 0.02-0.022 8 kg ai/ha at 61 and 115 DAA; 69.4%-71.2% of Lolium perenne (cv. citathon #3)and Poa annua were controlled with fall applications of Battalion at 0.045-0.052 5 kg ai/ha and Shadeout at 0.037 5-0.03 kg ai/ha at 49 plus 103 DAA. There was slight visible injury to Paspalum vaginatum cv. Salam at 2 WAA, of Shadeout at 0.06 kg ai/ha, Battalion at 0.067 5 kg ai/ha and chlosulfuron at 0.022 8 kg ai/ha with recovery at 4 WAA. There was visible injury to P. vaginatum 2-4 WAA of Shadeout at 0.18 kg ai/ha and recovery was not until 36 WAA.

Effects of malic acid supplementation on rumen fermentation, nutrient digestion
and metabolism in Simmental steer

WANG Cong, LIU Qiang, DONG Qun, YANG Xiao-min, HE Dong-chang, DONG Kuan-hu

2009, 18(3):  224-231. 

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This study evaluated the effects of malic acid on rumen fermentation, urinary excretion of purine derivatives, nutrient digestibility, energy metabolism, and nitrogen balance of steers. Eight ruminally cannulated Simmental steers were used in a replicated 4×4 Latin square experiment. The treatment without malic acid was the control, and treatments 1, 2, and 3 were supplemented with 70, 140, and 210 g malic acid per steer per day, respectively. Ruminal pH of steers supplemented with malic acid at 140 and 210 g/d was significantly (P<0.05) lower than that in the control. The ratio of acetate to propionate, ruminal ammonia nitrogen and ruminal lactate concentrations of steers supplemented with malic acid at 140 and 210 g/d were significantly (P<0.05) lower than those at 70 and in the control. Total VFA concentration and the molar proportions of propionate and butyrate of steers supplemented with malic acid at 140 and 210 g/d were significantly (P<0.05) greater than those at 70 and in the control. Ruminal dry matter, organic matter, neutral detergent fiber and acid detergent fiber degradation of corn straw in the 140 g/d malic acid treatment were significantly (P<0.05) greater than those in the control. Ruminal dry matter, organic matter and crude protein degradation of concentrate in the 210 g/d malic acid treatment were significantly (P<0.05) lower than those in thte other treatments. Allantoin concentration and urinary excretion of purine derivatives of steers in the 140 g/d malic acid treatment were significantly (P<0.05) greater than those in the 70, 210 g/d treatments and in the control. Dietary organic matter, nitrogen free extract, ether extract, neutral detergent fiber and acid detergent fiber digestibilities of steers supplemented with malic acid at 140 and 210 g/d were significantly (P<0.05) greater than those in the control. Digestible energy, metabolizable energy, retention energy and the ratio of retention energy to digestible energy of steers in the 140 g/d malic acid treatment were significantly (P<0.05) greater than those in the control. Retention nitrogen of steers in the 140 g/d malic acid treatment was significantly (P<0.05) higher than that in the control. The results indicated that the optimum dose of malic acid supplement was 140 g/d.

The development of Panicum virgatum as an energy crop

LIU Ji-li, ZHU Wan-bin, XIE Guang-hui, LIN Chang-song, CHENG Xu

2009, 18(3):  232-240. 

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Considerable interest has developed in renewable energy and energy. Switchgrass will be an ideal energy crop because of its strong adaptability to environment, big potential yield, and environmental friendliness. This paper reviews the biological characteristics, ecological needs, cultivation and management of switchgrass as an energy crop. We discusses the use patterns for energy production, existing problems and analyze development potential in China. We propose the the direction for development of switchgrass for energy use and considere that the main use of switchgrass will be for pellet fuel and small biomass power plant at present and in the near future. As a second generation fuel, production of ethanol may have the most potential in the future.

Molecular basis of signal transduction mediated by calcium-dependent protein kinases (CDPKs) in plants

WANG Jiao-jiao, HAN Sheng-fang, LI Xiao-juan, GU Jun-tao, LU Wen-jing, XIAO Kai

2009, 18(3):  241-250. 

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An important component of the Ca²⁺ signal cascade induced by signals of plant growth and development, and biotic or abiotic stresses, is the calcium-dependent protein kinases (CDPKs) which play a vital role in biological processes, such as regulation of the expression of downstream genes, modification of biochemical metabolisms, controlling the transportation of ions and water. In this paper, the structure characterization, distribution property, physiological and biological properties, role in signal transduction, and the biological function in plants of the CDPKs are summarized, to provide a theoretical guidance for identification of CDPKs and exploration of the signal transduction mechanisms mediated by CDPKs in forage crops.

Studies of factors that influence the daily dynamics of pod dehiscence in Vicia cracca

LIU Yu-ying, WANG Ying, MU Chun-sheng, LI Xiao-yu, WANG Jun-feng, Hou Yu

2009, 18(3):  251-254. 

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Factors influencing the daily dynamics of pod dehiscence in Vicia cracca were investigated on both sunny and cloudy days to find when the pods dehiscence and the relationships between pod dehiscence and environmental conditions. The results showed that the pod dehiscence rate had a significant positive correlation with air temperature, humidity, pod wall temperature, and moisture content on sunny days (P<0.01). On cloudy days, such factors, but not pod moisture content or wind speed, had a significant correlation (P<0.05) with pod dehiscence. Peak pod dehiscence occurred at 12:00 to 14:00 and there was little dehiscence before 8:00 or after 18:00. More pods dehisced on sunny days than on cloudy days. These results indicate that pod dehiscence rate is closely correlated with air temperature and humidity. To reduce seed loss, the optimum harvest time is in the morning before 8:00 or at dusk after 18:00.

Analysis of the grey incidence of wild Trifolium pratense drought resistance
in the three gorges reservoir area

HE Wei, FAN Yan, WANG Lin, XU Yuan-dong, QING Xiao-peng, PENG Yan

2009, 18(3):  255-259. 

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Ten indexes were determined for 9 wild accessions collecting from the three gorges reservoir area and 3 varietie of Trifolium pratense under drought stress at the seedling stage. Screeding identification indexes and comprehensive exaluation were studied by grey correlative degree analysis. The results showed that three indexes including ground biomass, MDA content and chlorophyll a content were important in drought stress. The sequence of drought resistance of 12 T. pratense from strong to weak was: Red>CQ5>CQ9> Dory>CQ2>CQ4>CQ7>CQ3>CQ1>WuXi>CQ8>CQ6.