Table of Content

22 February 2011, Volume 20 Issue 1

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The response of plants and soil on black soil patch of the Qinghai-Tibetan
Plateau to variation of bare-patch areas

MA Yu-shou, LI Xi-lai, LONG Rui-jun

2011, 20(1):  1-6. 

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Characteristics and variation of soil and vegetation in and surrounding, 93 bare patches of a typical “black soil patch” area of the Qinghai-Tibetan Plateau were investigated. Bare-patches formed “negative fertile islands” after sod layers breaking off in alpine meadows, i.e. soil nutrients in bare-patches were lower than those in the surroundings. There were obvious differences in total nitrogen, ammonium nitrogen, and organic carbon between the two parts. The pH values of bare patches were higher than those of the surroundings, so meadows lose nutrients in bare patches. If the bare-patch was more than 5 m², the heterogeneity was reduced compared with the surroundings. The maximum number of plant species in bare-patches was 20 to 25, considerably lower than that of the grassland covered with a sod layer. The major toxic weeds, Aconitum pendulum and Carum carvi, in the bare-patches had a linear positive correlation with the bare-patch area, and the number of rat holes was also linearly positively related to the bare-patch area.

Effect of N addition on plant community structure and index
of grassland quality of typical steppe mown grassland

BAOYIN Taogetao, LIU Mei-ling, BAO Qing-hai, HUGE Jiletu

2011, 20(1):  7-14. 

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In the grassland region of Inner Mongolia, herdsmen always mow tall grass in autumn in preparation for feeding livestock in winter. The grassland has become increasingly degenerate because of annual mowing so we studied the effects of N addition to mown grassland on standing crops, species composition, community structure, and nitrogen content of the main populations in Stipa grandis grassland of a typical steppe. 1) For plots mowed once a year, the community standing crops after adding N were higher than those of control plots, and the plots with more N (N3, 64.4 kg/ha, N4, 78.2 kg/ha) also had significantly higher productivity in the first two years after adding N. For plots mowed twice a year, only the plots with highest N addition (N4) had significantly higher standing crops than the controls. N addition to non-mowed plots had some effect although this was not significant. 2) Community species diversity of the two mown systems increasingly fluctuated with the added N except for the non-mown system, and generally, the evenness decreased with increased N addition. 3) For the three main populations, two aspects (crops and nitrogen content) affected by adding N were considered. First, after adding N, S. grandis and Leymus chinensis had equal and super compensation on standing crops in control plots and plots mowed once a year, but in plots mowed twice a year there was no compensation, while with Cleistogenes squarrosa standing crops had equal compensation to control plots, but super compensation in plots mowed after adding N. Second, nitrogen contents in S. grandis and L. chinensis plants were increased with the added N whether in plots mowed once a year or in non-mowed plots. But for C. squarrosa, this phenomenon could only be found in plots mowed once a year, while in non-mowed plots, nitrogen content was highest in the N2(50.6 kg/ha)plots and maintained this level with higher application rates. 4) N addition not only ensured productivity of grassland mowed once a year, but also improved the grassland quality to some degree. The N4 treatment had the best effect on grassland.

Effects of different tillages on weed communities in winter wheat fields

GAO Zong-jun, LI Mei, GAO Xing-xiang, GUO Xiao, SUN Ting-lin, ZHAO Wei

2011, 20(1):  15-21. 

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The effects of rotary tillage with no stubble (RT), rotary tillage with straw incorporation (RTS), no-till without stubble (NT), no-till with 6 000 kg/ha (NTS₆₀₀₀), and no-till with 3 000 kg/ha (NTS₃₀₀₀), on weed communities structure and species diversity was studied in field experiments using a community ecology method. Compared with RT, the NT, NTS₃₀₀₀, and NTS₆₀₀₀ treatments increased perennial weed species, but there was no significant difference in the species richness. NT, NTS₃₀₀₀ and NTS₆₀₀₀ significantly reduced the summed dominance ratio (SDR) of Lithospermum arvense, but increased the SDR of Capsella bursa-pastoris. RTS significantly reduced the SDR of L. arvense, but increased the SDR of Descurainia sophia. The species diversity of weed communities varied significantly between different tillage systems. The Bray-Curtis index and hierarchical cluster analysis classified the weed communities of different tillage systems into two categories: CategoryⅠ(NT, NTS₆₀₀₀ and NTS₃₀₀₀) where no-till was implemented, and category Ⅱ (RTS and RT) where rotary tillage was implemented. The species richness of categoryⅠwas a little larger than that of category Ⅱ, but the species diversity and community evenness were much larger than those of category Ⅱ. However, the community dominance of category Ⅰwas significantly smaller than that of category Ⅱ.

Production performance of alfalfa+maize intercropping systems and evaluation of interspecies competition

ZHANG Gui-guo, DONG Shu-ting, YANG Zai-bin

2011, 20(1):  22-30. 

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The variation of interspecies competitiveness, and its effects on the production performance of four intercropping treatments alternating alfalfa (Medicago) and maize (Zea mays) were investigated in a 2∶2,3∶2,4∶2,5∶2 design with three replications, and intercropping area rates of 33%∶67%, 43%∶57%, 50%∶50%, 55%∶45%, respectively. Maize and alfalfa as the monocultures were the control groups. Dry matter yields of different treatments were measured, and land equivalent ratio (LER), aggressiveness (A), and relative crowding coefficient (RRC) were introduced as indexes to evaluate the interspecies competition in each treatment. In the first year of establishment, yields of all the intercropping treatments were lower than that of the maize monoculture, but higher than that of the alfalfa. The 5∶2 treatment had a better production performance and economic returns than the other intercropping treatments. In the second year, alfalfa had a high-yielding period, and occupied the dominant niche for the whole growing stage in the intercropping systems. Total biomass of all the intercropping systems were not less than the maize or alfalfa monocultures. The 5∶2 intercropping treatment had the best productivity and economic returns.

Growth dynamics and optimum harvest period of sorghum hybrid sudangrass

GUO Pu, ZHANG Yan, GAO Xin-zhong

2011, 20(1):  31-37. 

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To understand the growth regularity and confirm the best harvest time for sorghum hybrid sudangrass, its growth rate, fresh and dry matter accumulation and distribution during different growth stages were investigated, and its nutrient values evaluated in a field experiment. Plant height, growth rate, yield and ratio of leaf to stem of sorghum hybrid sudangrass all fit a Logistic model under dry farming conditions. Growth rate was slow until the 50^th day after seeding when it increased until the 80^th day, after which, it slowed until the 110^th day. There were no obvious trends of crude fat (EF) and hydrocyanic acid (HCN) while crude fiber (CF), nitrogen-free extract (NFE), dry matter yield, gross energy (GE), digestible energy (DE), metabolizable energy (ME), and total digestible nutrient (TDN) all increased. Crude protein (CP) and crude ash (CA) declined from tillering to the booting stages. Fresh yield was maximal at the later jointing stage (121.7 t/ha) while CP, CA, EF, CF, NFE and TDN were maximal at the 1.915 t/ha, 1.956 t/ha, 0.271 t/ha, 7.749 t/ha, 10.75 t/ha and 13 358 MJ/ha stages respectively. Dry matter yield was maximum at the booting stage (31.1 t/ha) while CP, CA, EF, CF, NFE and TDN were maximal at 1.920 t/ha, 2.126 t/ha, 0.348 t/ha, 9.070 t/ha, 15.51 t/ha, and 17 383 MJ/ha, respectively. It is suggested that for a high grass yield of sorghum hybrid sudangrass to be used as a green feed, it should be harvested in the later jointing stages while for a better dry matter yield and nutritive value as processing silage or hay, it should be harvested at the heading stage.

Cutting management of Medicago sativa in the Lhasa river valley, Tibet

FAN Jiang-wen, OUYANG Ke-hui

2011, 20(1):  38-45. 

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Through systematic research of the cutting areas in the Lhasa river valley, dynamic models of Medicago sativa growth were structured to simulate and forecast the accumulation of dry matter and fresh forage of M. sativa in different cutting schemes. The effects of cutting times on accumulation of dry matter and fresh forage, height, dry weight/fresh weight ratio, nutrient component of M. sativa were studied and different cutting schemes were developed to suit different objectives. Cutting three times a year at branching for M. sativa pasture gave the maximum dry matter and best quality of M. sativa hay in the Lhasa river valley.

The response to different irrigation and fertilizer treatments of two tall fescues under heat and drought stress

LUO Yong, HONG Ru, YANG Lie

2011, 20(1):  46-54. 

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Tall fescue is a popular turfgrass species used in Chinese transition zones but it suffers from both heat and drought stress in summer. A field study was conducted at Hefei, Anhui, in 2009, to 1) assess the effectiveness of irrigation and fertilizer treatments on regulation of drought/high temperature stress tolerances of two tall fescues (Fie phoenix and Coalnaduo), 2) determine the optimum fertilizer and irrigation treatments that result in the most drought resistance and persistence of turfgrasses. 1) The stress resistance of tall fescue under different irrigation and fertilizer treatments significantly improved, MDA contents decreased, POD activity increased, chlorophyll contents were raised, relative water contents increased, tillers and leaves per unit area were higher, and moderate irrigation improved root growth. In addition, visible turf qualities were upgraded with different fertilizer and irrigation treatments; 2) Almost all the resistances of Fie phoenix were better than those of Coalnaduo, but the differences were not significant; 3) Both irrigation and fertilization significantly improved stress resistant, but the interaction effect between irrigation and fertilization was not significant. 4) B1C1 was the optimal irrigation and fertilization culture to increase stress resistance in summer; 5) The resistant mechanism for adaption to high temperate and drought stress in summer, differed in the various varieties and was favored by breeding/selecting and culture management in summer.

Effect of N application on yield of forage grass and the accumulation
of N and C under a sudangrass/ryegrass rotation

LI Wen-xi, LU Jian-wei, LU Jun-ming, LI Xiao-kun

2011, 20(1):  55-61. 

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Sudangrass and ryegrass rotation is a new type of cropping system in Jianghan Plain, which has developed very fast in recent years. Effects of N application on yield and accumulation of N and C in forage grass and of total N and organic C in soil under a sudangrass/ryegrass rotation regime were studied for four years in a field experiment in Jianghan Plain. With increasing N application rate, total yield of forage grass increased in the seasons 2005-2006, 2006-2007, 2007-2008, and 2008-2009. Compared with N0 (no N application) treatment, the yield in N1 (total 337.5 kg N/ha in the rotation) treatment increased 243.5%, 234.0%, 153.6%, and 127.0% in the four successive seasons while yield in N2 (total 675 kg N/ha in the rotation) treatment increased by 313.1%, 339.9%, 231.7% and 222.8%. Increasing N application improved the accumulation of N and C for the rotation. Total accumulations of N and C in N1 and N2 treatments were 134.7%, 261.9% and 110.2%, 181.5% higher than that of the N0 treatment. With the growth of the sudangrass/ryegrass rotation, soil total N in the N1 and N2 treatments increased but this was slight in the N0 treatment. Soil organic C in N0, N1, and N2 treatments all increased, and were significantly correlated with the treatment. Compared with the original soil, soil C/N ratios in the N1 and N2 treatments changed only slightly while that in the N0 treatment increased significantly.

Effects of cover cropping system on soil moisture content and water storage in a vineyard

XI Zhu-mei, LI Hua, ZHOU Pan, YUE Tai-xin

2011, 20(1):  62-68. 

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Soil water content was closely correlated with application and extent of vineyard cover crop in a semiarid area. A permanent inter-row cover crop of Trifolium repens, Medicago sativa, and Festuca arundinacea in a vineyard was compared with clean tillage. Localized observation of soil moisture content in the 0-80 cm layer with TRIME-FM TDR was carried out in the vineyard, and soil physical characteristics of the 0-60 cm layer were investigated using the cutting ring method. After planting grasses, the soil physical characteristics improved, soil bulk density of the 0-60 cm soil layer decreased by 8.5%-9.8%, and total soil porosity increased by 11.5%-13.9%. The soil moisture content of a grass-covered vineyard was considerably reduced in 2006 and 2007 compared with clean tillage and the average soil water content of the 0-80 cm depth was reduced by 2.3%-7.5% and 10.7%-15.9% respectively. The soil water content was severely reduced in a year with spring drought and shortage of soil moisture storage from the previous winter. Soil moisture storage and variation of water storage differed between sward treatments, and the M. sativa treatment had the lowest soil moisture storage.

Comparison of photosynthetic characteristic and the essential oils in crop rotation
and continuous cropping of Angelica sinensis

WANG Hui-zhen, ZHANG Xin-hui, LI Ying-dong, ZHANG En-he

2011, 20(1):  69-74. 

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Comparison of photosynthetic characteristic and essential oils in crop rotation and continuous cropping of Angelica sinensis was studied to explore the influence factor of dropping the yield and quality after continuous cropping, this conclusions will provide theoretical basis for investigation of continuous cropping obstacle of A. sinensis. Chlorophyll, photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO₂ concentration of A. sinensis were measured with CI-310 photosynthesis system. The yield and constituent of the essential oils extracted from the A. sinensis. Water steam and GC-MS were used. Chl a and Chl b of continuous cropping dropped apparently, at 26.5% and 57.0% less than rotation one, and the differences were significant(P<0.01); Daily mean photosynthesis of continuous cropping was 1.73 μmol/(m²·s), less than rotation (2.61 μmol/m²·s) by 50.9%, the differences were significant(P<0.05); In a day, transpiration rate in the morning was significant lower than that in the afternoon, the continuous cropping was significant lower than the rotation one. The difference of stomatal conductance average between rotation(11.4 mmol/m²·s) and continuous(10.6 mmol/m²·s) was not significant before 12:00,but had extremely significant difference between continuous(1.3 mmol/m²·s) and rotation(4.4 mmol/m²·s); Intercellular CO₂ concentration had the same variation. The yields of the essential oil of A. sinensis in crop rotation and continuous cropping are 0.95% and 0.70%, The relative amounts of ligustilide of essential oil are 71.62% and 29.49%. but the constiuents of the essential oil of A. sinensis from crop rotation and continuous cropping are identical. Continuous cropping decreased significantly the Chl, photosynthetic characteristica and essential oil of A. sinensis, which resulted in yield decreasing. Therefore Angelica contivation should think rotation low-toxin chemical.

Changes of pigment contents and photosynthetic electron transport activities of thylakoid
membranes of Polygonum viviparum grown at different altitudes

LI Ya-bo, AN Li-zhe, ZHANG Feng

2011, 20(1):  75-81. 

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The pigment content, chlorophyll fluorescence parameters and photosynthetic electron transport activities of thylakoid membranes were investigated in Polygonum viviparum grown at three different altitudes on the Tianshan Mountains. As altitude increased, the values of Chl (a+b) and Chl b decreased, while the values of Chl a/b, Car/Chl and NPQ increased. F_v/F_m was slightly higher in the leaves at 3 400 m than that at 2 200 m though the difference was not significant, whereas at 3 900 m, it had the lowest values and was significant (P<0.05). F_v/F₀ was stable in leaves at 2 200 and 3 400 m, but at 3 900 m, it became smaller (P<0.05). From 2 200 to 3 900 m, F₇₃₄/F₆₈₆ decreased significantly (P<0.05). The activities of PSⅠ, PSⅡ and the whole chain electron transport activity decreased with an increase in altitude. The decrease in the whole chain of photosynthetic electron transport activity was mainly attributable to the decrease in photosynthetic electron transport activity of PSⅠ, especially at 3 900 m. The study revealed that PSⅠ suffered more servere photoinhibition than PSⅡ at higher altitudes, and the decrease in whole chain electron transport activity of leaves exposed to low temperature and strong irradiation was caused mainly by PSⅠ photoinhibition.

Effects of KNO₃ on the growth and photosynthetic capacity of two varieties
of Helianthus tuberosus seedlings under NaCl stress

HUANG Zeng-rong, LONG Xiao-hua, LIU Zhao-pu, GENG Shou-bao, YE Hui-jun, LU Yan

2011, 20(1):  82-88. 

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Effects of KNO₃ under salt stress on the biomass and photosynthetic capacity of two varieties of Helianthus tuberosus seedlings (Nanyu No.1 and Qingyu No.2) treated with NaCl (0 and 150 mmol/L) and different levels of KNO₃ (2.5, 5, 10, 20 and 30 mmol/L) were studied by pot/sand experiments in a greenhouse. 1) Compared with the control (NaCl 0 mmol/L), the biomass, chlorophyll (Chl) content, and net photosynthetic rate (Pn) of two varieties of H. tuberosus seedlings declined as the KNO₃ concentrations increased. 2) Under 150 mmol/L NaCl stress, the K⁺/Na⁺ (shoot and root) ratio and chlorophyll content of different varieties of H. tuberosus seedlings increased with increasing concentrations of KNO₃. 3) Sensitivities of KNO₃ for alleviating salt injury differed between varieties. Effects of KNO₃ (20 and 10 mmol/L) significantly alleviated salt injury caused by 150 mmol/L NaCl stress for Nanyu No.1 and Qingyu No.2. 4) Under the same treatment, KNO₃ alleviated injury caused by 150 mmol/L NaCl stress better in Nanyu No.1 than in Qingyu No.2. In conclusion, suitable exogenous KNO₃ can alleviate salt injury and promote photosynthetic capacity and biomass accumulation in varieties of H. tuberosus seedlings.

Physiological role of Na⁺ in adaption of Zygophyllum xanthoxylum to osmotic stress

CAI Jian-yi, MA Qing, ZHOU Xiang-rui, ZHANG Jin-lin, WANG Suo-min

2011, 20(1):  89-95. 

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The effects of Na⁺ on the photosynthetic characteristics, protective enzyme activities and contents of organic osmotic adjustment substances in the seedlings of Zygophyllum xanthoxylum under different osmotic stresses (-0.5, -1.0 and -1.5 MPa) were measured in order to explore the significance of Na⁺ in the drought resistance of Z. xanthoxylum. Under different osmotic stresses, 50 mmol/L NaCl significantly increased the net photosynthetic rate and superoxide dismutase (SOD) and catalase (CAT) activities in leaves, but the soluble sugar and free proline contents decreased. The contents of free proline decreased by 66%, 55%, 31% (in -0.5, -1.0 and -1.5 MPa respectively) and contents of total sugar decreased by 41%, 33%, 30%. Since our previous experiments have shown that Na⁺ concentration in Z. xanthoxylum increased considerably under 50 mmol/L NaCl, it indicated that the reason why Na⁺ can improve the drought resistance of Z. xanthoxylum is not the promoting effect of Na⁺ on the accumulation of the organic osmotic adjustment substance, but the accumulation of Na⁺ as an osmotic adjustment substance in the plant.

Effects of temperature stress on chlorophyll fluorescence parameters
and photosynthetic rates of Stylosanthes guianensis

MO Yi-wei, GUO Zhen-fei, XIE Jiang-hui

2011, 20(1):  96-101. 

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In order to explore the adaptation mechanisms of Stylosanthes guianensis to temperature stress, the responses of Chlorophyll fluorescence parameters and photosynthetic rates in leaves under low and high temperature stresses were studied. 40 days old seedlings were divided into three groups and transferred to growth chambers with different temperature treatments. The first group was subjected to temperature at 6℃ for 2 days as low temperature stress, the second group at 36℃ for 5 days as high temperature stress, and the third group at 25℃ for 5 days as the control. The experimental results showed that the chlorophyll fluorescence parameters(Fv/Fm, Ф_PSⅡ, qP) and photosynthetic rates in the leaves of S. guianensis decreased significantly as treated with cold stress, and were not affected under heat stress, which indicates that photosystem Ⅱ activity in S. guianensis was more sensitive to cold stress than heat stress. In addition, ATP content and activities of RuBPcase and FBPase in the leaves of S. guianensis were also decreased under cold stress, but it was not affected under heat stress. Therefore, sufficient ATP content in leaves perhaps can prevent decreasing photosynthetic rate in S. guianensis leaves.

The effects of mannitol and AgNO₃ for perennial ryegrass transformation
mediated by Agrobacterium tumefaciens

QIAO Ding-jun, MAO Ping, MA Xin-rong, YANG Hong

2011, 20(1):  102-110. 

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Perennial ryegrass (Lolium perenne), a graminaceous crop, is one of the most widely distributed grass in the temperate regions for forage and turf. However, its transformation mediated by Agrobacterium tumefaciens is largely recalcitrant and lagged. In this paper, an improved method for perennial ryegrass mediated by A. tumefaciens was developed. And the transgenic plants were successfully obtained. Embryogenic calli induced from mature embryos of a perennial ryegrass variety Tove were transformed by A. tumefaciens strain EHA105 containing the plasmid pCAMBIA2301. In this protocol, 0.1 mol/L mannitol or 5 mg/L silver nitrate (AgNO₃) were added in preculture and coculture media. After selected with paromomycin and detected with PCR and GUS expression, we got 38 transgenic plants in all. The transgenic frequency was increased when 0.1 mol/L mannitol or 5 mg/L AgNO₃ or 5 mg/L AgNO₃+0.1 mol/L mannitol was added in the pre-cultivation and co-cultivation media, which was 1.96, 1.59 and 2.95 times compared to control respectively. Moreover, the transgenic frequency was highest when the two materials were jointly used. The results indicated that mannitol and AgNO₃ could improve the A. tumefaciens mediated transformation in perennial ryegrass evidently.

Transformation of Lolium perenne with a fructan:fructan 1-fructosyltransferase gene from
Agropyron cristatum and enhancement of drought tolerance in transgenic plants

ZHANG Xiao-yun, HE Jin-gang, SUN Xue-hui, WU Jin-xia

2011, 20(1):  111-118. 

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Ac1-FFT (fructan:fructan 1-fructosyltransferase) cloned from Agropyron cristatum was transformed into embryogenic callus lines of Lolium perenne using an Agrobacterium mediated method. Transgenic plants were analyzed by basta spraying and PCR amplification. In total, 18 independent transgenic lines were obtained with significantly improved drought tolerance. RT-PCR analysis showed that Ac1-FFT expressed strongly in transgenic L. perenne plants but not in control plants. Water soluble carbohydrate and fructan contents of Ac1-FFT transgenic L. perenne were significantly higher than those in control plants. Relative water content and chlorophyll content were significantly higher, while electrolyte leakage and malondialdehyde (MDA) content were significantly lower in the Ac1-FFT transgenic L. perenne than in control plants for 6 days after drought treatment. Relative water content, chlorophyll content, electrolyte leakage and MDA content were restored to their original levels after rewatering in Ac1-FFT transgenic plants but not in control plants. This suggests that the damage to Ac1-FFT transgenic plants was reversible but it was not in control plants. Ac1-FFT expression and fructan biosynthesis may play an important role in improving drought tolerance of Ac1-FFT transgenic L. perenne.

Cloning and sequence analysis of a vacuolar H⁺-PPase gene fragment from Zygophyllum xanthoxylum

XI Jie-jun, WU Guo-qiang, BAO Ai-ke, WANG Suo-min

2011, 20(1):  119-124. 

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Degenerate primers were designed based on conserved sequences of H⁺-Pase genes from other plants. Total RNA was extracted from the leaves of Zygophyllum xanthoxylum and the H⁺-PPase gene fragment was obtained by reverse transcription polymerase chain reaction (RT-PCR). It was cloned into PUCm-T vector and the positive clones identified by PCR were sequenced. Three H⁺-PPase gene fragments were gained from Z. xanthoxylum, each of which contains 898 bp and encodes a peptide of 299 amino acids. Similarity comparisons show that they share over 69% similarity in nucleotide sequence and over 78% similarity in amino acid sequence with those of other plant H⁺-PPase genes in GenBank.

Analysis of genetic diversity in Reaumuria soongorica populations in Gansu using ISSR markers

FENG Liang-liang, TANG Hong, LI Yi, MA Yan-jun, SU Shi-ping

2011, 20(1):  125-130. 

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Genetic diversity and genetic structure of 5 Reaumuria soongorica populations from Gansu (total about 50 individuals), were analyzed by ISSR (inter simple sequence repeat) markers. Twelve highly stable and repeatable ISSR primers (selected from 50 primers tested) detected a total of 69 loci of which 60 were polymorphic (86.96% of the total). The PCR products ranged from 500 to 3 000 bp. At the species level, the Shannon index (I) was 0.542 9, Nei’s gene diversity index (H) was 0.379 0, the coefficient of gene differentiation (G_st) was 0.096 4, and the gene flow (N_m) was 4.685 1. The software Popgen 32 analysis of the results showed that there was more genetic differentiation within populations than between populations. At the population level, I and H were 0.489 3 and 0.342 4, respectively. All of these results showed that R. soongorica has a high genetic diversity in Gansu. Cluster analysis showed no direct correlation between genetic distance and geographic distance, suggesting that genetic diversity of R. soongorica in Gansu was possibly related to species traits and communities.

Isolation and sequence analysis of the salt stress-induced gene GsPIP of Glycine soja

WANG Xi, LI Yong, BAI Xi, CAI Hua, JI Wei, ZHU Yan-ming

2011, 20(1):  131-139. 

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Salt stress affects plant growth and development and reduces productivity of crops. Glycine soja is an excellent material for isolation of abiotic stress related genes because of its tolerance to several kinds of stresses. An EST database of a salt tolerant variety of G. soja was constructed in previous work, and a gene expression profile was obtained by gene chip assay. Expression of all G. soja ESTs were analyzed, and one 3′-EST induced by cold, high salt and drought stress was chosen. This EST represents a plasma membrane intrinsic protein (PIP) gene, which belongs to the major intrinsic protein (MIP) family. A complete CDS of this gene was obtained with silico cloning and was developed with 5′-RACE. The translation product of this gene has 90% similarity with a PIP protein of Mimosa pudica and was named GsPIP. The translation product had the characteristic domain of MIP but has no signal peptide: This is consistent with PIPs of other plants. We isolated the GsPIP gene on our own and we have all intellectual property rights. It could become a new gene source for genetic engineering of stress tolerance. Further functional analysis would assist research on the mechanisms of osmotic stress tolerance.

SSR analysis of the linkage drag of endosperm mutation gene ae

QIAO Yan, WANG Han-ning, ZHANG Cheng, YANG Fang

2011, 20(1):  140-147. 

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Molecular assisted selection was used to analyse linkage drag of different recurrent parents on two flanks of two populations and for restoring the ratio of two populations by SSR markers for ae. These are evenly distributed on chromosome 5. Linkage drags at the two flanks were controlled in 13.2 and 17.2 cM of CHBC₁F₂ populations by SSR markers and the linkage drag at one flank was controlled in 13.9 cM of DHBC₁F₂ populations. Genetic background resemblance of individuals of the CHBC₁F₂ population to the recurrent parent’s was 85.7%. Genetic background resemblance of individuals of the DHBC₁F₂ population to the recurrent parent’s was 87.5%. It is possible to identify recombination individuals with the targeted gene through a high density (10-20 cM per marker) map. This reduced unnecessary fragmentation of chromosomes and eliminated linkage drag of the targeted gene in backcross breeding. The hitchhiking effect may have been reduced.

Effect of ultra-dry treatment on seed storage of Hedysarum laeve

CHEN Zhi-hong, GU Ji-cheng, LI Xiao-fang, YUN Xu-jiang, GAO Hong-wen

2011, 20(1):  148-154. 

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The effect of ultra-dry treatment on seed storage of Hedysarum laeve was researched. The seed moisture contents were reduced from 7.900% to 1.829%, 2.921%, 3.460%, or to 4.645% by silica gel, and were then stored at -4℃, at 4℃, at room temperature, or at 45℃. They were tested for physiological and chemical indexes after 12 months. Appropriate ultra-dry treatment enhanced storage effectiveness, increased membrane permeable and activity of SOD, POD, and CAT, but reduced the MDA content of H. laeve seeds. The optimal moisture content for ultra-dry storage was 3.460%. Ultra-drying at room temperature resulted in the same storage effects as treatment at low temperature. Appropriate ultra-dry treatment was therefore an effective conservation measure for H. laeve germplasm resources.

Effects of silicon addition on seed germination and seedling growth of alfalfa

LIU Hui-xia, SHEN Xiao-rong, GUO Zheng-gang

2011, 20(1):  155-160. 

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A previous pot experiment indicated that silicon addition encouraged alfalfa plants to grow and increased the biomass. Effects of silicon addition on seed germination and seedling growth of alfalfa using a water culture experiment were investigated in this study. Silicon addition had no effect on initial time of seed germination or on final germination rate. However, it enabled seeds to germinate faster and enhanced germination index, vigor index and germination energy, implying that silicon addition did not improve seed quality but did improve seed vitality. There were different responses of shoot and root lengths of alfalfa seedlings to silicon addition, indicating that silicon addition significantly increased the shoot length of alfalfa seedlings (P<0.05), but did not affect root length. Silicon addition increased the biomass of alfalfa seedlings (P<0.05). The concentration of silicon solution was not related to germination index, germination energy, length of shoot and root, or biomass of seedlings. Silicon is directly involved in the physiological process of seed germination and seedling growth of alfalfa.

Studies on seed filling characteristics of Astragalus membranaceus var. mongholicus

JING Zhi-yu, GUO Feng-xia, CHEN Yuan, XI Zhuo-xia, YAO Li-rong, ZHANG Xiao-hu

2011, 20(1):  161-166. 

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Flowers were labeled with cards during blossom of Astragalus membranaceus var. mongholicus plants cultivated in Weiyuan county, Gansu. The dynamic filling trends in the plant seeds were studied 10 d after blossom to provide a theoretical and technical basis for standards of seed production. The 100-grain fresh weight increased and reached its highest value on the 31st day following blossom, and then rapidly decreased to a level near its dry weight. Changes of dry matter fitted a Logistic equation with a rapid increase during 19－33 d after blossom and finished at the end of 50 d. Grain filling rate showed a “fast-slow-fast-slow” pattern. Grains dehydrated increasingly faster with prolonged filling duration and water content decreased to the end. The time of fastest decrease in water content indicated the finish of the maximum grain filling. All the above showed that the stability of dry weight and water content of seeds were important indicators for seed maturation. The best harvest time should be during the 50－56 d following blossom (at the end of July or beginning of August) during which time the water content of seeds should be lower than 3.0%, the seed pods are not bursting apart and they have no abscission-layer in their stalk. The seeds should be harvested in timely installments.

Evaluation method of ecological services function and their value for grassland ecosystems

LIU Xing-yuan, LONG Rui-jun, SHANG Zhan-huan

2011, 20(1):  167-174. 

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Grasslands not only support animal production, but also play an important role as an ecological safety barrier and they maintain herders’ livelihood as well as inherited culture. However, a series of ecological problems are becoming more and more serious because of increasing grassland degradation. The economic valuation of the grassland ecosystem service function will help conservation and rational development of grassland resources in China. Costanza’ evaluation method for ecological services value was widely adopted abroad but this method cannot fully reflect the intrinsic characteristics of grassland ecosystems. Based on the functions of ecology, production, and living systems of grassland ecosystems, the contribution rate of the top 12 items for ecological services function of grassland ecosystems (water storage, erosion control, nutrition cycling, waste treatment, resort sand and dust, biological control, release O₂, fixation CO₂, cut SO₂, recreation, culture, and animal production), were chosen for this study of a comprehensive consideration of regional differences, spatial heterogeneity, and difference of economic development levels of different areas. The evaluation index system and models of grassland ecological services value were established based on the theory of ecological economics. The values of grassland ecosystem functions of the northern Tibet region were evaluated using this method.

A method for classification of natural grassland quality based on SOFM

WEI Shu-zhen, WANG Fei-feng, ZHANG Jiang-shan

2011, 20(1):  175-182. 

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The self-organizing feature maps (SOFM) neural network was first applied to classification of the data from 31 natural grasslands in Sinkiang, China. The result was compared with that from set pair analysis, grey relational analysis and projection pursuit methods. Comparable results were consistent and the SOFM network reflected the complicated information between all samples. The classification effect was good and it could be widely applied to clustering analysis.

Effects of exogenous metallothionein on energy production and incretion of China Holstein cows

XIAO Ding-fu, LUO Jia-jie, WU Zong-ming

2011, 20(1):  183-188. 

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Effects of exogenous metallothionein (MT) on energy production and incretion of China Holstein cows were studied using 24 lactating cows, randomly allocated to groups A, B, C and D. MT was supplemented at 0.0, 6.0, 12.0 and 16.0 mg/capita, respectively, by intravenous injection. In groups B (during 1-30 d) and C (during 1-45 d), corrected milk yields were higher than that in group A. In group C during 31-45 d, milk fat percentage was significantly improved by comparison with group A. The INS serum content of group A was significantly lower than that of group B at 30 d; IGF-Ⅰor T₃ content of serum in group C was the highest at 45 d and the differences with group A were significant, while the IGF-Ⅰor T₃ of production in group D was inhibited. The ranges of variation of FSH or E₂ content in group C were the smallest of all the groups. The P content of in group B was significantly higher than that in other groups at 30 d, and the PRL content of group B was significantly higher than that in group A at 15 d. In groups B and C, MT contents of serum or milk were significantly higher than those in group A during the 30-45 d lactation period. In conclusion, the best choice was to supplement MT at 12 mg/capita for lactating cows by intravenous injection and a suitable time interval was once every 30-45 d.

HJ NDVI cross-calibration for grassland in Northern China

LIU Rui, SUN Jiu-lin, ZHANG Jin-qu, WANG Juan-le, LIAO Xiu-ying

2011, 20(1):  189-198. 

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The time series are being widely used. The Chinese HJ satellites which loaded 4 CCD sensors are capable of providing high spatial and temporal resolution observation data, which can establish the NDVI time series for environmental monitoring, disaster control and resources investigation, provide great opportunities for researches around China and its neighbouring areas. However, the band differences between sensors can significantly affect the NDVI accuracy. This paper based on band analysis of the 4 HJ CCD sensors and LandSat TM, ETM+, using simultaneous image pairs, obtained the NDVI cross-calibration factors for the 6 sensors of mid-temperate arid and semi-arid grassland in northern China. By verification with equivalent NDVI from our field investigation in Hulunbuir, the result shows that the difference between sensors can reach up to 5%, which can effectively be reduced to 2% by applying the cross-calibration factor. Meanwhile, we proved the influence of NDVI from the center wavelength is much more than the band width.

Isolation and identification of the pathogens causing Rheum palmatum root rot

LIU Ya-ya, CHEN Yuan, GUO Feng-xia, SHI You-tai, LI Zeng-xuan, LI Hui-mei

2011, 20(1):  199-205. 

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To provide a scientific basis for control of Rheum palmatum root rot, potential pathogens were isolated from rotted roots and identified before use in root segment inoculation pathogenicity tests. Eight species of fungi were isolated from rotted roots of biennial R. palmatum cultivated in Lixian county of Gansu. The chief pathogens were Trichothecium roseum, Fusarium oxysporum, and Rhizotonia solani. Their isolation frequencies varied with the pathogens and plant growth stage. T. roseum and R. solani could be isolated from different growth stages with frequencies of 41.18%-55.56% and 3.03%-44.44%, respectively. However, F. oxysporum could only be isolated from plants in the late growth stages, with an isolation frequency of 9.09%. The incidence of root rot after inoculation of pathogens into wounded radicles was significantly higher than that into non-wounded radicles. The incubation period of F. oxysporum was short with large disease spots indicating a strong pathogenic ability, while the incubation period of T. roseum and R. solani were long with small spots indicating a weak pathogenic ability. All the above shows that wounds are helpful for root rot pathogens to infect the plants. It suggests that transplanting and cultivation should be done carefully to maintain the plant integrity and prevent wounding. In addition, root segment inoculation is easy to do and may be extensively used in plant root disease research for its short inoculation time, high re-isolation frequency, and reliable result.

Progress of the herbage variety approval and registration in China

MA Jin-xing, ZHANG Ji-yu, SHAN Li-yan, YUN Xu-jiang

2011, 20(1):  206-213. 

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The paper introduced the progress of herbage variety approval and registration in China, including the development and change of registration organization, establishment of standard system of herbage variety registration, establishment of national variety regional trial net, as well as herbage variety identification and registration. Since 1986, 434 varieties have been registered by the Chinese Herbage Variety Registration Board (CHVRB), including 138 introduced varieties, 86 domestic varieties, 161 bred varieties and 49 local varieties. Great progress has been achieved on the registration standards, the national herbage variety regional trial and the varieties approved. Meanwhile, the problems of herbage variety registration were discussed and some strategies and suggestions were presented.

Effects of eco-environmental factors on the production and distribution
of arbuscular mycorrhizal fungal spores

SUN Xiang-wei, WANG Xiao-juan, CHEN Mu, DOU Cun-yan, GAO Fei-xiang, JIN Liang

2011, 20(1):  214-221. 

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The number of spores in soil is an important indicator of the formation and distribution of arbuscular mycorrhizal (AM) fungi. The distribution of spores is mainly affected by climatic factors, soil properties, herbivores, host plants, and farming systems. Climatic factors and seasonal dynamics are the two main factors which determine the generation and distribution of AM fungal spores, including the infection, sporulation, and distribution of AM fungi by direct effects on the fungi or indirect effects through the host plants. Soil is the natural medium for spores. The distribution of spores in the soil ecosystem is mainly influenced by soil type, pH, soil moisture, permeability, nutrient content, and soil microorganisms. Host plants, herbivores, and farming measures also have an important impact on the AM fungal community. On the basis of the above, the influence of the intra- and inter-relationship of ecological factors on AM fungal spores distribution, and perspectives on the dynamics of communities in mycorrhizal ecology are discussed.

Advances in studies on DREB/CBF transcription factors, and their applications
in genetic engineering for stress tolerance of turf and forage grasses

WANG Zhou, LIU Jian-xiu

2011, 20(1):  222-236. 

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Turf and forage grasses are critical to sustainable agriculture, but stresses negatively influence their survival, biomass and yield. It is essential to understand the molecular basis of stress tolerance since it is multigenic as well as a quantitative trait. Transcription factors that regulate expression of several genes related to stress have been discovered. One such class is DREB/CBF that binds to drought responsive cis-acting elements. DREBs belong to the ERF family of transcription factors consisting of two subclasses, i.e. DREB1/CBF and DREB2 that are induced by cold and dehydration, respectively. Tremendous progress had been made in genetic transformation of turf and forage grasses in the past decade. The rapid advancement of molecular biology and transgenic technology provides novel methods to accelerate and complement conventional breeding efforts. It is possible to engineer stress tolerance in transgenic plants by manipulating the expression of DREBs. This opens an excellent opportunity to develop stress tolerant grasses in future. This review intends to focus on the structure, role of DREBs in plant stress signaling and the present status of their deployment in developing stress tolerant transgenic turf and forage grasses.

Effects of simulated acid rain on photosynthetic characteristics of gas exchange
and yield of field-grown spring wheat at the booting stage

WANG Run-yuan, YAO Tao-feng, WANG He-ling, ZHAO Hong

2011, 20(1):  237-241. 

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To investigate the effects of acid rain on photosynthetic characteristics of spring wheat at the booting stage, plants were sprayed with simulated acid rain at pH levels of 1.5, 2.5, 3.5, 4.5, or 5.6. Yield and photosynthetic parameters of the spring wheat leaves were monitored. 1) The effects of simulated acid rain on photosynthetic characteristics of spring wheat leaves increased as the hydrogen ion concentration increased. 2) The pH values of simulated acid rain were significantly positively correlated with net photosynthetic rate, stomatal conductance, transpiration rate, water use efficiency, relative chlorophyll content, and yield, which in turn, were significantly negatively correlated with intercellular CO₂ concentration.

Site directed mutagenesis of the LpP5CS gene of Lolium perenne
and its transformation in Arabidopsis thaliana

CAO Li, YI Ming-fang, SUN Zhen-yuan, HAN Lei, JU Guan-sheng, MA Xin-rong

2011, 20(1):  242-247. 

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Full-length cDNA sequences of the LpP5CS gene, previously obtained using PCR amplification were used as a basis for developing a site-directed mutagenesis system of the Lolium perenne proline synthetase gene LpP5CS. The gene was used in Agrobacterium-mediated transformation technology to verify a functional mutant gene. A pair of primers was designed to the mutation sequence and was used with Pfu high-fidelity DNA polymerase and super-competent cells DMT in PCR amplification. The LpP5CSF128A mutant gene which contained the desired mutational sites was directly cloned into the eukaryotic expression vector pCAMBIA1300, for transformation into Arabidopsis for validation of gene function. The expected locus mutations had occurred in LpP5CS and changed the encoding codon No.128 from a phenylalanine residue (Phe or F) into an alanine residue (Alanine, Ala). This was proof that PCR technology had succeeded in site-directed mutagenesis of the LpP5CS gene. Four transgenic lines were obtained from the T₁ generation of transgenic Arabidopsis plants by PCR and RT-PCR. The T₂ generation of Arabidopsis plants were treated with 100 mmol/L NaCl solution for 7 d and the proline content of T₁ and T₂ transgenic plants were 4 262 and 5 623 μg/g FW respectively, higher than the 2 581 μg/g FW of wild-type strains. This indicated that transgenic strains can accumulate more proline.

Effect of humic substances on the reductive dechlorination of 2,4-dichlorophenoxyacetic
acid by Comamonas koreensis CY01

WANG Yi-bo, WU Chun-yuan, ZHOU Shun-gui

2011, 20(1):  248-252. 

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A facultative anaerobic bacterium which was a highly efficient humic substances and Fe (III)-reducing bacterium (designated CY01), was isolated from an ancient forest soil from Guangzhou, China and was identified as a strain of Comamonas koreensis. The role of the humic model compound, anthraquinone-2,6-disulfonate (AQDS), in the anaerobic reductive dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D) by C. koreensis CY01 was investigated. 1) Strain CY01 could couple glucose oxidation to 2,4-D reductive dechlorination; 2) Reductive dechlorination of 2,4-D by strain CY01 was greatly stimulated by the addition of AQDS which acts as an electron shuttle. 2,4-D reduction proceeded by oxidation of electron donors and transference of electrons to the acceptors through the redox mediator, AQDS.

Identification of Meloidogyne graminis on golf greens

ZHUO Kan, HU Mao-xiu, WANG Hong-hong, TANG Zhao-lei, SHAO Xiao-yong, LIAO Jin-ling

2011, 20(1):  253-256. 

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In 2009, yellow patches emerged on golf greens of two golf courses in Yangjiang and Zhuhai of Guangdong Province. Root knots were observed in turfgrass roots of the golf greens, and numerous juvenile second stage (J2) worms belong to the genus Meloidogyne were isolated from soils around turf grass roots. The root knot nematodes were identified by using morphology, isozyme and mtDNA-PCR-sequence. The results indicated the root knot nematode was M. graminis. M. graminis are known to be an important pathogen of golf course greens turf in USA, however the nematode is found firstly on golf course in China.

Study of life-history strategy of farmland weeds in semi-arid areas

WANG Bin-shi, ZHANG Rong

2011, 20(1):  257-260. 

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From 2008 to 2009, the response to environmental factors of the weed community structure in semiarid cropland was researched by selecting 10 native weeds and planting them in differentially treated cropland. 1) The same species in different climates showed different life-history strategies: Corispermum, Convolvulus arvensis, and Fagopyrum dibotrys tended towards the competitor (C) strategy, stress tolerant (S) strategy, and mixed competitor-stress tolerant (C-S) strategy in 2008, but towards the stress tolerant (S) strategy, competitor-stress tolerant(C-S) strategy in 2009. 2) Chenopodium glaucum, Setaria viridis, and Stipa breviflora tended towards the ruderal (R) strategy in 2008, but they did not show this strategy in 2009. Elsholtzia argyi, Androsace ncana, and Potentilla bifurca in both years, and Salsola in 2008, had no definite life-history strategies, although Salsola tended towards the S strategy in 2009. 3) With the variety of changing environmental factors, life-history strategies changed accordingly, that is, the life history characteristics responded to ecological attributes, so plant functionality moved in the C-R-S axis of the Grime model. F. dibotrys tended towards a mixed stress tolerant-ruderal (S-R) strategy and C. arvensis tended towards a mixed competitor-stress tolerance (C-S) strategy in annual variation from 2008 to 2009.