Acta Prataculturae Sinica

Spatio-temporal variation analysis of grassland net primary productivity and its
relationship with climate over the past 10 years in Inner Mongolia

MU Shao-jie, LI Jian-long, YANG Hong-fei, GANG Cheng-cheng, CHEN Yi-zhao

2013, 22(3): 6. DOI: 10.11686/cyxb20130302

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Net primary productivity (NPP) and its response to global change are two of the focuses in global change research. Based on MODIS NDVI data, land use classification data, and meteorological data, the spatio-temporal change in NPP of Inner Mongolia grassland was simulated using an improved light use efficiency model (CASA model). The relationships between NPP and climate factors were analysed based on partial correlation coefficients of the two-group elements. The average annual NPP from 2001 to 2010 was 281.3 g C/(m²·a) in the study area, with an obvious increasing trend from southwest to northeast. The mean NPP in the unit area of meadow steppe was 431.8 g C/(m²·a), in typical steppe it was 288.7 g C/(m²·a) and in desert steppe was 123.5 g C/(m²·a). There was a rising trend in the grassland NPP during the past ten years. Grassland NPP in Mu Us sandy land, Hunshandak sandy land, Horqing sandy, HulunBuir league and the southern slope of the Greater Hinggan Mountain exhibited the most obvious increasing trend, while in the Yin mountain region and the centre of Xilin gol league it showed the most obvious decreasing trend. As a whole, precipitation was the dominant driving force of NPP of Inner Mongolia grassland, while the NPP of meadow steppe correlated with both precipitation and temperature, but with more dependence on temperature. Compared with temperature, precipitation influenced NPP of typical steppe and more seriously, desert steppe.

Distribution of the existing natural vegetation in China based on CSCS

FENG Qi-sheng, XIU Li-na, LIANG Tian-gang

2013, 22(3): 16. DOI: 10.11686/cyxb20130303

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Vegetation type is the basis for the study of natural vegetation. The CSCS (comprehensive and sequential classification system) model reflects the potential natural vegetation types and their spatial distribution. Therefore, research on the spatial distribution of existing natural vegetation types based on the CSCS model has practical significance in grassland resource monitoring and animal husbandry production management. Based on the potential natural vegetation map of China produced by the CSCS model, the distribution was analysed and divided into typical areas of existing natural vegetation by combining it with the Chinese vegetation map and DEM (digital elevation model) data. This is the first time that the existing natural vegetation distribution map and the typical area of existing natural vegetation distribution map of China have been produced. It will play an important role in the sampling position selection of CSCS-based grassland types in field investigations and in the study of their plant biological characteristics.

Vegetation index feature and spatial-temporal process analysis of
desert grassland in the Fukang area of Xinjiang

QIAN Yu-rong, YANG Feng, YU Jiong, JIA Zhen-hong, LI Jian-long, Palidan Tuerxun

2013, 22(3): 25. DOI: 10.11686/cyxb20130304

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Change of typical desert grassland in the northern Tianshan Mountains was analysed to give some constructive suggestions of sustainable development for both the environment and livestock. After the radiometric and geometric correction of TM/ETM+ remote sensing images in 1990, 1999, and 2008, the classification of land cover based on decision trees was implemented based on the vegetation index feature and vertical zone. The NDVI value calculated by radiometric corrected apparent reflectance was close to the actual surface features and generally showed the pattern: alpine meadow>farmland>temperate meadow>plain desert grass>piedmont desert grass. In the past 20 years, increasing farmland area occupied previous plain desert grassland and piedmont desert grassland to the extent that the new agricultural land area (296.3 km²) had become 1.54 times the total area of farmland in 1990. The trend of melting alpine ice transformed into alpine meadow became more apparent, and the reduced snow and ice area (74.7 km²) has reduced to 0.345 that in 1990.

Monitoring grassland rodents with 3S technologies

HE Yong-qi, HUANG Xiao-dong, HOU Xiu-min, FENG Qi-sheng, WANG Wei, GUO Zheng-gang, LIANG Tian-gang

2013, 22(3): 33. DOI: 10.11686/cyxb20130305

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Grassland rodents seriously threaten the sustainable development of pasture husbandry in China. Monitoring grassland rodents with 3S technologies plays an important role in grassland rodents control and management. Using 3S technologies and field survey data, the main factors influencing the occurrence of grassland rodent hazard in Qinghai were used to build grassland rodent monitoring models. The threshold of the rodents region ranged from 0.344 1-0.378 2, and the thresholds of different rodent regions differed at different rodent hazard levels. The rodents area was 1.80 times larger than the area provided by the field survey and covered 99.95% of the area from the field survey. The model can well simulate the rodents area in this study region. The model simulation with 3S technologies can provide decisive support for grassland rodents management, and plays a pivotal role in protecting grassland productivity effectively and in realising the sustainable development of grassland animal husbandry.

Response of meadow steppe ANPP to climate change in Hulunbeir, Inner Mongolia - a simulation study

ZHANG Cun-hou, WANG Ming-jiu, ZHANG Li, YANG Li-Ping

2013, 22(3): 41. DOI: 10.11686/cyxb20130306

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Long-term ecological research has resulted in a large amount of data on aboveground biomass and productivity, and on climatic and soil regimes at the animal husbandry meteorological experiment station of Inner Mongolia Hulunbeir meadow steppe. Using monthly aboveground biomass data in the growing seasons of 1994-2009, dynamic changes of the simulated aboveground net primary production (ANPP) were studied with the CENTURY model in Inner Mongolia meadow steppe and the correlations of ANPP with 26 meteorological parameters from 1961-2010, were analysed. The r² for comparison of the observed and simulated aboveground biomass in the growing season was 0.53, the slope was 0.94, root mean square error was 72.07 g/m² and the ratio of the absolute mean error was 38.02%. These results suggested that the CENTURY model can successfully simulate the seasonal and inter-annual trend of ANPP in Hulunbeir meadow steppe. Over the last 50 years, the temperature has increased, the precipitation increased slightly and ANPP also increased. Along with temperature and precipitation changes, the change curve of simulated ANPP indicated significant seasonal changes. ANPP was significantly and positively correlated with the precipitation in the growing season, and was positively correlated with annual mean minimum temperature, mean surface temperature, annual mean temperature, precipitation of July, and was significantly negatively correlated with annual average wind speed but not with other meteorological parameters. Predicted cllimate data of RCM PRECIS output was analysed for 2021-2050. Under the SRES (special report on emission scenarios) B2, A2 and A1B scenarios, in Hulunbeir meadow steppe, mean maximum temperature and mean minimum temperature both showed significantl increasing trends in the future, with a slight increase in precipitation. ANPP significantly increased by 67.14%, 69.65% and 76.58% compared to that in 1961-1990, and the rising rates were 16.51, 17.34, and 16.42 g/m²·10 a, respectively. Under SRES B2, A2 and A1B scenarios, the climate change in the future would have significant positive impacts on the productivity of the Hulunbeir meadow steppe.

A study on the adaptability of sweet sorghum planted in different altitudinal areas of the Qinghai plateau

2013, 22(3): 51. DOI: 10.11686/cyxb20130307

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Evaluating the adaptation of 14 Brachiaria varieties in southern subtropical areas of Yunnan

LIU Jin-hai, WANG He-hua, ZUO Ying-mei, HUANG Bi-zhi, CHANG Ning, LIU Guo-dao, ZHOU Chao

2013, 22(3): 60. DOI: 10.11686/cyxb20130308

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Evaluation of the adaptation of 14 Brachiaria materials from Brazil, Australia and Hainan of China was conducted in southern subtropical areas of Yunnan, from 2006 to 2007 where low temperatures and drought were the disadvantaging factors for forage growth. The over winter rate of all forage materials was more than 97.00%, showing that these forages can adapt to the conditions and can therefore be used for pasture establishment in the southern subtropical zone. In the first year, the forages with higher yield of dry matter were B. hybrid Mulato 1, B. ruziziensis, B. brizantha Mekong, B. hybrid, B. brizantha cv. MG-5×Araes, B. brizantha cv. MG-5 Vitoria, B. brizantha cv. MG-4, and B. hybrid Mulato 2. Their yields were 34.84±3.98, 31.57±11.97, 31.13±5.31, 30.95±5.13, 28.41±0.84, 27.42±3.32, 26.83±3.49 and 25.14±2.23 t/ha, respectively but there was no significant difference between dry mater yields of the trialled forages. Leaf width was the most important component factor to yield in the southern subtropics, seed yield ranked second and stem/leaf ratio was third, followed by plant height and leaf length. In terms of a combination of dry matter yield, CP (crude protein), palatability and resistance, B. hybrid, B. hybrid Mulato 1, B. brizantha Mekong, B. hybrid Mulato 2, B. brizantha cv. MG-5×Araes, B. ruziziensis, B. brizantha cv. MG-5 Vitoria were the top seven promising species with high yield, good quality, palatability and resistance in these areas.

Properties and mechanisms of change of soil macro-fauna communities
in the desertification process of Horqin sandy grassland

ZHAO Ha-lin, LIU Ren-tao, ZHOU Rui-lian, QU Hao, PAN Cheng-chen, WANG Yan, LI Jin

2013, 22(3): 70. DOI: 10.11686/cyxb20130309

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Group richness, diversity and individual density of soil macro-fauna communities were studied from 2008－2009 in Horqin sandy grassland to understand the effect of grassland desertification on the soil macro-fauna community. With the development of grassland desertification, the richness, diversity and individual density was significantly reduced, and the evenness and dominance index significantly increased, with the maximum change observed at the light and at the severe desertification stages. Community composition changed constantly, the similarity between communities was reduced, and the community changed from many dominant groups to a single dominate group, or even to no dominant group, resulting in community succession. Grassland desertification had relatively large effects on soil phytophagous animals and relatively weak effects on soil omnivorous and predatory animals, resulting in significant changes of nutrient functional structure in the community. In the grassland desertification process, the changes of soil macro-fauna community resulted mainly from the degradation of vegetation and the deterioration of soil environment, especially the reductions in vegetation coverage and litter, as well as the deterioration of soil texture and nutrition. The effects of soil moisture, temperature and pH on soil macro-fauna communities were relatively weak.

Response of ground-dwelling arthropod guilds to reseeding and cutting
in artificial Caragana korshinskii plantations in desert steppe

LIU Ren-tao, YANG Xin-guo, CHAI Yong-qing, YANG Ming-xiu, ZHU Fan, LI Shu-jun

2013, 22(3): 78. DOI: 10.11686/cyxb20130310

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Artificial, 25-year-old Caragana korshinskii plantations in desert steppe were used to investigate the richness and biomass of ground-dwelling arthropods in cut and uncut stands, with and without reseeding. By classifying functional groups, the effects of cutting and reseeding and their interactions on ground-dwelling arthropod guilds are discussed in this study. There were five ground-dwelling arthropod guilds including phytophagous, predatory, saprophagous, necrophagous and omnivorous. The phytophagous group was the main component of ground-dwelling arthropod communities in this artificial desert steppe plantation. The management only by reseeding significantly improved the richness and biomass of the phytophagous group, while the management only by cutting considerably increased the biomass of the phytophagous group together with the richness of the predatory and omnivorous groups. Further, cutting with reseeding considerably enhanced the biomass of the phytophagous and predatory groups. It is suggested that cutting and reseeding could improve ground-dwelling arthropod guilds and the complexity of the food web, thus benefiting the effective restoration of sandy grassland ecosystems in desert steppe.

Effects of invasive weeds on relative grasshopper abundance in alpine steppe in the Qilian Mountains

SUN Tao, CHEN Qiang, ZHAO Ya-xiong, LONG Rui-jun

2013, 22(3): 85.

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The influence of weed (Stellera chamaejasme, Thermopsis lanceolata and Melica przewalsky) invasion on the community composition, relative abundance and population of grasshoppers was studied in alpine grassland of the Qilian Mountains. The vegetation community, physical-chemical characteristics of soil, species diversity and community numbers of grasshoppers were investigated from June to September 2008-2009. Weed invasion significantly (P<0.05) reduced species richness, diversity and the evenness index of vegetation but significantly (P<0.05) increased the height and biomass. The contents of organic matter and moisture from grassland invaded by M. przewalsky were the highest but the largest populations of grasshoppers were found in grasslands invaded by S. chamaejasme and T. lanceolata. The soil hardness in S. chamaejasme invaded grassland and total N content in natural grassland were strikingly (P<0.05) higher than in others. Weed invasion affected grasshopper community composition, reduced species diversity, and changed species relative abundance, while their effect on population size depended on the kinds of weeds: invasion by M. przewalsky inhibited, while that of S. chamaejasme and T. lanceolata increased grasshopper populations. The mechanism of community characteristics of grasshopper response to invasive weeds, not only offers reference for studying the impact of degradation of alpine grassland caused by weed invasion on the diversity of insect and invertebrates, but gives data for managing the maintainance and conservation of biodiversity in alpine grasslands.

A biological study on Exorista civilis, a tachinid parasitoid of Loxostege sticticalis

XIANG Hong-yan, LIU Ai-ping, GAO Shu-jing, XU Lin-bo, LIU Chang-zhong

2013, 22(3): 92. DOI: 10.11686/cyxb20130312

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The tachinid fly Exorista civilis (Diptera: Tachinidae) is an important parasitoid of the beet webworm, Loxostege sticticalis (Lepidoptera: Pyralidae) and other lepidopterous pests. The adult biology of the parasitoid was observed in the laboratory. The adults emerged mainly in daytime at 08:00-10:00 and 14:00-16:00, and males usually emerged earlier than females. The sex ratio of E. civilis was 1.26∶1 (♀/♂). The average number of eggs laid by one female was 159.8, and the ovipositional period lasted 16.6 days on average, with a peak on the fourth day of egg-laying. The greatest longevity of adults was in an illuminated incubator with a constant temperature of (23±1)℃. Abundant sugary media significantly prolonged adult longevity, especially when 20% honey solution was provided - they could then survive for 44 days. The emergence ratio significantly decreased with an increase in storage time of the parasitoid L. sticticalis, but there was no further significant decrease after 110 d.

A comparison of in vitro fermentation characteristics of eight fiber substrates
by faecal microbiota from Meishan and Landrace sows

AI Li-xia, SU Yong, ZHU Wei-yun

2013, 22(3): 99. DOI: 10.11686/cyxb20130313

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In vitro fermentation characteristics of different fiber substrates by faecal microbiota and fiber-degrading baceria in faeces from Meishan and Landrace sows were compared. Fresh faeces from Meishan and Landrace sows were collected and used as inoculum in an in vitro fermentation test. Eight different substrates, (pectin, cellulose, xylan, inilin, wheat hul, wheat bran, maize pulp, and alfalfa) were used in the test. After 96 h fermentation, gas production was recorded, and gas samples collected to determine VFA concentrations. Total bacterial DNA was extracted and used for DGGE and real-time PCR to analyse microbiota composition and the main fiber-degrading bacteria. Cumulative gas production, concentration of acetate and of total VFAs were significantly higher (P<0.05) when the faeces from Landrace sows were used as inoculum as compared with those from Meishan sows. There was no significant (P>0.05) difference in the concentrations of propionate and butyrate between the two breeds. T_1/2 and T_max were significantly lower (P<0.05) in Landrace sows than in Meishan sows. The order of degradability of all substrates was: inulin>wheat bran>pectin>alfafa>wheat hull>maize pulp>xylan>cellulose. DGGE anlysis of total bacterial communities showed that there were no pig breed specific bands in the profiles from the faeces of the two breeds. Real-time PCR analysis showed that the 16S rRNA gene copies of total bacteria in faeces of Meishan sows were significantly (P<0.05) higher than those in Landrace sows, while there was no significant (P>0.05) difference in the 16S rRNA gene copies of Bacteroidetes, Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus and their proportions within the total bacterial population. Although there was no significant difference in the numbers of main fiber-degrading bacteria between Meishan and Landrace sows, the Landrace sows may have a stronger ability to degrade fiber as compared to Meishan sows.

Effects of FJLB, LAB and glucose addition on fermentation quality
of napier grass (Pennisetum purpureum) silage

2013, 22(3): 108. DOI: 10.11686/cyxb20130314

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The effects of adding pre-fermented juice of epiphytic lactic acid bacteria (FJLB), lactic acid bacteria (LAB) and glucose (G) on fermentation quality of napier grass (Pennisetum purpureum) were evaluated. The treatments were control (without additives), FJLB, LAB, G, FJLB+G, and LAB+G. The silos were opened on 3, 7, 14, and 30 days after ensiling and the fermentation quality was analysed. Compared with the control, LAB addition had no significant effect on fermentation quality, while FJLB addition reduced fermentation quality In the FJLB addition treatment, lactic acid and water soluble carbohydrate decreased significantly (P<0.05) while pH, ammonia nitrogen, acetic acid and butyric acid increased significantly (P<0.05). In the G, LAB+G, and FJLB+G addition treatments, lactic acid content increased significantly (P<0.05) at an early stage of ensiling, maintaining a high lactic acid/acetic acid value throughout the fermentation process. pH and ammonia nitrogen content of the final silages decreased significantly (P<0.05), but with no significant difference between the three treatments. In conclusion, glucose addition was more important and efficient in stimulating homofermenter activity and in improving the fermentation quality of napier grass silage than inoculation with lactic acid bacteria (LAB or FJLB).

Effect of molasses addition on fermentation and nutritive quality of mixed
silage of hulless barley straw and perennial ryegrass in Tibet

YUAN Xian-jun, WANG qi, LI Zhi-hua, YU Cheng-qun, Masataka Shimojo, SHAO Tao

2013, 22(3): 116. DOI: 10.11686/cyxb20130315

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To investigate enlargement of feed sources in Tibet, mixtures of hulless barley straw and perennial ryegrass (6∶4) were ensiled with molasses at four levels (0, 3%, 4%, and 5% of fresh weight). Triplicate silos per treatment were opend on 7, 14, 30, and 60 days after ensiling and the fermentation characteristics and in vitro degradability of silages were analysed. Molasses addition quickly and greatly enhancedLA (lactic acid) production but decreased the pH value within 14 days of ensiling. Molasses supplemented silages showed higher (P<0.05) LA/AA (acetic acid), LA and WSC (water soluble carbohydrate) contents but lower pH values and AN (ammonia nitrogen)/TN (total nitrogen) (P<0.05) than the control silage. After 60 days ensiling, silages with added molasses had higher CP (crude protein), lower NDF (neutral detergent fiber) and ADF (acid detergent fiber) contents than the control, and the in vitro degradability of all silages were higher than that of fresh material. These results indicate that 3% molasses addition can effectively improve the fermentation and nutitive quality of mixed silages.

Control efficacy of 6 fungicides against 3 pathogens of turfgrass diseases

WEN Ke-jian, LUO Tian-qiong, ZHANG Li, CHEN Yan-ping, ZHOU Yu-feng, LONG Zhong-fu,WU Jia-hai, SU Sheng

2013, 22(3): 124. DOI: 10.11686/cyxb20130316

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Virulence determination on three pathogens of grass diseases and field trials with six fungicides were carried out. The EC₅₀ of benomyl to Rhizoctonia solani and Colletotrichum gloeosporioides were 0.492 4 and 0.446 6 mg/L, respectively. The EC₅₀ of carbendazim to Rhynchosporium secalis was 0.413 0 mg/L. Carbendazim had the highest toxicity of the fungicides to Rhynchosporium secalis. The field control efficacy of 50% benomyl against Rhizoctonia solani and Colletotrichum gloeosporioides of turfgrass was 75.40% and 72.06%, respectively, while the control efficacy of 25% carbendazim on Rhynchosporium secalis was 76.97%.

Isolation of endophytic fungi from the medicinal plant Tamarix chinensis
and their microbial inhibition activity

BI Jiang-tao, MA Ping, YANG Zhi-wei, GUAN Xiao-qing

2013, 22(3): 132. DOI: 10.11686/cyxb20130317

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To explore the resource diversity and microbial inhibition activity of endophytic fungi from the medicinal plant Tamarix chinensis, endophytic fungi were isolated from root, stem, and leaf of the host by tissue inoculation culture. Five pathogenic fungi and four bacterial strains were used as indicators to test microbial inhibition activity by agar plate antagonistic action and modified agar gel diffusion. Eighteen endophytic fungal strains were isolated: most from the stems and least from the leaves. The isolated strains were divided into seven genera, three families, and two orders based on morphological characteristics. Among the isolates, eleven strains (61.1% of the total isolated) were found to have some microbial inhibition activities against two or more pathogenic fungi, eight strains (44.4%) had evident inhibition activity against Staphylococcus aureus with strain TCEFL001 showing evident antifungal and antibacterial activities against Colletotrichum gloeosporioides, Gaeumannomyces graminis var. tritici and S. aureus, belonging to Phacodium sp. The medicinal plant Tamarix chinensis is a good endophytic fungal resource, which is worth further study for its development and application.

Effect of leguminous forage rotations on soil microbe consortiums and enzyme
activity in continuously cropped potato fields

CAO Li, QIN Shu-hao, ZHANG Jun-lian, SHI Shang-li, WANG Di

2013, 22(3): 139. DOI: 10.11686/cyxb20130318

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The effects of different leguminous forage rotations on soil microbe consortiums, quantitative distribution, and enzyme activity were studied in a continuously cropped potato field. The quantitative distributions of soil culturable bacteria and fungi, microbial activity, soil urease activity, the activities of alkaline phosphatase and catalase were significantly promoted in common vetch (Vicia sativa), Medicago lupulina, and Longdong alfalfa (Medicago sativa) rotation systems compared with continuously cropped potato fields. Fungal/bacterial ratios decreased by 50.72% after legumes were included in the rotations, showing that rotations with common vetch and Medicago lupulina, converted the soil microbe consortium of continuously cropped potato field from fungal to bacterial types. After the inclusion of legumes, the number of aerobic types of nitrogen-fixing bacteria increased by 283.69%, and urease activity increased by 6.4 times. There were also significant increases in the activities of alkaline phosphatase and catalase. However, the improving effect on the soil of continuously cropping potato field depends largely on leguminous forage species. The duration of continuously cropped soils depended on the different continuous cropping durations which showed different sensitivities to different types of forage legumes.

Effects of aluminum and acid stresses on the growth and antioxidant enzyme activities of
rhizobia isolated from Medicago lupulina and M. sativa

LI Zhi-yan, Xing Xue-feng, TANG Hua, YIN Ya-li, GUO Yan-jun

2013, 22(3): 146. DOI: 10.11686/cyxb20130319

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Acid soils are widely distributed in southern China and they significantly limit legume growth and reduce nodulation ability, particularly through the influences of high contents of H⁺ and aluminum in soils. Selecting acid tolerant rhizobium strains is believed to be important for planting Medicago sativa in acid soils. M. lupulina and M. sativa belong to the same genus and their rhizobia can infect each other and form nodules. Field studies have shown that M. lupulina could grow in acid soils, suggesting that its rhizobium might be acid tolerant. Therefore, in the current experiment, rhizobium strains from M. lupulina (R1) and M. sativa (R2) were isolated from the fields in Beibei, Chongqing, and propagated on YMA (Yeast Malt extract Agar) solid culture medium. The responses of growth and activities of antioxidant enzymes of the two strains to aluminum and acidity were studied. There were five aluminum levels (0, 25, 50, 75, and 100 μmol/L), and four pH levels (4, 5, 6, and 7). The OD_A600 of rhizobia isolated from both cultivars reduced significantly after aluminum and acidity stress. The OD_A600 from R1 was significantly higher than that from R2. No obvious growth of rhizobium from R2 was observed at less than pH 4 and 5. With increasing aluminum concentrations SOD activity of rhizobium from R1 decreased initially and then increased, while the activities of CAT, POD and GR significantly decreased. The activities of SOD, CAT and GR of rhizobium from R2 hardly changed under low Al concentrations, but decreased at high Al concentrations. All enzyme activities of rhizobia from R1 and R2 decreased with increasing soil acidity. Enzyme activities of rhizobium from R1 were significantly higher than those from R2. Overall, R1 had better tolerance to Al and acid than R2. Further study is needed to analyse the affinity between Rhizobium strains from M. lupulina and M. sativa.

Effects of cadmium stress on growth, accumulation and distribution of
biomass and nutrient in Catharanthus roseus

LIU Shi-liang, SHI Xin-sheng, PAN Yuan-zhi, DING Ji-jun, HE Yang, WANG Li

2013, 22(3): 154. DOI: 10.11686/cyxb20130320

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Little information has been available on the effects of soil cadmium contamination on plant nutrition. Because of the economical and biological benefits, ornamental plant has become a new source for phytoremediation in recent years. The valuable ornamental plant Catharanthus roseus is an important landscaping and anticancer drug source plant which is widely distributed in city gardens and on roadsides in China. In order to understand the effects of different cadmium stress on the growth and nutrient characteristics in C. roseus. A controlled pot-experiment was arranged with different treatments of six cadmium concentrations (0, 5, 10, 25, 50 and 100 mg/kg) to investigate the growth characteristics, biomass production and accumulation and distribution of carbon(C), nitrogen(N), phosphorus(P)and potassium(K)in C. roseus. The results indicated that the roots, stems and leaves cadmium accumulation increased with increased Cd supplies, while the plant organs biomass production and C, N, P and K accumulation showed the trend of increased at first, and then decreased except leaf P accumulation decreased. The treatments with higher cadmium concentrations(≥25 mg/kg)significantly inhibited C. roseus growth, biomass and C, N, P and K accumulation, as well as altered their distribution patterns, while the treatment with lower cadmium concentration(≤10 mg/kg)had no significant effects. To a certain extent, C. roseus has stronger tolerance to cadmium contamination. These results implied that C. roseus is a possible for urban landscaping and purification of heavy metal contaminated soil, and has some potential applications in the remediation of cadmium polluted soil.

Effect of phosphorus on Na⁺ and K⁺ concentrations and the growth of Zoysia matrella under salt stress

JIANG Qiao-feng, CHEN Jing-bo, ZONG Jun-qin, LI Shan, CHU Xiao-qing, GUO Hai-lin, LIU Jian-xiu

2013, 22(3): 162. DOI: 10.11686/cyxb20130321

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The effect of phosphorus (0, 1, 5 and 20 mmol/L) on biomass and ion regulation was investigated using Zoysia matrella under salt stress (300 mmol/L NaCl) in hydroponic solution. Both phosphorus deficiency and salinity retardation of plant growth were more severe under P deficiency than under salt stress. With or without salt stress, phosphorous promoted the growth of Z. matrella, but too high a P concentration (20 mmol/L) led to growth inhibition. P addition within reasonable amounts promoted root growth and tended to increase leaf Na⁺ secretion but inhibit Na⁺ transport from root to leaf. It also restricted leaf Na⁺ accumulation and increased leaf K⁺ accumulation, leading to a decrease in leaf Na⁺/K⁺. All of these factors together help improve salt tolerance.

Effects of Eucalyptus grandis leaf litter decomposition on the growth and
photosynthetic characteristics of Eremochola ophiuroides

LI Yi-qiao, LI Xi, HU Ting-xing

2013, 22(3): 169. DOI: 10.11686/cyxb20130322

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The essence of crop production is a complex system that is driven by light energy. The accumulation of 90% of the dry matter comes from the production of photosynthesis. In this study, we investigated the effect of Eucalyptus grandis leaf litter decomposition on the growth and photosynthetic characteristics of Eremochola ophiuroides. Four treatments with different amounts of leaf litter were designed, including T1 (30 g/pot), T2 (60 g/pot), T3 (90 g/pot) and control (0 g/pot, CK), and the blank experiment groups with distilled fallen leaves were set as the above. The growth indexes were measured at 30, 60 and 90 d after sowing, and the photosynthetic characteristics were tested on the mature leaf in the middle of stolon. The test results showed that increasing amounts of E. grandis leaf litter significantly inhibited the accumulation of biomass, growth, synthesis of photosynthetic pigments of E. ophiuroides seedlings (P<0.05). Meanwhile, the stomatal conductance and the adaptation capacity to the change of light and CO₂ in the environment of CK were significantly lower than which of treatments. This demonstrated that the allelochemicals from E. grandis leaf litter decomposition can negatively affect the photosynthetic capacity and decrease the accumulation of biomass, and eventually inhibit the growth of E. ophiuroides.

Effects of 6-BA pretreatment on photosynthesis characteristics and endogenous hormone
content in pepper seedlings under low temperature and weak light stress

ZHANG Guo-bin, YANG Fang-fang, YU JI-hua

2013, 22(3): 177. DOI: 10.11686/cyxb20130323

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The aim of the experiment was to explore the regulatory role of 6-benzylaminopurine (6-BA))on resistance ability of low temperature and weak light in pepper seedlings (Capsicum annuum).The effects of 0.08 mmol/L 6-BA pretreatment on gas exchange parameters, chlorophyll content, endogenous hormone content in pepper seedlings leaves under low temperature (15℃/5℃) and weak light (100 μmol/m²·s) stress were investigated. Results showed that the photosynthetic rate (Pn), stomatal conductance (Gs), chlorophyll a (Chl a) content, chlorophyll b (Chl b) content, total chlorophyll (Chl T) content and zeatin riboside(ZR) content of pepper seedling leaves were significantly declined, but intercellular CO₂ concentration (Ci), abscisic acid(ABA) content were significantly increased under low temperature and weak light stress. The reduction in photosynthesis rate caused by low temperature and weak light stress was considered to be a result of non-stomatal restriction mainly. 6-BA had no changed trend of the above index with treatment time prolonged. Under low temperature and weak light stress, treatment with 6-BA significantly declined Ci, ABA content compared with control, but Pn, Gs, Chl a content, Chl b content, Chl T content and ZR content in previous 6 days of strss period were significantly increased.The results suggested that pretreatment with 0.08 mmol/L 6-BA had obviously role on enhanced pepper seedlings tolerance to low temperature and weak light, especially for pepper cultivar were sensitive to low temperature and weak light stress.

Drought tolerance analysis of Miscanthus sinensis ‘Gracillimu’ seedlings

Drought tolerance analysis of Miscanthus sinensis ‘Gracillimu’ seedlingsCHEN Min, HOU Xin-cun, FAN Xi-feng, WU Ju-ying, PAN Yuan-zhi

2013, 22(3): 184. DOI: 10.11686/cyxb20130324

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To assess the drought tolerance of Miscanthus sinensis ‘Gracillimu’ seedlings, the effects of 80%, 60%, 40% and 20% of the maximum field water holding capacity on the botanical, physiological and biochemical characteristics were assessed in a seedling incubation pot experiment. With an increase in water stress, the height, leaf area, tillering and biomass decreased but root/shoot ratio increased. Compared with the CK, under mild stress, Pn, Gs, Ci and Tr decreased by 48.05%, 40.86%, 43.52% and 65.41%, respectively, while WUE increased by 50.21%. The relative leaf water content under mild stress decreased by 48.05% compared with the CK, while the contents of Chl a, Chl b and total Chl increased by 59.11%, 65.64% and 29.11%, respectively, but then decreased. Under heavy stress MDA content, SOD activity and Pro content increased by 73.68%, 95.20%, and 83.30%, respectively compared with the CK. Therefore M. sinensis ‘Gracillimu’ seedlings have some ability to adapt to a drought environment.

A study on the attractive function of different floral structures in Trollius ranunculoides (Ranunculaceae)

2013, 22(3): 190.

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The attractive function of different floral parts of Trollius ranunculoides was studied in two populations distributed in the east Qinghai-Tibetan Plateau. The sepals, petals, and stamens were separately removed, and the types of visitors and visiting frequency were recorded. After separately removing the sepals and petals, the visiting frequencies of flies in Hezuo (0.033 and 0.114 time/flower·min) and Maqu (0.065 and 0.133 time/flower·min) were significantly less than those of the control, indicating that the sepals and the petals of T. ranunculoides were important structures to attract flies. Furthermore, after separately removing the sepals, the visiting frequencies of bees in Hezuo (0.266 times/flower·min) and Maqu (0.006 times/flower·min) were significantly less than that of the controls. After separately removing the stamens, the visiting frequency of bees in Hezuo (0.444 times/flower·min) was also significantly less than that of the control, but in Maqu (0.010 8 times/flower·min), there was no difference. The sepals and the stamens were important attractive structures for bees. These floral structures were not preferentially visited by ants indicating that they were ineffective in attracting them.

Reproductive biology of Polygonum japonicum

LV Feng-jv, CUI Mei-chen, CHEN Ming-lin

2013, 22(3): 196. DOI: 10.11686/cyxb20130326

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Distyly was clearly confirmed in Polygonum japonicum. Research showed that in addition to dimorphic stigma and anther heights, the sepals, stigmas, pollen size, number and quality of seeds are also dimorphic. Compared with the thrums, the pins had larger sepals, and the stigmas had fewer but higher papillae, producing significantly smaller pollen grains but in greater numbers. The seeds of the thrum and the pin were ovoid and had no beak but did have paracerebroid omamentations. The pollen grains of the flower were spherical and suborbicular, with irregular margins and scattered holes. The micromorphological characteristics of pollen and seed supported P. japonicum belongingto the Persicaria-type. Ants were the main visitors to the flowers. P. japonicum often occured as a single population with greater setting rate of pin. The adaption of P. japonicum through its breeding system characteristics are discussed.

Effect of nitrogen application on the absorption of iron, manganese, copper and zinc
in Wancao 2 and Zea mexicana

ZHANG Xiao-yan, WANG Li-li, WANG Li-min, FANG Yi, DONG Shu-ting, RUAN Huai-jun

2013, 22(3): 204. DOI: 10.11686/cyxb20130327

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To study the effect of nitrogen application on the absorption of mineral elements in Wancao 2 and Zea mexicana, the contents, amount accumulated and output of iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) in the stem, leaf and whole plant were analysed. Fe content was the highest of the four elements in Wancao 2 and Z. mexicana, and it was higher in leaves than in stems. The contents of Mn, Cu and Zn were higher or significantly higher in Wancao 2 than in Z. mexicana, but Fe content was significantly lower. Fe content was the highest in both species after 300 kg/ha nitrogen (N1) was applied once. In the treatments with N fertilizer applied separately, there was a trend for Fe content to increase with an increase in the nitrogen application rate. For Wancao 2, Mn content was highest in the N1 treatment, but Cu and Zn contents were higher in treatments with less nitrogen fertilisation. For Z. mexicana, Mn content increased with an increase in the nitrogen rate, and the contents of Cu and Zn were higher in all treatments where nitrogen was used as a base fertiliser. The accumulation amount and output of Fe, Mn, Cu and Zn were highest in the N1 treatment, and were higher in Z. mexicana than in Wancao 2. The accumulation amount and output of the four elements showed different variations in different organs of Wancao 2 and Z. mexicana. In the leaves of Wancao 2, the accumulation amount and output of Fe were higher, while those of Mn, Cu and Zn were lower compared with those in the stem. However, in Z. mexicana, the accumulation amount and output of the four elements in the leaves were significantly higher than those in the stem. Harvest time also had different effects on the absorption of the four elements in Wancao 2 and Z. mexicana. For Wancao 2, the contents of Fe, Mn and Zn were the highest in the first harvest of the grass, while Cu content was the highest in the third harvest. For Z. mexicana, the first harvested grass had the highest contents of Mn and Cu, while the third harvested grass had the highest contents of Fe and Zn. The accumulation rate of the four elements in the regrowth tissues of Wancao 2 and Z. mexicana was in the order of Fe>Mn>Zn>Cu, and all showed a declining trend. The reduction in Z. mexicana was more serious than that in Wancao 2. In conclusion, selecting Wancao 2 and using 300 kg/ha nitrogen as base fertilizer was beneficial for obtaining herbage with higher mineral contents. The yield of first harvested herbage should be paid more attention.

Phosphorus accumulation and root morphological difference of two ecotypes of
Pilea sinofasciata grown in different phosphorus treatments

LIU Shuang, LI Ting-xuan, JI Lin, ZHANG Shu-jin

2013, 22(3): 211.

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Elevated phosphorus (P) concentrations in surface runoff from P-enriched agricultural soils have been commonly considered an important cause of the eutrophication of freshwater bodies. Plant-assisted approaches have proven effective in ameliorating the ecological hazards of excessive soil P. A hydroponic experiment was carried out to investigate the phosphorus (P) accumulation and root morphological difference of the two ecotypes of Pilea sinofasciata grown under five (0, 100, 200, 400 and 800 mg/L) P levels. The biomass of the mining ecotype (ME) of P. sinofasciata was significantly higher than that of the non mining ecotype (NME). Biomasses of both ecotypes initially increased but then decreased with increased P concentration. The highest biomass (400 mg/L) and P concentrations of root, stem, and leaf of both ecotypes increased with P concentration. P concentration of the ME was higher than that of the NME and peaked at 22.85 g/kg. Total root length, total root surface area, total root volume and number of lateral roots of the ME were higher than those of the NME. With an increase in P concentration, total root length, total root surface area, total root volume and number of lateral roots of the ME initially increased but then decreased. The average root diameters of the ME and NME were not significantly different at high P levels, and the difference between ecotypes was not significant. These results indicate that overall, ME has better P accumulation than NME and better root morphological characteristics such as total root length, total root surface area, total root volume and number of lateral roots, features that are important for a high P uptake ability. It confirmed that the ME ecotype of P. sinofasciata has superior efficiency for removing P from hydroponic conditions and could be a potential choice for cleaning P from contaminated water.

Effects of different fertilization models on the characteristics of weed
communities during the rice growing seasons

DONG Chun-hua, LIU Qiang, GAO Ju-sheng, XU Ming-gang, WEN Shi-lin, ZENG Xi-bai

2013, 22(3): 218. DOI: 10.11686/cyxb20130329

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An investigation was made at a double-rice paddy field set up in 1982 in the Red Soil Field Experimental Station, CAAS, China to study the species and biomass of weeds growing during the rice (Oryza sativa) growing seasons. Over a 30-year period, organic, chemical, and a mixed organic and inorganic fertiliser were applied with the same rates of nitrogen (N), phosphorus (P), and potassium (K). Compared with other treatments, long-term application of mixed fertiliser resulted in the least number of weed species in both rice growing seasons. Organic fertiliser application resulted in the greatest number of weed species in the early rice growing season, while treatment without fertiliser application resulted in the greatest number in the late growing season: 4.4% and 39.3% higher than the former two respectively. Long-term application of organic fertiliser resulted in the highest biomass of weeds in both seasons, 10.7%, 4.5% and 37.7% higher than the applications of mixed, chemical, and no fertiliser respectively. Long-term application of organic fertiliser resulted in the highest biomass of all weeds and floating weeds in the early season, the treatment without fertiliser application resulted in the highest biomass of both in the late season, while mixed fertiliser application resulted in the highest biomass of floating weeds in both seasons. Soil alkali-hydrolyzable N and available P were positively correlated with the dry mass of weeds (r=0.465, P<0.05 and r=0.517, P<0.05, respectively), and of wet weeds (r=0.482, P<0.05 and r=0.542, P<0.05, respectively). Dry mass of floating weeds was positively correlated with soil available P (r=0.666, P<0.01), and was negatively correlated with soil pH (r=0.516, P<0.01). Soil available P, under the co-effects of soil pH, alkali-hydrolyzable N and other factors, had an indirect effect on the dry mass of weeds. If effective control of the growth of wet and floating weeds in red soil paddy of south China is to be attempted by achieving a beneficial dynamic equilibrium between the weed species and total biomasses, the best way is to adopt various fertilisation measures to maintain proper alkali-hydrolyzable N and available P contents and soil pH.

Effects of irrigation and N supply levels on soil organic carbon, total nitrogen and
grain yield of spring wheat on no-tillage farmland with standing stubble

YU Hua-lin, ZHANG En-he, WANG Qi, LIU Qing-lin, LIU Chao-wei, WANG Tian-tao, YIN Hui

2013, 22(3): 227. DOI: 10.11686/cyxb20130330

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A controlled study of irrigation and nitrogen (N) supply was conducted in the Hexi oasis to investigate the effects of different irrigation and N supply levels on soil organic carbon(OC), soil total nitrogen(TN), soil carbon and nitrogen ratio (OC/TN) of spring wheat on no-tillage farmland with standing stubble. With an increase in N supply rate, TN and OC contents considerably increased in soils. However, when N supply rates were higher than 140 kg N/ha, TN did not continuously increase with the increase in N supply rate, and OC even showed a decreasing trend. Irrespective of nitrogen levels, with an increase in irrigation level, TN and OC contents initially increased but then decreased in soils. An appropriate amount of irrigation (20% water-saving irrigation) promoted the mineralization rate of soil nitrogen and carbon, thus increasing the TN and OC contents. However, a smaller amount of, or excessive, irrigation reduced soil nitrogen and carbon mineralization rates, and increase soil nitrogen and carbon losses. The highest TN (0.9 g/kg) and OC (14.22 g/kg) were measured under 20% water-saving irrigation. When the N supply rate was 221 kg N/ha, the grain yield reached a maximum (6 365 kg/ha) irrespective of the irrigation levels but the grain yield of spring wheat increased with an increase in irrigation level.

Effect of nitrogen topdressing on the growth of Suaeda salsa and the improvement of saline soil

LIANG Fei, TIAN Chang-yan, TIAN Ming-ming, LIANG Di, ZHANG Ke

2013, 22(3): 234. DOI: 10.11686/cyxb20130331

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The effects of topdressing different nitrogen levels on the growth of Suaeda salsa and on the improvement of saline soil, were conducted in field experiments where growth, accumulative amounts of K⁺, Na⁺, Ca²⁺, and Mg²⁺ of S. salsa, as well as salinity concentrations in soils were assessed. The yields of grain, stem, leaf and biomass increased with N topdressing. At the rate of 450 kg/ha, the biomass of component factors in S. salsa presented a linear growth trend with the amount of N topdressing. With a further increase of nitrogen application, the concentrations of K⁺, Na⁺, Ca²⁺, and Mg²⁺ barely changed. The accumulative amounts of K⁺, Na⁺, Ca²⁺, and Mg²⁺ increased with N topdressing. The concentrations of K⁺ and Na⁺ in surface soils (0-10 cm) showed decreasing trends with N topdressing. N fertilisation could therefore stimulate S. salsa growth and strengthen the effectiveness of bioremediation of saline soil.

Optimizing fertilisation for bermudagrass soilless sod using spent mushroom
compost as the main substrate over plastic

FU Ling, WANG Cai-yun, YIN Shao-hua

2013, 22(3): 241. DOI: 10.11686/cyxb20130332

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A ternary quadratic rotational combinational design was used to determine the effects of nitrogen (N), phosphorus (P) and potassium (K) fertiliser on bermudagrass soilless sod over plastic. The spent mushroom compost was used as the main substrate and coal cinder, sludge and sand as the assistant mixtures. Sod performance, such as establishment time, sod formation time, root activity, sod weight, aboveground and underground biomass, chlorophyll content and density, and integrated turf quality of different fertiliser mixture, were analysed. Sod weight was stable but there were significant differences in the other parameters. All three factors influenced integrated turf quality, but P was the most important. The interactions among the three factors were significant. The regression model between integrated turf quality and three ingredients was established with the method of fuzzy subordinate function analysis, and the optimal mixture of fertilisers was obtained using simulations, one of which was: 3.403 5-3.746 8 g/m² N, 8.673 7-9.450 7 g/m² P₂O₅ and 4.576 9-4.697 7 g/m² K₂O.

Functional analysis of drought-resistant transcription factors PeDREB2a
and HhERF2 in Lotus corniculatus

TAO Fei, MA Jiang-tao, TANG Yi-xiong, LI Jing-sheng, LU Yun-ming, XU Bing-liang, WU Yan-min

2013, 22(3): 250.

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Two drought-resistant genes (PeDREB2a and HhERF2) were identified through functional analysis of the four transcriptional factor genes cloned from Populus euphraticaand Halimodendron halodendron, respectively. PeDREB2a and HhERF2 were two factors which had positive effects in plants against drought stress. Based on this, a series of plant expression vectors either harboring PeDREB2a or HhERF2 were constructed with a non-resistant marker gene and transferred into the Lotus genome using an Agrobacterium mediated method. Transgenic Lotus had strong tolerance to drought. This showed that transcription factors significantly improved drought resistance of L. corniculatus, and the survival rate of transgenic L. corniculatus was 100% in a drought recovery water test.

Analysis of genetic diversity in Anemone obtusiloba populations with ISSR markers

SUN Tao, LIU Zuo-jun, LIU feng-mei, WU Guo-qiang, WANG Yong-gang, LI Bin

2013, 22(3): 259. DOI: 10.11686/cyxb20130334

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