Table of Content

20 March 2018, Volume 27 Issue 3

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Spatio-temporal characteristics and evolution of evapotranspiration of natural grassland in Ningxia during 2000-2014

LIU Ke, DU Ling-tong, HOU Jing, HU Yue, ZHU Yu-guo, GONG Fei

2018, 27(3):  1-12.  DOI: 10.11686/cyxb2017198

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Evapotranspiration (ET), a link between hydrological and ecological processes, is very important to the stability of terrestrial ecosystems. In arid and semi-arid regions, where more than 90% of the effective precipitation is consumed by ET, variations in ET processes may weaken the stability of a grassland ecosystem plagued by water stress. Ningxia is located in the north China farming-grazing transitional zone; long term excessive conversion to farmland and overgrazing have greatly decreased the ecological function of the grassland ecosystem and generated serious changes in ET processes. Background information on grassland ET in the region is unknown, due to inadequate research on the characteristics of ET in undisturbed grassland in Ningxia. Research on the ET characteristics of grassland ecosystems within fragile ecological environments are important for regional agriculture and animal husbandry development, ecological restoration and reconstruction, and the construction of eco-barriers. This study, based on MOD16 ET data, corresponding climate data and grassland type, analyzed the spatial-temporal changes in ET in Ningxia from 2000 to 2014 and predict future trends. Regression analysis, correlation analysis and rescaled range analysis were employed. The results indicated that during a recent 15-year period (2000-2014), the ET of grassland increased (with fluctuations) and average ET was 228.03 mm per year. The upward trend was not significant (P>0.05) because of regional differences in precipitation and heat, and the annual and monthly ET of various grassland types presented obvious heterogeneity. The annual average ET also had a strong spatial heterogeneity (135.84-732.12 mm), higher ET in the south and lower in the north, but the fluctuation was small. More specifically, grassland ET mainly presented a decreasing pattern from north to south in northern Ningxia, and increasing from north to south in central and southern Ningxia. However, the variation in ET is small and the change is not significant in most of the study area. In the future, the increasing trend of ET in the grasslands will probably become significant and only small parts of the grassland system will experience reduced ET. Precipitation was the main factor determining the distribution pattern and inter-annual fluctuation of ET in grassland in Ningxia. Nevertheless, the influence of land use change caused by human activities in ET cannot be ignored.

Analysis on the impact of climate change on vegetation in the Qaidam Basin

LI Hong-mei

2018, 27(3):  13-23.  DOI: 10.11686/cyxb2017372

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The Qaidam Basin is located on the Qinghai-Tibetan Plateau. The annual average precipitation is only about 110 mm. The ecological environment is extremely vulnerable. Under the context of global warming, temperature and precipitation have significantly increased in recent years, so the climate is gradually becoming warmer and more humid. The purpose of this study was to analyze vegetation dynamics using the NDVI (Normalized Difference Vegetation Index) and vegetation succession based on monthly temperature, precipitation, etc. in 10 meteorological stations in Qaidam Basin during 1961-2016, satellite remote sensing data from GIMMS (Global Inventory Modelling and Mapping Studies), and MODIS (Moderate-Resolution Imaging Spectroradiometer) data from 1982 to 2016. The linear trend analysis and comprehensive sequence classification methods were used to assess trends. The results showed that the NDVI increased significantly in the alpine area around the basin and the arid desert area in the basin during the period between 1982 and 2016 by 0.0090/10 yrs and 0.0011/10 yrs, respectively. The NDVI showed a slight increasing trend in temperate desert and lowland meadow vegetation; 0.0011/10 yrs and 0.0036/10 yrs, respectively, while the NDVI increased significantly in alpine meadow vegetation (0.0058/10 yrs). The climate is extremely arid in Qaidam Basin with water being the main factor limiting vegetation growth and development. The vegetation NDVI had a significant positive correlation with precipitation and a negative correlation with evaporation. The vegetation is gradually changing to species adapted to warm and moist conditions after the abrupt temperature increase in 1987.

Predicting suitable distribution of dominant herbaceous plant functional groups in a forest-steppe zone, Hebei, China

FAN Shun-xiang, ZHENG Jian-wei, WEI Shi-kai, HUANG Xuan-rui, ZHANG Zhi-dong

2018, 27(3):  24-32.  DOI: 10.11686/cyxb2017192

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Understanding the responses of herbaceous plant functional groups to environmental changes and their distribution pattern in a forest-steppe zone is helpful for clarifying the factors influencing different groups and for improving conservation strategies for herbaceous species diversity in the fragile landscape. A total of 184 sample plots (1 m×1 m) were established and assessed using a stratified random sampling design in the Saihanba Nature Reserve, Hebei. Herbaceous plant species were divided into C₃ and C₄ functional groups. Twenty environment factors related to topography and climate were obtained from the ClimateAP (Climate Asia-Pacific) model and by utilizing GIS (Geographic Information System) spatial analysis techniques. The ecological niche model (MaxEnt) was adopted in predicting the potential distribution of both C₃ and C₄ plant functional groups. Our results showed that the area under the receiver operating characteristics curves (AUC) for the C₃ and C₄ were all over 0.8, indicating that the MaxEnt model had good predictive performance. The C₃ functional group had a large potentially suitable distribution range, whereas the C₄ functional group had a relatively small distribution in the study area, accounting for 61.99% and 19.12% of the total area, respectively. The main environmental factors affecting the distribution of C₃ included: extreme maximum temperature, mean winter snow, degree-days above 5 ℃, mean annual temperature, and mean temperature of the coldest month. The main environmental factors affecting the distribution of C₄ species included: extreme maximum temperature, degree-days above 5 ℃, mean annual temperature, mean annual precipitation, and mean winter snow. Accordingly, the results confirmed that C₃ species potentially occurred in cooler and wetter conditions, whereas C₄ species might tend to potentially occupy warmer and drier locations in the study area. The distribution range and area of C₄ herbaceous species will probably increase in response to global climate warming.

Vegetation community characteristics of different meadows and their relationship with soil factors in Huihe wetland

LUO Yan, SU De-rong, JI Bao-ming, Lü Shi-hai, HAN Li-liang, LI Xing-fu

2018, 27(3):  33-43.  DOI: 10.11686/cyxb2017184

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Wetland soils affect the quantity, growth, development, morphology and distribution of plant communities. Selecting the core area of Huihe National Nature Reserve as the study area, the vegetation communities of wetland meadow, swamp meadow, transition meadow, mature meadow and saline-alkali meadow were investigated. Soil samples from the different meadows were also analyzed. The study investigated characteristics of the dominant plant communities, the distribution of soil elements and the relationship between the two. Results showed that the meadows’ vegetation characteristics were influenced by soil element distribution, hydrological regimes and plant growth characteristics. Changes in the Shannon-Wiener index and Simpson index showed a similar trend, with maximum values scored by mature meadow and minimum values by saline-alkali meadow. The Pielou index changes were: mature meadow<saline-alkali meadow<wetland meadow<swamp meadow<transition meadow. Swamp meadow had the highest aboveground and underground biomass, saline-alkali meadow the lowest. Meadow plants influenced soil nutrient content and change, while soil factors also had important feedback effects on vegetation growth. The results showed significant differences in soil elements across the different meadow plant communities. Transition meadows had the strongest capacity for absorbing and retaining soil carbon, nitrogen and phosphorus. There was a significant positive correlation between the Shannon-Wiener index and soil moisture content (MC), while there was a significant negative correlation with soil available phosphorus (AP). Soil organic matter (SOM), total nitrogen (TN) and available nitrogen (AN) were significantly positively correlated with vegetation height, soil SOM, TN and vegetation coverage. Vegetation aboveground and underground biomass were significantly negatively correlated with soil AP but positively correlated with AN. Soil total phosphorus (TP) had little effect on vegetation diversity, growth and biomass in this study. Redundancy analysis suggested that there was a certain degree of succession across the different meadows in Huihe wetland: mature meadow and wetland meadow might be the initial or final stage of the succession, and transitional meadow the middle stage. Soil nutrients were significantly affected by community succession.

Comparison of phytolith assemblages in the herbaceous communities of forest and grassland regions in Northeast China

XIA Ying-fan, JIE Dong-mei, LI De-hui, ZHOU Pei-fang, SONG Li-na, MENG Meng, JIANG Xue-chun

2018, 27(3):  44-56.  DOI: 10.11686/cyxb2017177

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In order to investigate variations in the phytolith assemblages of different plant communities, the authors have analyzed the characteristics of 26 herbaceous communities from forest and grassland regions in Northeast China. A detailed comparison has been made of two aspects, phytolith morphology and the quantities of the various phytolith types found in the two regions’ herbaceous communities. Qualitative analysis of morphological characteristics revealed 15 phytolith species: saddle, trapeziform, rondel, bilobate, elongate, hair, lanceolate, papillate, parallepipedal bulliform cell, cuneiform bulliform cell, tabular stellate, silicified stomata, silicified vascular, globular papillate and oblong reticulate. Quantitative analysis of phytolith type distributions was carried out using variance and cluster analyses. Results showed that the forest and grassland regions can produce the same types but that some, such as tabular stellate, were found only in forest regions while others, such as cross, were found only in grasslands. There were also some differences in the quantity of phytolith types present in the two regions’ herbaceous communities. One-way ANOVA was done with data on the 26 phytolith assemblages and found that the average percentage of phytolith such as silicified vascular showed no significant differences between forest and grassland regions, while papillate and silicified tissue types showed disparities. Moreover, the percentage of short cell phytolith showed highly significant differences. Based on the results of cluster analysis, herbaceous phytolith assemblages from forest and grassland non-understory were often similar while understory assemblages in the two regions were different. I_c index scores indicated that the habitats of herbaceous communities in forest regions were colder than those of grasslands. It is worth noting that the globular papillate type described in previous work was also found in this study, while the oblong reticulate type reported here has not been described in previously published literature.

Simulation model of photosynthesis and dry matter accumulation in oilseed flax based on APSIM

LI Yue, Wu Ling, Gao Zhen-ni, Niu Jun-yi

2018, 27(3):  57-66.  DOI: 10.11686/cyxb2017163

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Photosynthesis and dry matter accumulation simulation models are the core of crop growth models. Taking existing models and using radiation use efficiency, and considering the influence of environmental factors and respiration consumption on photosynthetic rate, a physiological and ecological processes model for photosynthesis and dry matter accumulation in oilseed flax was established. This model produced improved simulation and applicability during validation experiments with different sowing methods, planting density and nitrogen and phosphorus levels. For example, the root mean squared error (RMSE) value with different planting densities ranged from 0.0807 to 0.2086, with a mean of 0.1584 while the R² ranged from 0.9677 to 0.9965, mean 0.9869. The RMSE value with different nitrogen and phosphorus levels ranged from 0.0952 to 1.2375 with a mean of 0.4000 while the R² range from 0.8964 to 0.9959, mean 0.9700. The biomass simulations from this model were compared with the APSIM (Agricultural Production System Simulator) and AquaCrop (FAO Crop Model to Simulate Yield Response to Water) with different nitrogen and phosphorus levels. The results of this study lay the foundation for the further development of oilseed flax growth models, and provide the basis for the application of growth model and management decisions in flax.

Transcriptome-wide identification and expression analysis of HD-Zip I transcription factors in Festuca arundinacea

ZHUANG Li-li, WANG Jian, YANG Zhi-min

2018, 27(3):  67-77.  DOI: 10.11686/cyxb2017422

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Homeodomain-leucine zipper proteins are unique to plants and regulate many aspects of plant development as well as plant tolerance to abiotic stress. However, the function of the most family members is largely unknown. Molecular studies of tall fescue lag behind other model species even though this plant is widely used as a cool-season turf grass. A local nucleotide database file was created in Bioedit software based on published and our own unpublished tall fescue transcriptome data. Using 14 HD-Zip I protein sequences of rice as the query, 13 counterparts in tall fescue were obtained by the Tblastn search program. Based on these obtained sequences, a full length open reading frame of the 13 FaHD-Zip I was cloned by nest PCR method. Phylogenetic and MEME motif analyses showed that all 13 FaHD-Zip I were closely related to the corresponding orthologs in rice. In addition, the number and arrangement mode of conserved motifs was nearly the same in the two species. qRT-PCR was adopted to analyze the expression pattern of 11 FaHD-Zip I in crowns under polyethylene 6000 (PEG6000) treatment. The relative expression level of FaHD-Zip I genes (except FaHOX4 and FaHOX6) were up- or down-regulated under short-term PEG6000 treatment, with FaHOX22 the most significantly up-regulated. All gene expression was induced in crowns of PEG6000-treated plants compared with that in control plants at 7 or 14 d. Relative expression level of FaHOX22 was up-regulated by 76.3 fold. This study provides a fast and efficient method for molecular cloning of certain transcription factor family members in species that lack genomic sequences. Furthermore, it promotes the future investigation of the molecular function of key factors that may serve a useful role in molecular breeding.

Biocontrol efficiency of Bjerkandera adusta M-1 against Sclerotinia sclerotiorum

ZHANG Hong-nan, ZHANG Xu-hui, WU Di, LI Yong

2018, 27(3):  78-89.  DOI: 10.11686/cyxb2017174

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In this study, the biocontrol efficiency of isolated Bjerkandera adusta M-1 strain (BaM1) against Sclerotinia sclerotiorum was evaluated and the conditions required to optimize culture of BaM1 were determined. This work provides new technical data for the biological control to Sclerotinia stem rot. The inhibitory effects of BaM1 against S. sclerotiorum were evaluated by a dual culture assay and by a liquid culture experiment. In addition, the antagonistic and the mycoparasitic properties of antagonistic BaM1 against S. sclerotiorum were observed by optical microscope and scanning electron microscope (SEM). The thermal stability of fermentation broth of BaM1 was investigated under different temperature regimes. Subsequently, the liquid culture conditions were optimized according to the single factor test and response surface methodology (RSM). Based on that, the biocontrol efficiency of BaM1 against S. sclerotiorum in plants was investigated in a greenhouse pot experiment. It was found that the inhibition of S. sclerotiorum by BaM1 in the dual culture assay was as high as 67.9%, greater than the inhibition rates achieved by carbendazim treatment (22.7%) and thiophanate methyl treatment (31.4%). The inhibition rate of the BaM1 fermentation broth was up to 51.8% in the liquid culture experiment, which was also higher than in the two chemical treatments. BaM1 had an obvious antagonistic effect on S. sclerotiorum and the mycelia of both organisms changed when growing together. Hyphae of BaM1 pierced and penetrated the mycelium of S. sclerotiorum, resulting in swelling of S. sclerotiorum hyphae, deformation and even fracture, when viewed under the scanning electron microscope, thus showing a strong mycoparasitism. Furthermore, the inhibition rate of BaM1 fermentation broth remained above 35% after heated 30 min in the water bath at 80 ℃, which illustrated the thermal stability of BaM1 fermentation broth. The identified optimal liquid culture conditions were C/N of 7.5, pH of 4.7, culture volume 33% of bottle capacity, a culture time of 22 d, a rotation speed of 180 r·min^-1, and a culture temperature of 32 ℃. Under these conditions an inhibition rate of 80.9% was achieved for BaM1 fermentation broth. Moreover, the biocontrol efficiency of BaM1 against S. sclerotiorum reached 71.4% in the greenhouse experiment, compared to 53.2% with carbendazim treatment. In conclusion, as a biocontrol fungus, BaM1 had strong antagonistic efficacy against S. sclerotiorum, and the inhibition rate of the fermentation broth was enhanced when culture conditions were optimized. The biocontrol efficacy in a greenhouse experiment indicated good prospects for field use of BaM1 against S. sclerotiorum.

Effects on the quality of corn silage, of 5 strains of lactic acid bacteria with different combinations of added CaCO₃, enzyme and urea

WANG Jian-fu, LEI Zhao-min, WAN Xue-rui, JIANG Hui, LI Jie, WU Jian-ping

2018, 27(3):  90-97.  DOI: 10.11686/cyxb2017115

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Lactic acid bacteria (LAB) have the ability to suppress aerobic bacteria, yeast and fungi during forage fermentation. The effects of 5 LAB strains on fermentation quality and nutritive value of corn silage were evaluated at days 3, 10 and 30 after being ensiled. LAB strains were combined with CaCO₃, an enzyme formulation, and urea in 7 different treatment combinations, with 1 additional blank control treatment. The results show that a mixture of the 5 LAB strains increased the fermentation quality and nutritive value of whole corn crop silage. The addition of CaCO₃ with lactic acid bacterial compounds further increased the lactic acid (LA) and acetic acid (AA) levels, especially AA. This fermentation pattern is linked to avoidance of excessively low pH and improvement of the silage nutritional quality. A treatment combination of urea and LAB also increased the AA, NH₃-N and crude protein (CP) contents, again indicating prevention of excessively low pH and improved silage nutritional quality. A treatment combination of cellulase and amylase with LAB compound improved the quality of silage by increasing the production of water soluble carbohydrate (WSC), LA and AA. A treatment combination of CaCO₃, urea, cellulose and amylase with LAB gave the best overall results, in terms of fermentation and nutritional quality of corn silage. The values for measures of silage fermentation quality and nutritive value changed rapidly in first 3 days of fermentation, and followed a different time course for the different additives.

The effects of linolenic acid content and composition of feed on the growth and meat quality of finishing pigs

LI Huan-huan, SHI Ying-hua, ZHANG Xiao-xia, LIU Xiao, JIA Ze-tong, WANG Cheng-zhang

2018, 27(3):  98-107.  DOI: 10.11686/cyxb2017309

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The objective of this study was to explore the effects of different linolenic acid levels and composition of feed on growth performance, carcass traits and meat quality of finishing pigs. 900 Duroc×Landrace×Yorkshire finishing pigs, about 60 kg live weight, were divided into five treatments, with 3 replicates of each treatment and 60 pigs in each replicate using a random block design. Five treatment groups were fed a basic diet (control), 10% alfalfa meal, 20% alfalfa meal, soybean oil supplemented (linolenic acid level is consistent with 10% alfalfa meal group), and linseed oil supplemented group (linolenic acid level is consistent with 20% alfalfa group), respectively. The experiment was conducted for 67 days. The daily weight gain of 10% alfalfa meal group was significantly higher than those of 20% alfalfa meal group and linseed oil group. Lean meat content of the pigs from the two alfalfa meal groups was higher than those from the other 3 groups, however, their dressing percentage were lower. The eye muscle area of the control group was lower than all other groups; the 10% alfalfa meal group has the highest eye muscle area. Marbling and meat texture of the two alfalfa meal groups was better than that of the both of soybean oil and flax oil group. Compared with the control group, the saturated fatty acid (including palmitic acid and stearic acid) contents of the pigs from the four experimental groups were reduced, while the polyunsaturated fatty acid (including linoleic acid and linolenic acid) contents were increased; and the linolenic acid content in the meat of alfalfa meal fed pigs was higher than those supplemented with plant oils. These results showed that adding 10% alfalfa meal to the diet of pigs improved meat yield and quality and was more effective than supplementation with plant oils.

Assessment of mineral nutrition of forage in the natural habitat of Przewalski’s gazelle (Procapra przewalskii)

SHEN Xiao-yun, HUO Bin, MIN Xiao-ying, WU Ting, LIAO Jian-jun, CAI Ping, ZHANG Yu, HE Yu-bang, SUN Jian-qing, WU Yong-lin

2018, 27(3):  108-115.  DOI: 10.11686/cyxb2017166

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Mineral nutrition is essential for higher forms of animal life. This study investigated mineral nutrition distributions in the habitats of Przewalski’s gazelle (Procapra przewalskii). Dietary analysis of the Przewalski’s gazelle has already been done by microanalysis. Mineral concentrations were determined by inductively coupled plasma atomic emission spectroscopy. We found that concentrations of selenium in the soil and forage of the gazelle’s habitats were significantly lower than that in healthy areas. The copper nutrition of forage was also significantly lower than that in healthy areas during the herbage growing period. The contents of copper and selenium in forage in the seeding period were significantly higher than in the growing period (Cu, F_2,27=3.27, P=0.008; Se, F_2,27=3.27, P=0.009). There were no significant differences in the mineral contents of forage between the seeding and withering periods. Ramulus clematidis (Clematis tangutica), sand sagebrush (Artemisia desertorum) and shining speargrass (Achnatherum splendens) were found to be rich in selenium, with shining speargrass having the highest selenium content. Speargrass is not a preferred forage plant for Przewalski’s gazelle (selectivity indices=-0.886, food from shining speargrass made up 13.68%). Artemisia abrotanum (Artemisia anethifolia), artemisia frigida willd (Artemisia frigida) and Stipa purpurea were found to be rich in copper, with S. purpurea having the highest content. S. purpurea is not a preferred forage plant for Przewalski’s gazelle (selectivity indices=0.037, food from S. purpurea made up 9.40%). This study shows that there is a severe selenium deficiency in Przewalski’s gazelle’s habitats in the Qinghai Lake watershed area. The copper content of forage is rich in the seeding and withering periods. There are significant temporal dynamics in the mineral contents of herbage. Shining speargrass increases the selenium content in Przewalski’s gazelle’s food, and S. purpurea adds copper content. Approaches to restocking the Przewalski’s gazelle population should include increased percentages of such selenium and copper rich plants.

Correlation between soil enzyme activities and soil physical chemical properties in Chabuchar Grassland

Saiyaremu·Halifu, Aikebaier·Yilahong, SONG Rui-qing, Abudousaimaiti·Naihemaiti, Mirenisha·Maimaitiming, Diliduer·Aili

2018, 27(3):  116-125.  DOI: 10.11686/cyxb2017203

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As one of the components of soil ecosystems, soil enzymes are biological catalysts in ecological systems, playing an important role in the process of soil material cycling and energy conversion. In this research, soil from a site at 1191-2656 m elevation in Xinjiang Yili Chabuchar county was studied. The variation in soil enzyme activity at different altitudes, the vertical distribution of soil enzymes and the effect of soil fertility on soil enzyme activities were evaluated. The activities of catalase, alkaline phosphatase, urease and invertase were 0.237-0.722 mg·(g·20 min)^-1, 0.767-2.673 mg·(g·24 h)^-1, 0.029-0.106 mg·(g·24 h)^-1, and 3.384-23.801 mg·(g·24 h)^-1, respectively. Soil enzyme activities were greater in the topsoil than in the subsoil layers. Enzyme activity increased with increase in altitude. Activities of urease and invertase in 0-20 cm soil layer were significantly positively correlated with altitude, while in 20-40 cm layer, this was true for alkaline phosphatase only, and in 40-60 cm layer urease activity was positively and significantly correlated with altitude. The soil enzyme activity and organic matter tended to show similar patterns, but correlations were not significant. It was also found that with increase in soil depth, the correlation between soil enzyme activity and soil fertility diminished.

Investigation of growth characteristics of seedlings from three types of heteromorphic seeds of Atriplex aucheri

MA He, WEI Yan, MU Chen

2018, 27(3):  126-134.  DOI: 10.11686/cyxb2017193

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Atriplex aucheri is an important wild forage germplasm resource in Xinjiang desert regions. It exhibits seed heteromorphism, with 3 types of seed produced: brown seeds (non-dormant), large black and small black seeds (dormant). Seeds from a single A. aucheri plant (grown from one particular seed type) were used as experimental material. The three types of seeds were cultivated under natural conditions, and comparative studies of germination phenology and growth characteristics of three types of seeds carried out. It was found that: 1) The germination phenology of heteromorphic seeds were unsynchronized, and different types of seeds had different germination strategies. The germination of brown seeds was rapid with an emergence rate of up to 74.30% within 3 days. The germination of the other two types was delayed with emergence rates of 6.58% and 1.55%, after 21 and 17 days, respectively, for large and small black. 2) The cotyledons of all three types of seeds were retained for an extended time during germination, but the retention time varied with the seed size. The smaller the seeds were, the shorter the cotyledon retention time. 3) The cotyledon size, root length, and above- and below-ground biomass of brown seeds were all significantly greater than those of the two types of black seeds in the early growth stages, but as seedlings developed, the size differences between plants from different seed types decreased gradually. 4) The seedlings from different types of seed displayed different biomass allocation strategies. Seedlings grown from brown seeds showed comparatively greater development of the above-ground organs, while the two types of black seeds prioritized below-ground development. Seed heteromorphism therefore provides different seedling survival strategies (rapid establishment after occasional rain or stress tolerance in less favourable conditions). This seed heteromorphism is an important ecological adaptive mechanism for plants growing in the hash desert environment. This study provides novel insight into the ecological significance of seed heteromorphism in this desert environment and also provides a basis for a new theoretical theory of ecological bet-hedging.

Response of microbial C, N and respiration characteristics to sowing rates in alfalfa cultivation grasslands in Hulunber, Inner Mongolia

WANG Di, PANG Huan-cheng, LI Da, CHEN Jin-qiang, XIN Xiao-ping, XU Li-jun, TANG Xue-juan, GUO Ming-ying, ZHU Shu-sheng

2018, 27(3):  135-143.  DOI: 10.11686/cyxb2017321

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This study investigated changes in microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and the respiration characteristics of alfalfa under 5 different sowing rates (6, 9, 12, 15 and 18 kg·ha^-1). The study was undertaken from July to September 2015 in Hulunber, Inner Mongolia. The results showed that aboveground and underground biomass reached the maximum when the sowing amount was 12 kg·ha^-1. The highest MBC value appeared at 18 kg·ha^-1 sowing quantity among all soil layers and months. As a whole, the value of MBC presented higher in July than September, with this difference more significant at the 0-10 cm than 10-20 cm soil layers. MBN values also presented higher in July than September. Changes in soil respiration entropy (qCO₂) were coincident with microbial respiration, with the lowest qCO₂ levels appearing in the 12 kg·ha^-1 sowing treatment. There were no significant differences in microbial respiration and qCO₂ between the 18 kg·ha^-1 and 12 kg·ha^-1 treatments in July and September. We found that MBC, microbial respiration and qCO₂ varied according to the sowing rate of alfalfa. To summarize, taking into consideration such factors as aboveground biomass, microbial respiration and qCO₂, our study suggests that the best sowing quantity for alfalfa cultivation in Hulunber is 18 kg·ha^-1.

Effect of nitrogen fertilizer on the growth, herbage bio-energy yield and nitrogen utilization of Pennisetum glaucum×P. purpureum on arid infertile hill land in South China

LI Wei-liu, QIN Wei-zhi, XIONG Jun, WEI Min-zheng, TANG Xiu-hua, YAN Hai-feng

2018, 27(3):  144-153.  DOI: 10.11686/cyxb2017182

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To explore the biomass production response of hybrid Pennisetum to nitrogen nutrition in arid hill land in South China, the effects of four different nitrogen (N) application levels (0, 112.5, 225.0 and 337.5 kg N·ha^-1) on morpho-agronomic traits were studied. Parameters measured included yield, SPAD value, bio-energy characteristics and nitrogen utilization efficiency of P. glaucum×P. purpureum (cultivar Guinengcao-1). Application of N fertilizer promoted horizontal plant spread and shoot number, vertical growth, plant height, and stem diameter, but the fresh weight and hay yields were little changed at N fertilizer application rates above 225.0 kg N·ha^-1. Application of nitrogen fertilizer also increased the contents of cellulose and hemicellulose, calorific value and the yield of standard coal, while significantly decreasing the contents of dry matter, lignin and ash. The calorific value decreased and the yield of standard coal showed little further increase when the rate of N fertilizer application was raised beyond 337.5 kg N·ha^-1, with the result that bio-energy yield of Guinengcao-1 was also decreased. The nitrogen utilization efficiency of Guinengcao-1 did not decrease significantly with increase in N fertilization rate from 112.5 to 225.0 kg N·ha^-1, but decreased significantly at 337.5 kg N·ha^-1. Therefore, when growing Guinengcao-1 hybrid Pennisetum on arid infertile hill land in South China, N fertilizer is best applied at rates that optimize bio-energy yield. This is achieved when the N application rate is less than 225.0 kg N·ha^-1.

Effect of phosphate fertilizer application on alfalfa yield, nutritive value and N and P use efficiency

YU Tie-feng, LIU Xiao-jing, HAO Feng

2018, 27(3):  154-163.  DOI: 10.11686/cyxb2017168

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In order to investigate how phosphorus application affects the yield, nutrient value and nitrogen (N) and phosphorus (P) utilization of alfalfa, the effects of different phosphorus levels (P₀: 0 kg·ha^-1; P₁: 126 kg·ha^-1; P₂: 252 kg·ha^-1) on the performance, nutrient value, nitrogen and phosphorus utilization and key enzymes of nitrogen metabolism in alfalfa were studied, to examine the optimal nitrogen fertilizer rate under field conditions. The variety Gannong No.3 was used as experimental material. With optimal N supply, alfalfa total annual yield under P₁ was 33312 kg dry matter·ha^-1, significantly higher than in P₀ or P₂. Activities of nitrate reductase (NR) and glutamine synthetase (GS), crude protein content, total protein yield, nitrogen uptake efficiency and nitrogen production of alfalfa were all significantly higher under P₁ and P₂ than under P₀. Although often not differing significantly, values for all the above indexes were numerically higher in the P₁ treatment than under P₂. The results show that application of phosphate fertilizer to alfalfa significantly increases productivity, and improves forage quality, and N and P utilization. The application rate of P fertilizer followed the law of diminishing returns in terms of the yield, forage quality and utilization rate. In conclusion, the best P supply level was 126 kg·ha^-1 in this test. The appropriate phosphorus supply enhances plant metabolic activity by promoting the absorption and assimilation of N through the activation of NR and GS activity, thereby enhancing yield, quality and nitrogen use efficiency in alfalfa.

Effects of planting density on yield and secondary metabolite content of Codonopsis pilosula

JIN Peng-bo, HU Jia-dong, MAO Ge, ZHANG Zhi-wei, MA Cun-de, LIANG Zong-suo, DONG Juan-e

2018, 27(3):  164-172.  DOI: 10.11686/cyxb2017165

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To research the effects of planting density on growth, yield and accumulation of secondary metabolites of Codonopsis pilosula, we conducted a single-factor randomized block experiment with 5 planting density treatments: 20 cm×10 cm, 20 cm×15 cm, 20 cm×20 cm, 30 cm×10 cm, 30 cm×15 cm. The roots were harvested at three different times; 30th August, 30th September and 20th October. The root yield and secondary metabolite content were subject to statistical analysis. Planting density had a significant effect on growth, yield and secondary metabolite content; yield and secondary metabolite content were much higher in the 20 cm×10-15 cm treatments. It was also observed that C. pilosula in Tanchang was still growing in late October, and that the quality of the extract conformed with the necessities of the China Pharmacopoeia. Consequently, late October is the suggested harvest period.

History of foxtail millet planting, husbandry, and societal utilization in China

ZHANG Da-zhong, LIU Jia-jia, FENG Bai-li

2018, 27(3):  173-186.  DOI: 10.11686/cyxb2017191

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Foxtail millet originated in northern China. It is one of the oldest crops in the world, and also traditionally the dominant crop in China. Foxtail millet has played an important role in Chinese farming and civilization. Over centuries of cultivation, a rich experience in the husbandry of foxtail millet was accumulated by the ancient Chinese, summarized by Jia Si-xie in the Northern Wei Dynasty (386-534 CE). During the Tang Dynasty (618-907 CE) foxtail millet planting gradually declined, but the husbandry knowledge continued to evolve steadily. Here we review information on areas planted, political and cultural status, evolution of husbandry knowledge, and the utilization of foxtail millet in ancient China.

Effect of Ephedra distachya extracts on moss crust growth

JI Xue-hua, WANG Lu-jie, PANG Sheng-qun

2018, 27(3):  187-193.  DOI: 10.11686/cyxb2017366

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Moss crust is the advanced stage of biological soil crusts and plays a vital role in the prevention of soil erosion and sand stabilization. In recent years, a lot of attention has been paid to these crusts because as a major component of desert vegetation, the ecology and function of biological soil crusts is crucial. In this study, distilled water and ethanol were used to extract different parts of Ephedra distachya (leaf, root and rhizosphere soil), and the extracts solution were added to glass dishes which had been filled with desert sand soil and moss fragments which were then cultivated. Growth indicators such as chlorophyll content, moss density, height and respiration were measured. The results showed that both water and ethanol extracts inhibited moss growth. As for different parts of extracts, leaf extracts showed stronger inhibition than root and rhizosphere soil. Respiration rate indicated that E. distachya extracts promoted CO₂ release from the moss crust, which resulted in the crust becoming sparse with any moss present being small. Compared with ethanol, moss crusts respiration treated with water extracts solution increased much more. The results suggest that there is an allelopathic effect from E. distachya on moss crust.

Effects of Mn²⁺ and Pb²⁺ on seed germination and seedling growth of Elymus nutans

XU Ya-mei, WANG Chuan-qi, WU Jun-xi, ZHANG Wen-jing, WANG Xiao-chuan, Chilie Cuizhen, XU De-fei, Baosai Heina, MIAO Yan-jun

2018, 27(3):  194-200.  DOI: 10.11686/cyxb2017387

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In order to provide reference for contaminated soil and vegetation restoration in the Tibetan mining area, a study has been undertaken of the physiological response of Elymus nutans’ seed germination and seedling growth to heavy metal Mn²⁺ and Pb²⁺ stress in Baqing county, Tibet. Select wild E. nutans from the county were used as test materials for investigation using germination methods. The results showed that Mn²⁺ and Pb²⁺ ion stress had a significant effect on seed germination and seedling growth. With increasing Mn²⁺ and Pb²⁺ concentrations, the germination percentage, germination vigor, germination index, vigor index and bud length of E. nutans showed a declining trend. Under a solution concentration of 200 mg·L^-1 Mn²⁺ and Pb²⁺, the shoot length of E. nutans was slightly longer than that of the control. With increasing Mn²⁺ and Pb²⁺ concentrations, the contents of chlorophyll a and chlorophyll b in leaves decreased while electrical conductivity and malondialdehyde content showed a rising trend. This study suggests that E. nutans has some tolerance to Mn²⁺ and Pb²⁺ ion stress that makes it a useful application for soils that are mildly contaminated with these toxins.

Effects of exogenous H₂O₂ treatment on the vigor of oat seeds

XIA Fang-shan, WANG Ting-ting, DONG Qiu-li, MAO Pei-sheng, ZHU Hui-sen, DU Li-xia, TONG Li-rong

2018, 27(3):  201-207.  DOI: 10.11686/cyxb2017183

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In order to determine the effect of exogenous H₂O₂ on oat (Avena sativa) seed vigor during the germination process, oat seeds were pre-treated with 5 different concentrations of H₂O₂ (0, 0.24, 0.48, 0.96, 1.92, 3.84 mol·L^-1) for 0 (CK), 3, 6, 9 and 12 h. The performance indices measured included germination percentage (G_p), germination index (G_i), mean germination time (MGT) and seedling vigor index (SVI). The results showed that with high H₂O₂ concentrations the G_p, G_i and SVI of oat seeds decreased but their MGT increased. The effects of H₂O₂ on changes in G_p, G_i, MGT and SVI were significantly related to treatment concentrations, times and their interactions. The G_p, G_i and SVI of oat seeds reached their minimum level and MGT its maximum level after treatment with H₂O₂ concentration of 3.84 mol·L^-1 for 12 h. These results indicate that the higher the H₂O₂ concentration and the longer of treatment time, the more serious the loss of oat seed vigor. The lipid peroxidation damage caused by high concentration H₂O₂ treatments might be a major reason for the loss of seed vigor. This study suggests that the application of H₂O₂ in seed pre-treatment should be prudently undertaken.