Table of Content

20 March 2017, Volume 26 Issue 3

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Orignal Article

Dynamic monitoring of alpine grassland coverage based on UAV technology and MODIS remote sensing data-A case study in the headwaters of the Yellow River

GE Jing, MENG Bao-Ping, YANG Shu-Xia, GAO Jin-Long, FENG Qi-Sheng, LIANG Tian-Gang, HUANG Xiao-Dong, GAO Xin-Hua, LI Wen-Long, ZHANG Ren-Ping, WANG Yun-Long

2017, 26(3):  1-12.  DOI: 10.11686/cyxb2016165

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In this study, MODIS NDVI and EVI data from 41 field measurements in the eastern headwaters of the Yellow River were used. In combination with the alpine grassland coverage data obtained by an Agricultural Digital Camera (ADC), ordinary digital camera (i.e., Canon 70D) and Unmanned Aerial Vehicles (UAV) images, grassland coverage inversion models were constructed using MODIS vegetation indices. The optimal remote sensing model was used to analyze the grassland coverage dynamics from 2000 to 2015. The results indicated that: 1) the correlation between MODIS NDVI and grassland coverage calculated by UAV images was better than that of MODIS EVI and UAV, and the correlation between MODIS EVI and grassland coverage calculated by ADC and Canon images was higher than that of MODIS NDVI and ADC and the Canon 70D. 2) Compared to ADC, the accuracy of the models established using the Canon 70D was much higher, indicating that ordinary digital cameras may be more reliable for calculating the alpine grassland vegetation coverage. 3) Compared with the grassland coverage calculated with the Canon, images from the ADC and UAV under 30 m and 100 m flight height with the two MODIS vegetation indices respectively, the MODIS NDVI was more sensitive to grassland vegetation coverage retrieved by UAV under 30 m flight height; the optimal model was y=65.4132ln(NDVI)+109.1763 (R²=0.7575, RMSEP=8.4780). 4) Vegetation coverage during the study period in the southeast area of the study area was stable at 71.5%. Increases in vegetation cover occurred primarily in the western and northern regions while decreases in vegetation were mostly found in northern and southern regions of the study area.

Simulation analysis of land surface processes in central Asian desert grassland ecosystems using CoLM

JING Chang-Qing, AN Sha-Zhou

2017, 26(3):  13-32.  DOI: 10.11686/cyxb2016385

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The performance of a land surface heat flux model known as the Common Land Model (CoLM) was investigated in arid and semi-arid areas, in desert grassland ecosystems over Central Asia. The model performance was tested for three sites; Fukang, the Aral sea, and Balhash Lake, and the characteristics of the land surface were also analyzed for these three sites. It was found that water status of the grassland ecosystem had a major impact on the pattern of energy flux. Sensible heat flux was the dominant component of the diurnal energy balance at the Fukang site and Aral sea sites, which displayed obvious drought characteristics. The dominant energy component was the latent heat flux at Balhash Lake site, which was less arid than the other sites. CoLM performed well in typical desert grassland ecosystems, and correctly described the diurnal variation in energy fluxes. The simulations for sensible heat flux and ground heat flux overnight were less accurate. At night, the simulated sensible heat flux was higher than the observed values, and the simulated ground heat flux was significantly lower than the observed data. The deviation was greater than 50 W/m² at each site. The model does not adequately describe the soil heat flux exchange process at night in arid areas which have a large temperature differential between day and night.

Effects of the award-allowance payment policy for natural grassland conservation on income of farmer and herdsman families in Tibet

CUI Ya-Nan, Li Shao-Wei, YU Cheng-Qun, TIAN Yuan, ZHONG Zhi-Ming, WU Jian-Shuang

2017, 26(3):  22-32.  DOI: 10.11686/cyxb2016268

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The status of alpine grasslands on the Tibetan Plateau not only has a major impact on the welfare of local residents, but also contributes to economic activity in East China, and thus has an important role to play in the overall ecological security of China. To stop grassland degradation, to recover degraded pastures, and to conserve healthy natural grasslands, in 2011 the government implemented an economic payment policy including awards and allowances to local families for their efforts in grassland conservation. We conducted face-to-face interviews with local families in Agriculture counties (AC), Agriculture-Animal-Husbandry counties (AAHC), and Animal-Husbandry counties (AHC) in 2014, with husbandry activities and economic income data collected at the family level, to assess the social and economic influence of this policy. The results showed that economic benefits arising from this policy are unevenly distributed between different family types. Herdsmen families in AHC received much more benefit than those in either AC or AAHC. We found that the policy has altered the income structure of herdsmen families in AHC, and the transferred income accounted for a great proportion of the total income at the family level. In addition, the policy has reduced the family income gap between AHC and AC, but has provided little incentive or increase in income for families in AAHC. It is necessary therefore, to adjust the criteria, methodology and levels of payment to take into account zonal differences in ecosystem functionality, in order for the system to promote the sustainable development of animal husbandry on the Tibetan Plateau.

Use of life cycle assessment methodology to compare environmental impacts of the same food equivalent for corn and alfalfa production

XU Gang, WANG Jin-Xian, LIN Hui-Long, REN Ji-Zhou, CHEN Lei, CUI Xia

2017, 26(3):  33-43.  DOI: 10.11686/cyxb2016423

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The study used life cycle assessment (LCA) methodology to calculate environmental impacts of producing 1 kg of corn and 1 kg of alfalfa for animal feed, from agricultural raw materials, including cultivation and other aspects of on farm production and associated transport. Data used are for the years 2014 and 2015. The calculation predicts how structural adjustment to crop production patterns will affect China’s environment. In addition, the life cycle environmental impact differences between production of 1 food equivalent unit (FEU) of corn and alfalfa were compared with calculations based on protein and energy content. It was found that life cycle environmental impacts of 1 kg of corn and 1 kg of alfalfa, respectively, were 9.35 and 1.22 MJ of primary energy demand (PED), 889.33 and 144.37 kg of water use (WU), 0.13 and 0.02 kg antimony-eq of depletion of abiotic resources (DAR), 1.21 and 0.10 kg CO₂-eq of global warming potential (GWP), 4.23 and 0.19 g PM_2.5-eq of respiratory inorganics (RI), 2.41 and 0.17 g NMVOC-eq of photochemical oxidant formation potential (POFP), 0.00855 and 0.00080 kg SO₂-eq of acidification potential (AP), 1.20 and 0.09 kg P-eq of freshwater eutrophication potential (FEP), and 0.0126 and 0.0015 CTU of ecotoxicity. Meanwhile, life cycle environmental impacts of 1 FEU alfalfa compared to corn are: PED 20.50%, WU 25.43%, DAR 21.08%, GWP 12.99%, RI 6.98%, POFP 11.15%, AP 14.76%, FEP 12.31%, and ecotoxicity 18.58%. In view of the ecological and economic superiority of alfalfa, subsidies no less than those for other grains should be given. Moreover, agricultural reform such as shifting corn production to alfalfa, cannot only help meet China’s food requirements internally, but also is a convenient and economical way to reduce the resource consumption and environmental pollution in agricultural production. This study provides a scientific basis for a policy to shift from grain to forage production in China.

Interspecific associations in plant communities under yak dung depositions in an alpine meadow

KONG Yang-Yun, YU Ying-Wen, HOU Fu-Jiang

2017, 26(3):  44-52.  DOI: 10.11686/cyxb2016145

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Plant community composition and interspecific associations reflect inter-dependence and competition between species, influencing their spatial distribution. To explore the evolutionary trends and stability mechanisms of grassland communities influenced by the interaction between yak dung depositions and vegetation we analyzed the importance values (IV) of different species, Jaccard association indices and Spearman rank correlation coefficients of the main species present in patches of grass/forb and Kobresia/forb swards under yak dung deposition in an alpine meadow on the northeast Qinghai-Tibetan Plateau. The results indicated that: 1) dung deposition (DP) increased the Agropyron cristatum IV and decreased the Stipa krylovii IV in grass/forb patches, while decreasing the Kobresia capillifolia IV for Kobresia/forb parches; 2) in grass/forb patches, the species-pairs ratios of positive and negative associations under DP and control (CK) were 0.61 and 0.63, respectively and their respective associated species-pairs were 6.6% and 6.4%. For Kobresia/forb patches, the species-pairs ratio of positive and negative associations in DP and CK were 0.90 and 0.72, respectively and their respective associated species-pairs were 2.8% in DP and 14.5% in CK, exhibited mainly between the dominant or sub-dominant species and the companion species; 3) the interspecific association of most species-pairs was weak in both vegetation types; yak dung strengthened the stability of Kobresia/forb patches benefiting the generation of grass/forb patches; 4) according to their adaptability to environment and the key ecological factors affecting plants, the main plant species of two patches were divided into three ecological groups: shade-intolerant and drought-tolerant plants, shade-tolerant and drought-intolerant plants, and, shade-intolerant and drought-intolerant plants.

Effect of population density on the allometric growth of Agriophyllum squarrosum

FAN Gao-Hua, HUANG Ying-Xin, ZHAO Xue-Yong, SHEN Xiang-Jin

2017, 26(3):  53-64.  DOI: 10.11686/cyxb2016147

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The allometric relationships between plant organs determine the strategies of life history, affecting the coexistence and biodiversity of species. Traditional methods are not able to distinguish the responses of plant traits to environmental or genetic differences but allometric analysis can help solve this problem. Allometric analysis was used to study the relationships between different organs of Agriophyllum squarrosum by simulating different population densities of A. squarrosum (16, 44.4, 100 and 400 plants/m²) during the restoration of degraded grassland. The results showed that there are significant allometric relationships between organ pairs. Changes in root vs. aboveground biomass, root vs. main stem biomass, leaf vs. root biomass and main stem vs. aboveground biomass were not influenced by population density, indicating ‘apparent plasticity’. The allometric relationships of root vs. stem, stem vs. aboveground, leaf vs. stem biomass and their respective biomass ratio were significantly affected by population density, reflecting ‘real plasticity’. The allometric index of leaf vs. aboveground biomass at 44.4 plants/m² was approximately 0.75, while the allometric indices at other plant densities were significantly different from 0.75 (P<0.001), suggesting that environmental changes resulted in changes in growth strategy of A. squarrosum. The influence of population density on the allometric relationships between reproductive and other organs is not significant, indicating that A. squarrosum will adopt the same strategy under different densities, but that density differences will result in different allometric scaling and size of individual reproductive organ during different periods of reproductive development. It is important to consider changes in plant growth stages when investigating the relationships between reproductive organs and individual plants.

Improvement of soil quality by Chinese dwarf cherry cultivation in the Loess Plateau steep hill region

WANG Peng-Fei, JIA Lu-Ting, DU Jun-Jie, ZHANG Jian-Cheng, MU Xiao-Peng, DING Wei

2017, 26(3):  65-74.  DOI: 10.11686/cyxb2016233

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In the process of ecological restoration in the Loess Plateau hilly gully region, selection of species for planting is important. Recently, Chinese dwarf cherry (Cerasus humilis) has been used for vegetation restoration in this region, but its ecological impact needs to be systematically evaluated. In this study, 5-year-old plantings of Chinese dwarf cherry and Chinese pine (Pinus tabulaeformis) on level terraces near Liuyu town in Liulin county, Shanxi province, in the steep hill region of the Loess Plateau were compared. Soil samples were collected from 20 and 40 cm depth under the canopy of Chinese dwarf cherry bushes (UCC₂₀, UCC₄₀) and from the same soil depths at inter-row sites (IRC₂₀, IRC₄₀), and corresponding samples were collected from P. tabulaeformis plantations (designated UCP₂₀ & UCP₄₀), to compare the effects of the two plant species on soil properties. It was found that: 1) compared with inter-row soil in Chinese dwarf cherry (IRC₂₀ and IRC₄₀), the pH values, nutrient contents (except available phosphorus) and enzyme activity values (except catalase activity for UCC₄₀) were improved to differing degrees; 2) planting with Chinese dwarf cherry (C) or pine (P) each had their own respective advantages. Alkali-hydrolysable nitrogen, total phosphorus content and enzyme activities of soil under the canopy of C (UCC₂₀ and UCC₄₀) were superior to those of P plantations (UCP₂₀ and UCP₄₀), while soil water content, electrical conductivity and other nutrient levels under the canopy of C were reduced compared to those under P. Results of a principal component analysis indicated that key factors for differentiation between different soil samples were, in descending order, invertase activity, organic matter content, pH value, total phosphorus, alkali-hydrolysable nitrogen and alkaline phosphatase activity. Mean scores for principal component 1 ranked in descending order: UCC₂₀, UCP₂₀, UCC₄₀, IRC₂₀, UCP₄₀ and IRC₄₀. In summary, the cultivation of Chinese dwarf cherry significantly enhanced comprehensive soil quality of the Loess Plateau steep hill region.

Screening of reference genes for real-time fluorescence quantitative PCR in Kentucky bluegrass

ZHANG Lan, TAN Peng-Hui, TENG Ke, YAN Meng-Ju, HE Chun-Yan, GAN Lu, YIN Shu-Xia

2017, 26(3):  75-81.  DOI: 10.11686/cyxb2016297

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To select the most stable reference genes of Kentucky bluegrass (Poa pratensis) for real-time quantitative PCR, we assessed the mRNA expression in different tissues of six traditional candidate reference genes at various leaf development stages, under abiotic stress, or following various hormone applications. Genes assessed included ACT, GAPDH, UBQ, EF-1α, 18s rRNA and β-tubulin. The expression stabilities of these six reference genes were evaluated by geNorm, NormFinder and BestKeeper. It was found that mRNA expression of the candidate reference genes differed significantly between the tissue types, developmental stages, hormone applications or under abiotic stress. In Kentucky bluegrass leaves, GAPDH is recommended as the reference gene for analyzing the mRNA expression in different tissues; EF-1α was the most stable gene under abiotic stress; β-tubulin was most consistent with different hormones; ACT was stably expressed in the different leaf development stages. In conclusion, use of the most appropriate reference genes under different conditions would enhance the accuracy analysis of gene expression in the Kentucky bluegrass. These findings may be applicable when selecting reference genes for analysis of mRNA expression in other members of the Poa genus.

Cloning and expression analysis of homogentisate phytyltransferase from Medicago sativa and its genetic transformation in Arabidopsis thaliana

JIANG Ji-Shan, FANG Zhi-Hong, CHEN Min, WANG Yun-Qi, WU Xin-Ming, JIA Hui-Li, WU Yu-Di, GAO Hong-Wen, WANG Xue-Min

2017, 26(3):  82-90.  DOI: 10.11686/cyxb2016007

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Vitamin E is an essential nutrient for humans, but we cannot synthesize it by ourselves. Homogentisate phytyltransferase (HPT) is a key enzyme that determines vitamin E content. In this study, according to the sequence of MtHPT from Medicago truncatula, we cloned the Opening Reading Frame (ORF) of HPT from Medicago sativa by homology cloning strategy and termed MsHPT. NCBI blast results showed that it encoded a protein of 412 amino acid and belonged to the PT_UbiA superfamily. Multiple sequence alignment results showed that the similarity between the MsHPT protein and other HPT was 80%. In order to further study the gene, promoter sequences were cloned using genome walking technology. Analysis of the MsHPT promoter showed that defense and stress responsiveness cis elements, hormone (MeJA, ABA, GA and ethylene) responsiveness cis elements and light responsiveness elements presented in the promoter. Quantitative Real-time PCR results revealed that MsHPT was expressed throughout the plant, mainly in the leaves. Expression levels of MsHPT increased significantly in response to cold, NaCl, PEG, GA₃ and ABA treatments. The ORF of MsHPT was amplified with restriction enzyme recognition sites added, inserted into vector pBI121 and transformed into Arabidopsis thaliana by Agrobacterium tumefaciens-mediated transformation. According to the PCR results, seven positive lines were obtained. This study provides the basic information for further studies of the function of MsHPT in vitamin E biosynthesis and stress tolerance of M. sativa.

Effects of substitution of corn and fermented cassava residue in the diet on growth, carcass characteristics and meat quality of Hu lamb

FAN Yi-Xuan, WANG Feng, WANG Qiang, Nie Hai-Tao, WANG Zi-Yu, Tao Xiao-Qiang

2017, 26(3):  91-99.  DOI: 10.11686/cyxb2016156

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To evaluate the optimal replacement ratio of energy source (mainly corn) with fermented cassava residue in diets of Hu lambs at 3 months of age 48 Hu lambs [(18.4±1.4) kg liveweight] were randomly divided into four groups with 4 replicates (3 lambs in each replicate), and fed diets containing 0 (control), 20% (A group), 40% (B group), and 60% (C group) fermented cassava residue in place of the normal diet of corn. The experiment lasted for 60 d. Growth and blood biochemical indices were determined after feeding for 60 days; four lambs of each group were killed to measure slaughter performance and meat quality. Lambs in group C were removed from the trial after 2 weeks due to animal health problems. The results showed that the average daily feed intake of lambs in A group was significantly higher than that of B group and the control (P<0.05). Both A and B group lambs had improved feed: liveweight gain ratios compared with the control group (P>0.05). Liveweight, carcass weight and the weight of the liver, abomasum and kidney’s in A group were significantly higher than the control and B group (P<0.05). There were no treatment differences (P>0.05) in blood serum biochemical indices and meat quality. Saturated fatty acids, including myristic acid and palmitic acid in B group lambs were significantly lower than in A group; heptadecanoic acid and arachidic acid in B group lambs were significantly higher than A group and control lambs (P<0.05). The optimal replacement rate of corn with fermented cassava residue in Hu lamb’s diet was 20%, a substitution rate which is feasible based on feed costs.

Effect of dietary calcium and phosphorus on growth, blood metabolites, and digestion in Chahaer lambs in Inner Mongolia

HU Feng-Ming, SI Bing-Wen, ZHANG Bo, Siqinbateer, Sarenhua, Sudebilige, JIN Hai, DIAO Qi-Yu, TU Yan

2017, 26(3):  100-110.  DOI: 10.11686/cyxb2016137

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The present study was conducted to investigate the effect of dietary calcium (Ca) and phosphorus (P) on growth performance, digestibility and output of Ca and P, and bone characteristics of weaned Chahaer lambs. 120 weaned Chahaer lambs [liveweight (16.3±3.3) kg; age 70 days] were randomly assigned into 4 groups: Ca and P levels in the diets of group Ⅰ, Ⅱ, Ⅲ and Ⅳ were 0.49% and 0.28%, 0.55% and 0.32%, 0.64% and 0.47% and 0.87% and 0.70%, respectively. The feeding trial lasted for 65 days; 6 lambs (3 male and 3 female) were randomly selected to be slaughtered from every group to collect data on Ca and P metabolism and digestion. The results showed that dietary Ca and P levels had no effect on liveweight gain, dry matter intake and feed conversion (P>0.05). Blood serum Ca content in group Ⅳ was the highest among the four groups (P<0.05), whereas serum alkaline phosphatase in group Ⅰ was higher than other three groups (P<0.05). The apparent digestibility of Ca in group Ⅰ was significantly higher than other three groups (P<0.05). Ca and P outputs were significantly increased with increasing dietary Ca and P levels (P<0.05). The tibia ash and P content from lambs in group Ⅳ was significantly higher than that in group Ⅰ (P<0.05) and the metatarsal ash content in group Ⅰ was lower than those in group Ⅲ and Ⅳ (P<0.05). Increased Ca and P in the diet of lambs increased Ca and P input into the grassland during winter and spring. It was concluded that increased Ca and P levels in the diet of weaned lambs reduced the apparent digestibility of Ca but significantly increased the Ca and P content in the feces and bones. Optimal levels of Ca and P in the diet of weaned Chahaer lambs was 0.49% and 0.28% respectively.

Effects of elevated CO₂ on development and reproduction of green pea aphid (Acyrthosiphon pisum)

LI Run-Hong, LIU Chang-Zhong

2017, 26(3):  111-120.  DOI: 10.11686/cyxb2016359

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To study the effect of elevated CO₂ on development and reproduction of three consecutive generations of green pea aphid (Acyrthosiphon pisum), the reproductive performance of three consecutive generations of green pea aphid fed detached Vicia faba leaves was recorded under ambient CO₂ [(375±18) μL/L] and two elevated CO₂ concentrations: moderate [(550±27) μL/L] and double ambient [(750±37) μL/L]. It was found that developmental duration of three consecutive generations of green pea aphid was shortened, while larval weight, adult weight, weight difference and mean daily relative growth rate all displayed increasing trends under elevated CO₂ conditions. Also, the reproductive period was prolonged, and the average and maximum fecundity of larvae were both increased. Net reproductive rate (R₀) of three consecutive generations of green pea aphid was increased and generation time (T) prolonged, while intrinsic rate of increase (r_m) and finite rate of increase (λ) were decreased. The population of green pea aphid declined under elevated CO₂ conditions. Hence, elevated CO₂ may have negative effects on green pea aphid population numbers.

Physiological response of new strains of Festuca arundinacea mutated in space under high temperature stress and comprehensively evaluated

LI Juan, LEI Xia, ZHONG Li, WANG Xiao-Li, YANG Chun-Yan, WU Jia-Hai

2017, 26(3):  121-131.  DOI: 10.11686/cyxb2016157

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The influence of high temperature stress on the eco-physiological characteristics of 11 Festuca arundinacea was studied in a pot experiment for 4 days. Physiological and biochemical indexes, including soluble protein content, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity, were measured and analyzed. Subordinate function and grey correlative analyses were used to comprehensively evaluate the 11 F. arundinacea materials under high temperature stress. The results showed that the content of soluble protein decreased, while SOD, POD and CAT contents showed an upward trend. The high temperature resistance of the 11 F. arundinacea was obtained by subordinate function. The resistance order is: SP5-85>SP5-60>SP5-71>SP5-42>SP5-94>SP5-7>SP5-88>F. arundinacea cv Shuicheng>SP5-5>SP5-89=F. arundinacea cv Qiancao No.1. The high resistance correlative order obtained by grey correlative analysis is SOD>CAT>POD>content of soluble protein.

Physiological response of Amorpha fruiticosa to drought stress under paclobutrazol application and an evaluation of drought resistance

FAN Zhi-Xia, LI Shao-Cai, SUN Hai-Long

2017, 26(3):  132-141.  DOI: 10.11686/cyxb2016138

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A study has been undertaken to investigate the response of Amorpha fruiticosa to drought stress under different paclobutrazol applications. Physiological parameters, including peroxidase (POD) activity, the contents of malondialdehyde (MDA), soluble protein, soluble sugar and chlorophyll, and the ability of leaves to conserve water, were measured using pot experiments with six levels of paclobutrazol application (0, 10, 50, 100, 150 and 200 mg/L, represented by D₀, D₁, D₂, D₃, D₄ and D₅ respectively). Drought resistance was investigated using subordinate function analysis. With increasing drought stress, POD activity, MDA content and the rate of leaf water loss increased while soluble protein content decreased. Chlorophyll content increased except under D₀ and soluble sugar content increased overall. Under mild and severe drought stress, POD activity under D₅ was highest, MDA contents under D₂ and D₃ were lowest, and the contents of soluble protein, chlorophyll, soluble sugar and leaf water conservation ability under D₄ were greatest. The order of drought resistance was D₄>D₅>D₃>D₂>D₁>D₀, suggesting that the resistance of A. fruiticosa is elevated by paclobutrazol application and that D₄ is the optimum application level. Grey correlation analysis showed that soluble protein, chlorophyll and soluble sugar were closely correlated with drought resistance under paclobutrazol application, suggesting that they could be key indicators in evaluating resistance under such applications. This study provides references for the utilization of paclobutrazol applications for rock slope protection with plantings of A. fruiticosa.

Effect of lead stress on the chlorophyll fluorescence characteristics and antioxidative enzyme activities of Paspalum notatum

HOU Xiao-Long, CAI Li-Ping, HAN Hang, ZHOU Chui-Fan, WANG Guo, LIU Ai-Qin

2017, 26(3):  142-148.  DOI: 10.11686/cyxb2016159

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Paspalum notatum is considered one of the best grass species for controlling soil and water loss in south China. To test the feasibility of P. notatum as a restoration plant in mining wasteland, a pot experiment was undertaken with various concentrations of lead (Pb) (150, 250, 500, 1000, 1500 and 2500 mg/kg). Chlorophyll fluorescence, SPAD value, chlorophyll content, antioxidative enzyme activities and malondialdehyde content were measured to investigate physiological responses to Pb stress. The inhibitory effect of Pb stress on chlorophyll fluorescence was observed at the early stage (August), while significant promotion was found at later stages (September and October). Pb stress inhibited the SPAD value of chlorophyll and the chlorophyll content of P. notatum, but no significant differences from the control were observed. Pb stress promoted the activities of peroxidase and superoxide dismutase, but showed little effect on catalase activity. Malondialdehyde content of P. notatum increased under Pb stress, but there were no significant differences from the control at higher Pb concentrations. These results demonstrate that Pb stress inhibits some physiological characteristics in P. notatum and that the antioxidant system and chlorophyll fluorescence may play important roles in alleviating Pb toxicity.

Effects of different patterns of fertilization and mulching on the post-anthesis dry matter remobilization, sugar metabolism and grain yield of winter wheat in dry lands

ZHANG Li-Jun, LU Qing-Lin, BAI Yu-Long, ZHOU Gang, WANG Heng-Xing, ZHOU Jie

2017, 26(3):  149-160.  DOI: 10.11686/cyxb2016194

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To study the effects on winter wheat of different combinations of fertilizer, manure and mulching on the dynamics of dry matter accumulation and remobilization, water-soluble sugar content (WSC), sucrose sugar content (SSC) and seed yield, a field experiment was carried out during 2012-2015 at the Qingshui Experimental Station of the Gansu Academy of Agricultural Science (located in a typical semi-arid and rain-fed farming area). Different combinations of fertilizer (chemical+manure) and mulching were applied. Compared to T₁ (no fertilizer, control), grain yield under the other treatments increased in the following order: high level of chemical fertilizer combined with manure (T₆)>equal application of chemical fertilizer and manure (T₄)>high application of chemical fertilizer with plastic mulching (T₅)>equal application of chemical fertilizer with plastic mulching (T₃)>conventional application of chemical fertilizer (T₂)>T₁. Manure application increased post-anthesis accumulation of dry matter, dry matter remobilization rate, contribution rate to grain filling, grain weight per seed and spike number per square meter, thus increasing the grain yield. Compared to T₁, T₆ and T₄ resulted in yield increases of 119.22% and 118.24% respectively. Plastic mulching (T₃, T₅) increased post-anthesis accumulation of dry matter in the leaf, stem, sheath and glume, and grain number per spike, setting the foundation for yield improvement. However, plastic mulching also decreased the remobilization rate of dry matter and its contribution rate to grain filling. Nitrogen fertilizer application (T₃-T₆) increased the accumulation of dry matter in leaves, but excessive levels were detrimental to grain weight and decreased the remobilization rate and contribution rate to grain filling. Different combinations of fertilizer+mulching (T₂-T₆) decreased the water-soluble sugar content (WSC) and sucrose sugar content (SSC) of different vegetative organs during the mid-early period of filling (from 10 to 20 d after anthesis) and delayed the decrease in WSC and SSC in the leaf and sheath. The sharpest decrease in WSC and SSC in the leaf, stem, sheath and glume occurred from 30 to 40 d after anthesis, while in seeds it occurred from 10 to 20 d after anthesis. The yield, plant height, spike number per unit area, spike length and flag leaf area were significantly and negatively correlated with WSC and SSC in the leaf, stem and sheath from 10 to 20 d after anthesis. In the semi-arid and rain-fed farming area of Gansu, optimal application of nitrogen and phosphorus fertilizers, combined with manure application, is capable of achieving the same increase in yield achieved with plastic mulching and is a more sustainable way to produce wheat in dry lands.

Comprehensive evaluation of production performance and nutritional value of 20 alfalfa cultivars in two ecological areas of Gansu province

SUN Wan-Bin, MA Hui-Ling, HOU Xiang-Yang, MU Huai-Bin

2017, 26(3):  161-174.  DOI: 10.11686/cyxb2016141

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Twenty alfalfa (Medicago sativa) varieties were used as research materials in Huangyang and Yongdeng. The hay yield, plant height, stem/leaf and fresh/dry ratios, crude protein, acid detergent fiber, neutral detergent fiber, crude ash and ether extract content of the early bloom alfalfa were measured in two consecutive years, and comprehensive evaluations were conducted using grey relational analysis. The results showed that the hay yields of M. sativa cv Alfaqueen was the highest in both Huangyang and Yongdeng at 8.15 and 7.78 t/ha respectively. In Huangyang, M. sativa cv Gannong No.4 showed the highest plant height (102.44 cm), while in Yongdeng M. sativa cv AC Caribou was the highest (96.44 cm). In Huangyang, M. sativa cv Longdong had the highest crude protein (18.08%), but in Yongdeng M. sativa cv Longzhong showed the most crude protein content (17.91%). M. sativa cv Alfaking had the lowest acid detergent fiber content in Huangyang (31.19%), while in Yongdeng and M. sativa cv Sun-god, M. sativa cv Pltao tied for the lowest scores (33.99%). In Huangyang, neutral detergent fiber content of M. sativa cv Alfaking was the lowest (39.08%), while M. sativa cv Polaris was the lowest in Yongdeng (42.96%). The evaluation results showed that M. sativa cv Alfaking, M. sativa cv Gannong No.4, M. sativa cv Longdong, and M. sativa cv Polaris performed excellently in the Huangyang, while M. sativa cv Pltao, M. sativa cv Alfaqueen, M. sativa cv Alfaking and M. sativa cv Polaris performed excellently in Yongdeng. The use of these varieties deserves extension in each of these areas.

Comparison of ten corn varieties as silage material in Guangzhou

SHI Qing-Ping, XU Zhao-Hong, ZHANG Jian-Guo

2017, 26(3):  175-182.  DOI: 10.11686/cyxb2016155

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In order to select the best corn variety for silage material, ten candidates have been studied: Jingke Silage 301, Nongda 108, Gandan 2, Dafeng 3, Yihuang Dan 4, Yayu 8, Xianyu 335, Zhengdan 958, Yayu 26 and Huayu 8 (control). The corn was planted in the Zengcheng Experimental Field of South China Agricultural University and their dry matter yield, nutrient composition and silage fermentation quality were evaluated at the dough stage. Results were as follows: 1) There were significant differences in dry matter yield (P<0.05) and digestibility (P<0.01) among the varieties. All the tested varieties scored higher than the control (Huayu 8), with Yayu 8 having the highest dry matter yield (14.30 t/ha) and Jingke Silage 301 the highest dry matter digestibility (78.15%). The relative feeding value (RFV) of the varieties showed significant differences (P<0.05). The RFV of Jingke Silage 301 was 123.52, 17.90% higher than the control (P<0.05), while the scores for Zhengdan 958, Gandan 2, Xianyu 335, Yayu 8 and Nongda 108 were higher than the control. 2) The dry matter (DM), crude ash and nitrogen-free extract (NFE) contents also presented significant differences (P<0.05). The DM contents of the tested varieties were higher than the control, with Yayu 26, Dafeng 3, and Yayu 8 up to 40% higher. Yayu 26, Dafeng 3, Nongda 108 and Yayu 8 had higher NFE contents than the control (65.31%, 63.94%, 63.38% and 62.17% respectively). There were no significant differences between the varieties for crude protein, crude fat and crude fiber contents (P>0.05). 3) The amounts of lactic acid bacteria and fungi on plants were significantly different among the varieties (P<0.05). Lactic acid bacteria on Zhengdan 958 exceeded 10⁶ cfu/g of fresh matter (FM), higher than the other varieties. 4) There were significant differences in silage pH values, lactic acid and propionic acid contents among the varieties (P<0.05). Huayu 8 (control) had the lowest pH value (3.63) and the highest content of lactic acid (9.16% DM), while Yayu 8 had the highest pH value (4.22). There were no significant differences in butyric acid content between the varieties (P>0.05). Butyric acid was not detected in the silage of Zhengdan 958 and Yayu 8. NH₃-N contents were significantly different among the varieties (P<0.01), with Yayu 8, Zhengdan 958 and Dafeng 3 8.81%, 10.04% and 10.61% lower than the control. Based upon yield, nutrition composition and silage fermentation quality, Yayu 8 is the best variety for planting in the Guangzhou area as an ensiling material.

Effects of seeding rate and variety on branch number and plant height of alfalfa

WANG Yan-Hua, LI De-Feng, QI Sheng-Li, WANG Cheng-Zhang, GAO Yong-Ge, ZHENG Chun-Lei, LI Peng-Fei

2017, 26(3):  183-190.  DOI: 10.11686/cyxb2016426

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In order to explore the effects of the seeding rate and alfalfa varieties on the branch number and plant height, we carried out a field experiment comprising a split plot design with 3 seeding rates (15.0, 22.5, 30.0 kg/ha) as the main plots and 8 alfalfa varieties with different fall dormant classes as subplots in 2012-2014 (Concept, WL-319HQ, Adrenalin, WL-343HQ, WL-363HQ, Icon, WL-525HQ, WL-903HQ). The results indicated: 1) Seeding rate had no significant effects on the primary and secondary branch number in alfalfa, and the primary and secondary branch number differences among varieties also were not significant. With increase in stand age, the primary and secondary branch number of all varieties increased (planted in 2012>2013>2014). 2) Average branch number of different varieties did not differ significantly between 2012 and 2013, but in both cases was higher than that of 2014-sown plants. 3) Seeding rate and stand age did influence plant height. With increase in seeding rate from 15.0 to 30.0 kg/ha, plant heights of most varieties were gradually decreased, but branch number was unchanged. Plant height was greater for 2013-sown plants, than for those sown in 2012 and in 2014.

Developing an agro-grassland think tank system to assist agricultural structure transformation in China

REN Ji-Zhou, MA Zhi-Fen, LIANG Tian-Gang, WU Jian-Ping, LI Fa-Di, LIN Hui-Long, HOU Fu-Jiang, FENG Qi-Sheng, XU-Gang

2017, 26(3):  191-198.  DOI: 10.11686/cyxb2016160

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Agro-grassland is a new agricultural system that gives consideration to ecological and production systems, food and forage. It allows integration with the global economy and adaptation to development. Agro-grassland helps to meet the development of the urban and rural areas, to resolve the traditional agricultural development problems in China, and it will be a milestone on optimizing the agricultural structure. The agro-grassland system was developed in order to implement the party’s “decision” in the Third Plenary Session of the 18th Central Committee of the China Central Committee, which proposed “to strengthen the construction of new think-tank with Chinese characteristics, to establish and improve the system of decision-making consultation”. This paper outlines a concept for building the proposed think-tank information system based on new cloud computing technology, so as to consolidate the existing research results, combine research resources, promote timely information collection and analysis, to make this the “nervous system” of the Agro-grassland concept. A strength will be the sharing of information. The Agro-grassland think tank should be independent, scientific, timely and effective, and be an intelligence platform to provide services for the front-line production enterprises, research institutes and government agencies. It will provide the technology support for the development of Agro-grassland system practice, facilitating structural transformation of Chinese agriculture from the traditional grain-based agriculture to the Agro-grassland system with consideration of both food and forage production in China.

Application of exogenous enzymes in ruminant nutrition

WANG Hong-Mei, TU Yan, ZHANG Nai-Feng, SI Bing-Wen, MA Tao, SA Ru-La, NA Ya, DIAO Qi-Yu

2017, 26(3):  199-213.  DOI: 10.11686/cyxb2016262

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Digestion of cell wall fractions of fiber in the rumen is incomplete due to its resistance to microbial degradation. The ability to effectively utilise forage with high fiber content is important for the development of efficient animal husbandry systems. Exogenous enzymes able to modify forages before feeding are of considerable interest to researchers; important potential benefits include improved environmental outcomes. In situ assessment and in vitro gas production were used to evaluate rumen degradation characteristics and in vitro fermentation characteristics of forage. An in vivo study was used to evaluate the effects of exogenous enzyme application to ruminant forage. Recent studies have shown that adding exogenous enzymes to ruminant diets can increase animal production as a result of enhanced digestion of feed, although results have been inconsistent. This inconsistency is due to range of factors including enzyme properties, diet composition, enzyme addition rates, animal species and animal growth performance. One of the main problems for researchers is the lack of adequate biochemical characterization of different enzymes which leads to a poor understanding of their mode of action and effectiveness. The biochemical characteristics of enzymes are very important but enzymes are not always evaluated prior to use and there are no global standards for assessing the activity and quality of enzymes. This paper reviews the research on the development of exogenous fibrolytic enzyme use in animal production, mechanisms of activity on plant cell walls, animal responses, the factors influencing the use of exogenous enzymes in ruminant nutrition and problems associated with their use. The aim of the review is to help the development of improved, safer and more consistent enzyme additives for use in ruminant nutrition.

Research progress in water uptake models by plant roots

WANG Yu-Yang, CHEN Ya-Peng

2017, 26(3):  214-225.  DOI: 10.11686/cyxb2016146

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The uptake of water by roots is the beginning of water transport within a plant, with such uptake directly controlling the amount of water available for transporting and, as a result, strongly affecting the life of the plant. Research on this uptake is thus not only a key to understanding the process of water transfer in the soil-plant-atmosphere continuum, but also an important topic for interdisciplinary research in such areas as hydrology, climate, soil, agriculture and ecology. Models for root uptake of water provide a numerical tool for quantitatively understanding this plant process. The establishment of a suitable model will provide not only a basic tool for estimating the amount of water absorbed but will also help to discover the water sources and requirements of plants. It can thus assist the development of effective agricultural water management programs, with far-reaching significance for restoring vegetation in extremely arid regions. In this paper, we review the development of models for root uptake of water, sum up the mechanisms identified and classify the models into different types at macroscopic and microscopic scales. We analyze the macroscopic models in detail, including Ohm’s law model, Feddes model, Transpiration segment model, Hybrid model, Compensatory root uptake water model and the Matric flux potential model, which are widely used in practical experiments. We illustrate the application range and discuss the limitations of existing models. We conclude with three suggestions for future research: 1) the establishment of dynamic models for root uptake of water, 2) the combination of microscopic and macroscopic models, and 3) the development of models for trees and herbages.

Reproduction output of seed-heteromorphic Atriplex micrantha

MA He, WEI Yan

2017, 26(3):  226-232.  DOI: 10.11686/cyxb2016143

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Atriplex micrantha, an important wild forage germplasm resource in desert regions, has seed dimorphism. It has two types of seeds that are different in shape, size, color and the size of bracts attached to fruits. Small, black seeds with a glossy, smooth testa are covered by extended bracteoles. Brown seeds are relatively larger and covered by bigger, extended bracteoles. Study of the germination phenology and reproduction output from heteromorphic seeds has significant value for understanding mechanisms of adaptation to habitat and the evolution of plant life-history strategies. In the reproduction output study, we selected 3 different micro-habitats (abrupt slope, gentle slope and base of slope) in a low mountain, gravel desert population of Junggar and randomly selected 10 plants of A. micrantha in each habitat to measure plant height, seed output scale and biomass allocation. The results showed: 1) There were significant differences in the sizes of individual plants growing in different micro-habitats. Plants growing at the base of slope were biggest, those in the abrupt slope smallest. 2) The total reproductive allocation and the reproductive allocation of brown and black seeds significantly increased with the increasing size of the individual parent plant. The reproductive allocation of big plants was 57.57%, with the reproductive investment of brown seeds equal to that of black seeds. The main reproductive investment of medium and small sized plants was to the black seeds, with their reproductive allocation less than 30%. 3) With the increase of parent plant size, both the number and the ratio of black seeds outputted by the three plant height grades were significantly higher than those of brown seeds. The ratio of black seeds to brown seeds was 2.16-7.41∶1. The flexible reproductive output of heteromorphic seeds evidence how A. micrantha adapts to harsh desert environments.