Table of Content

20 November 2018, Volume 27 Issue 11

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Orginal Article

Effects of utilization patterns on the carbon sequestration capacity of warm-temperate tussock and shrub-tussock grasslands

ZHAO Wei, LI Lin

2018, 27(11):  1-14.  DOI: 10.11686/cyxb2018229

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Differences in utilization patterns affect the carbon cycle of grassland ecosystems. Evaluating the carbon sequestration capacity of grassland ecosystems under different utilization patterns will help to establish relevant ecological management strategies, and so have practical significance for mitigating greenhouse gas emissions from grasslands. Based on a field survey and laboratory tests, the carbon sequestration capacity of two typical grassland types (WT: warm temperate tussock, and WS: warm temperate shrub-tussock) under four utilization patterns (FUG: fenced and unexploited grassland, SMG: scattered grazing+mown grassland, SGG: seasonally grazed grassland and AGG: all-year-grazed grassland) in Henan Province were studied. The results indicated that no difference was found in the vegetation biomass of WT (P>0.05). However, the vegetation biomass of WS under SMG was significantly greater than that of FUG and AGG (P<0.05). Under FUG, the vegetation biomass of WT was significantly greater than that of WS (P<0.05). No significant difference existed in the underground and root carbon density between WT and WS (P>0.05). With respect to the carbon density of vegetation (shoot+root), the management regimes ranked: FUG>SMG>AGG>SGG (2187.93-4211.56 g C·m^-2) in WT. However, the soil carbon density of WT under SGG (13369.07 g C·m^-2) was significantly greater than that of FUG (2544.25 g C·m^-2) (P<0.05). For WS, the root carbon storage was no significant difference among them (P>0.05). For all utilization patterns, the root system was the major contributor to vegetation carbon density in both WT (87.42%) and WS (81.52%). With respect to the carbon density of the total grassland ecosystem, soil C (excluding roots), accounted for 91.72% and 84.98% of total C in WT and WS, respectively. Hence, soil carbon density was the major factor determining carbon sequestration capacity of both types of grassland, under all utilization patterns. This study provides scientific data to assist with rational allocation of grassland resources and for accurate assessment of carbon sequestration capacity of Henan grasslands.

Characterization of readily oxidizable carbon and dissolved organic carbon within the soil carbon pool during desertification of grassland in central China

YAN Xin, LIU Ren-tao, AN Hui

2018, 27(11):  15-25.  DOI: 10.11686/cyxb2017529

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The readily oxidizable carbon (ROC) and dissolved organic carbon (DOC) are important indicators of transformation status of soil organic carbon in areas undergoing land use change. However, there is no consensus as to which indicator is best suited for assessing change in soil organic carbon status during desertification of grassland in arid and semiarid regions. The content and proportion of ROC and DOC, an index called here the carbon management indicator (CMI) and sensitivity indices based either on DOC or ROC data were compared. ROC and DOC decreased gradually during the grassland desertification process. Grasslands had the highest values for ROC and DOC, while semi-fixed dunes had the lowest values. With increasing desertification of the arid grassland under study, CMI values calculated from ROC data initially decreased and then increased, while the CMI calculated from DOC data steady decreased. There was a significant positive correlation between ROC, DOC and soil organic carbon, and the correlation coefficient between DOC and soil organic carbon was higher than that between ROC and soil organic carbon. In the transition from grasslands to fixed dunes, sensitivity indices of carbon activity and of the carbon pool calculated using ROC data were more sensitive than those using DOC data. However, in the transition from fixed dunes to mobile dunes, the two sensitivity indices were more sensitive when derived from DOC data, than when derived from ROC. Hence, ROC data is more suitable for evaluation of grassland status during the early stage of desertification in arid grassland, while DOC is a better indicator of change in soil organic carbon status in the middle and later stages of desertification in the grassland studied.

The interaction effects of vegetation and soil nutrients on vegetation succession in abandoned farmland on the Loess Plateau

WANG Chun-yan, YAN Xia, GU Meng-he

2018, 27(11):  26-35.  DOI: 10.11686/cyxb2017507

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The interaction effects between vegetation and soil are highly significant for vegetation restoration and reconstruction during the succession of abandoned farmland. We chose four kinds of abandoned farmland in the Loess Plateau (1, 6, 12, and 22 yr) to investigate species richness and aboveground biomass. We also determined soil bulk density, pH value, soil organic matter and soil total nitrogen in the 0-60 cm layer. We analyzed species variation processes and trends in aboveground biomass, soil organic matter and soil total nitrogen, as well as the interaction effect between vegetation and soil during the succession stages. Species richness showed an increasing-decreasing-increasing trend and soil bulk density showed a decreasing trend at first, then tended to stabilize during the succession stages. Soil organic matter and soil total nitrogen were significantly different in the soil layers of the 4 kinds of abandoned farmland, and they showed obvious gathering effects at the soil surface. Abandonment time was negatively correlated with soil organic matter and soil total nitrogen. Soil organic matter and soil total nitrogen indicated obvious time effects during the succession stages. Aboveground biomass was significantly correlated with abandonment time, soil organic matter and soil total nitrogen. The results showed that soil organic matter and soil total nitrogen have negative effects on aboveground biomass and that abandonment time has positive effects on aboveground biomass during the succession of abandoned farmland.

Effects of grazing on photosynthetic characteristics of Leymus chinensis in meadow steppe of Inner Mongolia, China

ZHANG Zi-he, GONG Ji-rui, YAN Xin, HUANG Yong-mei, AN Ran, QI Yu, ZHANG Zi-yu, LIU Min

2018, 27(11):  36-48.  DOI: 10.11686/cyxb2017516

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In a study of grazed and ungrazed (fenced) plots in meadow steppe grassland located at Hulun Buir, Inner Mongolia, we investigated the diurnal pattern of ecophysiological behavior in Leymus chinensis, including water relations, gas exchange characteristics, light interception, osmotic adjustment and osmolytes, L. chinensis was sensitive to water deficit and able to cope with grazing disturbance by decreasing transpiration rate (T_r) and increasing water use efficiency (WUE). In response to grazing disturbance, L. chinensis showed a range of adaptations, including increased chlorophyll content, increased activity of Φ_PSⅡ and Rubisco, increased tissue concentrations of nitrogen and phosphorus, increased photosynthetic utilization efficiency (PNUE, PPUE) and assimilate accumulation, and changed electron flow (ETR). Photosynthetic rate (P_n) in both grazed and fenced plots displayed a mid-day depression, attributable to a combination of stomatal and nonstomatal factors. Similarly, the maximum photochemical quantum yield (F_v/F_m) of PSⅡ in both grazed and fenced plots showed photoinhibition. L. chinensis in grazed plots displayed increased non-photochemical quenching (NPQ) and photochemical quenching (qP) with diurnal fluctuation linked to light stress. From these results it is deduced that L. chinensis in grazed plots could absorb more light energy in the photosynthetic reaction center, and respond more rapidly and sensitively. Thus, moderate grazing disturbance can promote growth of L. chinensis and maintain a higher productivity in meadow steppe grassland, than in ungrazed grassland. These findings therefore provide a scientific basis for planning productivity restoration in meadow steppe grassland in Inner Mongolia.

Whole genome identification and comparative analysis of old prokaryotic genes in Glycine max and Lotus corniculatus

WEI Xing-yi, LI Yu, LIU Wen-xian, JIN Xiao-yu, MIN Xue-yang, ZHANG Zheng-she, Ndayambaza Boniface, WANG Yan-rong

2018, 27(11):  49-57.  DOI: 10.11686/cyxb2017521

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Eukaryotes have acquired a large number of genes from prokaryotes during their evolution. The identification and analysis of these genes can provide a theoretical basis for study of the systematic evolution of higher plants. In order to further investigate the significance old prokaryotic genes during the evolution of Glycine max and Lotus corniculatus, the old prokaryotic genes in these two species’ genomes were comprehensively identified using bioinformatics methods and the functions and relations of these genes were further analyzed. Our results suggest that the number of old prokaryotic genes is higher in G. max (40.6%) than in L. corniculatus (33.9%). The largest fractions of these protein-encoding genes were found to be localized in endo-symbiotic organelles, such as mitochondria and chloroplasts.Similar distributions of the domain architecture of old prokaryotic proteins were found in both G. max and L. corniculatus genomes, revealing that they may share high collinearity and conservation during evolution.Based on Gene Ontology (GO) functional classifications, we found that the old prokaryotic proteins were mainly distributed in membrane, cell, and cell parts. In terms of molecular function, the old prokaryotic proteins mainly participated in metabolic and developmental processes in G. max, which may have been caused by human selection pressure for better agronomic productivity.In terms of biological processes, the old prokaryotic proteins mainly participated in catalytic reactions and binding reactions, indicating that they may play a role as enzymes. Using comparative analysis, our work has indicated a distinctive pattern in the evolution of old prokaryotic proteins in G. max and L. corniculatus, with the results suggesting a theoretical basis for the genomic analysis of other leguminous plants.

The identification and expression analysis of genes related to seed germination in Leymus chinensis

LIU Shu, LIU Pan-pan, YANG Wei-guang, QI Dong-mei, LI Xiao-xia, LIU Gong-she

2018, 27(11):  58-66.  DOI: 10.11686/cyxb2017502

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Previous studies have suggested that the variable temperature (28 ℃ 12 h/16 ℃ 12 h) can significantly increase the germination rate of Leymus chinensis seed, and that the first day of germination was key for responses to variable temperature. A transcriptome analysis of L. chinensis seed germination under variable temperature treatment was performed. Based on sequencing, 24 genes related to seed germination, low temperature and dormancy were selected for heat map analysis using the reads per kilo base per million mapped reads (RPKM) value. In addition, under the treatment of constant temperature (28 ℃) for 12 h and variable temperature (28 ℃ 12 h/16 ℃ 12 h) for 1 d, the relative expression of the selected genes in two L. chinensis genotypes (high and low germination rate) were quantified by qRT-PCR. Our results indicated that the expression of SAIN1, PP2C62, EXPB3, EXPB4, GA3ox, EXPA2 and EXPA7 were significantly up-regulated in the seeds treated at 16 ℃ for 12 h, while the expression of bHLH49, GID1, ABI8, Chi1, 11833, CBF3, NAC2, PP2C72, SAIN2 and 5423 were significantly down-regulated, compared with the constant temperature (28 ℃) control. Further analysis of the gene expression in the two genotypes suggested that Chi1, CBF3, GA3ox, EXPB4, 5423 and SAIN1 were the putative genes related to germination in L. chinensis.This research may lay the foundation for further studies on the molecular mechanisms in seed germination of L. chinensis.

QTL analysis of nine biomass-related traits in tetraploid orchardgrass using ultra-high-density genetic mapping

TANG Lu, HUANG Lin-kai, ZHAO Xin-xin, ZHANG Xu, NIE Gang, ZHANG Xin-quan, MA Xiao

2018, 27(11):  67-76.  DOI: 10.11686/cyxb2017506

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We have identified the QTLs(quantitative trait locus) of biomass-related traits in tetraploid orchardgrass in order to improve selection efficiency for good yield genotypes and to provide a basis for molecular-assisted breeding. The test materials used were a hybrid offspring population consisting of 214 individuals from a cross of two cultivars, ‘Kaimo’ (female parent) and ‘01436’ (male parent). In 2014, phenotypic identification and correlation analyses were carried out on nine biomass-related traits in two different habitats, Hongya and Baoxing. Based on the integrated map, the QTLs of nine biomass-related traits were analyzed using MapQTL 5.0: plant height (PH), flag leaf length (FLL), second leaf length (SLL), flag leaf width (FLW), secondleaf width (SLW), stem diameter (SD), inflorescence length (IL), tiller number (TN) and dry weight per plant (DW). Results indicated that most of the traits showed significant differences between parents and followed the normal distribution of continuous variation among populations, conforming with the hereditary characteristics of quantitative traits. Correlation analysis showed that most of the traits were significantly positively correlated with dry weight. The highest correlation with plant dry weight was tiller and plant height. A total of 60 QTLs were identified and distributed into 5 linkage groups (except for LG6 and LG7), with genetic contribution ranging from 5.7%-24.7%. For all of the 60 QTLs, the numbers for controlling plant height, flag leaf length, second leaf length, flag leaf width, second leaf width, stem diameter, inflorescence length, tiller number and dry weight per plant were 12, 15, 4, 2, 2, 4, 12, 3 and 6 respectively.

Research on genetic and phenotypic differences of Pennisetum purpureum mutants generated by irradiation

WU Bing-chao, ZHANG Huan, TONG Lei, DU Zhao-chang, HU Jia-ling, CHEN Yi, ZHANG Xin-quan, LIU Wei, HUANG Lin-kai

2018, 27(11):  77-86.  DOI: 10.11686/cyxb2018006

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In order to provide a theoretical basis for mutation-induced breeding of Pennisetum purpureum, stems of P. purpureum were irradiated with ⁶⁰Co-γ rays at differing doses of 10, 20 and 30 Gy. Then, we screened the resulting mutants and defined their phenotypic variation, and identified the genetic differences at a molecular level, using SSR. The irradiated plants showed a tendency to dwarfism. The number of tillers, stems and the length of leaves were the traits most sensitive to radiation and most easily mutated. Among all the mutants, two designated F30-39 and F30-41 were significantly shortened plants, and were determined by cluster analysis to belong to a group which had the greatest genetic difference from the control material. The genetic similarity coefficient between controls and “30 Gy” mutants ranged from 0.3793 to 0.9655, with the average being 0.8276, while the number of mutation sites ranged between 4 and 66, with an average of 19.3. Both indices were greater than those of “10 and 20 Gy” mutants. Considering the survival rate and genetic mutation frequency of irradiated plants, 30 Gy was selected as the most suitable radiation dose level for mutagenesis.

Effects of kinetin on telomerase activity and physiological characteristics of Elymus sibiricus seedings under salt stress

SUN Shou-jiang, SHI Shang-li, WU Zhao-lin, HE Li-juan, JIN Xin, QI Juan

2018, 27(11):  87-94.  DOI: 10.11686/cyxb2018250

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A study has been undertaken to investigate the effects of kinetin on the telomerase activity and physiological characteristics of wild Elymus sibiricus seedlings under different levels of salt stress in order to provide a scientific basis for agricultural production in areas with severe soil salinization and the improvement of artificial grassland. Wild E. sibiricus were collected from Qinghai-Tibet Plateau alpine grassland in 2015 and used as test material in sand culture experiments. When the third leaf of the seedlings extracted and unfolded, the seedlings were treated with sodium chloride (NaCl) solution at different concentration levels (0, 50, 100, 150, 200 mmol·L^-1) for 168 hours. The seedlings’ leaves were then sprayed with kinetin solutions of different concentrations (0, 5, 10, 20, 30 mg·L^-1) for 240 hours and measurements taken of telomerase activity and physiological parameters: chlorophyll, free proline (Pro), malondialdehyde (MDA), soluble sugar (SS), and soluble protein (SP) content. The results showed that with the increase of salt stress, telomerase activity firstly increased and then decreased, peaking under the 50 mmol·L^-1 NaCl treatment. When NaCl concentrations were higher than 50 mmol·L^-1, telomerase activity decreased and the content of free proline, soluble sugar and soluble protein increased with increasing salt stress, among which the SS increment (101.5%) of seedlings under 250 mmol·L^-1 NaCl was significantly different from that of the control (P<0.05). Following spraying with 10 mg·L^-1 kinetin, the MDA content of seedlings treated with 0 mmol·L^-1 NaCl decreased by 64.9%. High concentrations of kinetin can significantly relieve the salt stress of seedlings (P<0.05), with chlorophyll content (under 250 mmol·L^-1 NaCl stress) and SS content (under 100 mmol·L^-1 NaCl stress) increasing by 17.3% and 165.6% respectively after spraying with 20 mg·L^-1 kinetin.These results indicate that exogenous kinetin alleviates salt stress to some extent. Suitable NaCl concentrations induced telomerase activity, whereas high concentrations of NaCl stress may cause oxidative damage to E. sibiricus cells and result in decreased telomerase activity.

Responses of photosynthetic physiological traits in transgenic alfalfa expressing multi-functional genes during soil moisture change

LI Min, SU Guo-xia, XIONG Pei-feng, KANG Ji-yue, KWAK Sang-soo, WANG Zhi, XU Bing-cheng

2018, 27(11):  95-105.  DOI: 10.11686/cyxb2017504

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The photosynthetic and fluorescence characteristics of alfalfa (cv. Xinjiang Daye) and four transgenic lines (SN: transgenic AtNDPK2, SC: transgenic codA, SOR: transgenic IbOr, SAF: transgenic AtABF3) at the early flowering stage were investigated and compared under different soil moisture conditions in a pot experiment. Results showed that the net photosynthetic rate (P_n), transpiration rate (T_r) and stomatal conductance (G_s) of all lines showed a decreasing trendas soil moisture decreased from 80% FC (field capacity) to 40% FC, while instantaneous water use efficiency (WUE_i) exhibited an increasing trend. At 40% FC, P_n values of transgenic lines were 11.19-21.58 μmol·m^-2·s^-1, significantly (P<0.05) higher than that of non-transgenic (NT) plants (6.06 μmol·m^-2·s^-1). There were no differences in WUE_i among all alfalfa lines and the SAF line had the highest value (3.22 μmol·mmol^-1). As soil moisture decreased, the initial fluorescence (F_o), maximum photochemical efficiency (F_v/F_m) and photochemical quenching coefficient (qP) values exhibited declining trends, and actual photochemical efficiency (Φ_PSⅡ) and apparent electron transfer efficiency (ETR) values initially increased and then declined, while non-photochemical quenching coefficient (NPQ) values showed an increasing trend.The qP values of transgenic lines decreased significantly at 50% FC, while that of NT was 70% FC. Under 40% FC, F_v/F_m values of transgenic lines were 0.78-0.82, and were significantly higher than that of NT (0.58). This suggests that the expression of multi-functional genes could improve photosynthetic properties of Xinjiang Daye to some extent and that transgenic codA is able to sustain a high photosynthetic rate, transgenic IbOr line can maintain higher light use ability, transgenic AtABF3 is able to utilize water more efficiently, while transgenic AtNDPK2 had the highest total biomass production with decreasing soil moisture.

Effect of low temperature stress on physiology and gene expression in Bermuda grass

SHU Bi-chao, YANG Yong, LIU Xue-yong, JIANG Yuan-li, XIANG Zuo-xiang, HU Long-xing

2018, 27(11):  106-119.  DOI: 10.11686/cyxb2018133

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In order to investigate the effects of low temperature stress on the plant growth rate, turf quality, MDA content, F_v/F_m, photosynthesis [P_n (net photosynthetic rate); G_s (stomatal conductance); C_i (intercellular CO₂ concentration); T_r (transpiration rate)], H₂O₂ and O2·- content, antioxidant enzyme activities (SOD, POD, CAT, APX), gene expression levels of antioxidant enzymes and cold-tolerance related genes (CBF1, COR, LEA), three Bermudagrass cultivars with differential cold tolerance, Tifsport, Tifway and Baoding Bermuda grass were selected and treated under a range of temperatures: optimum (30 ℃/25 ℃, day/night), suboptimum (18 ℃/12 ℃), chilling (8 ℃/4 ℃) and freezing (4 ℃/-4 ℃) in growth chambers. It was found that plant growth rate, turf quality, F_v/F_m and photosynthesis decreased while H₂O₂, MDA content and O2·- production rate increased with reduction in temperature, but the three cultivars varied in their response, with more rapid changes in the less cold-tolerant Baoding Bermuda grass. Leaf antioxidant enzyme activities were significantly increased with reduction in temperature, especially in the more cold-tolerant Tifsport. Similarly, the expression levels of CBF1, COR and LEA cold-tolerance genes were also significantly enhanced with decline in temperature, with Tifsport again exhibiting the greatest response. In summary, low temperature stress induced up-regulation of antioxidant enzyme genes and cold tolerance-related genes resulting in more active antioxidant defense systems, which in turn contributed to improved cell membrane stability, maintenance of higher photosynthesis levels and delay of chlorosis in Bermuda grass. These changes collectively were the basis for the higher cold tolerance.

Effects of composite exogenous hormone application on induction of systemic resistance to Rhizoctonia solani in creeping bentgrass

ZHAO Chun-xu, JIANG Han-yu, DONG Wen-ke, CHEN Hong, FANG Yan-xia, XIE Li-ping, MA Hui-ling

2018, 27(11):  120-130.  DOI: 10.11686/cyxb2018255

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Composite plant hormone formulations with different concentrations of epibrassinolide (EBR), salicylic acid (SA) and ethephon (ET) were applied exogenously to “Penn-A4” bentgrass with induction times of 5, 7, and 10 days to test if the hormone treatments could enhance disease resistance. The effect of the exogenous composite hormone application and induction time treatments on the brown spot resistance of creeping bentgrass was assessed by determining a disease index, the control efficacy, antioxidant enzyme activity and ascorbic acid/glutathione cycle changes. Some treatments did improve the disease resistance of creeping bentgrass. The disease index for an ET+EBR hormone treatment with 7 days induction was significantly lower than other treatments, and the anti-disease effect was quantified at 40.51%. Moreover, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities increased by 130.53%, 197.40% and 101.66%, respectively, while ascorbate peroxidase (APX), dehydroascorbate reduction (DHAR), and glutathione reductase (GR) activities increased by 316.26%, 41.95% and 80.34%, respectively, compared with the control, after this treatment. In addition, active deoxyascorbic acid (AsA), oxidized glutathione (GSH) content, and AsA/hydroascorbic acid (DHA), and GSH/reduced glutathione (GSSG) ratios were all higher for the ET+EBR combination, than for the control and other treatments. In summary, exogenous application of mixtures of EBR, SA and ET were able to induce brown spot resistance in creeping bentgrass, and an ET+EBR combination with an induction period of 7 days had the best effect. The results of this study provide technical information for the development and promotion of novel hormone-based agents for induction of plant disease resistance.

Arbuscular mycorrhizal fungi and Festuca elata can improve fertility of compacted soil

LI Wen-bin, NING Chu-han, XU Meng, LIU Run-jin, GUO Shao-xia

2018, 27(11):  131-141.  DOI: 10.11686/cyxb2018221

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The ability of arbuscular mycorrhizal fungi (AMF) to improve soil physical and chemical characteristics, regulate soil microorganism community and rehabilitate degraded soil were assessed. The recent development of urban construction and tourism, especially the increase in mobile suburban populations has resulted in compaction of suburban land soil resulting in negative effects on plant growth. The purpose of the present study was to evaluate the ability of AMF and Festuca elata to rehabilitate compacted soil. A greenhouse experiment was carried out with F. elata inoculated with either Funneliformis mosseae or Rhizophagus intraradices, or both, under different soil bulk densities; 1.2, 1.3, 1.4 and 1.5 g·cm^-3. The results showed that inoculation with both F. mosseae+R. intraradices incresed soil water content by 38%, porosity by 9%, soil fungi by 166%, of soil bacteria by 64%, soil actinocyces by 127%, available potassium by 123%, available phosphorus by 176%, invertase activity by 271%, urease activity by 249%, catalase activity by 98% and polyphenol oxidase activity by 268%. Extractable glomalin-related soil protein content and total glomalin-related soil protein content were 3.4 and 3.8 times higher than that of the control, respectively, and reduced soil compaction and pH by 9% and 7.6% respectively compared to the control when initial soil bulk density was 1.5 g·cm^-3. It was concluded that the F. mosseae+R. intraradices+tall fescue combination had the greatest effect on improving soil physical and chemical properties, soil microbe community, nutrient availability, increasing soil enzyme activity and glomalin content; this suggests that this treatment combination has good potential improvement of suburban garden soil.

Effects of dietry oregano oil on growth and carcass traits of Hexi cashmere goats

JIANG Hui, LEI Zhao-min, JIAO Ting, LIU Ting, WANG Jian-fu, LI Chong, TANG De-fu, ZHANG Jian-qiang

2018, 27(11):  142-149.  DOI: 10.11686/cyxb2018129

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Oregano oil can significantly improve growth and immunity in domestic animals.The purpose of this research was to study the effects on growth performance, slaughtering performance and carcass quality of Hexi cashmere goat by adding oregano oil to their diets. The control group was fed a basic diet, while in the trial groups, 4 and 7 g additives with oregano essential oil 52 and 91 mg respectively were added to the basal diet, respectively. Animals both in control and treatments groups were the same age and weight. Each treatment had 3 replicates each consisting 5 goats.The feeding period was 90 days with monitoring undertaken every 30 days. The results showed that the average daily gain of Hexi cashmere goats in control group, 4 g group and 7 g group was 96.30, 172.22 and 169.82 g·d^-1, respectively, with the control group being significantly less than those groups supplemented with oregano oil (P<0.05). The carcass weights were 20.24, 24.18 and 23.90 kg in control, 4 and 7 g groups respectively. The slaughter rate, carcass net meat weight and the marbling of the longissimus dorsi muscle of 4 g group and 7 g group were significantly higher than them of control (P<0.05), but there was no difference between the oregano treatments groups (P>0.05). There were no differences in meat pH, cooked meat rate, water loss rate, tenderness and loose on cooking between treatments (P>0.05). Adding oregano oil to the diet improved the growth of Hexi cashmere goats; the optimum level was 52 mg·goat^-1·d^-1.

Effects of biochar and arbuscular mycorrhizal fungi on soil nutrients and growth of Cassia occidentalis under heavy metal contamination

GUO Xiong-fei

2018, 27(11):  150-161.  DOI: 10.11686/cyxb2018230

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The effects of the interaction between biochar and arbuscular mycorrhizal fungi (AMF) under heavy metal stress on soil nutrients and growth of Cassia occidentalis were studied in a pot treatments. AMF had no effect on soil pH and nutrient content, whereas biochar significantly increased soil pH, organic matter, total nitrogen, total phosphorus, available phosphorus and available potassium, but had no effect on alkali hydrolysable nitrogen and total potassium. Biochar significantly increased the AMF infection rate, but iron modified biochar reduced AMF infection rate. AMF significantly increased a number of root morphological parameters. Under conventional biochar the total root length, root surface area, total projection area, root tip number and root fork number were increased, whereas the corresponding parameters decreased under the iron-modified biochar treatment; both biochar treatments reduced root volume and average root diameter. Compared with the control, AMF inoculation and conventional biochar treatments, all root morphological parameters were increased by the combination of AMF and biochar. AMF and biochar did not influence height, leaf length and leaf width of C. occidentalis in young plants but growth of C. occidentalis with inoculation was significantly higher than that of the non-inoculation treatment as growing period increased. Biochar treatments did not increase plant height, leaf length and leaf width, but biochar and AMF treatments did increase these traits. Shoot and root dry weights of C. occidentalis were associated with plant height. Overall, the interaction between biochar and AMF produced the greatest influence on soil pH, soil nutrients and root system, plant growth and dry matter accumulation.

Effects of S₃₃₀₇ and DTA-6 on the photosynthetic characteristics and yield of kidney bean plants in the reproductive stage

WANG Chang, ZHAO Hai-dong, FENG Nai-jie, ZHENG Dian-feng, LIANG Xiao-yan, QI De-qiang, LI Jian-ying, HAN Yi-qiang, HUANG Wen-ting

2018, 27(11):  162-170.  DOI: 10.11686/cyxb2017508

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A study has been undertaken to investigate the photosynthesis and yield mechanisms of two plant growth regulators in kidney beans. Using “Yingguohong” as test material, leaves at the early flowering stage were sprayed with of 50 mg·L^-1 uniconazole (S₃₃₀₇) and 50 mg·L^-1 diethyl aminoethyl hexanoate (DTA-6) in order to study the regulators’ effects on photosynthetic characteristics at the flowering, podding and grain-filling stages, as well as on plant yields. The results showed that: 1) Except for the slightly lower net photosynthetic rate of DTA-6 at the podding stage, both S₃₃₀₇ and DTA-6 increased the net photosynthetic rate, transpiration rate, stomatal conductance and leaf area index of kidney bean plants. 2) S₃₃₀₇ increased chlorophyll content during the podding to grain-filling stages, whereas DTA-6 reduced the rate of chlorophyll decomposition from the flowering to grain-filling stages. 3) S₃₃₀₇ and DTA-6 increased above-ground single plant biomass accumulation at different stages, with the effects of the two regulators being the most significant at the grain-filling stage. Compared with CK, single plant biomass accumulation of S₃₃₀₇ increased by 14.55% and 36.05% respectively. 4) S₃₃₀₇ and DTA-6 decreased the shoot-leaf partitioning rate from the flowering to grain-filling stages, significantly increased the pod distribution rate and promoted the transfer of assimilation material from “source (leaf)” to “sink (kernel)”. The pod distribution rate of S₃₃₀₇ was 2.24% higher than that of DTA-6 and the decrease rate of the leaf area index was larger. 5) S₃₃₀₇ significantly increased pod number, while DTA-6 significantly increased the pods per plant and grain weight per plant. S₃₃₀₇ and DTA-6 significantly increased yield by 4.30% and 10.16% respectively compared with the control. Comprehensive analysis showed that both S₃₃₀₇ and DTA-6 effectively improve photosynthesis during the reproductive stage of kidney beans, promote single plant biomass accumulation and the distribution of pods, and significantly increase yield, with the rate of increase for DTA-6 being higher than S₃₃₀₇.

Effects of brassinolide and N, P, K fertiliser on growth of Leymus chinensis under drought stress

SONG Ji-xuan, LÜ Jun, ZONG Xue-feng, HE Xiu-juan, XU Yu, WU Xiao, WANG San-gen

2018, 27(11):  171-178.  DOI: 10.11686/cyxb2017512

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Climate change is one of the main environmental factors with the potential to influence the productivity of Leymus chinensis. In this paper, potted plants were used to study the effects of brassinolide (BR) and nitrogen, phosphorus and potassium (N, P, K) on the growth and drought resistance of L. chinensis under normal (soil water content 80% of field capacity) and drought (soil water content 50% of field capacity) conditions. The results showed that appropriate BR concentration could alleviate plant injury under drought stress while the combination of BR and N, P, K (1% urea+1% potassium dihydrogen phosphate+0.10 mg·L^-1 BR) could promote plant growth and nutrient accumulation, further improving drought resistance in L. chinensis. This was closely related to key physiological characteristics including regulation of plant growth, enhanced osmotic adjustment, reduced membrane lipid peroxidation and enhanced antioxidant enzyme activity. Plant height, fresh weight, dry weight and root vigour increased by 28.96%, 62.46%, 45.21% and 19.08% in the BR treated plants and with N, P, K by 20.74%, 236.84% and 42.31% respectively compared with the CK. The activities of nitrate reductase (NR), acid phosphatase (ACP) and malate dehydrogenase (MD) changed with proline content; soluble protein and soluble sugar increased by 57.20%, 22.82% and 5.94% respectively. Malondialdehyde conductivity and leaf permeability were reduced by 37.42% and 55.79% respectively, while superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR) and ascorbate peroxidase (APX) activity increased (158.40%, 38.15%, 32.97%, 30.00% and 28.74% respectively).

Seasonal variation in nutritive value of twelve main forage plant species of grazed grassland in Shaertao mountain, Xinjiang

ZHANG Fan-fan, He Hai-xiu, YU Lei, YANG Kai-hu, LU Wei-hua, MA Chun-hui

2018, 27(11):  179-191.  DOI: 10.11686/cyxb2018017

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Twelve of the main forage plant species contributing to livestock diets in grazed grassland of Shaertao mountain in Zhaosu county, Xinjiang, were assessed for nutritive value and in vitro digestibility in order to define the seasonal variation in these traits for each forage. Large seasonal changes were observed for each forage species. Data for six indicators offorage quality (dry matter, crude protein, neutral detergent fiber, acid detergent fiber, ether extract, crude ash), together with rumen in vitro digestibility of organic matter and herbage metabolic energy were analyzed using a “Fuzzy similar priority ratio” method. The main conclusions were:1) For the three species Stipa capillata, Achnatherum splendens and Iris ruthenica, the best comprehensive nutritive value score occurred in the spring vegetative growth period (June), while the best season for utilization of the remaining 9 species was summer flowering period (July). 2) Dactylis glomerata had the best nutritional value in spring (June) and post-flowering (September), while Alchemilla sibirica had the best nutritional value at summer flowering (July). During autumn (August), Trifolium pratense with the highest comprehensive nutritional value score. 3) In the hay season (November), species with the best nutritional value were S. capillata and I. ruthenica. All species ceased growth in winter.

Effects of five plant phenolics on in vitro ruminal fermentation and methane production of a high concentrate-based substrate

WEI Huan, LI Xiang-yu, YU Quan-ping, CHEN Yong

2018, 27(11):  192-199.  DOI: 10.11686/cyxb2018023

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As methane emission is one of the major factors driving global warming and climate change, its reduction from ruminant farming has attracted widespread attention. This research was carried out to evaluate the effect of different levels [0, 0.05%, 0.10% and 0.20%, w/v (weight/volume)] of tannic acid, p-hydroxybenzoic acid, ellagic acid, syringic acid and rutin on ruminal fermentation and methane production in vitro. A mixture of concentrate and forage (65∶35) was used as the substrate. The results showed that adding 0.05% and more tannin significantly reduced the level of ammonia nitrogen (NH₃-N) (P<0.05). Adding 0.20% tannin significantly reduced the fermentation end point pH (P<0.05) and significantly increased the cumulative gas yield at 48 h and the C₂∶C₃ ratio (P<0.05). Adding 0.10% or more p-hydroxybenzoic acid significantly reduced the concentration of NH₃-N and acetate and increased the cumulative gas yield (P<0.05). There was no significant effect of p-hydroxybenzoic acid on the production of volatile fatty acids, with the exception of acetate (P>0.05). When ellagic acid was added, CH₄ production and the C₂∶C₃ ratio significantly reduced (P<0.05). When the addition level of ellagic acid reached 0.10%, TVFA (total volatile fatty acids) decreased significantly (P<0.05), and when the addition level reached 0.20%, pH and NH₃-N also decreased significantly (P<0.05). After the addition of syringic acid, NH₃-N and cumulative gas yield decreased significantly (P<0.05), and when the addition level reached 0.10%, CH₄ and TVFA increased significantly (P<0.05). Rutin significantly decreased NH₃-N and increased TVFA (P<0.05). When the addition level of rutin reached 0.10%, the C₂∶C₃ ratio decreased significantly (P<0.05), and when the addition level reached 0.20%, pH decreased and cumulative gas production increased significantly (P<0.05). In summary, adding a certain level of phenolic acids and rutin can reduce the concentration of NH₃-N and increase gas production. Syringic acid and rutin can increase TVFA production, but ellagic acid reduces TVFA production. Among the additives, only ellagic acid inhibits the production of methane, while syringic acid promotes methane production by ruminal microorganisms.

Effect of additives on fermentation quality and cattle rumen degradability of mixed potato pulp and corn straw silage

SHEN Rui-rui, LI Qiu-feng, LI Yun-qi, SUN Xiao-yu, CAO Yu-feng, YUE Kang-ning, WANG Yong-sheng, WANG Mei-mei, GAO Yan-xia, LI Jian-guo

2018, 27(11):  200-208.  DOI: 10.11686/cyxb2017510

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The purpose of this experiment was to investigate the effect of different additives on fermentation quality and cattle rumen degradability of a mixed silage made with potato pulp and corn straw, and to screen for suitable additives. The sealed bucket storage method was used in the experiment. The mixed storage ratio of sweet potato pulp and corn straw was 1∶2 and the moisture content was 70%. Five different treatments were assessed: a control (CK), Weizhu group (treatment 1), silage-help group (treatment 2), LaBaX composite additive group (treatment 3) and Yaxin group (treatment 4); each treatment was replicated 3 times and the storage period was 60 days. Laboratory chemical analysis and in situ technology were used to determine the fermentation quality, aerobic stability and rumen degradation rate on the 60th day.There were no differences between treatments in the sensory evaluation; fermentation quality of the missed silage was improved by the additive treatments; lactic acid content in treatment 4 was the highest (P<0.01) whereas the pH and ammonia nitrogen content in treatment 4 were the lowest (P<0.05). Aerobic stability was increased by all additive treatments with treatment 4 (162 hours) again the best (P<0.01). Rumen degradability of dry matter (DM) in the treatment groups was significantly higher than that the CK group (P<0.05); crude protein (CP) rumen degradation rate was also significantly higher than that in the CK group (P<0.01).The neutral detergent fiber (NDF) rumen degradation rate in treatment 4 was the highest, significantly higher than that of treatment 3 (P<0.05), but was not different to other treatment groups (P>0.05).The acid detergent fiber (ADF) rumen degradation rate of treatment 4 was significantly higher than that of treatment 3 and CK (P<0.05), but was not different from treatment 1 and treatment 2 (P>0.05).The rumen degradability of starch in treatment 1 was 2.83% (P<0.01) higher than that of CK. The rumen degradation rate of starch in other treatment groups were not different (P>0.05). In conclusion, the additives used in this study improved fermentation quality, aerobic stability and rumen degradability of mixed potato pulp and corn straw but the Yaxin treament produced the best quality silage.