Table of Content

20 October 2017, Volume 26 Issue 10

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Effects of enclosure duration on plant propagation and vegetation regeneration in the semiarid steppe of Yunwu Mountain

ZHAO Ling-Ping, TAN Shi-Tu, BAI Xin, WANG Zhan-Bin

2017, 26(10):  1-9.  DOI: 10.11686/cyxb2017158

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To provide a theoretical basis for vegetation restoration and the maintenance of biodiversity, we studied the effects of the duration of enclosure on plant propagation and vegetation regeneration in the semiarid perennial steppe of Yunwu Mountain. We compared non-enclosed (grazed) grasslands and grasslands enclosed for 5, 15, 23, 32 years using the field root-digging method to investigate plant reproductive strategies. The results showed that the duration of enclosure significantly affected species richness (P<0.05). Species richness was significantly higher in grazed sites than in grasslands with 23 and 32 years of grazing exclusion. However, there was no significant difference in species richness among grazed grassland, grassland with 5 years grazing exclusion, and grassland with 15 years grazing exclusion (P>0.05). The duration of enclosure significantly affected the densities of total offspring, asexual offspring, rhizomes, tillers, stolons, and branches (P<0.05), however, the densities of sexual offspring and root suckers did not differ significantly among the treatments (P>0.05). With prolonged duration of enclosure, the total density and asexual reproduction density decreased; the offspring density from rhizomes and tillers first increased and then decreased; the offspring density from root suckers and branches first decreased and then increased; the offspring density from stolons increased gradually; and the ratio of asexual and sexual reproduction densities first increased and then decreased. There were significant positive correlations between vegetation density and asexual offspring density, and between vegetation density and total offspring density. Our results indicate that short-term enclosure was conducive to offspring recruitment, and long-term enclosure was disadvantageous for grassland regeneration. Fencing for 5 years was the most conducive to offspring recruitment and grassland regeneration in the semiarid steppe of Yunwu Mountain. Compared with sexual offspring, asexual offspring contributed more to total offspring density, which directly affects the density of the plant community. The trends in the change in density in the plant community could be predicted from offspring density during the succession process.

Spatial and temporal dynamics of grassland yield and its response to precipitation in the Three River Headwater Region from 2006 to 2013

ZHANG Ya-Xian, FAN Jiang-Wen, CAO Wei, ZHANG Hai-Yan

2017, 26(10):  10-19.  DOI: 10.11686/cyxb2017008

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The Three River Headwater Region is one of the source areas of China’s major rivers. For better grassland management under future climate change scenarios and for the sustainable development of animal husbandry in this region, it is very important to understand the spatiotemporal dynamic changes of grassland yield and the relationship between grassland yield and local precipitation. In this study, we used MODIS-NDVI (Moderate Resolution Imaging Spectrometer-Normalized Difference Vegetation Index) data and 442 ground sampling data from 2006 to 2013 to construct empirical models for the correlation between NDVI and the yields of three types of grasslands. Then, we used these models to estimate the distribution of grassland yield in The Three River Headwater Region during 2006-2013. We also studied the response of grassland productivity to changes in precipitation patterns in the Three River Headwater Region based on the correlation between grassland yield and annual, monthly, and cumulative precipitation. The major conclusions were as follows: (1) Grassland yield showed an increasing trend during 2006-2013 in the Three River Headwater Region, and the yield of different grassland types showed different responses to annual precipitation. (2) The most important rainfall month for grassland yield was October of the previous year; rainfall in April and May of the current year also strongly contributed to grassland yield. (3) The cumulative precipitation from October (previous year) to May in the current year was the main cause of inter-annual variations in grassland yield. (4) The cumulative precipitation in autumn of the previous year and in spring of the current year was a key factor in current-year grassland output.

Estimation of soil organic carbon content in alpine grassland using hyperspectral data

CUI Xia, SONG Qing-Jie, ZHANG Yao-Yao, XU Gang, MENG Bao-Ping, GAO Jin-Long

2017, 26(10):  20-29.  DOI: 10.11686/cyxb2016509

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Soil degradation is often reflects grassland degradation. Monitoring soil organic carbon (SOC) content over large areas using remote sensing technology can help assess soil condition allowing better understanding of grassland degradation. Alpine grassland in the Gannan Prefecture was selected for this research. NIR-Visible spectral reflectance of grassland soil samples was measured using ASD (analytical spectral devices) spectroradiometer under laboratory conditions. Correlation analyses between eight transformations of soil spectral reflectance and SOC content were undertaken and sensitive wavebands selected. Three multivariate regression techniques (stepwise multiple linear regression, SMLR, principal components regression, PCR, partial least squares regression, PLSR) were compared with the aim of identifying the best inversion model to estimate alpine grassland SOC. The determination coefficient of validation dataset (R_v²), the root mean square error (RMSE), and the residual prediction deviation (RPD) were used to evaluate the models. The result indicated that differential transformation could improve the correlation between spectral characteristics and SOC content. The first derivative of reflectance had the best correlation with SOC content during transformation, the maximum correlation coefficient value was 0.865; Three multivariate regression models based on the first derivative of reflectance had excellent SOC prediction capability and recommended as a good spectral transformation for reliably estimating SOC. Comparing the multivariate regression techniques based on all transformations, PLSR performed best (high R_v² and RPD, low RMSE), which suggests that PLSR is the most suitable method for estimating SOC content in this study. The optimal SOC estimation model of Gannan alpine grassland was the combination of PLSR and the first derivative of log reflectance spectra [(lgR)'], providing a relatively high coefficient of determination for the validation set (R_v²=0.878), the highest residual prediction deviation (RPD=2.946) and the lowest root mean square error (RMSE=7.520). The RPD of the optimal model was higher than 2.5, which suggested that the model was robust and stable enough to be applied for estimation of SOC in other areas.

Automatic classification of grassland type in Xinjiang Ili based on spatial interpolation of remote sensing and other data

QIAO Yu-Xin, ZHU Hua-Zhong, SHAO Xiao-Ming, ZHONG Hua-Ping, ZHOU Li-Lei, WU Zhao-Wen

2017, 26(10):  30-45.  DOI: 10.11686/cyxb2017013

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With support of remote sensing and geographic information system technology, the inventory of grassland types in China has advanced rapidly. This study used a range of input data including among others grassland community height, ground cover, aboveground biomass, underground biomass, the surface soil bulk density, soil total carbon content, soil organic carbon content, soil total nitrogen content, and soil total phosphorus content. With the collected data, a spatial interpolation algorithm was applied using a Decision Tree Classifier approach to produce an automated classification and index of grassland type in Xinjiang Ili. The grassland types identified based on these nine input variables, consistently matched grassland survey data collected in the 1980s, and showed the methodology to be reliable This study provides a tool for decision makers involved in managing the utilization of grassland resources and livestock production in the Xinjiang Ili region.

Crop yield and soil fertility affected by continuous potato/soybean intercropping systems along the Yellow River

CHEN Guang-Rong, WANG Li-Ming, YANG Ru-Ping, DONG Bo, ZHANG Guo-Hong, YANG Gui-Fang

2017, 26(10):  46-55.  DOI: 10.11686/cyxb2017162

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The objective of this work was to explore the mechanisms for the yield advantage of a potato/soybean continuous intercropping system. Potato, variety Kexin 4 and soybean, variety Jidou 12 were used in a long-term field experiment undertaken from 2011 to 2014 in Guochen, Huining County, Gansu Province in the Northwest irrigation district. The treatments included potato monocropping (PM), soybean monocropping (SM), potato-soybean rotational system (P-S), potato/soybean continues intercropping (IC) and potato/soybean rotational intercropping (IR). The influences of different cultivation systems on crop yields and soil fertility were analyzed. Continuous intercropping systems produced higher yields; IC and IR treatments enhanced yield by 28.5%-254.1% and 39.4%-284.0% compared with PM and SM, respectively and by 57.5% to 70.8% compared with P-S. There was no difference in yield between IC and IR in 2011 and 2012 but in 2013 and 2014 IR yield was significantly higher than those of PM, SM, IC and P-S, achieving 9913 kg/ha and 9590 kg/ha, respectively. Cultivation system influenced yield over time. For PM, yield was stable after 1 year but declined significantly by 22.1% and 42.1% after two and three years of continuous cropping, respectively. The SM and IC treatments significantly reduced yields by 31.2%-53.6% and 13.9%-24.2% after two years, respectively. The P-M and IR treatments did not influence yield over the four years of the study. Topsoil fertility was improved to some extent by different cultivation systems; Olsen P>available N>total N>total P>available K>organic carbon>total K>pH. Topsoil fertility in the IC and IR treatments decline after four years of continuous cropping compared with PM, SM and P-S; Olsen P and available K decreased by 26.2%-42.9% and 18.5%-30.2%, respectively. The results of this study showed that potato/soybean intercropping systems (IC or IR) produced better yields after four years of continuous cropping compared with monocropping and rotational cropping with the potato/soybean rotational intercropping system clearly superior.

Adaptation of salt-tolerant forage grasses to saline soil and their ability to improve saline soil utilization in southern Xinjiang region

JING Peng-Cheng, WANG Shu-Lin, CHEN Yi-Shi, LU Wei-Hua, MA Chun-Hui

2017, 26(10):  56-63.  DOI: 10.11686/cyxb2016467

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In order to provide a theoretical basis for the utilization of saline soil, we used controlled salinization to analyze the feasibility of improving saline soil utilization using four different salt-tolerant forage grasses (alfalfa, Sudan grass, wild forage sorghum and Mexico corn) in southern Xinjiang. The results show that maize had significantly better yield performance on saline soil (P<0.05), followed by alfalfa which also produced good yields with good nutritive value and with the advantages of biological nitrogen fixation and high economic value, making it the most appropriate plant species for saline soil in southern Xinjiang. The use of both maize and alfalfa with selective use of sweet sorghum and Sudan grass can effectively reduce the limitation of saline soil in southern Xinjiang.

Synergistic effects of shade and drought on the photosynthetic characteristics of Arthraxon hispidus

XIE Rui-Juan, ZHANG Xiao-Jing, LIU Jin-Ping, YOU Ming-Hong, WU De

2017, 26(10):  64-76.  DOI: 10.11686/cyxb2016506

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The objective of this study was to clarify the synergistic effects of shade and drought on the photosynthetic characteristics of Arthraxon hispidus and to explore the resistance and ecological characteristics of this plant under shade and drought stress. Wild A. hispidus, a plant with potential use in sloping lawn development, was subjected to different 20 treatments, combining five shading intensities (0, 10%, 30%, 50%, 70%) and four drought intensities; sufficient moisture (W₀), mild drought (W₁), moderate drought (W₂), and severe drought (W₃). After 36 days of treatment, the leaf biomass allocation ratio, photosynthetic pigment content, light response ability, and photosynthetic parameters were determined. The extent of shade and drought and the synergy between shade and drought significantly affected the area, number, biomass, and allocation ratio of A. hispidus leaves (P<0.05). Shade and drought had a strong synergistic effect on leaf area, number, biomass, and biomass allocation ratio (P<0.01), with the strongest effect on the allocation ratio, followed by leaf number, leaf area, and then leaf biomass. Shade, drought, and the synergy between shade and drought also significantly affected the contents of chlorophyll a (Chla), chlorophyll b (Chlb), Chla+b, and Chla/b (P<0.05). The Chlb content was more sensitive to habitat than was Chla content. Compared with drought, shade had stronger effects on chlorophyll content and photosynthetic rate. Shade and drought had significant synergistic effects on Chlb, Chla+b, and Chla/b (P<0.05). Shade, drought, and the synergy between shade and drought had highly significant effects on the light response capability (P<0.01). Shade and drought had significant synergistic effects on the light saturation point (LSP), light compensation point (LCP), and maximum net photosynthetic rate (P_nmax), with the strongest effect on P_n max followed by LSP and then LCP. Shade, drought, and the synergy between shade and drought significantly affected the photosynthetic rate (P_n), transpiration rate (T_r), intercellular CO₂ concentration (C_i), and stomatal velocity (G_s) (P<0.05). Shade and drought had a strong and significant synergistic effect on photosynthetic parameters (P<0.01). Shade mainly affected P_n, drought main affected G_s, C_i, and T_r, and their synergy mainly affected T_r. Shade of 30% or less reduced the size of the decrease in P_n, T_r, C_i, and G_s caused by drought, but shade of more than 30% exacerbated these decreases. Compared to each single stress, the synergistic effect of shade and drought increased the photosynthetic leaf area and chlorophyll content and altered the light response ability and photosynthetic parameters of A. hispidus. These changes contributed to the stress resistance and ecological adaptation of A. hispidus.

Effects of silicon on the antioxidant system and membrane stability of Saponaria officinalis under drought stress

YANG Hui-Ying, DENG Ya-Nan, XU Ling-Xin, YAN Jun-Xin

2017, 26(10):  77-86.  DOI: 10.11686/cyxb2016486

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The aim of this study was to determine the effect of silicon on the antioxidant system and membrane stability of Saponaria officinalis under drought stress. Silicon was added to soil at four concentrations (0.1, 0.2, 0.3, 0.4 g/kg SiO₂) and the soil moisture content was adjusted to impose normal conditions, mild drought stress, and severe drought stress on S. officinalis. The protective enzyme activity, antioxidant content, malondialdehyde (MDA) content, and relative electrical conductivity of the leaves of S. officinalis were determined. The results showed that with increasing severity and longer duration of drought stress, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the contents of reduced glutathione (GSH) and ASA (ascorbic acid) in the leaves of S. officinalis first increased and then decreased, and the MDA content and relative electric conductivity increased. Compared with the control, the treatments with silicon added to soil showed higher activities of SOD, POD, CAT (>30% higher) under drought stress, and lower MDA content and relative electrical conductivity (>25% lower), resulting in more stable GSH and ASA contents. These results indicated that silicon can effectively alleviate damage to S. officinalis cell membranes under drought stress by improving the performance of the antioxidant system. As the concentration of silicon increased, the drought resistance of S. officinalis increased gradually and then stabilized. The optimal concentration of SiO₂ in soil was 0.3-0.4 g/kg.

Effects of drought stress on the physiological characteristics of new lines of Festuca arundinacea induced by spaceflight and their comprehensive evaluation

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

2017, 26(10):  87-98.  DOI: 10.11686/cyxb2016502

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In this study, the ecophysiological characteristics of 14 lines of Festuca arundinacea, including some induced by spaceflight, were studied in a pot experiment. The plants were subjected to drought stress conditions, and physiological and biochemical indices including soluble protein content, chlorophyll (Chl) content, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity were determined. These indexes of the 14 F. arundinacea were used to quantitatively evaluate their drought tolerance. The soluble protein content and Chl content increased, and the activities of SOD, POD, and CAT decreased under drought conditions. The drought resistance of the 14 F. arundinacea lines was calculated using the subordinate function, and the lines were ranked, from most drought tolerant to least drought tolerant, as follows: SP5-32>SP5-75>F. arundinacea cv. Shuicheng>SP5-60>SP5-94>SP5-97>SP5-89>SP5-71>SP5-7>SP5-85>SP5-42>SP5-5>F. arundinacea cv. Qiancao No.1>SP5-88. The average subordinate function of SP5-32, the most drought tolerant line, was 0.533. A grey correlative analysis was conducted to determine which indices were most strongly related to drought resistance. The indices were ranked, from strongest correlation with drought resistance to weakest, as follows: POD activity>soluble protein content>SOD activity>catalase activity>Chl content (correlation coefficients, 0.55-0.65). Therefore, SP5-32 is more suitable for cultivation in drought-affected areas as its antioxidant enzyme activity, soluble protein content, and chlorophyll content are unaffected by drought stress.

HPLC-MS analysis of anthocyanin components and content in new strains of colored potato

JIANG Chao, YU Xiao-Xia, YU Zhuo, GAO Zhe, ZHANG Ming-Fei, YANG Dong-Sheng, SHI Yue

2017, 26(10):  99-107.  DOI: 10.11686/cyxb2017051

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To identify differences in anthocyanin composition and content in new varieties Mengcai-01 and Mengcai-02, and a control Hongmei and provide a foundation for colored potato breeding and the development and application of potato anthocyanin, qualitative and quantitative analysis of anthocyanin in each variety using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS). The control variety Hongmei had a total anthocyanin content of 169.88 mg/100 g FW, and contained four anthocyanin components; pelargonidin-3-rutinoside, cyanidin-3-coumaryl-glucoside, pelargonidin-3-(4'''-feruloylrutinoside)-5-glucoside and pelargonidin-3-(4'''-p-coumarylrutinoside)-5-glucoside, of which pelargonidin-3-(4'''-p-coumarylrutinoside)-5-glucoside and cyanidin-3-coumary-glucoside were the main components, accounting for 48.95% and 39.97% of the total anthocyanin content, respectively. The new variety, Mengcai-01, had a total anthocyanin content of 1051.65 mg/100 g FW, and contained four anthocyanin components; petunidin-3-(4'''-p-coumarylrutinoside), petunidin-3-(4'''-p-coumarylrutinoside)-5-glucoside, petunidin-3-(4'''-feruloylrutinoside)-5-glucoside and malvidin-3-(4'''-p-coumar ylrutinoside-5-glucoside) of which petunidin-3-(4'''-p-coumarylrutinoside)-5-glucoside was the main component accounting for 79.14% of the total anthocyanin content. Mengcai-02 had a total anthocyanin content of 159.41 mg/100 g FW and contained five anthocyanin components; petunidin-3-(4'''-p-coumarylrutinoside), petunidin-3-(4'''-p-coumarylrutinoside)-5-glucoside, petunidin-3-(4'''-feruloylrutinoside)-5-glucoside, peonidin-3-(4'''-p-caffeylrutinoside)-5-glucoside and peonidin-3-(4'''-p-coumarylrutinoside)-5-glucoside, of which petunidin-3-(4'''-p-coumarylrutinoside)-5-glucoside was the most important followed by peonidin-3-(4'''-p-caffeylrutinoside)-5-glucoside was the second, accounting for 54.08% and 24.06% of the total anthocyanin content, respectively. In conclusion, there were clear differences of anthocyanin components between the two new colored potato strains and the control variety Hongmei.

Effect of combined microbial fertilizer on plant species diversity and biomass of common species in the Hulunbuir Leymus chinensis meadow steppe

YAO Jing, CHEN Jin-Qiang, XIN Xiao-Ping, WEI Zhi-Jun, WU REN Qi-Qi-Ge, YAN Rui-Rui, BAI Yu-Ting, DAI Jing-Zhong

2017, 26(10):  108-117.  DOI: 10.11686/cyxb2017171

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The aim of this study was to evaluate the responses of grassland plant species diversity and the aboveground biomass of several common plant species to microbial fertilizer. We set up a factorial experiment to test the interactive effect of six microbial fertilizers in the Leymus chinensis meadow steppe in Hulunbuir in August 2014-2016. The seven treatments were as follows: control (CK), humic acid (F), alginic acid (H), fermented molasses (T), humic acid+fermented molasses+alginic acid (F+H+T), humic acid+compound microbial inoculant (F+J), and alginic acid+compound microbial inoculant (H+J). The results showed that addition of F and H from 2014 to 2016 did not significantly affect plant communities. Addition of F+H+T in 2014, 2015, and 2016 increased plant density by 26.72%, 17.92%, and 34.64%, respectively, and increased aboveground biomass by 7.18%, 49.97%, and 47.64% respectively. Addition of F from 2014 to 2016 did not significantly affect the plant community, but addition of T, H, F+H+T, and H+J increased the importance of the Gramineae and Leguminosae. Rhizome-type grasses (L. chinensis) showed greater responses to compound microbial fertilizers than did clonal grasses and rosettle grasses. Addition of F in 2014, 2015, and 2016 decreased the Margalef index by 16.40%, 5.22%, and 37.22%, respectively. Addition of H in 2014-2016 did not affect the diversity index, but addition of F+H+T in 2014-2016 increased the Margalef index, the Shannon-Wiener index, and the Pielou index. Addition of H+J in 2014 to 2015 increased the Pielou index by 7.62% and 8.70%, respectively. These results show that application of microbial fertilizer can significantly affect the plant community, species diversity, and aboveground biomass in the Hulunbuir L. chinensis meadow steppe. The combination of F+T+H had the strongest effect to increase plant community species diversity and aboveground biomass. Precipitation should also be taken into consideration in the restoration of grassland resources.

Impacts on alfalfa productivity and soil fertility of partially replacing phosphate fertilizers with microbial fertilizers

QI Juan, YAO Tuo, BAI Xiao-Ming, GAO Meng-Ying, MENG Xiang-Jun

2017, 26(10):  118-128.  DOI: 10.11686/cyxb2017016

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A field experiment was carried out to study the effects on alfalfa yield, soil microbial characteristics and soil enzyme activities, of partially replacing phosphate fertilizers with microbial fertilizers, and comprehensive evaluation were conducted using grey relational analysis. The aim of the research was to explore the effect of the biological fertilizer and to scientifically determine the optimum optimal application rate for alfalfa. The experiment had seven treatments: P₁₀₀, 100% phosphate fertilizer (80 kg/667 m²); M₁₀₀, phosphate solubilizing bacteria+nitrogen-fixing bacteria (0.5 kg/667 m²); P₇₅M₂₅,75% P+25% M; P₅₀M₅₀, 50% P+50% M; P₂₅M₇₅, 25% P+75% M; R₁₀₀, 100% nitrogen-fixing bacteria; CK (no fertilizer). P₁₀₀ increased the alfalfa yield significantly at the first cut, while the treatment P₇₅M₂₅ had produced the highest yield (P<0.05) at the second cut. Comparing the total yield from two cuts with CK, P₅₀M₅₀ was highest yielding and increased the alfalfa yield by 60.45%, while P₁₀₀ had the second highest yield, which increased about 58.40% than CK. Partially replacing phosphorus fertilizers with microbial fertilizers increased soil microbial population. P₅₀M₅₀ significantly increased the number of bacteria, fungi and actinomyces in the 0-10 cm soil layer at the first cutting by 204.6%, 174.5% and 33.2%, respectively, compared to CK. P₅₀M₅₀ and P₂₅M₇₅ improved soil enzyme activity significantly in the 10-20 cm soil layer at the first cut. Grey correlation analysis indicated that sucrase had the highest grey correlation value (0.842), followed by yield (0.814), while microbial biomass of phosphorus and carbon had lower grey correlation value (0.512 and 0.513), respectively. The treatment P₅₀M₅₀ demonstrated soil fertility improvement while reducing the application rate of chemical fertilizers, and was therefore agronomically beneficial.

Protective effect of salicylic acid on reactive oxygen levels and antioxidant system of Coronilla varia seedlings under drought stress

MA Le-Yuan, CHEN Nian-Lai, HAN Guo-Jun, LI Liang, SUN Xiao-Mei

2017, 26(10):  129-139.  DOI: 10.11686/cyxb2017134

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The aim of these experiments was to determine whether exogenous salicylic acid (SA) could protect Coronilla varia seedlings against drought stress. Leaves of C. varia seedlings grown in pots were sprayed with salicylic acid at four concentrations (0.25, 0.5, 1 and 2 mmol/L) and then the membrane lipid peroxide index, antioxidant enzyme activity, and the contents of non-enzymatic antioxidants in seedling leaves were determined during a drought stress treatment. At concentrations of 0.5-2.0 mmol/L, SA decreased the superoxide anion (O₂^-·) production rate, hydrogen peroxide (H₂O₂) content, malondialdehyde (MDA) content, and cell membrane permeability, and increased the activities of the antioxidant enzymes catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), which increased the antioxidant index capacity. However, at concentrations of 0.5-2.0 mmol/L, SA did not affect the ascorbate acid (ASA) and glutathione (GSH) contents in seedling leaves. At 11 days of drought stress, the O₂^-· production rate, MDA content, and cell membrane permeability were 79.78%, 34.42%, and 36.96% lower, respectively, and CAT activity was 2.45-fold higher in seedlings treated with 0.5 mmol/L SA than in untreated seedlings (P<0.05). At 16 days of drought stress, the SOD and POD activities were 3.85-fold and 3.63-fold higher, respectively, in seedlings treated with 0.5 mmol/L SA than in untreated seedlings. These results demonstrated that exogenous SA could improve the drought resistance of C. varia by reducing reactive oxygen levels under drought stress, increasing the activity of the antioxidant system, and alleviating oxidation damage to cell membranes resulting from drought-induced membrane lipid peroxidation. The most effective concentration of SA was 1 mmol/L.

Ruminal degradation characteristics of Moringa oleifera in dairy cows

LI Yuan, DIAO Qi-Yu, KONG Lu-Xin, ZHANG Ting-Ting, ZHANG Bo, ZHOU Chao-Long, TU Yan

2017, 26(10):  140-148.  DOI: 10.11686/cyxb2016497

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This experiment was conducted to study the degradation characteristics of Moringa oleifera in the rumen of dairy cows and to explore the possibility of using Moringa as a feed resource for ruminants. Three dairy cows with permanent rumen fistula were selected to determine the disappearance rate and degradation parameters of Moringa leaves, branches, and stems. The disappearance rates and degradation parameters of DM (dry matter) and OM (organic matter) were nearly the same and reached a plateau at 48 h, while the degradation rates varied greatly among the different plant parts. At 96 h, Moringa leaves showed the highest disappearance rate (69.34%), followed by the branches and then the stems. The effective degradation rate of DM and OM differed significantly among the Moringa plant parts (P<0.05). The disappearance rate of CP (crude protein) of Moringa leaves was up to 90.86%, which was 22.84% and 38.92% higher than that of CP in the stems and branches, respectively. The effective degradability of CP was highest in the leaves, followed by the branches and then the stems, while the effective degradability of stem CP was higher than that of DM and OM. The rumen-degradable protein (RDP) content of Moringa leaves was up to 15.57%, and the contents of undegradable protein (RUP) were higher than that of RDP in the branches and stems. The disappearance rate was highest for the leaves, followed by the branches and then the stems (50.55%, 27.11%, and 41.43%, respectively). At 96 h, the disappearance rates of the branches and leaves were similar. The effective degradability of NDF (neutral detergent fiber) and ADF (acid detergent fiber) were significantly higher in Moringa leaves than in the stems and branches (P<0.05). In conclusion, the three parts could be ranked, from highest nutritional value to lowest, as follows: Moringa leaves>Moringa branches>Moringa stems. When feeding dairy cows, Moringa leaves should be individually fed, Moringa branches should be mixed with high nutrient content feed, while Moringa stems are not recommended as cow feed.

Lucerne common leaf spot (Pseudopeziza medicaginis) decreases the photosynthetic performance and forage quality of Medicago sativa

LI Yang, SHI Juan, CUI Na-Na, HAN Yu

2017, 26(10):  149-157.  DOI: 10.11686/cyxb2017073

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The aim of this study was to determine the effect of common leaf spot on the photosynthetic performance and forage quality of alfalfa, and to evaluate the importance of this disease. Five indices of photosynthetic performance were measured in diseased and healthy leaves using an LI-6400 photosynthetic analyzer, and the concentrations of 10 nutrients were determined in diseased and healthy leaves and stems. The results showed that the ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), calcium (Ca), tannin, and total phenols content in diseased leaves was 19.94%, 71.21%, 39.68%, 136.42%, 21.93% and 50.55% higher, respectively, than their corresponding contents in healthy leaves; the correlation coefficient for each of these indexes with disease severity was 0.95, 0.95, 0.91, 0.85, 0.89, and 0.85, respectively. Crude protein (CP) and potassium (K) content was decreased by 15.67% and 29.91%, respectively, in diseased leaves, and their respective correlation coefficients with disease severity were -0.99 and -0.86. Crude fat (EE) and phosphorus (P) contents were decreased in diseased leaves, but they were not significantly correlated with disease severity. Correlations between nutrient indexes and disease severity were not determined for stem material, but the ash and NDF contents were lower in diseased stems than in healthy stems, while other nutrients showed the same trends as observed in diseased leaves. Compared with healthy leaves, diseased leaves showed a higher intercellular CO₂ concentration (C_i), but this was not correlated with disease severity. The net photosynthetic rate (P_n) and transpiration rate (E) of diseased leaves decreased by 93.27% and 68.34%, and their correlation coefficients with disease severity were -0.82 and -0.86, respectively. Stomatal conductance (G_s) and water use efficiency (WUE) tended to be lower in diseased leaves than in healthy ones, but they were not significantly correlated with disease severity. There was no significant correlation between leaf P content and photosynthetic parameters; however, there were extremely significant or significant correlations between other quality indices and P_n and E. In a principal components analysis of leaf quality and photosynthetic performance data, principal component 1 accounted for 80.94% of data variance and showed positive coefficients for ash, ADF, NDF, Ca, tannins, total phenols, and C_i, and negative coefficients for CP, EE, K, P_n, E, G_s, and WUE. In conclusion, common leaf spot negatively affects the quality and photosynthesis of alfalfa, and also affects the interaction between photosynthetic performance and forage quality.

Cultural characteristics of fungal endophyte from 3 locoweed species in China

WANG Zhi-Gang, CAO Shi, XU Na, XU Shan, LI Yan-Zhong

2017, 26(10):  158-169.  DOI: 10.11686/cyxb2017009

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Locoweeds contain swainsonine-producing fungal endophytes. Endophytes in several locoweed species in China are known to belong to the same taxonomic species of fungus. However, since these endophytes are isolated within their respective hosts and vertically transmitted to seed of the next plant generation, it is likely that the fungal endophytes of the various locoweed species have developed distinctive biological traits. Colony growth rate and morphological characteristics of endophytes from Oxytropis glabra, O. ochrocephala and O. kansuensis (strains LYZ0091, LYZ0093 and LYZ0109, respectively) were studied under different temperature and pH regimes and grown on various media to test this hypothesis. It was found that: 1) The maximum temperature for growth differed between strains (LYZ0109 ceased growth at 30 ℃, while LYZ0091 and LYZ0093 continued to grow at 30 ℃); 2) The optimum temperatures for colony growth were 20, 25 and 25 ℃, respectively, for LYZ0091, LYZ0093, and LYZ0109; 3) The growth rate of LYZ0091 at 5, 10 and 15 ℃ was significantly (P<0.05) higher than LYZ0109, while significantly (P<0.05) lower than LYZ0109 at 20 and 25 ℃. 4) No significant growth difference between fungal strains was found over the pH range pH 4 to pH 11; 5) The colony growth rate of strain LYZ0109 was significantly (P<0.05) higher than that of LYZ0091 on NA, PCA, PDA, PSA and WHDA media for most growth measures; 6) No conidia were produced by any fungal strain in any of temperature, pH and media combinations tested; 7) Hyphae of LYZ0091 and LYZ0109 were waved, and seldom produced chlamydospores; hyphae of LYZ093 were straight with plentiful chlamydospores arranged as tree-like structures from the media bottom to the surface.

Grazing alters soil microbial community in alpine grasslands of Northern Tibet

FU Gang, SHEN Zhen-Xi

2017, 26(10):  170-178.  DOI: 10.11686/cyxb2017011

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A grazing experiment was conducted in two alpine steppe meadows (winter pasture and summer pasture) and one alpine meadow (summer pasture) in Northern Tibet in July 2008. The phospholipid fatty-acid (PLFA) method was used to characterise the soil microbial community. Fungi, gram-negative bacteria, actinomycetes and protozoa in ungrazed soils were significantly higher than grazed soils in winter pasture on the alpine steppe meadow. Total PLFA, fungi, bacteria, gram-positive bacteria, gram-negative bacteria, actinomycetes, arbuscular mycorrhizal fungi and protozoa in the ungrazed soils were also significantly higher than those of grazed soils in the summer alpine meadow. There were significant differences in soil microbial community structure between ungrazed and grazed soils for all three alpine grasslands based on redundancy analysis. Soil inorganic nitrogen and dissolved organic nitrogen significantly affected the variation in the soil PLFA profile in the alpine steppe meadow for the winter pasture, whereas nitrate nitrogen and dissolved organic carbon significantly affected the variation of soil PLFA profile for the summer pastures. Our findings suggested that clarifying the effect of grazing on alpine soil microbial communities needs to consider grazing season and grassland types in Northern Tibet.

Comparison of functional diversity of rhizosphere soil microorganisms between the exotic plant Xanthium italicum and its native partner Xanthium sibiricum by the Biolog method

ZHANG Ming-Li, CHANG Hong-Lei, MA Miao

2017, 26(10):  179-187.  DOI: 10.11686/cyxb2016500

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The aim of this research was to analyze differences in functional diversity and the carbon source utilization of the rhizosphere soil microbial community between the invasive plant Xanthium italicum and its native partner, Xanthium sibiricum. The two plants were cultivated in a put experiment and their soil microbial communities were analyzed using the Biolog technique. Soil with no plants served as the blank control (CK). The results indicated that the functional diversity of the soil microbial community was significantly higher for the invasive plant X. italicum than for the native plant X. sibiricum. The rhizosphere soil microbes from X. italicum significantly increased the average well color development (AWCD) (72 h, P<0.05) for 31 carbon sources. The treatments were ranked, from largest change in AWCD to smallest, as follows: X. italicum>X. sibiricum>CK. The values of Shannon’s diversity index (H), Simpson’s dominance index (D), and substrate richness index (S) were significantly higher for X. italicum rhizosphere soil microbes than for those of X. sibiricum and CK. The Shannon’s indexes (H, D, S) of the X. italicum rhizosphere soil microbial community were 3.13%, 0.77%, and 21.67% higher, respectively, than those of X. sibiricum; and 4.59%, 0.89%, and 35.18% higher, respectively, than those of CK. The lowest values of H, D, and S, were in CK. The carbon metabolic fingerprint analysis showed that carbon source utilization differed significantly between X. italicum soil microbes and X. sibiricum soil microbes. The rhizosphere soil microbes of X. italicum showed the highest utilization of amines, phenolic acids, amino acids, and sugars. A principal component analysis (PCA) showed that the carbon utilization features of soil microbial communities differed between the two plants. The soil microbial community of X. italicum was concentrated in the first principal component (score coefficient, 3.3102) and that of X. sibiricum was concentrated in the second principal component (score coefficient, -1.9616). Carbohydrates, carboxylic acids, polymers, and amino acids were the major carbon sources utilized by rhizosphere soil microbes. Therefore, the reasons for the successful invasion for X. italicum could include: (1) changes in the structure and function of soil microbial communities; (2) increased metabolic activity of rhizosphere soil microbes; and (3) the formation of a soil microenvironment that benefits its own growth.

Effects of nitrogen fertilizer on leaf chlorophyll content and enzyme activity at late growth stages in maize cultivars with contrasting tolerance to low nitrogen

WU Ya-Wei, LI Qiang, DOU Pan, MA Xiao-Jun, YU Dong-Hai, LUO Yan-Hong, KONG Fan-Lei, YUAN Ji-Chao

2017, 26(10):  188-197.  DOI: 10.11686/cyxb2017006

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The aim of this study was to investigate the effects of nitrogen (N) fertilizer on the activity of N metabolism and growth of two maize (Zea mays) cultivars with contrasting tolerance to low N. An experiment was laid out in a split-plot design with three replicates. The main plot consisted of two maize cultivars with contrasting tolerance to low N (the low-N tolerant cultivar ZH311 and the low-N sensitive cultivar XY508). The split plot consisted of six N treatments: 0, 90, 180, 270, 360, and 450 kg/ha. The chlorophyll content and the activities of enzymes involved in N metabolism (NR: nitrate reductase, GS: glutamine synthetase, GDH: glutamate dehydrogenase) at late growth stages were determined, as well as the seed protein content and yield. The results showed that N fertilizer increased chlorophyll content and enzyme activities at late stages, and promoted protein content and yield. As the amount of N fertilizer increased, these indexes increased to a greater extent in XY508 than in ZH311, while all indexes were higher in ZH311 than in YX508. Compared with the low-N sensitive cultivar, the low-N tolerant cultivar retained a higher chlorophyll content and higher activities of enzymes involved in N metabolism, especially at the mid to late grain-filling stage. In addition, the low-N tolerant cultivar required low to mid N levels to improve seed protein content and yield. These results provide information about the physiological mechanisms involved in tolerance to low-N conditions.

Gender differences in physiology and enzyme activity in response to temperature in Humulus scandens

GUO Hai-Yan, DUAN Jing, LIU Jin-Ping, YOU Ming-Hong, XIE Rui-Juan

2017, 26(10):  198-206.  DOI: 10.11686/cyxb2016493

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The purpose of the study was to explore gender differences in physiology and protective enzyme activity of dioecious plant species at different temperatures. Seed of the dioecious climbing herb Humulus scandens were planted in pots; at the 1-2 true leaf stage seedlings were moved to an incubator with three temperature settings (15, 20, 25 ℃) based on the mean temperature of the area of seed provenance origin. Photosynthesis, metabolism, antioxidant enzyme activity and cell membrane integrity were measured. The effect of temperature on photosynthesis, respiration and resistance of H. scandens to temperature was determined. Temperature significantly affected leaf chlorophyll content, light-saturated photosynthetic rate (P_n) and biomass which significantly decreased with decreasing temperature. The P_n of female plants was always significantly higher than that of males (P<0.05). Soluble sugar (SS) and pyruvic acid (PA) contents and nitrate reductase activity (NRA) were also affected by temperature change (P<0.05); SS content was lower but NRA higher with decreasing temperature. Sugar metabolism and respiration rate of males was significantly higher than females (P<0.05), while nitrogen metabolism was not influenced by gender. Temperature affected metabolism more than gender. Temperature significant affected superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) (P<0.05) activity which increased with decreasing temperature; SOD and POD activity in females plants were significant higher than those of males (P<0.05) but CAT activity was not influenced by gender. The effect of temperature on cell membrane traits was greater than that of gender. H₂O₂, malondialdehyde (MDA), proline (Pro) and soluble protein (SP) content also increased significantly with decreasing temperature. Higher H₂O₂ and SP but lower MDA and Pro were observed in male compared to female plants. Our results indicated that gender differences in photosynthesis, respiration, antioxidant enzyme system and cell membrane integrity response to low temperature were of less importance than differences due to temperature.

Effects of different nitrogen levels on key enzyme activities associated with nitrogen metabolism of feed ramie

CHEN Ji-Kang, TAN Long-Tao, YU Chun-Ming, ZHU Ai-Guo, CHEN Ping, WANG Yan-Zhou, ZHU Tao-Tao, XIONG He-Ping

2017, 26(10):  207-218.  DOI: 10.11686/cyxb2016501

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Ramie (Boehmeria nivea) is an important source of plant protein in South China. Few studies investigating the physiological mechanisms of nitrogen utilization in feed ramie have been reported. To evaluate the activities of key enzymes associated with nitrogen metabolism in ramie, a potted experiment was conducted under different nitrogen levels. Two ramie varieties, H2000-03 which has high nitrogen utilization efficiency (NUE, 46.01%) and Ceheng Jiama with low NUE (15.81%) were treated with 0, 6, 9, 12 and 15 mmol/L nitrogen, and enzyme activity tested at the seedling stage (15 days), maximum growth (40 days) and at maturity (54 days). The results showed that as nitrogen concentration increased plant height, fresh yield and leaf protein content of both varieties increased and subsequently decreased or plateaued, indicating that the range of treatments imposed was able to meet the nitrogen requirement of the ramie plants. Plant height and fresh yield of H2000-03 were significantly higher than that of Ceheng Jiama under all treatments. The leaf protein content of H2000-03 was distinctly higher than that of Ceheng Jiama under a range of nitrogen levels (9-12 mmol/L). These results suggest that H2000-03 has better productivity under a range of nitrogen availabilities and more stable production under nitrogen deficient conditions. At different growth periods, the activity of NR (nitrate reductase) in H2000-03 and Ceheng Jiama gradually increased with increased nitrogen supply, while the activities of glutamine synthetase (GS), glutamate synthase (GOGAT), glutamic dehydrogenase (GLDH), catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) first increased and then decreased. The activities of POD, GS, GOGAT, CAT in H2000-03 under all nitrogen levels and the activities of SOD and POD under high nitrogen levels were higher than in Ceheng Jiama, while lower GLDH at all nitrogen levels and lower SOD and POD at low nitrogen levels were detected in H2000-03 compared to Ceheng Jiama. These results indicate that H2000-03 had a better physiological response and adaptability to different nitrogen fertility levels. The dynamic characteristics of ramie yield and quality were consistent with enzyme activity related to nitrogen metabolism and resistance which could be used to monitor and characterize nitrogen utilization differences among genotypes. Our research suggests that an appropriate nitrogen fertility range, rather than continuously increasing nitrogen should be ascertained to coordinate productivity with physiological characteristics. The activity of key enzymes during the rapid growth phase is suggested as an important trait for feed ramie breeding.

Textual research on alfalfa in local records of the Minguo period

SUN Qi-Zhong, LIU Qian, TAO Ya, XU Li-Jun

2017, 26(10):  219-226.  DOI: 10.11686/cyxb2017081

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Local records of government agencies are a valuable source of information about natural and social history and can help to understand the present situation of the region they pertain to. Alfalfa as an important agricultural crop, alfalfa use was listed in many local records of the Minguo period (1912-1949), We obtained and assessed 56 local admistrative records, dating from the Minguo period, of alfalfa use in provinces of East China, North China and Northwest China. The records showed that alfalfa was widely planted in east China, north China and northwest China in the Minguo period. The most extensive use was in Anhui, Jiangsu, Shandong, Chahar, Hebei, Shanxi, Shaanxi, Ningxia, Gansu, Qinghai and Xinjiang provinces. Alfalfa’s ecological characteristics were described in many of the records. It was clear that different Medicago species were planted in different regions. For example, Medicago sativa and M. falcata were typically planted in Hebei province; M. sativa, M. falcata and M. hispida were planted in Shandong Province. Alfalfa can be used on a range of land classes from alkaline soils to fertilized alluvial or loessial soils, and is an important crop resource. Alfalfa is also an excellent honey plant.

Physiological activation and feed value of mulberry for livestock and poultry

DU Zhou-He, ZUO Yan-Chun, YAN Xu, ZHOU Xiao-Kang, LIU Bin-Bin, WU Jian-Mei, LIU Jun-Feng, KOU Jing, CHEN Yi-An, ZHANG Jian-Fei

2017, 26(10):  227-236.  DOI: 10.11686/cyxb2017104

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Mulberry is a perennial forage crop with high protein content, rich in amino acids, low cellulose content and physiological activators. Mulberry is palatable to livestock and poultry including cattle, sheep, pigs, rabbits, chickens and fish. Mulberry leaf powder in the diet of laying hens can help increase yellow pigmentation of egg yolks, raise phospholipid and unsaturated fatty acid content in the yolk and increase viscosity of egg whites, improve the quality and taste of egg products. The addition of mulberry leaf in the diet of livestock and poultry can improve meat colour, raise inosinic acid and unsaturated fatty acid content in meat, reduce cholesterol content in meat, retain meat moisture, postpone pH decrease and prevent lipid oxidation. In large-scale meat production systems such as beef cattle, pigs, mulberry leaf supplementation can also reduce subcutaneous fat and increase intramuscular fat. Mulberry is a sort of fine perennial forage crop with higher protein content, rich sorts of amino acids, lower cellulose content and many sorts of physiological activators. In this study we review the content, structure, function, feed value and the physiological benefits of mulberry forage and summarize the effects of mulberry on livestock and poultry production performance and improving the product quality. We also propose measures to negate the potential effects of anti-nutritional factors and improve crop management. Finally, the opportunity to utilize mulberry forage is assessed.

Heavy metal absorption and enrichment characteristics of dominant weed species naturally growing on farmland in Northern Guizhou

YAN Lian-Ying, FAN Cheng-Wu, ZHAO Zhen-Yu, LIU Gui-Hua, HU Gang, QIN Song

2017, 26(10):  237-244.  DOI: 10.11686/cyxb2016499

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The aim of this research was to provide reference data for the remediation of sites contaminated by heavy metals in Guizhou Province, a mountain-and-hill area. The heavy metal absorption and enrichment characteristics of 12 dominant weeds naturally growing in farmland in northern Guizhou and their root soils were analyzed. The weeds were sampled from the field, and the soils were analyzed to determine the background concentrations of heavy metals. The quality of the soil environment with reference to heavy metal pollution was judged against the Agricultural Environment Quality Evaluation Standards, and on the basis of the single factor pollution index and the Nemerow pollution index. The bioconcentration factor and transfer factor were calculated to evaluate the enrichment characteristics of the dominant weeds. The soil had single factor pollution indexes for Cu, Zn, Cd, and Pb ranging from 0.30 to 1.71 and a Nemerow comprehensive pollution index of 1.31. Therefore, the soil was judged as lightly polluted, and Cd was the main contributor. The dominant weeds in the study area were Acalypha australis, Solanum nigrum, Artemisia argyi, Lapsana apogonoides, Digitaria sanguinalis, Abelmoschus esculentus, Viola verecunda, Amaranthus spinosus, Gynura crepidioides, Youngia heterophylla, Clinopodium chinensis, and Allium fistulosum. The ranges of heavy metal contents in these weeds were as follows: Cu, 42.15-110.27 mg/kg; Zn, 35.89-157.87 mg/kg; Cd, 0.29-6.08 mg/kg; and Pb, 2.99-37.19 mg/kg. These values were within the normal range and were not indicative of hyperaccumulating plants. The bioconcentration factors and transfer factors were greater than 1 in A. australis, A. esculentus, and G. crepidioides for Cu, Zn, and Cd; in L. apogonoides for Cu and Zn, and in V. verecunda, A. spinosus, and Y. heterophylla for Cd. These species showed some characteristics of hyperaccumulation plants. The contents of heavy metals in lightly polluted farmland soil did not significantly affect the heavy metals contents in weeds. The absorption of Pb by the roots of weeds promoted Pb accumulation. In conclusion, the contents of heavy metals in the dominant weeds were in the normal range, but some dominant weeds possessed some important characteristics of hyperaccumulation plants, and have the potential to be hyperaccumulation plants.