Table of Content

20 September 2016, Volume 25 Issue 9

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Effects of different land-use types on soil active organic carbon in the Stipa klemenaii desert steppe of Inner Mongolia

QIU Xuan, ZHAO Jian-Ning, LI Wen-Ya, ZHANG Nai-Qin, YANG Dian-Lin

2016, 25(9):  1-9.  DOI: 10.11686/cyxb2015537

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In order to explore variation in the contents and components of soil active organic carbon under different land-use types in the Stipa klemenaii steppe of Inner Mongolia, five field treatments were studied. These treatments included three grazing intensities, 0.50 sheep/hm² (G_0.50), 0.94 sheep/hm² (G_0.94) and 1.25 sheep/hm² (G_1.25), as well as one fenced enclosure and one tract of reclamation land. Analysis was undertaken to determine the contents of soil organic carbon (SOC), soil dissolved organic carbon (DOC), soil readily oxidizable organic carbon (ROC), soil microbial carbon (MBC) and soil physical and chemical properties: total nitrogen (TN), total phosphorus (TP), and carbon nitrogen ratio (C/N). The results showed that the contents of SOC, TN, TP and C/N were in the following order: enclosure>G_0.50>G_0.94>reclamation>G_1.25. The contents of soil organic carbon and TN of the fenced enclosure were significantly higher than that of G_0.94, G_1.25 and the reclamation land (P<0.05). The contents of SOC, TN, TP and C/N showed a gradually decreasing trend with the increase of stocking rates. Grazing and reclamation significantly decreased the contents of DOC, ROC and MBC when compared to enclosure (P<0.05). The contents of SOC and soil active organic carbon decreased gradually with the increase of stocking rates. In general, the allocation proportion of active organic carbon increased in 0-20 cm soil layers after 4 years of fenced enclosure in the S. klemenaii steppe, whereas it decreased after grazing and reclamation. The MBC/SOC of the fenced enclosure was significantly higher than that of grazing and reclamation (P<0.05). The contents of SOC, DOC, ROC and MBC had a significant positive relationship with each other (P<0.05). Soil active organic carbon and soil physical and chemical properties had a close relationship. These results indicate that fenced enclosure enhances soil quality and improves the S. klemenaii steppe environment.

Soil nutrient characteristics of different land-use types in the Three Gorges Reservoir

QIN Chuan, HE Bing-Hui, JIANG Xian-Jun

2016, 25(9):  10-19.  DOI: 10.11686/cyxb2015528

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This study explores variations in soil organic matter, pH value and nutrients in soil under different land-use types in the Three Gorges Reservoir Area. Four different land-use types, including sloping farmland (PG), plantation (RG), barren grassland (HC) and economic forest (JG) in Zhuxi Town of Kaixian County in Chongqing, were selected as the study sites. Three 10 m×10 m sample plots were chosen for each land-use type and soil sat the 0-20 cm layer were collected with “S” shape samples in each plot. Chemical analysis was undertaken to determine soil pH, soil organic matter (SOM) and contents of N, P and K. The results showed that SOM content and pH were not significantly different among four different land-use types. SOM results were in following order: RG (24.99±2.34 g/kg)>JG (19.71±1.89 g/kg) >HC (13.72±1.79 g/kg)>PG (10.20±0.69 g/kg). Soil pH value was the highest in PG (7.19) and the lowest in RG (5.67). Total nitrogen content varied from 0.55 g/kg to 1.38 g/kg, and available nitrogen content in RG soil was significantly different from PG, HC and JG. Total nitrogen content had a very significant positive correlation with organic carbon. C/N varied little under the four land-use types. Total phosphorus and total potassium contents followed similar trends. Total phosphorus content ranged from 0.41 g/kg to 0.59 g/kg, with significant differences between JG and RG. However, available phosphorus and available potassium showed no significant differences between these two land-use types, while total potassium content ranged from 3.73 g/kg to 21.43 g/kg. The pH value was very significantly negatively correlated with soil organic matter, total nitrogen and available nitrogen, and also significantly negatively correlated with available potassium, but was significantly positively correlated with total phosphorus and total potassium. Soil organic matter had a very significant positive correlation with total nitrogen, available nitrogen, available phosphorus and available potassium. These results provide important information for the determination of rational land-use patterns, fertilizing modes and land-use structure adjustment plans that aim to maintain and enhance soil fertility and productivity.

Age structures of modules in a Calamagrostis epigejos population in single-species dominant patches in the Songnen Plain of China

ZHANG Lu-Dan, LI Hai-Yan, YANG Yun-Fei

2016, 25(9):  20-27.  DOI: 10.11686/cyxb2016065

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Calamagrostis epigejos is a typical clonal rhizomatous plant. It always forms mono-dominant patches in the meadows of the Songnen Plain, China. In this research, a survey of age structures of plant modules was conducted in the late growing season of 2013 and 2014 and analysis was carried out. Age structures of ramets, rhizomes, daughter ramets and buds were classified according to the generation of vegetative propagation. Vegetative propagative ability was calculated by the ratio of the total buds or daughter ramets to total ramets or rhizomes and storage ability of rhizome was calculated by the ratio of rhizome biomass to its length in C. epigejos populations. It was found that ramets in C. epigejos population consisted of two age classes (1st and 2nd age class) and the proportion of number and biomass on 1st age class of ramets was higher than 80%, which was an increasing age structure. Rhizomes could be grouped into three age classes (1st, 2nd and 3rd age class) and the proportion of accumulate length and biomass was the greatest (more than 40%) on 2nd age class, which age structure was stable. Ramet productivity (ramet biomass/ramet number) of 1st age class was 4% higher in 2013 and 21.6% higher in 2014 than 2nd age class, so ramets on 1st age class had greater contribution to the population. Storage ability of rhizome on 1st age class was the highest, so rhizomes on 1st age class were the main storage part of the underground nutrients. Potential population include daughter ramets, tiller buds, apical rhizome buds and nodal rhizome buds, and the 1st age class tiller buds was dominant, which it was a stable age structure. The vegetative propagative ability of ramets was significantly higher than rhizomes. Comparing the two years of rainfall, the growth of 2nd age class modules was more sensitive to the extreme drought in 2014 than others.

Grain-filling characteristics and accumulation dynamics of nitrogen, phosphorus and potassium in high-yield winter wheat cultivars under limited irrigation and nitrogen supply

ZANG He-Cang, ZHANG Ying-Hua, ZHANG Xing-Juan, CAO Lian, WANG Zhi-Min

2016, 25(9):  28-36.  DOI: 10.11686/cyxb2016095

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Irrigation-nitrogen regulation is one of the most important measures to increase crop yield in agricultural production. The two main local winter wheat cultivars, Jimai 22 and Shimai 15, were used in a field experiment to investigate their grain-filling characteristics and nitrogen, phosphorus and potassium accumulation dynamics under limited irrigation and nitrogen in the North China Plain. The experiment was carried out at the Wuqiao experiment station of China Agricultural University in the 2009-2010 growth seasons. There were two irrigation treatments: W₁ (spring irrigation at jointing stage) and W₂ (spring irrigation at jointing and anthesis stages); and two nitrogen fertilizer treatments: N₁ (192 kg/ha) and N₂ (270 kg/ha). The results showed that at the grain-filling stage the grain weight of superior and inferior spikelets for both cultivars presented a “S” variation tendency, whereas the grain-filling rate presented a parabola variation tendency. The grain weight and grain-filling rate of superior spikelets was significant higher than inferior spikelets in both cultivars. Under the same irrigation level, grain-filling durations of superior and inferior spikelets in the N₁ treatment were higher than N₂, whereas the grain-filling rate was contrary. Under the same N level, the grain-filling durations of superior and inferior spikelets in W₂ was higher than W₁. Under different irrigation and nitrogen regimes, grain weight, grain-filling rate and durations of superior and inferior spikelets of Jimai 22 were higher than Shimai 15. During the grain-filling period, grain nitrogen, phosphorus and potassium accumulation amounts present a “S” variation tendency in both cultivars. Under the same irrigation level, grain nitrogen, phosphorus and potassium accumulation amounts in the N₂ treatment were higher than N₁. Under the same N level, grain nitrogen, phosphorus and potassium accumulation amounts in the W₂ treatment were higher than W₁. Under different irrigation and nitrogen regimes, the grain nitrogen, phosphorus and potassium accumulation amounts of Jimai 22 were higher than Shimai 15. The results suggest that moderate irrigation and nitrogen supply enhances the grain-filling rate of superior and inferior spikelets at the late grain-filling stage, prolongs grain-filling durations, promotes balance filling of superior and inferior grains and equilibrium in the distribution of nutrient elements, improves grain weight and quality, producing in sum high yield gains and efficiency.

Allelopathic effects of leaf-stem litter water aqueous extracts of three plant species on tobacco seedlings

ZHAO Xin-Mei, WANG Jun, MO Jing-Jing, YANG Shui-Ping, WEN Ming-Xia, ZHANG Xue, ZHAO Jian, CHEN Da-Xia, JIANG Wei

2016, 25(9):  37-45.  DOI: 10.11686/cyxb2016104

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Tobacco, and the two Chinese herbal medicine crops Scrophularia ningpoensis and Chuanminshen violaceum, all present husbandry difficulties under continuous cropping systems, and allelopathic effects are considered to be a significant contributing factor. There have been relatively few studies of auto-allelopathy in tobacco crops or of allelopathy between tobacco and the Chinese herbal medicine crops S. ningpoensis and C. violaceum. To investigate problems arising in continuous cropping of tobacco, a study was conducted on leachate effects on seedlings. Flue-cured tobacco K126 and 1 year old leaf and stem litter were used to prepare aqueous extracts of leachates of tobacco (LeT), and leaf and stem litter were also used to prepare aqueous extracts of S. ningpoensis (LeS), and C. violaceum (LeC), with pure water as control. Treatment concentrations were 0.01, 0.02, 0.05, 0.10 mg/L. LeT had an inhibitory effect on seedlings below ground and above ground growth, as indicated by elevated antioxidant enzyme activity. For LeS the highest concentration of 0.10 mg/L showed significant inhibition, while the lowest concentration of 0.01 mg/L had a stimulatory effect. Meanwhile, LeC had little impact on tobacco seedlings, or tended to induce positive growth promotion effects. Following application of the aqueous extracts of S. ningpoensis and C. violaceum, SOD, POD, CAT activities were increased with increasing concentration of the extracts, and soluble protein, initial chlorophyll fluorescence (F₀), the maximum enhanced fluorescence (F_m), variable fluorescence (F_v), PSⅡ potential photochemical activity (F_v/F₀), and PSⅡ maximum photochemical efficiency (F_v/F_m), also showed better adaptation. Therefore, S. ningpoensis and C. violaceum may be an alternative rotation or intercropping plant species for tobacco, and intercropping may help ease husbandry problems encountered in continuous cropping of tobacco.

Seed germination and physiological responses of Vicia costata under saline-alkali stress conditions

LI Li, ZHANG Yi-Gong, JIANATI, LI Xue-Sen

2016, 25(9):  46-53.  DOI: 10.11686/cyxb2016023

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The effects of NaCl (0, 50, 100, 150, 200 mmol/L) and Na₂CO₃ (0, 10, 20, 30, 40 mmol/L) stresses on seed germination and early seedling metabolism were studied in Vicia costata. Parameters measured included: soluble sugar, proline, malondialdehyde, and superoxide dismutase (SOD) and peroxidase (POD) antioxidant enzyme activities. Key results were: 1) Seed germination rates were significantly reduced under both types of stress, but germination reduction under Na₂CO₃ stress was much greater than under NaCl stress; 2) Concentrations of MDA and proline increased under both kinds of stress, but increases associated with Na₂CO₃ stress were much greater than with NaCl stress; 3) The activities of SOD and POD were increased at low stress and decreased at high stress, but the decease under high NaCl stress was small; 4) The soluble sugar concentration was increased under Na₂CO₃ stress, but under NaCl stress was increased at low stress and decreased at high stress. In summary, the inhibition of Vicia costata under Na₂CO₃ stress is much greater than under NaCl stress. This research provides data about this forage species that will assist with the formulation of crop husbandry guidelines.

Effects of different forms of nitrogen on the growth and physiology of Tamarix ramosissima seedlings under water stress

LV Hao-Hao, MA Xiao-Dong, ZHANG Rui-Qun, ZHONG Xiao-Li, ZHU Cheng-Gang, YANG Yu-Hui

2016, 25(9):  54-63.  DOI: 10.11686/cyxb2016064

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Tamarix ramosissima is a dominant species in the lower reaches of the Tarim River, and plant survival and growth is affected by a double stress of nutrient and seasonal water deficit in the sandy soils in this locality. More detailed information on the stress responses of this species will assist the process of ecological restoration in the Tarim River lower reaches. Four soil watering regimes (D₁-20%, D₂-35%, D₃-50% and D₄-75% of relative field capacity) and two forms of fertilizer N; KNO₃ (N₁) and NH₄Cl (N₂) were provided in order to explore drought stress and nitrogen responses. Changes in plant growth and photosynthetic physiological traits were measured shortly before flowering. Key results were: 1) Water is the main limiting factor for growth of T. ramosissima seedlings, and an increase in plant height occurred with the enhancement of N supply. For D₁, ammonium nitrogen significantly affected plant height, but nitrate nitrogen was more significant for D₄. 2) When seedlings were subjected to water stress, the two forms of nitrogen affected chlorophyll content differently. At higher soil moisture content in D₂ and D₃, chlorophyll b was increased more by ammonium nitrogen supply than chlorophyll a. At D₃, the nitrate nitrogen was only increased the contents of chlorophyll a. 3) With enhanced N supply, we found an increase in photosynthetic efficiency (φ_PS(Ⅱ)-quantum yield of PSⅡ and ETR-estimated electron transport rate). At D₁ and D₃ the effect of ammonium nitrogen was more significant, but at D₂ the effect of nitrate was more significant. 4) Ammonium nitrogen was more easily absorbed by the root to promote total biomass accumulation, and nitrate nitrogen significantly increased the total biomass of seedlings only in the D₄ soil water regime. With enhancement of N supply, the specific root length decreased significantly when the soil water content is D₂ and D₃, it indicated that aboveground biomass of plant occupied more assignments. Under reduced water supply, the root:shoot ratio of nitrate nitrogen was significantly increased, and captured nitrogen appears to have been consumed by growing roots. With adequate water (D₃), ammonium nitrogen effects root:shoot ratio was significantly decreased, and the N appears to have been used to increase crown diameter. Therefore, water is the key factor in management of T. ramosissima seedlings, and when seedlings absorb nitrogen, the combined effect of water and nitrogen can improve seedling photosynthesis and growth and allow the seedlings to grow successfully in these undesirable surroundings.

Auxin signaling pathways respond to low-nitrogen stress as revealed by metabolomic profiling analysis in tall fescue

LI Xiao-Dong, SHU Jian-Hong, WANG Qian, CHEN Ying, WU Jia-Hai, CAI Yi-Ming, WANG Xiao-Li

2016, 25(9):  64-73.  DOI: 10.11686/cyxb2015542

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Nitrogen is indispensable for plant growth and development. We can increase yield in many crops using nitrogen application, however, excessive application of nitrogen fertilizer is uneconomic and harmful to the environment. Forages generally suffer more severe nutrition stress than other crops. In this study, metabolites were analyzed with LC-ESI-MS (liquid chromatography-electrospray ionization-mass spectrometry) in tall fescue leaves under normal and low-nitrogen stress conditions. A total of 1424 and 1251 metabolites were detected in the two groups respectively using OPLS-DA (orthogonal partial least squares discriminant analysis). Thirteen major metabolites were identified through a search of public databases, including auxin (indole acetic acid, IAA). Eight genes related to auxin signaling were up-regulated by nitrogen stress, detected using quantitative real-time PCR (qRT-PCR). The IAA concentration was elevated in tall fescue leaves after nitrogen stress, detected by enzyme-linked immuno sorbent assay (ELISA). Our research provides valuable information for studying the mechanisms of the response of tall fescue to low nitrogen. The results suggest that application of IAA could be used to alleviate the harmful effects of nitrogen deficiency.

Antioxidant enzyme activity and gene expression in creeping bentgrass under salt stress

XIAO Guo-Zeng, TENG Ke, LI Lin-Jie, CHAO Yue-Hui, HAN Lie-Bao

2016, 25(9):  74-82.  DOI: 10.11686/cyxb2016107

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The aim of this research was to investigate the antioxidant enzyme activity and gene expression mechanisms in creeping bentgrass (Agrostis stolonifera) under salt stress. Two different salt-resistant creeping bentgrass cultivars, Penncross and SeasideⅡ, were treated with 0 (CK) and 200 mmol/L NaCl solutions. The activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) were measured. The qRT-PCR primers for the CytSOD, FeSOD, CAT, APX and POD genes of creeping bentgrass were designed using partial gene segments, which were identified with homology cloning techniques. The gene expression levels of CytSOD, FeSOD, CAT, APX, and POD were measured and the activities of antioxidant enzymes and gene expression of the two different salt-resistant creeping bentgrass cultivars were analyzed. Salt stress had different effects on antioxidase activities and gene expressions on the two creeping bentgrass cultivars. At the beginning of salt stress, SOD activity of salt-sensitive Penncross was higher than that of salt-resistant SeasideⅡ. However, in the later stages of the treatment, the activity of Penncross SOD declined dramatically while the activity of SeasideⅡ SOD declined slowly and tended to be relatively stable, during which the activity of SeasideⅡ SOD was significantly higher than Penncross. The activities of CAT, APX and POD increased with salt treatment. The CAT and APX activities of Penncross were lower than those of SeasideⅡ, while POD activity was not different. Under the salt treatment, CytSOD, CAT, APX and POD expression of Penncross increased while FeSOD expression decreased. For SeasideⅡ, gene expression of the five antioxidases increased; CytSOD, FeSOD, CAT and APX gene expression were significantly higher in SeasideⅡ than Penncross, but POD was not different. The relative expression levels of CytCu/ZnSOD, CAT, APX and POD genes changed consistently with enzyme activities, but the relative expression level of the FeSOD gene in Penncross was not consistent with enzyme activity.

Anatomical mechanism of Melilotus officinalis tolerance to NaHCO₃ aline-alkaline stress

ZHANG Yong-Mei, TIAN Chen-Xia

2016, 25(9):  83-95.  DOI: 10.11686/cyxb2015447

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Salinization and alkalization of soil is one of the ecological factors seriously limiting agricultural production. This study investigated the adaptive mechanisms of salt-tolerant plants to help make full use of the abundant halophyte resources to improve the utilization of vast areas of saline and alkaline soil. Seedlings of Melilotus officinalis were treated with NaHCO₃ solution at three concentrations, 0 (control), 150 and 200 mmol/L. The anatomical structure of three organs (roots, stems and leaflets) and ultrastructure of two organelles (chloroplast and mitochondria) were observed using paraffin sections and ultrathin sections. The results showed that NaHCO₃ treatments significantly affected the vascular system of M. officinalis. With NaHCO₃ treatments, vascular tissue throughout the roots, stems and leaflets of seedlings were smaller. In particular, the diameter of xylem vessels was drastically reduced which greatly limited the transportation and transverse diffusion of water. The cross section of stems was changed from near quadrangle to irregular shape, which increased the surface area of the stems and furthered opportunity for photosynthesis. Epidermis cell wall cutinization occurred and the diameter of xylem vessels in vascular bundles greatly decreased which reduced water loss through stomata and non-stomata pathways. Chloroplast in stems and leaflets and mitochondria in root tissue were only slightly damaged. Thylakoid in chloroplasts and ridges in mitochondria still had an intact membrane system and a sharp-edged laminated structure. All changes indicated that structural integrity of organelles was protected by active structural morphological changes in M. officinalis tissue under saline and alkaline stress.

Genetic diversity of ten Vicia unijuga populations by ISSR markers

CHEN Hui, YANG Hui, QIANG Wei-Ya

2016, 25(9):  96-103.  DOI: 10.11686/cyxb2015547

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Inter-simple sequence repeat (ISSR) markers were used to investigate the genetic diversity within and among ten natural populations of Vicia unijuga. Ten ISSR primers generated 115 discernible DNA bands, of which 110 (95.65%) were polymorphic. On average each primer produced 11.5 bands, including 11 polymorphic bands. At the species level, high genetic diversity was detected-PPB (percentage of polymorphic loci): 95.65%; Nm (gene flow): 0.4553; Gst (genetic differentiation coefficient): 0.5283; Hs (gene diversity in subdivided populations): 0.2632. However, relatively low genetic diversity existed within populations; the percentage of polymorphic loci rate ranged from 24.35% to 48.70%. A relatively high level of genetic differentiation among populations was revealed by Shannon’s information measure (0.4046) and analysis of molecular variance (AMOVA, 0.5051). The results showed that the ten populations of V. unijuga had high genetic diversity, but among the populations a certain degree of genetic differentiation had occurred: the genetic differentiation among populations was higher than within populations. The results suggest that environmental pressure has a selective relationship with genetic diversity. Low environmental pressure in Yantai and high environmental pressure in Hezuo regions were associated with high levels of genetic diversity, but in the medium pressure regions there was low genetic diversity. This study suggests an important relationship between V. unijuga genetic evolution and the environment and can also be used as a reference for working with genetic resources and breeding.

Uniformity analysis of DUS traits of different orchardgrass (Dactylis glomerata) varieties

WANG Xin-Yu, JIANG Lin-Feng, ZHANG Xin-Quan, HUANG Lin-Kai, LI Ning, WANG Peng-Xi

2016, 25(9):  104-116.  DOI: 10.11686/cyxb2015513

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Orchardgrass (Dactylis glomerata) is a globally important perennial forage grass. The objectives of this study were to optimize the guidelines and formulate the standards for distinctness, uniformity and stability (DUS) tests of orchardgrass to fit Chinese conditions. Thirty DUS characters from 9 varieties were utilized for DUS testing over two consecutive years. The results indicated that quality characteristics were consistent over both years apart from spindle base branch number. The expression of 7 pseudo-qualitative characteristics was also consistent. There were significant differences (P<0.01) among quantity characteristics especially plant height, second leaf ligule width and green yield. The qualitative characteristics were affected by environment; the mean coefficient of variation for qualitative characteristics ranged from 26.3% (‘Grasslands Wana’, 2013) to 48.2% (‘01472’, 2014). The uniformity of quality characteristics and pseudo-qualitative characteristics is higher than the uniformity of quantity characteristics. In general, ‘Baoxing’, ‘Gulin’ and ‘Cambria’ could be used as example varieties because of their lower coefficient of variation and more stable qualitative characteristics.

AFLP analysis of genetic differences among elitehybrid potato lines

WANG Dan, YU Xiao-Xia, YU Zhuo, JIANG Chao, SHI Yue

2016, 25(9):  117-124.  DOI: 10.11686/cyxb2015522

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To identify heredity differences among 17 elite hybrid lines selected from three cross combinations of ‘1867’בLongshu.7’, ‘MB09’בLongshu.7’ and ‘MB09’בLongshu.6’ potatoes, we used four parent lines as controls and analyzed genetic differences using AFLP molecular markers. A total of 321 loci were amplified using 10 AFLP primer pairs, of which 277 were polymorphic, accounting for 87.29% of all loci. The experiment established an AFLP fingerprint map of elite hybrid lines. The average polymorphism information content (PIC) from 21 samples was 0.5617; Nei’s gene diversity index was 0.3623 and the Shannon information index was 0.5407. The average genetic distance (GD) of the tested lines was 0.5281 and were classified into four categories based on a GD value of 0.51: ‘1867’, A-10, A-12, A-21 and A-29; ‘Longshu.6’, ‘Longshu.7’, A-14, A-23, A-26, B-13 and B-14; ‘MB09’, B-1, B-2, B-7, B-15, B-20 and C-22, and C-2 and C-21. This study provided a basis for selection and utilization of potato hybrid parents and breeding of new hybrid varieties.

Analysis of actin sequences from Epichloё endophyte in Festuca sinensis

KUANG Yu, WANG Jian-Jun, XU Wen-Bo, TIAN Pei

2016, 25(9):  125-131.  DOI: 10.11686/cyxb2015339

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This study detected Epichloё endophyte in the seeds of eight collections of Festuca sinensis, collected from Qinghai, Gansu, Sichuan and other parts of China, with an infection rate of 100%. This provided excellent material to evaluate the taxonomic status of Epichloё endophyte in F. sinensis. A phylogenetic tree was constructed with actin gene sequences by cloning from the collected F. sinensis seeds and comparison with published actin gene sequences downloaded from GenBank. The actin sequences of Epichloё endophyte strains isolated from the eight F. sinensis accessions were clustered together and formed a separated clade, which suggests that endophyte strains in different F. sinensis accessions belonged to the same taxon, but may be a new species. Moreover, population genetic distance analysis also confirmed these 8 Epichloё strains to be conspecific. The phylogentic tree also distinguished Epichloё endophyte strains isolated from F. sinensis at the same or nearby sampling sites from strains collected from more distant sites. In summary, the findings indicate a possible new species of Epichloё in F. sinensis, with distinct strains at geographically different sampling sites.

Efficacy of fungicides for control of head smut (Sporisorium destruens) in broomcorn millet

LIU Jia-Jia, ZHOU Yu, ZHANG Pan-Pan, CHAO Gui-Mei, ZHU Ming-Qi, FENG Bai-Li

2016, 25(9):  132-141.  DOI: 10.11686/cyxb2015514

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Six fungicides potentially useful for control head smut in broomcorn millet (Panicum miliaceum) were assessed for toxicity and field efficacy against Sporisorium destruens by assessing teliospore germination on agar medium in a laboratory and the growth of broomcorn millet in the field over two seasons. The results of laboratory toxicity tests showed that tebuconazole exhibited the greatest inhibition of S. destruens, with the EC₅₀ (median effective concentration) value of 0.1127 μg/mL, followed by diniconazole, difenoconazole, thiophanate-methyl and carbendazim with the EC₅₀ values of 1.0634, 6.1775, 12.4969 and 54.4021 μg/mL, respectively. Thiram showed the lowest toxicity with the EC₅₀ value of 1169.6448 μg/mL. Compared with the control (no fungicide), fungicide treatments significantly decreased the germination rate and vigor of broomcorn millet seeds. Diniconazole reduced germination and vigor the most. The results of field efficacy trials were similar; tebuconazole had the best control efficacy, followed by diniconazole, thiophanate-methyl and carbendazim. The control efficacy of difenoconazole was good only at high concentration. Thiram had the poorest control efficacy. Carbendazim significantly reduced the area of the second and the third leaf, dry weight of leaves and the number of tillers. Compared with the control, all fungicide treatments reduced grain weight but increased the grain yield. Broomcorn millet yields following tebuconazole application were the highest in both years, while thiram didn’t significantly increase yield in 2014. In summary, tebuconazole produced the best control efficacy at the lowest application rate and could be used for broomcorn millet production.

Effects of efficient microbial deodorizer in livestock manure composting and its deodorizing mechanism

ZHANG Sheng-Wei, HUANG Wang-Zhou, YAO Tuo, YANG Qiao-Li, WANG Peng-Fei, LI Sheng-Gui, YAN Zun-Qiang, GUN Shuang-Bao

2016, 25(9):  142-151.  DOI: 10.11686/cyxb2015388

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To explore a new method of controlling environment pollution from malodorous gas produced by livestock manure, several previously isolated efficient deodorizing and cellulose-decomposing microbes strains were grouped optimally as a compound microbial deodorizer; their effects on odor and compost characteristics during livestock manure composting were assessed. The dynamic changes and emissions of nitrogen and sulfur were analyzed during composting to explore the deodorizing mechanisms of the compound mix. The results showed that the compound microbial mix had outstanding deodorization capability with increased removal rates of NH₃ and H₂S to 70% and 60% respectively in the first 20 days, reduced pH, moisture content and carbon-nitrogen ratio, rapidly improved stack temperature and extended high temperature period of compost. Stack temperature of pig manure and chicken manure reached the highest value after 25 and 20 days respectively and the period above 50 ℃ was maintained for 15 and 20 days, respectively. At the end of composting microbial deodorization reduced 25.84% and 28.65% N-loss of swine and chicken manure respectively and significantly increased (P<0.05) total nitrogen (TN) and nitrate nitrogen (NO₃^--N) in composts compared with natural composts. The microbial deodorizer promoted sulfur transformation into inorganic sulfur (SO₄^2-) and significantly increased (P<0.05) the SO₄^2- content. These results suggested that microbial deodorizers were able to efficiently reduce odor, reduce nutrient losses and accelerated compost maturity of livestock manure, as well as help amelioration environmental pollution.

Effects of microecological agents on the fermentation quality, nutrition composition and in situ ruminal degradability of corn stalk silage

TAO Lian, FENG Wen-Xiao, WANG Yu-Rong, DIAO Qi-Yu

2016, 25(9):  152-160.  DOI: 10.11686/cyxb2015511

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A study has been undertaken to investigate the effects of probiotics on the fermentation quality, nutrition composition and in situ ruminal degradability of corn stalk silage. Green corn stalk without ears (dry matter=42%-44%) was chopped to 2 cm lengths and then 1 kg of chopped corn stalk was packed with additives (zymin, fungus-preparation, and a mixture of the zymin and fungus-preparation) in polyethylene bags (24 cm×40 cm) using a vacuum packager. After 45 days of fermentation at room temperature, the corn stalk silage’s fermentation quality, nutrition composition and in situ ruminal degradability were analyzed using laboratory chemical methods and in situ technology. The results showed that, compared to the control, the pH value and ammonia nitrogen (NH₃-N) content of the two lactobacillus (LAB₁ and LAB₂) treatments decreased (P<0.05), whereas contents of lactate acid (LA), organic matter (OM), water soluble carbohydrates (WSC), and the in situ ruminal degradability of DM, OM and crude protein (CP) increased significantly (P<0.05). The addition of lactobacillus increased WSC content (P<0.05) compared with the control and cellulase treatments. Compared with the control, the pH value, NH₃-N content, neutral detergent fiber (NDF), acid detergent fiber (ADF), and cellulose content of the cellulase treatments (CE₁ and CE₂) significantly decreased (P<0.05). Furthermore, the acid detergent lignin (ADL) content had a decreasing trend (P>0.05). The mixture of cellulase and lactobacillus treatments (MCL₁ and MCL₂) had the lowest pH value and the highest in situ degradation of NDF and cellulose compared with other treatments (P<0.05). In addition, in situ degradation of ADL increased but did not reach significance (P>0.05). Compared with the control, the NDF, ADF and cellulose contents of the cellulase and lactobacillus mixture treatments significantly decreased (P<0.05). In conclusion, the application of cellulase and lactobacillus mixtures to the fermentation of corn stalk contributed to the breakdown of lignin-cellulose-hemicellulose composite structures and the improvement of fermentation quality, which consequently resulted into high nutrient digestibility and utilization efficiency. The MCL₂ treatment had the best effect in this regard.

Study of associative effects of wheat straw mixed with rice bran meal on in vitro fermentation parameters

MENG Mei-Juan, TU Yuan-Lu, BAI Yun-Feng, YAN Shao-Hua, GAO Li-Peng, LIU Ping

2016, 25(9):  161-172.  DOI: 10.11686/cyxb2015516

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This study used an in vitro gas production technique to investigate the associative effects of wheat straw (WS) and rice bran meal (RBM), on the fermentation characteristics of WS mixed with RBM at rations of 100:0 (RBM0), 75:25 (RBM25), 50:50 (RBM50), 25:75 (RBM75) and 0:100 (RBM100). Key results were:1) For gas measurements, 12, 24 and 48 h gas production (GP), maximum theoretical (HM) and rate of biogas production (B) increased while the lag time reduced incrementally (P<0.05) with the percentage of RBM added; 2) The RBM25 group had the highest positive associative effects for B (P<0.05); 3) For dry matter degradation (DMD), neutral detergent fiber degradation (NDFD) and acid detergent fiber degradation (ADFD),the RBM75 group had the highest values (P<0.05), while for DMD, the RBM25 group had the highest positive associative effects (P<0.05). For NDFD and ADFD, the RBM75 group had the highest positive associative effects (P<0.05); 4) With the RBM75 mixture, the acetate, propionate, butyrate and total volatile fatty acid production were highest, and acetate:propionate was the lowest; 5) For the 48 h GP, B was positively related to dry matter (DM), crude protein (CP), crude ash (Ash) and neutral detergent soluble (NDS) (P<0.01), but was negatively related to neutral detergent fiber (NDF), acid detergent fiber (ADF), organic matter (OM), hemicellulose (HC) and NDS/CP (P<0.01); HM was positively related to DM, CP, Ash, NDS (P<0.05), but it was negatively related to NDF, ADF, OM and HC (P<0.05); the lag was negatively related to NDS/CP (P<0.01). It is concluded that for B and DMD, the RBM25 mixture gave the best associative effects in this experiment. For fiber degradation rate, a RBM75 mixture gave the best associative effects.

Changes to feeding value and fermentation quality of three C₄ grass species during wilting for silage production

ZHANG Wen-Jie, XU Neng-Xiang, DONG Chen-Fei

2016, 25(9):  173-181.  DOI: 10.11686/cyxb2015539

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The forage nutrient content and fermentation quality of three C₄ forage grass species (Pennisetum purpureum, Sorghum bicolor×Sorghum sudanese and Zea mays) planted in Nanjing, Jiangsu Province, were analyzed after different wilting times, to investigate the patterns of change and formulate scientifically based guidelines for optimal wilting time during silage production. Six wilting treatments (CK, 1.5 h, 3.0 h, 4.5 h, 6.0 h and 7.5 h) were test, and samples from the different wilting treatments were analyzed for feed quality [dry matter content, in vitro dry matter digestibility (IVDMD), nonstructural carbohydrates (NSC), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents], and fermentation quality [pH, lactic acid (LA) and NH₃-N content] were analyzed. The dry matter content of all three C₄ forage grass species increased during wilting, the water content of S. bicolor×S. sudanese and Z. mays decreasing rapidly (P<0.05), while P. purpureum dried slowly and still retained a water content of 75.73% after wilting for 7.5 h. The NSC content decreased during the wilting period, but the water soluble carbohydrates (WSC) and starch which were the main components of NSC showed different time courses: the pattern of WSC change was like an inverted V, with an increase at the start of the wilting process, and then a decrease, while the starch content showed a steady decrease throughout the test period. The optimal wilting time for three C₄ grass species was 7.5 h for P. purpureum, 3.0 h for Z. mays, and 1.5 h for S. bicolor×S.sudanese.

Growth model prediction and trend analysis of Hu sheep and their hybrid progeny in the arid and cold area of northwest China

LA Yong-Fu, XI Rui, LI Fa-Di, WANG Wei-Min, ZHANG Xiao-Xue, LI Chong, LIU Ting, TANG De-Fu, LI Bao-Sheng

2016, 25(9):  182-188.  DOI: 10.11686/cyxb2015404

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In this study, the body weight of 215 Hu sheep and 60 Hu×(Dorper×Hu) hybrid lambs were measured from 0 to 12 months’ age under the condition of barn feeding. The growth process of lambs was matched by Compertz and Logistic models. The growth parameter and estimated value of the models were analyzed to evaluate the hybrid effect of Hu×(Dorper×Hu) hybrid lambs. The results showed that the fitting degrees (R²) of the two models were over 0.96. The fitting effect of the Gompertz model was better than that of the Logistic model. The day of growth inflection points of Hu sheep rams and ewes were 2.55 and 1.73 months, while the weights at inflection point were 17.00 kg and 13.14 kg respectively. The day of growth inflection point of Hu×(Dorper×Hu) hybrid lambs was earlier than that of Hu sheep, and the weights at inflection point were 17.74 kg and 15.80 kg respectively. The cumulative growth pole of Hu×(Dorper×Hu) was significantly higher than that of Hu sheep (P<0.01). These results indicate that the growth speed of Hu×(Dorper×Hu) hybrid lambs is faster than Hu sheep in early stages and that hybrid effects are evident.

Study of the pollen viability and stigma receptivity of Agastache rugosa from different areas

SU Yun-Yun, WANG Kang-Cai, XUE Qi

2016, 25(9):  189-196.  DOI: 10.11686/cyxb2015544

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A study was undertaken to explore the pollen viability, stigma receptivity and pollen morphology of Agastache rugosa from different areas. Pollen viability was evaluated by red ink method; stigma receptivity was evaluated by benzidine-H₂O₂ method; pollen morphology was observed by scanning electron microscopy. The results showed that, the flowering habit was identical in the different areas under natural conditions. The majority of A. rugosa bloomed from July to August; the flowering stage of the populations was approximately 15-28 days and the life span of a single flower was about 3-5 days. The pollen viability of A. rugosa from different areas showed at first an increased and then a decreased trend with the increase of blooming time, with average pollen viability ranging between 18.46% and 26.52%. Among the five areas, the highest average pollen viability was from Chengdu and the lowest from Jilin. The life span of pollen was 4-5 days while stigma receptivity continued for 5-6 days. The stigma of A. rugosa from different areas had receptivity in the first day of blooming and higher receptivity in 2-3 days. This result indicated that the optimum artificial pollination time of different sources of A. rugosa is 2-3 days after blooming. The pollen shapes of A. rugosa from different areas were mainly spheroid and subglobose. The pollen size ranged between 42.93 μm×31.99 μm and 46.59 μm×37.67 μm. With 6 germinal furrows, the shape was long and narrow, almost reaching the poles. The surface emblazonry was netting and the shapes of pollen mesh were mostly irregular polygons to nearly round. These results provided a theoretical basis for the artificial cultivation and elite breeding of A. rugosa in the future.

The effect of dietary NDF levels on blood immune system cells and intestinal characteristics of Rex rabbits at weaning

REN Zhan-Jun, GAO Yu-Qi, WANG Jin-Li, LI Fa-Di

2016, 25(9):  197-203.  DOI: 10.11686/cyxb2015151

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This research evaluated the effect of dietary neutral detergent fiber (NDF) level on blood immune cells and intestinal characteristics of Rex rabbits at weaning in order to define the relationship between dietary NDF and intestinal health, and provide a theoretical basis for diet formulation for Rex rabbits at weaning. Fifty-six newly weaned rabbits (35 d) were randomly assigned into 4 groups (14 rabbits per group with each rabbit considered a replicate for statistical purposes), and the groups received different diets with NDF levels of 29%, 33%, 37% and 41%, respectively. The experiment comprised a 5 d pre-trial period and a 28 d experiment period. Diarrhea rate and mortality were recorded during the entire trial. At the end of the trial, 6 rabbits from each group were slaughtered for sampling of blood and intestinal indicators. It was found that with increasing dietary NDF, the count of white blood cells did not differ between treatments (P>0.05), while the lymphocyte count was significantly increased (P<0.05). sIgA+ cell counts in the duodenum and jejunum were increased with dietary NDF level (P<0.05), but this trend was not observed in the ileum (P>0.05). Moreover, the total number of intestinal bacteria was similar for the 4 treatments (P>0.05). Bacteroides was increased at lower MDF with the 33% NDF group being significantly higher than the other groups (P<0.05). Cecum Lactobacillus and Escherichia coli numbers generally decreased with increasing dietary NDF level: specifically, the 29% NDF group got the highest Lactobacillus count while 41% NDF group had the lowest E. coli number (P<0.05). Furthermore, cecum pH was increased with dietary NDF level while diarrhea rate and mortality were decreased. In summary, among tested treatments, the 41% dietary NDF level optimized the intestinal health of Rex rabbits at weaning.