Table of Content

20 July 2018, Volume 27 Issue 7

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Effects of wild large herbivore populations on the grassland-livestock balance in Maduo County

YANG Fan, SHAO Quan-qin, GUO Xing-jian, LI Yu-zhe, WANG Dong-liang, ZHANG Ya-xian, WANG Yang-chun, LIU Ji-yuan, FAN Jiang-wen

2018, 27(7):  1-13.  DOI: 10.11686/cyxb2017311

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The number of wild large herbivores, including Equus kiang, Procapra picticaudata and Pseudois nayaur was investigated using remote sensing technology or an unmanned aerial vehicle (UAV). The balance of grassland-livestock, including wild and domestic herbivores, was estimated from data (30 m resolution) in Maduo County in 2016 and the effects of wild herbivore population on the balance of grassland-livestock analyzed. The population of large herbivores was estimated from animal density from sample flights, and the results compared with data from summer monitoring. The estimated number of E. kiang, P. picticaudata and P. nayaur were 1.71, 1.60 and 0.93 million respectively, while the number of yak, Tibetan sheep and horses were 7.08, 10.22 and 0.12 million respectively. The number of large wild herbivores present was equivalent to 47.5 million sheep stock units. The ratio of sheep stock units from wild herbivores to the number of domestic herbivores was 1∶4.5. The carrying capacity index of domestic livestock was 1.13, indicating that the grassland was slightly overstocked; the carrying capacity index for wild herbivores was 0.25 and the combined carrying capacity index (1.38) indicated that the grassland was overstocked. Not including wild herbivores in the grassland-livestock balance accounting system resulted in the carrying capacity index being underestimated by 22%. Overstocking is one of the main drivers of grassland degradation in Maduo County; feeding of 79000 tons of hay or reducing livestock numbers by 30% would be required to achieve balance.

Ecological changes in the Minqin oasis belt over the past 20 years

ZHANG Yong, YANG Zi-hui, GUO Shu-jiang, WANG Qiang-qiang, ZHAN Ke-jie, ZHANG Jian-hui, WEI Huai-dong

2018, 27(7):  14-24.  DOI: 10.11686/cyxb2017333

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Three sides of the Minqin oasis are surrounded by sand; the local population has made unremitting efforts to construct an oasis protection system and monitor and evaluate vegetation changes occurring in the protection belt. This study utilized Landsat TM/OLI remote sensing satellite data from 1996, 2006 and 2016 collected during the vegetation growth period in the Minqin oasis protection belt. Using ENVI 5.3 and Arcgis 10.4 as image processing tools, a normalized difference vegetation index (NDVI) for the study area was calculated while a dimidate pixel model (DPM) was used to calculate vegetation coverage to determine the spatial distribution and dynamic changes in different vegetation types in the Minqin Oasis. A decision tree classification technique based on a CART algorithm and combined multivariate data were used to classify land use types, allowing the area of the oasis protection belt and vegetation changes to be estimated. The results showed that compared with 1996, the area of low and high coverage vegetation in 2006 was 32.48% and 27.65% greater, respectively. However by 2016 the area of low coverage and middle and high coverage vegetation had decreased by 26.28% and 24.00% respectively. In addition, the proportion of low, medium and high vegetation had increased by 205.47%, 4.12% and 44.22%, respectively. Over the past 20 years, the area of low coverage vegetation initially increased and then decreased. Land use classification showed that compared with 2006 the area of farmland shelterbelt and dune windbreak in 1996, was 148.68% and 16.47% higher, respectively. The area of farmland protected by shelterbelts in 2016 was 33.99% lower than in 2006 but the area of windbreak and sand stabilizing plantations forest increased by 3.55%. The research revealed that over the last 20 years, the area of low coverage vegetation in the Minqin oasis has been decreasing and that the ecological environment has improved. The area of windbreak and sand stabilizing forest increased rapidly at first and but more slowly latterly.

Effects of nitrogen addition on the stoichiometric characteristics of plants and soil in the Stipa baicalensis grassland of Inner Mongolia, China

LIU Hong-mei, LI Jie, WANG Li-li, ZHAO Jian-ning, WANG Hui, YANG Dian-lin

2018, 27(7):  25-35.  DOI: 10.11686/cyxb2017312

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The objective of this study was to investigate the effects of nitrogen addition on soil and plant carbon (C), nitrogen (N), phosphorus (P) and C∶N∶P ecological stoichiometric characteristics in the Stipa baicalensis grassland of Inner Mongolia, China. The plant study focused on six dominant species: S. baicalensis, Leymus chinensis, Achnatherum sibiricum, Filifolium sibiricum, Melissitus ruthenica and Serratula yamatsutanna. A randomized block design experiment was conducted, with six blocks of five treatments each: N₀ (0 kg N·ha^-1), N₃₀ (30 kg N·ha^-1), N₅₀ (50 kg N·ha^-1), N₁₀₀ (100 kg N·ha^-1) and N₁₅₀ (150 kg N·ha^-1). The results showed that there were significant differences in leaf C, N and P contents and in the stoichiometric characteristics of the six species under natural conditions. Pocockia ruthenica had the highest leaf C, N, and P contents and leaf N∶P, while S. baicalensis had the lowest leaf N and P contents and F. sibiricum had the lowest leaf C content. Leaf C contents did not respond to nitrogen addition in all the six plant species. Leaf N contents, leaf C∶P and leaf N∶P significantly increased but leaf P contents and leaf C∶N decreased with nitrogen addition in five of the species, other than M. ruthenica, which did not respond to nitrogen addition. Soil organic carbon and soil N∶P increased significantly, while soil total nitrogen and soil C∶N showed no significant responses to nitrogen addition. The individual leaf N contents of L. chinensis, A. sibiricum, F. sibiricum and S. yamatsutanna were positively correlated with soil organic carbon and soil N∶P. The leaf N∶P of S. baicalensis, L. chinensis, A. sibiricum and S. yamatsutanna were positively correlated with soil organic carbon and soil N∶P. In conclusion, soil organic carbon, soil N∶P and soil C∶P were the main factors that affected leaf C, N, P contents and the C∶N∶P ecological stoichiometric characteristics of the six plant species, but different species had different responses to nitrogen addition, meaning that long-term nitrogen addition may change the structure of the S. baicalensis grassland ecosystem.

Variation in stomatal characteristics of eight plant species along a soil moisture gradient in alpine meadow of the Dongda Mountains in southeast Tibet

ZHANG Da-cai, ZHU Yu-huai, LI Shuang-zhi

2018, 27(7):  36-46.  DOI: 10.11686/cyxb2017505

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The density, length and width of stomata are plastic, and these traits can vary with the degree of external stress, and thereby provide an important mechanism for adaptation to variation in environmental factors. In order to survey the typical changes in stomatal characteristics across a moisture deficit gradient in an alpine meadow, eight dominant or common plant species of the alpine meadow in southeast Tibet, were chosen for study, and sites representing a ten-step gradient in soil moisture were identified. The results indicated there are 4 types, based on the degree of water dependency. Kobresia macrantha belonged to a helophyte type, and its stomatal density increased with decreasing soil moisture, but stomatal length and guard cell width decreased. Commelina communis, Rheum pumilum, Kobresia humilis and Polygonum viviparum were a ‘high moisture environment’ type, and the variation in stomatal density, length and guard cell width was typically unimodal across the soil moisture gradient studied. Polygonum macrophyllum and Kobresia capillifolia were species of drier environments, and the variation of stomatal density, length or guard cell width was almost opposite to that of the helophyte type. Stomatal characteristics of Kobresia pygmaea, were not significantly related with soil moisture, and it had a wide distributional range along the soil moisture gradient, hence it is a widely adapted type. Each plant species had its own soil moisture optimum, with growth stress evident at higher or lower soil moisture. In summary, numerous relationships between stomatal characteristics and soil moisture were elucidated.

A bibliometric analysis of grass endophytic fungi research in China based on the Web of Science database

SHI Qian, TIAN Pei, NAN Zhi-biao

2018, 27(7):  47-54.  DOI: 10.11686/cyxb2017325

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Articles on grass endophyte fungi published between 1996 and 2016 were identified in the Web of Science database and their bibliometrics analyzed. From 1996 to 2016, grass endophyte fungi research developed rapidly in China. The number of articles published with Chinese authors rose sharply to become 4th ranked in the world. With many articles published in high-level journals, we have achieved remarkable results in this field over the past 20 years. The published research currently focuses mainly on the growth of endophytic fungi, alkaloids, drought tolerance and symbiosis. We argue that future research should focus on taxon evaluation and functional genomics, the comparative genomics of Epichloё, and the development and utilization of biological pesticide from Chinese native grasses.

Anastomosis groups and pathogenicity differentiation of the rice sheath blight pathogen in China

WANG Ai-jun, WANG Na, GU Si-si, ZHAO Wen-juan, LI Ping, ZHENG Ai-ping

2018, 27(7):  55-63.  DOI: 10.11686/cyxb2017316

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In order to confirm the anastomosis groups of rice sheath blight and their pathogenicity in rice-growing areas of China, samples of rice sheath blight were collected from Heilongjiang, Jilin, Liaoning, Henan, Anhui, Zhejiang, Jiangsu, Sichuan, Chongqing, Guizhou, Yunnan, Hubei, Hunan, Guangxi, Guangdong and Fujian in 2015. The pathogens were isolated from the samples using the water agar separation method. The isolated pathogens were then screened and identified according to morphological characteristics, nucleus fluorescence staining and rDNA-ITS sequence analysis. The growth rate, sclerotium structure and number of cell nuclei of pathogen isolates from different regions were compared. The pathogenicity of these pure cultured strains from the infected rice tissues was tested according to Koch’s law. The sixty-one isolates had loose mycelium and were identified as Rhizoctonia solani AG1IA. Mycelia were much branched and diaphragmatic and were multinucleate. Branches were at right angles or close to 45°. Pathogen isolates from different regions displayed different growth rates, sclerotia structures, and numbers of cell nuclei. Pathogenicity tests showed that 16 of the 61 strains could cause symptoms of rice sheath blight. The pathogenicity of isolates from Guangdong, Guangxi, Fujian and Chongqing was much higher than the pathogenicity of other strains.

Cloning and prokaryotic expression analysis of LcMADS12 from Leymus chinensis

JIA Jun-ting, ZHAO Pin-cang, LIU Zhu-jiang, YUAN Guang-xiao, YANG Wei-guang, LIU Shu, CHEN Shuang-yan, LI Xiao-xia, LIU Gong-she

2018, 27(7):  64-72.  DOI: 10.11686/cyxb2017323

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In flowering plants, the E-function genes, which belong to the MADS-box gene family, play central roles in floral meristem and floral organ development. To understand the molecular mechanisms of floral development in Leymus chinensis, a MADS-box gene, LcMADS12, was cloned according to RNA-sequencing data obtained in this research. The LcMADS12 gene contained a 741 bp open reading frame (ORF) which encoded 246 amino acids. Bioinformatics analysis showed that the LcMADS12 encoded an amino acid sequence which did not include signal peptide and the transmembrane region. Multi-sequence alignment and functional domain analysis showed that LcMADS12 had a conserved MADS-box domain and a semi-conserved K region, which was a member of the E-class functional gene SEP subfamily. Phylogenetic analysis showed that LcMADS12 had a 99% homology with wheat TaAGL16, and 86% homology with OsMADS7. Tissue-specific analysis showed that no expression of LcMADS12 gene was detected in the vegetative organs (root, stem, leaf) of L. chinensis. In the floral organ, the expression of LcMADS12 was detected higher in the mature stamen, pistil and palea, and was lower or not expressed in lemma and glume. These results indicate that expression of the LcMADS12 gene is tissue-specific. We suggest that LcMADS12 could play an important role in the reproductive development of L. chinensis. A yeast one-hybrid experiment showed that LcMADS12 had a transcriptional activation function. In addition, a prokaryotic expression vector was constructed and the fusion protein could be expressed highly. The cloning of LcMADS12 and the acquisition of fusion proteins has laid the foundation for further study of the function of this gene.

Effects of ALA application on plant growth, hormone levels, and transcriptome in Leymus chinensis under drought stress

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

2018, 27(7):  73-83.  DOI: 10.11686/cyxb2017482

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Drought stress is an environmental constraint with many ramifications, restricting Leymus chinensis growth and productivity. A pot experiment was undertaken to investigate the influence of foliar applied 5-aminolevulinic acid (ALA), on dry matter accumulation, enzyme activities, hormone concentrations and the transcriptome of L. chinensis under drought (soil water content 50% of field capacity) and well-watered conditions (soil water content 80% of field capacity). Concentrations of ALA tested were: 10, 50, and 100 mg·L^-1, with a pure water treatment as a control. Healthy and uniform-sized seeds of L. chinensis were collected and germinated in a biochemical incubator, and then the seedlings were transferred to pots after one week. When seedlings attained a height of 18-21 cm, ALA was applied at the concentrations indicated above, with a repeat application 7 days later to exploit the full potential of ALA application. The sampling for morphological, physiological, and biochemical attributes was conducted 7 days after the second application. As expected, it was found that drought stress caused a reduction in growth and development of the plant as compared to well-watered conditions. Nonetheless, application of ALA improved plant height, fresh weight, and root activity, and effectively alleviated the damage of drought stress to L. chinensis. The most effective concentration of ALA was 50 mg·L^-1. Furthermore, production of sugars, proteins and N, P and K concentrations in plant tissues were enhanced. These changes might reflect increased activities of metabolic enzymes, such as nitrate reductase, malate dehydrogenase and acid phosphatase. Endogenous hormone concentrations (indole acetic acid, gibberellins, zeatin riboside and abscisic acid) were also increased. The effect of the plant growth regulator ALA on the drought resistance of L. chinensis, and the changes in the physiological indices were mirrored by changes in gene expression. Under drought stress 1373 genes exhibited significantly different expression compared to well-watered plants, with 733 genes down-regulated, and 640 genes upregulated. Comparing the drought stressed control plants with drought stress + ALA treatment, 1315 genes displayed significantly different expression, among which 676 genes were up-regulated. The mechanism of ALA modulation of L. chinensis growth, physiological processes and gene expression needs further research.

Enzyme activity and histological analysis of the abscission zone of Elymus sibiricus

ZHANG Jun-chao, XIE Wen-gang, ZHAO Xu-hong, ZHANG Zong-yu, ZHAO Yong-qiang, WANG Yan-rong

2018, 27(7):  84-92.  DOI: 10.11686/cyxb2017484

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Histological and enzyme activity analysis of the abscission zone of seed from six Elymus sibiricus accessions from the northeast margin of the Qinghai-Tibet Plateau at different stages of seed maturation was undertaken. The results showed that the abscission layer of seeds were present before seed shattering. The abscission layer was composed of 2 to 3 layers of small volume cells, oval in shape and with a compact arrangement. The degree of lignification of these cells was higher than surrounding cells. The lignified cell number of low seed shattering accessions was higher than high seed shattering accessions; low seed shattering accessions did not have an abscission layer at the seed maturity stage. These accessions had a rough fracture surface and an integrated abscission layer structure. High seed shattering accessions developed a clear fracture or abscission layer during seed maturation. These materials had a smooth fracture surface and incomplete abscission layer structure. Changes in cellulase (CE) and polygalacturonase (PG) activity among accessions differed at different seed developmental stages. The activities of these cell wall hydrolases were both closely related to seed shattering; the CE and PG activity of high seed shattering accessions at the time of shattering was high and consistent with electron microscopy observations. The high seed shattering accession (XH09) possessed the highest enzyme activity (XH09_CE=479.52 IU·L^-1, XH09_PG=188.87 pg·mL^-1) during the seed shattering period while the low seed shattering accession (ZHN03) had the lowest enzyme activity. This study showed that there were clear differences in the degree of lignification of the abscission layer, fracture surface smoothness, structural integrity of the abscission layer and the activities of cell wall hydrolases between low and high seed shattering accessions during the critical period of seed shattering. The degree of lignification of the abscission layer and activities of cell wall hydrolases at the seed shattering stage were the most important factors influencing seed shattering in wild E. sibiricus accessions.

Impact of cold-season grazing and supplementary feeding on rumen metabolic parameters and micro-organisms in the ewes of Gansu Alpine Fine Wool Sheep

JIN Ji-peng, GUO Wu-jun, ZHANG Xiao-yan, ZHANG Chang-ji, ZHANG Yong, WANG Chun-hui, ZHANG Li-ping

2018, 27(7):  93-103.  DOI: 10.11686/cyxb2017331

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An experiment was conducted to scientifically identify the appropriate feed for Gansu Alpine Fine Wool ewes in order to change the animals’ breeding mode, which currently can only be mated at the age of 2.5 years due to insufficient nutritional supply. The experiment selected 48 12-month-old ewes and randomly divided them into group a (Diet 1), group b (Diet 2), group c (Diet 3), and a control group with no supplementary feeding. The feed test was run for 90 days. The rumen pH of groups a and b were very significantly higher (P<0.01) or group c significantly lower (P<0.05) than control group. The rumen ammonia nitrogen, protein nitrogen and total nitrogen of groups a, b and c were all higher than control group (P<0.01). The total volatile fatty acids of group a and b were all higher than the control group (P<0.01), group b significantly higher than group c (P<0.05). The molar ratio of acetic acid and propionic acid in group a was very significantly higher than control group (P<0.01), group b and c were significantly higher than control group (P<0.05). The molar ratio of butyric acid in group a was very significantly higher than group c (P<0.01). The ratio of acetic acid and propionic acid in group b was significantly lower than control group (P<0.05). The number of several rumen fiber-degrading bacteria and protozoa in groups a, b and c were very significantly (P<0.01) or significantly (P<0.05) higher than the control. In conclusion, this study shows that supplementary feeding can positively affect the rumen metabolic parameters and the number of several rumen microorganisms in Gansu Alpine Fine Wool ewes. In general, the effects of Diet 1 were the strongest, while Diet 2 also produced notable improvements.

Effects of germplasm and changing temperature on seed germination of Leymus chinensis

YANG Wei-guang, LIU Pan-pan, YUAN Guang-xiao, MAO Pei-sheng, QI Dong-mei, DONG Xiao-bing, LIU Hui, LI Xiao-xia, LIU Gong-she

2018, 27(7):  103-111.  DOI: 10.11686/cyxb2017327

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To clarify the reasons for low seed germination rate, germination of 43 different germplasm lines of sheep grass was studied at constant temperatures of 16, 20, 22, 28 and 37 ℃, and under a variable temperature regime of 28 ℃ (12 h) and 16 ℃ (12 h). It was found that seed germination percentage of sheep grass differed between germplasm lines, with values ranging from 10% to 95%. Seed germination was low under constant temperature conditions, while the alternating 28 ℃/16 ℃ treatment increased the seed germination rate by 50%-90% (P<0.01). Furthermore, the longer the daily high temperature exposure, the higher germination rate was. The seed germination rate was increased very significantly (P<0.01) on 1 day or 2 days of variable temperature treatment, compared with the constant temperature control. However, on the first day of germination, variable temperature less than 2 hours cannot significantly promotes germination, and germination rate improves significantly in 8-12 hours treatments, which considers as the “window period”.

Effect of planting density and phosphorus fertiliser on seed yield of Melilotus officinalis

LUO Kai, ZHANG Ji-yu, WANG Yan-rong

2018, 27(7):  112-119.  DOI: 10.11686/cyxb2017305

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Efficient seed production technology provides the main foundation for ensuring the successful extension of elite cultivars. Field trials were conducted on the Hexi Corridor, Gansu Province, from 2014 to 2016 to determine the effects of different within-row spacing (30, 45, 60 cm) and phosphorus fertiliser application rates (0, 40, 80 and 120 kg·ha^-1 P₂O₅) on seed yield and yield components of two Melilotus officinalis cultivars, Tianshui and Norgold. Seed yield was affected significantly (P<0.01) by within-row spacing, fertilizer rate and their interactions. The 60 cm within-row spacing and fertilizer rate of 80 kg·ha^-1 P₂O₅ produced the highest mean seed yield over 2 years in Tianshui; 1234 kg·ha^-1. The highest seed yields in Norgold were produced by 80 P₂O₅ kg·ha^-1 and 45 cm within-row spacing resulting in seed yields of 1613 and 1428 kg·ha^-1 in 2015 and 2016, respectively. Path coefficient analysis indicated that, among the seed yield components, the number of fertile shoots had the greatest influence on seed yield.

Structural characteristics of the inflorescence and grain traits of triticale and rye corn

LIU Han-cheng, TIAN Xin-hui, DU Wen-hua

2018, 27(7):  120-132.  DOI: 10.11686/cyxb2018140

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Morphological characteristics of inflorescences are important factors in seed production performance. In Gramineae, the size of the inflorescence, number of spikelets and florets, and the characteristics of the lemma, palea and awn can influence the development of seeds. Inflorescence characteristics of different lines of triticale (C2 and C35) and rye corn (C13 and C33) were compared. The inflorescence of triticale [(14.30±0.52) cm×(1.24±0.09) cm] was clearly larger than the rye inflorescence [(13.20±0.35) cm×(0.82±0.02) cm)], spikelet numbers in rye corn (30.20±0.79) were higher than that of triticale (21.35±1.47), flowers number in rye was 2 flowers per spikelet with little variation, while flower numbers in triticale did vary ranging from 3-4 flowers/spikelet. Comparisons of flowers from the middle of the inflorescence indicated that the length [(1.27±0.11) cm] and width [(0.26±0.03) cm] of lower glume and the length [(1.30±0.09) cm] and width [(0.23±0.04) cm] of the upper glume in triticale were significantly larger than the length [(1.04±0.05) cm] and width [(0.08±0.01) cm] of the lower glume and the length [(0.94±0.10) cm] and width [(0.06±0.01) cm] of the upper glume in rye (P<0.05). The width [(0.32±0.03) cm], height [(0.24±0.03) cm] of lemma and awn length [(8.35±0.51) cm] in the first flower and the width [(0.35±0.04) cm] and height [(0.25±0.05) cm] of lemma and awn length [(8.37±1.19) cm] in the second flower of triticale was significantly higher than those in rye [(0.26±0.01) cm, (0.25±0.01) cm, (0.15±0.01) cm, (0.17±0.01) cm, (5.50±0.19) cm and (5.18±0.23) cm respectively]. Lemma [(1.35±0.06) cm; (1.37±0.06) cm] and palea [(0.84±0.04) cm; (1.41±0.06) cm] length in the first and second flower in triticale were less than in rye, (1.49±0.05) cm; (1.47±0.05) cm and (1.45±0.05) cm; (1.47±0.04) cm respectively. The number of grains per panicle in triticale [(52.50±1.80) grains] was significantly lower than that of rye (P<0.05) but the grain weight per ear [(2.08±0.04) g], grain weight [(0.04±0.00) g] and grain width [(3.04±0.32) mm] were significantly higher than rye (P<0.01). Triticale grains were oval or elongated oval in shape, pale yellow in colour, plump with a wrinkled epidermis while rye grains were narrowed fusiform with smooth skin and a laurel-green colour. Results of Pearson correlation analysis between flower structure and grain traits of rye and triticale revealed there were positive correlations between seed length and length of the inflorescence and the number of spikelet in the base of the inflorescence (P<0.05), and seed width was significantly positively correlated inflorescence length (P<0.01). Grain weight per ear and the number of grains per spike were significantly correlated with the width of the lower and upper glume (P<0.01), respectively. Seed length in rye positively correlated to glume length of the second flower in the middle spikelet (P<0.05), while grain number per ear and the height of lemma in the second flower of the middle spikelet were negatively correlation (P<0.01). The structural characteristics of triticale and rye inflorescences are important for correctly distinguishing the two and understanding seed production differences.

The effect of sod-culture on orchard soil properties and the floral physiology of olives

JIAO Run-an, JIAO Jian, LI Chao-zhou

2018, 27(7):  133-145.  DOI: 10.11686/cyxb2017330

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This study investigated the sod-culture of olive orchards either intercropped with vetch (Vicia sepium) or with natural grass mulch applied. Measurements were taken of the soils’ physical and chemical properties, enzyme activities and the number of microorganisms. The number of new olive shoots, rate of flower bud differentiation, per inflorescence flower number and a number of other indexes were also measured. The results showed that the sod-culture produced by both vetch intercropping and natural grass mulching improved the soil water content, alkali-hydrolysable nitrogen content, available phosphorus content, soil urease activities, phosphatase and invertase activities. As a whole, the enhancement effect of intercropping with vetch was higher than that of natural grass mulching. Both intercropping with vetch and natural grass mulching improved the content of soil organic matter and reduced soil pH values. Intercropping with vetch reduced catalase activity, while natural grass mulch increased catalase activity. The sod-culture produced by both intercropping with vetch and natural grass mulching increased the number of the soil bacteria, actinomyces and fungi, inhibited new shoot elongation and improved the development of short and middle length bearing branches. This is very beneficial for improving the structure of fruit-bearing branches. Intercropping with vetch also improved the flower bud differentiation rate and the number of flower buds per length of the single branch, and especially the bud differentiation rate in short shoot branches. In conclusion, the sod-cultures produced in olive orchards by both intercropping with vetch and natural grass mulching checked the over-luxuriant growth of new shoots and promoted flower bud differentiation by improving soil properties and fertility levels.

Seed germination and seedling growth responses of Isatis indigotica in five populations from saline environments

WANG Yu, ZHOU Rui-ying, MA Li-min, BAI Yu, GUAN Jia-li, TANG Xiao-qing

2018, 27(7):  145-154.  DOI: 10.11686/cyxb2017322

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Seedlings of Isatis indigotica from five localities [Baoding, Hebei (HB); Baotou, Inner Mongolia (NB); Tie ling, Liaoning (LT); Bozhou, Anhui (AH); Binzhou, Shandong (SB)] were used as research materials, to investigate the seed germination and seedling growth of I. indigotica subjected to pure water (0 mmol·L^-1 NaCl) or three concentrations of NaCl solution (0, 50, 100, 150 mmol NaCl·L^-1). Salt tolerance among the five populations differed significantly. In general, the germination rate, germination potential, germination index and vitality index decreased with increase in NaCl concentration. NaCl at 50 mmol·L^-1 promoted the fresh weight, hypocotyl length and radicle length of I. indigotica seedlings from the HB and SB localities. The same three traits were significantly decreased in seedlings from all five localities under 100 mmol·L^-1 NaCl stress, and malondialdehyde (MDA) concentration increased greatly. The fresh and dry weights of leaf laminae and roots of I. indigotica seedlings from LT and AH localities area were decreased under salt stress at 150 mmol·L^-1 NaCl.With increasing NaCl concentration, the activities of superoxide dismutase (SOD) and peroxidase (POD) and proline contents of I. indigotica seedlings from the five localities increased to a peak at 100 mmol·L^-1 NaCl, with values decreasing somewhat at the 150 mmol·L^-1 NaCl concentration. From a comprehensive appraisal of membership function method, the salt resistance of I. indigotica seeds from the five different localities was ranked: HB>SB>LT>NB>AH.

Effects of aluminum stress on germination characteristics and seedling growth of wild Elymus nutans seeds in Tibet

LIN Yong-he, WU Jing, FANG Jiang-ping, ZHANG Wei-hong, MIAO Yan-jun, LI Yong-sheng

2018, 27(7):  155-165.  DOI: 10.11686/cyxb2017341

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In general, Elymus nutans grows well in hostile environments at high altitudes. Aluminum (Al) stress is one of the serious factors limiting plant productivity in acidic soils. However, studies of the influence of aluminum on this plant are still lacking. The seeds of wild E. nutans from three different areas in Tibet (Naqu, Shenza and Langkazi Counties) were used as materials in this study. The major experimental method involved hydroponic culture with four concentrations of Al³⁺ (0, 0.5, 1.0 and 1.5 mmol·L^-1) under acidic conditions (pH 4.5). In order to provide robust germplasm resources for the improvement of acid-aluminum soil, the effects of Al³⁺ stress on the seed germination and seedling growth were initially explored. Our investigations indicated that there were no significant differences (P>0.05) in the germination rate of the three samples of wild E. nutans seeds at lower concentrations of Al³⁺ stress (0.5 and 1.0 mmol·L^-1) compared to the control, but that results were adverse at higher concentrations (1.5 mmol·L^-1). The results showed that root length, plant height, root weight and shoots’ weight in the three samples decreased with increasing Al³⁺ concentration. In addition, the MDA and soluble sugar contents of seedlings substantially increased with Al³⁺ application. Data showed that Al was poorly translocated from the roots to aerial parts of the three seedling samples. In the treatment groups, the Al content of roots increased 12.2, 15.3 and 17.5 times more than that of the aerial parts. Al toxicity and phosphorus (P) deficiency often co-exist in acidic soils and limit plant growth and crop production. In this study, we observed that Al stress induced a reduction in P accumulation in the plants. Using eight indicators for seedlings under Al stress, we performed a comprehensive evaluation of Al tolerance of the three E. nutans samples and showed that the Shenza County sample was highly tolerant to aluminum and so could be used for domestication and breeding to provide good germplasm resources for the improvement of acid-aluminum soils.

Effects of moisture content and sowing-mix ratio on the quality of baled oat and common vetch/hairy vetch silage mixtures in the pastoral area of southern Qinghai

LI Lei-lei, HUA Deng-feng, ZHENG Xing-wei, LI Cong

2018, 27(7):  166-174.  DOI: 10.11686/cyxb2017326

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In order to provide an optimum reference for local forage production, this experiment evaluated the silage quality of oat-vetch and oat-hairy-vetch sown with different mix ratios and produced with different moisture contents and silage methods in the pastoral area of southern Qinghai. An initial comparison of forage production indicated that mixes of Denmark No.444 oat+Ximu333 vetch and Denmark No.444+hairy-vetch performed the best as silage raw materials. The test was located in the Henan Mongolian Autonomous County (elevation 3600 m, longitude and latitude 34°45' N, 101°34' E) of Qinghai Province. The trial design included different sowing mix ratios (18∶2、17∶3、16∶4、15∶5), moisture contents (40%, 45%, 50%, 55%, 60%, 65%, 70%) and different silage methods (whole silage, chopped silage). Oat-vetch and oat-hairy-vetch seeds were mixed and sown on 20 May 2015. The sowing ratio of 15∶5 oat-vetch produced the highest yields at 12525 kg·ha^-1. The oat and vetch forages were harvested at the milk stage, then wilted and their primary moisture contents tested, with the forages then sprayed to obtain the target moisture contents. Two silage methods were tested-long silage, in which whole plants were baled and ensiled, and short silage, with the forage cut to 3-5 cm before ensiling. All treatments had 6 replicates. Bales were sampled at 150 days after ensiling. Based on the DLG silage evaluation system, there were 35 treatments with sensory scores in the range 20-16 (Quality-level 1), accounting for 50.0% of the total treatments. There were 18 treatments with scores 15-10 (Quality-level 2, 25.7% of the total), 15 treatments with scores 9-5 (Quality-level 3, 21.4% of the total) and 2 treatments with scores 4-0 (Quality-level 4, 2.9% of the total). Of all the 70 treatments, the chopped silage sensory score was at the highest level when the raw material moisture content was in the range of 50%-60%. Silage quality was also evaluated using four indexes: pH value, lactic acid content, crude protein content and AN/TN ratio. The results indicated that in terms of yield, sensory and chemical evaluation, the treatment with sowing mix ratios at 15∶5, moisture contents at 50% and chopped silage, produces the best quality forage.

Effects of tillage system and long term fertilizer application on winter wheat yields

ZHANG Jian-jun, FAN Ting-lu, ZHAO Gang, DANG Yi, WANG Lei, WANG Yong, LI Shang-zhong, CHENG Wan-li

2018, 27(7):  175-186.  DOI: 10.11686/cyxb2017310

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The objective of this research was to determine the effect of tillage method and long-term fertilization on yield of winter wheat in semi humid and semi-arid areas of the Loess Plateau. The study was based on a long-term experiment of tillage and fertilizer conducted for 12 years. A split-plot design was adopted for the experiment, traditional tillage and no tillage were set as the main treatments, and 6 fertilizer treatments [control check (CK), nitrogen (N), phosphate (P), manure (M), nitrogen and phosphate (NP), & nitrogen and phosphate and manure (NMP)] as the sub-treatments. The cultivation system comprised a rotation of 1 year in maize and 3 years winter wheat. Highest wheat yields were produced by application of inorganic and organic fertilizers (NMP). Wheat yields after manure application (M) were significantly higher than NP chemical fertilizer application while the yield from N application was significantly higher than that of P. Under same fertilizer treatments, traditional tillage treatments had higher grain yields than no tillage treatments; yield were highest in high rainfall years, intermediate in normal rainfall years and lowest in dry years. In dry years the increased yields of cultivation and fertilization treatment was significantly higher than wet and normal years, while no significance was found between wet year and normal year. The combination of traditional tillage and NMP fertilizer optimized the canopy temperature and increased the photosynthetic rate, stomatal conductance and transpiration rate, increasing key yield components including number of productive spikes, grain number per spike and 1000 grain weight and resulting in increased yields. In the arid rain-fed planting areas of Eastern Gansu Province (mean rainfall of 550 mm·annumal^-1), the long-term use of organic and inorganic fertilizer or a combined application of N & P had a positive effect on crop yields under traditional tillage, no tillage systems and different years. The combined application of organic and inorganic fertilizers was the best strategy for enhancing winter wheat yields in semi humid and semi-arid areas of the Loess Plateau, eastern Gansu.

Textual research on the utilization of the Republic of China era in the northwest region

SUN Qi-zhong, LIU Qian, TAO Ya, LI Feng, XU Li-jun

2018, 27(7):  187-195.  DOI: 10.11686/cyxb2017399

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Alfalfa has been highly valued since it was introduced to China in the Han dynasty, some 2000 years ago. This paper reviews literature reporting the cultivation and utilization of alfalfa in the Republic of China up to 1949. The sources studied indicate that the northwest of China (including the provinces Shanxi, Gansu, Xinjiang, Suiyuan, Ningxia and Qinghai) possessed the greatest concentration of alfalfa planting during the time of the Republic of China. Based on extracted information from multiple sources dated between 1932 and 1970, 52 counties reported plantings of alfalfa in the Republic of China, in the years leading up to 1949; Shaanxi had the highest number of counties with plantings (22 counties), followed by Gansu (14 counties), and Xinjiang, Suiyuan, Ningxia and Qinghai (8, 3, 2, and 1 counties with plantings, respectively). The increase in alfalfa area was particularly notable in the Shaanxi, Gansu, and Ningxia regions. In 1942, the government organized planting of 2000 ha of alfalfa in Yanan, Ansai, Zhidan, Jingbi, Ganquan, Dingbian, and other counties, and 1500 ha in Longdong county. In 1944, 1300 ha of alfalfa was planted in Yanchuan county, and by 1949, 66000 ha of alfalfa had been planted in Shaanxi province. In addition, alfalfa-grain crop rotations were practiced in the Suiyuan-Hetao area, and through this alfalfa planting expertise was established. From 1941, various policy initiatives of the government in the Shaanxi Gansu Ningxia border region encouraged the development of alfalfa industry. For example, an “Instruction letter of the Government Construction Department of Shaanxi Gansu Ningxia border region on forage grass” was circulated in 1941, and a document “Improving implementation methods” appeared in 1942. In a strategic management plan for the Yellow River, Li Yizhi advocated alfalfa cultivation on account of the agricultural, ecological, environmental and economic benefits. Li Zhuchen noted that the deep root system of alfalfa gave good drought resistance. Alfalfa is more effective than crops in reducing soil erosion. In addition to its value for feeding livestock, alfalfa is suitable for human consumption as a vegetable. This use is more common in times of famine, but alfalfa often appears in the farm produce markets in Lanzhou. Hence, on account of its climatic adaptation and many applications, alfalfa has been widely cultivated in Northwest China.

Progress in understanding of one-step nitrification (complete ammonia oxidizing) microorganisms: A review

SHI Xiu-li, GUO Meng-meng, ZHANG Ying, QIN Hua, WAN Qi-hui, XIE De-ti, JIANG Xian-jun

2018, 27(7):  196-203.  DOI: 10.11686/cyxb2017525

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One-step nitrification whereby the whole process of nitrification from NH₃ to NO3- is completed by one microorganism (complete ammonia oxidizers; comammox), was first reported in late 2015. The discovery of one-step nitrification and comammox, ended a 100-year-old belief that biological nitrification was necessarily a two-step process, and raised many important scientific questions about the implications for the global nitrogen cycle, such as the ecological niche of these microorganisms in the environment and their relative contribution to nitrification. This study briefly reviews the progress in understanding one-step nitrification and comammox during the past two years. The reported comammox are all members of the genus Nitrospira spp. Linage Ⅱ, including two clades (A and B). They are widely distributed in agricultural soils, forest soils, paddy and fresh water environments. The comammox Nitrospira inopinata has a much higher affinity for ammonia than most cultured ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), which confers them a competitive advantage in ammonia-limited environments. This finding changed our view of the potential role of complete ammonia oxidizers in nitrification. Rather than being rare organisms inhabiting peripheral habitats, it turns out that comammox bacteria are well adapted to the low ammonia environments that characterize most of the world’s biosphere. Additionally, the comammox members of Nitrospira possess different C and N metabolism pathways compared to AOA and AOB, and thus may also have different ecological roles or niches in the environment. The relative contribution of one-step and two-step nitrification pathways in different environments and the niche differentiation of comammox will be important fields for future study. So far, only a few ecosystems have been studied for the abundance of comammox, but the studies to date demonstrate that these microbes are widely distributed in low-ammonia environments. There is now an urgent need to determine their contribution to nitrification in other ecosystems. Their abundance in some ammonia-depleted environments is probably due not only to their high affinity for ammonia, but also to other factors, including their ability to grow on substrates other than ammonia, and their low energy requirements.