Acta Prataculturae Sinica

Improving the accuracy of forest identification in mountainous areas from multi-source remote sensing data——the Sunan County section of Qilian Mountains National Park as an example

Jie SONG, Xue-lu LIU

2021, 30(10): 1-14. DOI: 10.11686/cyxb2020496

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The aim of this study was to develop a method to improve the accuracy of identifying mountain forests from multi-source remote sensing data. The Sunan County section of Qilian Mountains National Park was used as the test area. Data from the ICESat/GLAS （geoscience laser altimeter system） space borne LiDAR， Landsat OLI images， Google Earth high-resolution images， digital elevation model data， and field inventory data were used in the classification process. The vertical structure and the spectral， seasonal， and topographic characteristics identified from these data sources were integrated to extract forest information hierarchically. The results show that， after using a physically based terrain correction model to eliminate the influence of terrain on GLAS waveforms， the vertical structure derived from GLAS data combined with spectral information accurately identified forests at medium spatial resolution from remote sensing images of mountainous areas with complex terrain conditions. Compared with the classification based only on spectral characteristics， the classification incorporating vertical structure characteristics showed significantly improved accuracy， with overall accuracy improved by 10.67%. These results show that the vertical structure information provided by GLAS data can enhance the separability between different land cover types， and make forest range identification more effective. Secondly， for different forest types with similar spectral and vertical structure characteristics， the addition of terrain information reduced the impact of different objects with the same spectrum and the same objects with different spectra caused by terrain shadows， thereby significantly improving the classification accuracy of forest types. The addition of aspect information had a more significant effect than the addition of elevation information on improving the classification accuracy in this region. In addition， seasonal characteristics provided by multi-source and multi-temporal remote sensing images improved the classification of different forest types， while different band combinations had little effect on classification accuracy. The results of this study provide a reference for exploring mountain forest identification methods with low cost， high time efficiency， convenient operation， and a certain guarantee of accuracy.

Responses of niche characteristics and species diversity of main plant populations to duration of enclosure in the Hulun Buir meadow steppe

Ying-ying NIE, Jin-qiang CHEN, Xiao-ping XIN, Li-jun XU, Gui-xia YANG, Xu WANG

2021, 30(10): 15-25. DOI: 10.11686/cyxb2021127

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In this study， we determined the responses of main plant populations in the meadow steppe area to enclosure for various periods of time. Levin’s niche index， Pianka’s niche overlap index， and species diversity indexes were calculated to analyze the niche response characteristics of the main plant populations. The results showed that the niche breadth of main plant populations in degraded grassland changed after enclosure. The largest niche breadth of the perennial herb Taraxacum mongolicum was in the unenclosed （control） plot. At 4 and 13 years of enclosure， pinegrass had the largest niche breadth. At 5， 6， 8， and 10 years of enclosure， the species with the largest niche breadth were Leymus chinensis， Serratula komarovii， Iris ventricosa， and Stipa baicalensis. After the enclosure of degraded grassland， the niche overlap index between species was concentrated in the range of 0.6-0.9， while the niche overlap index between species in the unenclosed plot was in the range of 0.0-0.3. As the period of enclosure increased， the total average value of the niche overlap index tended to first increase and then decrease. The lowest total average value of the niche overlap index of main plant populations was in the unenclosed （control） plot. The highest total average value of the niche overlap index of the main plant populations was 0.68 at 5 years of enclosure. The total average value of the niche overlap index of main plant populations in enclosed grassland was 40.76%-93.68% higher than that in unenclosed grassland. The highest values of the Shannon-Wiener diversity index， Simpson’s diversity index， Margalef’s richness index， Pielou’s evenness index were obtained at 5 years of enclosure， and were 45.46%， 16.51%， 45.80% and 23.38% higher than their respective values in the control （unenclosed） site. Enclosure significantly increased community diversity， richness， and evenness， and intensified interspecific competition. However， as the period of enclosure extended beyond 5 years， the diversity， richness and uniformity gradually decreased. This led to niche differentiation， the slowing of inter-species competition， and stabilization of the community. Therefore， from the perspective of species diversity alone， the enclosure time should not be too long. After 5 years of enclosure， appropriate measures may be implemented to protect community diversity.

Effects of trampling intensity on the quality of artificial carpet hybrid turf

Tong-rui ZHANG, Fu-cui LI, Lie-bao HAN, Yu-feng CHEN, Gui-long SONG, Ya-nan ZHANG, Jia-bao CHEN, Bin TANG, Wei-hao DOU

2021, 30(10): 26-40. DOI: 10.11686/cyxb2021079

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We conducted a plot experiment to evaluate the effects of trampling intensity on the quality and root growth of ‘artificial-natural’ hybrid turfgrass constructed of carpet mesh filled with perennial ryegrass （Lolium perenne） cultivar ‘Neruda 1 BT’. Plots were 0.6 m×1.0 m in area and plots of two carpet mesh types filled with soil were compared with natural turfgrass （control plots） without carpet. We evaluated the performance quality， growth quality， and playing performance under different trampling intensities （no trampling， light trampling， medium trampling， and heavy trampling）， as applied using a trampling machine. Under the different trampling intensities， the color， cover， and performance quality were all better in the artificial-natural hybrid turfgrass than in the natural turf. Under trampling conditions， the artificial-natural hybrid turfgrass showed a lower degree of injury than the natural turfgrass， indicating that the artificial carpet protected the turf to some extent. The higher the trampling intensity， the larger the differences in quality between the hybrid turfgrass and natural turfgrass. After 4 weeks of trampling treatments， for the heavy trampling treatment that was most affected， the color score of the two carpet treatments， designated A and C was， respectively 45.5% and 39.0% higher， and the cover was increased by 136.4% and 150.0%， respectively， compared to control plots. Root biomass and root length were greatly reduced in trampling treatments， compared to control plots， but less so in hybrid turfgrass plots. Turfgrass without mat showed 105.3%， 239.1%， and 152.6% greater root length after 4 weeks of light， moderate， and heavy trampling， respectively. Compared with the natural turf control plots， artificial-natural hybrid turfgrass developed increased hardness and soil compaction， and this would further increase the injury danger when used for certain sports. Therefore， appropriate maintenance measures should be taken with artificial-natural hybrid turfgrass incorporating carpet mesh， to avoid the risks associated with a hard playing surface.

Environmental factors influencing soil organic carbon and its characteristics in desert grassland in Altay， Xinjiang

Hui-xia LIU, Yi-qiang DONG, Yu-xuan CUI, Xing-hong LIU, Pan-xing HE, Qiang SUN, Zong-jiu SUN

2021, 30(10): 41-52. DOI: 10.11686/cyxb2020389

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The aim of this research was to explore the spatial distribution characteristics of soil organic carbon in desert grassland in the Altay region of Xinjiang. We investigated 104 sampling plots using a combination of transect surveys and conventional plot layouts in August 2018， and collected soil samples for 0-5 cm， 5-10 cm and 10-20 cm soil depths in the centre of the sample plots. The factors influencing the content and spatial variation of soil organic carbon density were evaluated using quantitative ecology and geostatistics methodologies. It was found that the range for desert soil organic carbon content was 0.98-11.80 g·kg^-1in the 0-20 cm layer， with an average value of 3.79 g·kg^-1. The soil organic carbon density was 257.57-2904.19 g·m^-2 in 0-20 cm layer， with an average value of 1057.49 g·m^-2. With increasing soil depth， the soil organic carbon content （0-5 cm，5-10 cm，10-20 cm） and density （0-10 cm，10-20 cm） decreased. Localities with high soil C values were mainly concentrated in the northern part of Fuyun County， while areas with low soil C were mainly distributed in Habahe County， Burqin County and southern Fuhai County. In different desert subtypes， the content and density of organic carbon ranked： soil desert>gravel sandy desert>gravelly desert>sandy desert. The values for organic carbon content and organic carbon density in soil of the soil desert soil were， respectively 1.74 and 1.72 times those of the sandy desert soil （P<0.05）. From the results of redundancy analysis， the proportion of variation in soil organic carbon by various environmental factors was 30.93%， with the leading explanatory factors being vegetation cover， soil∶rock ratio， and soil moisture level in the root zone. This study has updated and expanded the available data on soil organic carbon pools in desert grassland in the Altay area and clarified the leading factors of organic carbon change， and has provided data support for desert grassland management， sustainable utilization and carbon budgeting.

Effects of phosphorus on root growth and photosynthetic physiology of alfalfa seedlings under aluminum stress

Ru-yue WANG, Shi-li YUAN, Wu-wu WEN, Peng ZHOU, Yuan AN

2021, 30(10): 53-62. DOI: 10.11686/cyxb2020351

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In order to explore the effects of phosphorus （P） on growth and photosynthesis physiology of alfalfa seedlings under aluminum stress. Simple Ca（NO₃）₂ nutrient solution （pH=4.5） containing 200 μmol·L^-1 P or 100 μmol·L^-1 Al or 200 μmol·L^-1 P+100 μmol·L^-1 Al was used to treat ‘Wl440’ seedlings， and Ca（NO₃）₂ nutrient solution （pH=4.5） without P and Al was as control. It was found that application of P significantly decreased the Al content in roots （81.53%） and leaves （61.47%） of alfalfa under Al stress. Application of P significantly increased the root length， root activity， leaf chlorophyll content， transpiration rate， stomatal conductance， photosynthetic rate， and electron transfer rate of photosystem I and Ⅱ， and significantly decreased electrical conductivity and malondialdehyde （MDA） content. The contents of oxalic acid and malic acid in Al-stressed alfalfa roots were significantly increased by phosphorus addition. In summary， these results indicate that phosphorus addition can effectively increase organic acid contents， improve the photosynthetic system， and consequently alleviate alfalfa aluminum toxicity.

The effects of Vicia sativa planting density on soil microbial nutrient metabolism

Shi-jing ZHOU, Jia-ning LUO, Zhong-miao LIU, Chao DONG, Yan QIN, Shu-juan WU, Hong-jun GAN, Fei XIE, Guang-hui ZHUANG, Bing-zhe FU, De-cao NIU

2021, 30(10): 63-72. DOI: 10.11686/cyxb2020393

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Vicia sativa is an excellent green manure crop which provides nitrogen fixation and soil structure improvement. It is very common in agricultural production. However， there is still little published research on the effects of planting V. sativa on the characteristics of soil microbial nutrient metabolism. This research is based on a pot experiment and set up V. sativa treatments with a range of planting densities， including a low-density group （19 plants·pot^-1）， a high-density group （40 plants·pot^-1）， and bare soil as a control， to study the effects of the above treatments on the soil. It was found that： 1） The biomass and nutrient accumulation of V. sativa in the high-density group were greater than in the low-density group. Thus， nutrients extracted from the soil were increased at high planting density， and plant growth was restricted by P. 2） In the high-density planting of V. sativa， the content of soluble soil inorganic phosphorus was significantly reduced. While the density treatments did not differ significantly for soluble organic carbon and soluble total nitrogen， the values for soluble total nitrogen with V. sativa planting were significantly lower than for the control. As a result， the soil soluble nutrient ratios R_C：N， R_C：P， R_N：Pwere altered， though not significantly so. 3） Planting of V. sativa increased the contents of soil microbial biomass C， soil microbial biomass N， soil microbial biomass C∶P， and soil microbial biomass N∶P， and decreased the contents of soil microbial biomass P and soil microbial biomass C∶N， indicating that the demand for N for microbial growth increased. 4） Planting V. sativa increased ［β-N-acetylglucosaminidase （NAG）+leucyl aminopeptidase （LAP）］ and alkaline phosphatase （AP） enzyme activities， and decreased β-1，4-glucosidase （BG） enzyme activity， BG∶（NAG+LAP）， BG∶AP and （NAG+LAP）∶AP， indicating that the soil microbes increased the activities of （NAG+LAP） and AP enzymes to increase access to nutrients in short supply. Therefore， different planting densities of V. sativa not only changed the soil nutrient content， but also changed the characteristics of soil microbial nutrient metabolism. The microbes adjusted their internal nutrient contents and the secretion rates and ratios of extracellular enzymes to adapt to the prevailing resource supply characteristics.

Growth characteristics and nutritive value of multiple oat varieties in mountainous Northern Nepal

Tenzin Tarchen, Purna Bhadra Chapagain, Shankar Raj Pant, Jiebu, Dunzhu Gesang, Shao-feng CHEN

2021, 30(10): 73-82. DOI: 10.11686/cyxb2020577

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Animal husbandry plays an important role in the livelihood of inhabitants of the mountainous region in Northern Nepal. Enhanced forage production capacity is one of the main priorities of agricultural technology in this region. To screen for oat varieties suitable for cultivation in the mountainous region of Northern Nepal， we conducted a comparative study of 12 oat （Avena sativa） varieties （Everleaf， Titan， Baler 1， Monida， Kona， Lena， Qingyin No.1， Qinghai 444， Qinghai sweet oat， Longyan No.2， Longyan No.3， Kamadhenu） in Langtang from May to October in 2019. We measured their phenological development， plant height， fresh and dry （hay） yields， ear content， stem to leaf ratio， and nutrient content. Only six varieties completed the growth cycle：Monida， Kona， Qingyin No.1， Qinghai 444， Qinghai sweet oat， and Kamadhenua. The growth period ranged from 115 to 141 days， and only six varieties reached the milking stage. The plant height of the 12 varieties ranged from 134.8 to 177.7 cm， and five of them （Titan， Qinghai 444， Qinghai sweet oat， Monida， and Lena） had plant heights 6.3%-20.4% greater than that of Kamadhenu， a local forage variety. The hay yields of Qinghai sweet oat， Qinghai 444， and Monida were 14723.0， 13491.0， and 13369.6 kg·ha^-1， respectively， which were 36.0%， 24.7%， and 23.6% higher， respectively， than that of Kamadhenu. The leaf to stem ratios of Baler 1， Kona， and Titan were 0.40， 0.38， and 0.36， respectively， much higher than that of Kamadhenu. The dry matter content ranged from 93.5% to 95.6%； the crude protein content ranged from 5.7% to 9.9%； the total ash content ranged from 4.4% to 6.9%； the neutral detergent fiber content ranged from 68.2% to 78.4%； and the acid detergent fiber content ranged from 39.3% to 48.7%. The crude protein content of Titan was 1.57 times that of the local Nepalese variety Kamadhenu （P<0.01）. A principal component analysis was used to evaluate the 10 agronomic characteristics of the above varieties， and showed that Qinghai sweet oat， Monida， Qinghai 444， and Titan are suitable varieties for cultivation in the mountainous region of Northern Nepal.

Allelopathic effects of Stellera chamaejasme on seed germination and growth of three crops

Yu-lian GAO, Jing CHANG, Yi-hui WANG, Feng LI, Hai-ping LI, Chong-yong MA

2021, 30(10): 83-91. DOI: 10.11686/cyxb2020387

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Stellera chamaejasme is one of the main poisonous weeds in the grassland of Northern China， and has a great impact on grassland ecology. The effects of a range of concentrations of ethanol extract from S. chamaejasme root （SCR） on seed germination， seedling growth and physiological and biochemical characteristics of sorghum （Sorghum bicolor）， wheat （Triticum aestivum） and oats （Avena sativa） were studied， in order to provide scientific data to aid in the future development and utilizationof botanical herbicides.SCR did not affect the germination rate of sorghum seed， compared to controls， at any of the concentrations tested. However， in wheat and oats SCR application at different rates induced a “low promotion and high inhibition” germination rate response. SCR also induced a “low promotion and high inhibition” response in root and stem lengths of sorghum and oat seedlings， but it had inhibitory effect root and stem length of wheat seedlings which was stronger at higher concentration of the extract. SCR increased the MDA content of oat and sorghum seedlings， the MDA content of wheat was significantly higher than that of control at 5 mg·mL^-1. The peroxidase activity in seedlings of all three tested crops was higher than that of the controls at some tested concentrations. There was no significant difference in SOD activity of sorghum seedlings treated with SCR， but SOD activity of wheat seedlings was significantly higher than that of controls at high SCR concentration， and SOD activity of oat seedlings with 0.01 mg·mL^-1 SCR treatment was significantly higher from that of controls. The activity of catalase in the seedlings of all three crops was lower than that of the controls at some SCR concentrations. Overall， the inhibition of S. chamaejasme root ethanol extract on wheat was the strongest， followed by oats and sorghum.

Pathogen identification and cell physiological changes of Trifolium repens leaves infected with powdery mildew

Kai YANG, Juan SHI, Yu-tao YUAN, Li-ting WANG

2021, 30(10): 92-104. DOI: 10.11686/cyxb2020360

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This experiment investigated the cytological mechanism of Trifolium repens and powdery mildew interaction， clarified the classification status of powdery mildew infecting T. repens， and provided information for breeding disease-resistant clover varieties and scientifically directed prevention and control of forage fungal pathogens. Optical and electron microscopy methods were used to observe the changes to cellular physiological characteristics caused by pathogens invading T. repens. The pathogen was identified as Erysiphe pisi based on traditional observation of morphological characteristics and sequence analysis of rDNA-ITS （ribosomal RNA internal transcribed spacer）. The water agar slide method was used to observe conidial germination characteristics of E. pisi. The results showed that E. pisi directly invaded the epidermal cells of T. repens at the junction of epidermal cells and stomatal guard cells， resulting in degradation and darkening of color in the cell wall tissue of at the location where the hypha invaded the cell wall. A large quantity of cell wall deposits were produced inside the corresponding cells. After the cell wall was no longer intact， the stomatal channel deformed to cause plasma membrane separation of the guard cells. The haustorium that invaded the epidermal cell was surrounded by the host plasma membrane to form an interface. The chloroplasts in the palisade tissue cells swelled， changing from elliptical to nearly spherical and clustering， starch grains were changed in shape from elongated to elliptical， and osmophilic particle numbers increased. The conidia inoculated on the leaf germinated and grew primary bud tubes within 4 hours post-inoculation （hpi）， formed mature appressoria in 10 hpi， formed infection pegs after 12 hpi， and secondary hyphae formed after 48 hpi. Germ tubes of abundant branches differentiated into hyphae and produced mature conidiospore after 96 hpi. At the same time leaves showed symptoms， the conidiophore differentiated into 2 to 3 conidia at 144 hpi， the top matured first， and the powder layer was expanded to 2/3 of the leaf at 168 hpi； at 240 hpi， the area of the powder layer had covered more than 90% of the leaf， and the powder layer was thick and its leaves were curled. The pathogen E. pisi grows best at 25 °C and pH 7.0， and light conditions are conducive to spore germination.

Expression characteristics and functional analysis of the LcCBF6 gene from Leymus chinensis

Qian LI, Xiao-xia LI, Li-qin CHENG, Shuang-yan CHEN, Dong-mei QI, Wei-guang YANG, Li-jun GAO, Ba-yin XIN, Gong-she LIU

2021, 30(10): 105-115. DOI: 10.11686/cyxb2020375

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Chinese wild rye（Leymus chinensis） is an important forage grass in China， and is also ecologically important because it has high tolerance to saline-alkali soil， drought， and low temperature stresses. Chinese wild rye can therefore be an excellent gene pool for molecular breeding to enhance stress tolerance. CBF/DREBs belong to the AP2 transcription factor family and play an important role in plant stress resistance. In this study， the LcCBF6（L. chinensis C-repeat binding factor 6） gene was cloned. It encoded 245 amino acids and contained the AP2 domain. Amino acid sequence alignment showed that the LcCBF6 gene had high sequence conformity to its homologous proteins from Agropyron mongolicum （92%） and Secale cereale （91%）. Expression analysis confirmed that LcCBF6 gene was expressed in roots， leaves and seeds， and was significantly induced by salt stress. Overexpression of LcCBF6 significantly enhanced the salt resistance of transgenic Arabidopsis thaliana. Under the salt stress， the number of green cotyledons， the root length， plant biomass and survival rate of transgenic lines were all significantly higher than in the wild type. The results suggest that the LcCBF6 gene might play an important positive role in salt stress tolerance， and be an excellent gene to utilize for enhancing stress tolerance in forages and other important crops.

Analysis of differentially expressed protein kinase related genes in the xerophyte Pugionium cornutum under salt treatment

Fang-zhen WANG, Cheng-hang YANG, Zi-hua HE, Zi-ru LIN, Hao-yuan ZENG, Qing MA

2021, 30(10): 116-124. DOI: 10.11686/cyxb2020368

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The xerophyte Pugionium cornutum possesses strong salt tolerance. Study of the molecular basis of its salt tolerance will provide important genetic resources for the genetic improvement of stress tolerance in crops and forages. In previous studies， by using transcriptomic analysis， the expression pattern of important functional genes in P. cornutum under salt stress has been analyzed， and a number of candidate functional genes related to salt-tolerance of P. cornutum were identified； however， the expression of regulatory genes responding to salt stress in P. cornutum have not been reported. In order to further explore the molecular mechanism concerning salt tolerance of P. cornutum， in this study， the expression pattern of protein kinase related genes in P. cornutum under salt treatment was analyzed， based on the transcriptomic data of root and shoot tissues of P. cornutum exposed to 50 mmol·L^-1 NaCl for 6 and 24 h. The results showed that there were significant changes in the expression of a large number of protein kinase related genes in P. cornutum under 50 mmol·L^-1 NaCl. Among them， the expression of numerous genes encoding leucine-rich repeat receptor protein kinases （LRR-RLKs） were significantly up-regulated in both the root and shoot of P. cornutum after treatment with 50 mmol·L^-1 NaCl for both 6 and 24 h； many genes related to mitogen-activated protein kinase cascade pathways （MAPK/MAPKK/MAPKKK） were significantly up-regulated under short-term salt stress （50 mmol·L^-1 NaCl for 6 h）. Some genes encoding CTR1， an important negative regulator of the ethylene signal transduction pathway， were expressed in roots of P. cornutum under control condition but not expressed in roots under 50 mmol·L^-1 NaCl treatment for 6 h. These results indicate that LRR-RLK proteins may play an important regulatory role in the adaptation of P. cornutum to salt stress， MAPK/MAPKK/MAPKKK may be involved in regulating the response of P. cornutum to short-term salt stress， and CTR1 might function as a negative regulator in the response of P. cornutum to salt stress.

Effects of nitrogen application on accumulation of organic osmotic regulating substances in forage rapeseed （Brassica napus） under salt stress

Tian TIAN, Hai-jiang WANG, Jin-gang WANG, Yong-qi ZHU, Xiao-yan SHI, Wei-di LI, Wen-rui-yu LI

2021, 30(10): 125-136. DOI: 10.11686/cyxb2020397

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Forage rapeseed is an important cash crop and can grows under salt stress. In order to explore the regulatory effect of nitrogen （N） on the accumulation of organic osmoregulation substances for forage rapeseed under salt （NaCl） stress， we selected one cultivar （Hua You Za No. 62） and designed a pot experiment for this purpose. The plot experiment includes four NaCl stresses （0， 2， 4， or 6 g·kg^-1） and four pure N levels （0， 120， 240， 360 kg·ha^-1）. Five physiological indexes， including leaf water content and contents of malondialdehyde （MDA）， proline， soluble sugars， chlorophyll and total N in the leaves were measured and used to evaluate this effect of N. The results showed that the growth of forage rapeseed was significantly inhibited under salt stress. The contents of MDA and organic osmotic regulating substances （proline and soluble sugars） increased with increasing salt content in the soil， while the leaf water content， the contents of chlorophyll and total N decreased. The contents of proline and soluble sugars were significantly higher and the MDA content was significantly lower under the 240 kg·ha^-1 N level. The higher level of N supplementation （360 kg·ha^-1） resulted in significant decreases of the leaf water content， MDA content and soluble sugars content， while significant increases the contents of chlorophyll and total N. The principal component analysis for five growth stages showed that N significantly affected the contents of MDA， proline， chlorophyll， and total N at the early growth stage， but significantly affected the leaf water content and soluble sugars content at later growth stages. In conclusion， appropriate N supplementation can promote the accumulation of organic osmoregulation substances and weaken the adverse effects of salt on the growth of forage rapeseed.

A study of the appropriate seeding rates for four winter green manure crops in an upland red soil of Southern China

Xiao-fen CHEN, Lu-ping ZHANG, Wen-jing QIN, Jing-rui CHEN, Yang-geng XU, Ming LIU, Zhong-pei LI, Chang-xu XU, Jia LIU

2021, 30(10): 137-146. DOI: 10.11686/cyxb2020359

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This research studied effects of seeding rate in four winter green manure crops： Vulpia myuros， Vicia villosa， Brassica napus and Raphanus sativus， sown in a field trial in an upland red soil. The trial included five seeding rate treatments： 15， 30， 45， 60 and 75 kg·ha^-1. The effects of the different seeding rates on aboveground biomass， nutrient contents and nutrient accumulations of the tested varieties were investigated to determine the appropriate seeding rates of the four winter green manures， and to provide the relevant technical information for increasing soil fertility by green manure planting， so as to ensure sustainable agricultural development in the red soil region. It was found that the aboveground biomass （fresh and dry weight） of the four winter green manures followed a pattern of increase with increasing seeding rate at lower seeding rates and then decreased or tended to be stable at higher seeding rates. The biomass of V.myuros was highest when sown at the seeding rate of 30 kg·ha^-1， while biomass of the other three crops was highest when sown at 60 kg·ha^-1. Seeding rates significantly affected elemental concentrations of carbon， nitrogen， phosphorus， potassium， calcium and magnesium of the various green manure crops. Also， particular nutrient elements of different green manure crops responded differently to crop seeding rate. The nutrient accumulation of the four green manure crops increased with increasing seeding rate at lower seeding rates， and decreased at higher seeding rates. From multivariate evaluation of biomass and nutrient accumulation and based on regression equations， the appropriate seeding rates of V. myuros， V. villosa， B. napus and R. sativus in upland red soil under this experimental condition were 30.7-32.7 kg·ha^-1， 50.4-63.4 kg·ha^-1， 53.5-61.4 kg·ha^-1 and 63.0-80.1 kg·ha^-1， respectively.

Fermentation quality and in rumen degradability of mixed silage from maize stalk and tomato pomace in varying proportions

Dong-qing FU, Chun-ying JIA, Xiao-chun LIAN, Li ZHANG, Fan-fan ZHANG, Chun-hui MA

2021, 30(10): 147-158. DOI: 10.11686/cyxb2020367

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The purpose of this study was to provide technical data to inform silage production practice and promote effective utilization of agricultural waste in Southern Xinjiang. The fermentation quality and rumen degradation characteristics of mixed silage of maize stalk and tomato pomace were evaluated by chemical analysis and using rumen fistula sheep animal models. A plastic-wrap method was used for silage fermentation and seven feed treatments were prepared as follows： treatment T₁=100% maize stalk； treatment T₂ tomato pomace∶maize stalk ratio （TP∶MS）=3∶7； treatment T₃TP∶MS=4∶6； treatment T₄ TP∶MS=5∶5， treatment T₅ TP∶MS=6∶4； treatment T₆ TP∶MS=7∶3； treatment T₇=100% tomato pomace. Silage fermentation quality indicators analyzed included dry matter （DM）， crude protein （CP）， water soluble carbohydrates （WSC）， neutral detergent fiber （NDF）， acid detergent fiber （ADF）， ether extract （EE）， crude ash （Ash）， pH value， ammonium nitrogen （NH₃-N）， lactic acid （LA）， acetic acid （AA）， propionic acid （PA）， butyric acid （BA） and NH₃-N∶TN. In rumen degradability analyzed included dry matter degradability （DMD）， neutral detergent fiber degradability （NDFD）， acid detergent fiber degradability （ADFD）， organic matter degradability （OMD）， effective degradability （ED）. and degradation parameters of mixed silage for 90 days. The results showed that the T₂ and T₃ treatments had the highest DM and LA contents， while the T₃ treatment had the highest CP， WSC and EE contents. However， the NH₃-N/TN of the T₃ treatment was the lowest among the seven treatments. The T₃ and T₄ treatments had the lowest NDF and ADF contents. The T₃， T₄ and T₅ treatments were highest for Ash content. The T₂， T₃ and T₄ treatments had the lowest pH value. The AA content of the T₂ treatment was lower than other treatments. The T₁， T₂， T₃ and T₄ treatments had the lowest PA content. The BA and NH₃-N contents of the T₁， T₂ and T₃ treatments were lower than for other treatments. The ED_NDF of the T₄ treatment， the ED_ADFof the T₁ and T₇ treatments and the ED_OMof the T₃ and T₇ treatments were higher than other treatments in each case. Other indexes did not differ significantly among treatments （P>0.05）. The total fermentation quality and the effective degradability of 15 core indicators were evaluated by a ‘fuzzy similarity priority ratio’ analysis. Overall silage quality and degradability was best for the tomato pomace∶maize stalk silage ratio of 4∶6 （treatment T₃， water content about 67.27%）.

Effects of fucoidan on the growth performance， serum biochemical indexes， and nutrient apparent digestibility of meat rabbits

Lei ZHANG, Xue-lin HAN, Juan ZHANG, Su-tao LI, Wen-jiao SHI, Fu-lin YANG

2021, 30(10): 159-168. DOI: 10.11686/cyxb2021075

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The aim of this experiment was to investigate the effects of dietary fucoidan at different levels on the growth performance， slaughter performance， internal organ indexes， serum biochemical indexes， and the apparent digestibility of nutrients in meat rabbits. The ultimate aim of this research was to provide a theoretical basis for the use of fucoidan as an antibiotic substitute in the diet of meat rabbits. Thirty-six healthy rabbits with similar body weight were selected from 200 weanling Fujian yellow rabbits at 35 days of age， and were randomly assigned to four groups （three replicates of three rabbits per group）. Rabbits in the control group were fed with a basal diet while those in experimental groups I， II， and III， were fed diets supplemented with 100， 200， and 300 mg·kg^-1 fucoidan， respectively. The pre-trial period was 5 days and the experimental period was 22 days. The main findings were as follows： 1） The final body weight， average daily feed intake （ADFI）， and average daily gain （ADG） were significantly higher in group III than in the control group （P<0.05） and the feed to gain ratio （F/G） was significantly lower in group III than in the control group （P<0.05）. 2） The live weight before slaughter was significantly higher in group III than in the control group （P<0.05）； But the other indexes were not significantly different among the treatment groups and the control （P>0.05）. 3） The thymus index was higher in all of the experimental groups than in the control group （P<0.05）. The spleen index and round cyst index did not differ significantly among the treatment groups and the control （P>0.05）. The protrusion index was significantly higher in groups II and III than in the control group （P<0.05）； But the other indexes showed no significant differences among the treatment groups and the control （P>0.05）. 4） The levels of alanine aminotransferase were significantly lower in group III than in the other groups （P<0.05）. The levels of low-density lipoprotein cholesterol and cholesterol were significantly lower in groups I and II than in the control group （P<0.05）. The activity of superoxide dismutase was significantly higher in group III than in the control group （P<0.05）. The levels of malondialdehyde were significantly lower all in all the experimental groups than in the control group （P<0.05）. The activity of glutathione peroxidase was significantly higher in the treatment groups than in the control group （P<0.05） and significantly higher in group III than in group I （P<0.05）； No significant differences were detected for the other antioxidant indices （P>0.05）. 5） The apparent digestibility of dry matter （DM）， neutral detergent fiber （NDF）， and crude ash （Ash） were significantly higher in the experimental groups than in the control group （P<0.05）. The apparent digestibility of acid detergent fiber （ADF） was significantly higher in group III than in the control group （P<0.05）. The apparent digestibility of crude protein （CP） did not differ significantly among the treatment groups and the control. Together， these results show that dietary supplementation with fucoidan can significantly increase the ADFI and ADG， significantly decrease the F/G， improve internal organ indices and antioxidant capacity， and significantly improve the apparent digestibility of ADF， NDF， Ash， and DM in meat rabbits. On the basis of these results， the optimum dietary supplementation level of fucoidan for meat rabbits is 300 mg·kg^-1.

Effects of different additives on fermentation quality and protein degradation of Broussonetia papyrifera silage

Chang-rong WU, Sheng DAI, Long-fei LIANG, Wen-tao SUN, Chao PENG, Chao CHEN, Jun HAO

2021, 30(10): 169-179. DOI: 10.11686/cyxb2020379

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The study evaluated the effects of different additives on nutritive value， fermentation quality， nitrogen components and protease of Broussonetia papyrifera silage. Molasses was added to B. papyrifera after 1.5 h drying in the air as a control treatment （CK）. In the additive treatments， formic acid （FA）， cellulase （CE） or lactic acid bacteria （LB） were added to the B. papyrifera with molasses， with 3 replicates of each treatment. The changes in nitrogen components and enzyme activity were measured at 0， 3， 7， 15， 30 and 45 days of ensiling， and nutritional quality and fermentation quality were measured after 45 days. Results showed that contents of dry matter， crude protein， lactic acid and acetic acid were increased， while crude fiber， neutral detergent fiber， acid detergent fiber， propionic acid content， pH and ammonia nitrogen/total nitrogen were decreased （P<0.05） in FA， LB and CE treatments relative to CK. pH value， total nitrogen content， activities of acid protease， carboxypeptidase and aminopeptidase decreased with increase in time ensiled， while non-protein nitrogen， ammonia nitrogen and free amino acids gradually increased as fermentation progressed， and these indexes mentioned above in FA， LB and CE treatments were lower than in the CK treatment at each sampling time （P<0.05）. The contents of peptide-N in FA， LB and CE groups were higher than in the CK treatment at each sampling time. As ascertained by membership function analysis， the overall nutritional value of B. papyrifera silage treated with different additives， ranked from high to low was： LB>CE>FA>CK.

A bibliometric analysis of research on the role of alkaloids produced by grass endophytic fungi based on the Web of Science database

Ruo-chen ZHANG, Tao LI, Xiang YAO, Zhen-jiang CHEN, Chun-jie LI

2021, 30(10): 180-190. DOI: 10.11686/cyxb2020348

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Alkaloids produced by grass endophytic fungi have the ability to enhance resistance to a wide range of stress environments faced by the host plant. We reviewed the status and developing trends of research into alkaloids of grass endophytic fungi， based on the Web of Science database. Papers about alkaloids of grass endophytic fungi published in the past 20 years from 2000 to 2019 were retrieved and screened， with Epichlo? alkaloids or Neotyphodium alkaloids as keywords. The papers retrieved numbered 646； 33 reported domestic research in China. According to the quantitative analysis of the retrieved papers， the top three countries for the number of alkaloid publications were the United States， New Zealand and China. China was the country with the most citations on average. Over the past 20 years， the number of articles on endophytic fungal alkaloids in China has been steadily increasing， and some articles have been accepted by international journals at a high level. The laboratories researching endophytic fungi in grasses in China were mainly concentrated in Lanzhou University and Nankai University. The research outputs primarily included biological characteristics of alkaloids， ecological functions and factors affecting alkaloid production in symbionts. However， there are some studies on the mechanism of alkaloid toxicity and the biological synthetic pathways of alkaloids， which potentially could form a foundation for development of new technologies for human benefit.

Progress in research on the photosynthetic characteristics of green non-leaf organs in plants

Hui WANG, Hao-qi TIAN, Pei-sheng MAO, Wen-hui LIU, Zhi-feng JIA, Lu-ping WEI, Qing-ping ZHOU

2021, 30(10): 191-200. DOI: 10.11686/cyxb2021117

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Photosynthesis is one of the most important biochemical reactions in plants， and is a vital process for producing food and oxygen and purifying water resources for humans and animals. Efforts to improve photosynthesis in plants have traditionally focused on increasing photosynthesis in the leaves to increase yield. However， green non-leaf organs may also contribute to improving the overall photosynthetic capacity of plants. Compared with leaves， some non-leaf organs show a lower transpiration rate， higher water use efficiency， and stronger osmotic regulation ability under stress conditions， indicative of better stress resistance. Thus， non-leaf organs may make a considerable contribution to yield. In this paper， we review recent studies on photosynthesis in green non-leaf organs， including those on the photosynthetic performance of reproductive organs and stems， the methods used to evaluate the relative contribution rate， the influences of abiotic stress， the identification of photosynthetic pathways， and CO₂ fixation in non-leaf green organs. We discuss the advantages and disadvantages of the methods used to evaluate the contributions of these organs to photosynthesis in the whole plant， and outline future directions for research on the photosynthetic ability of non-leaf organs.

New focus for the study of the Comprehensive Sequential Classification System for grassland： A review from 2008 to 2020 and prospects for future research

Hui-long LIN, Di FAN, Qi-sheng FENG, Tian-gang LIANG

2021, 30(10): 201-213. DOI: 10.11686/cyxb2020362

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The Comprehensive Sequential Classification System for grassland （CSCS） has become the only quantifiable grassland classification system with Chinese intellectual property rights after more than 60 years of continuous development and improvement. Notably， in 2008， Ren et al publicised the CSCS in the Rangeland Journal， stimulating a new upsurge of CSCS research in China and abroad. In this paper， we report a literature review using CSCS as the keyword. We retrieved 48 Chinese papers from the China national knowledge internet and 29 English papers from Web of Science， published from 2008 to 2020. From this systematic review， the conclusions are as follows： 1） Comparing CSCS with two internationally recognized classification systems， Holdridge Life Zone and BIOME4 on a global scale， it emerges that CSCS has outstanding advantages in grassland classification. 2） A digital elevation data model （DEM） taking account of slope gradient， slope direction， rate of slope change， and other similar factors has been constructed to modify traditional spatial interpolation methods， and introduce altitude， slope and other variables into multiple regression and residual analysis interpolation. This has efficiently solved climate data interpolation errors arising from high altitude and complex terrain， making CSCS classification more accurate and providing a methodological basis for extensive application. 3） Because of the structural characteristics of CSCS， it provides a framework and a new technique to study grassland response to global climate change. Responses of grassland ecosystems to global climate change have been studied at regional， national and global scales， providing the base data for further precise grassland management and related policymaking. 4） The combination of heat and moisture conditions at a locality is the most fundamental factor determining grassland phenomena and processes. In the theoretical framework of the CSCS， a classification index model has been built by using classification indices as parameters. This model not only reveals the inner connection between grassland types and their net primary productivity （NPP）， but also makes it possible to further study the production potential of zonal grassland types and regional and global distributions of grassland NPP. After comparative validation at regional， national and global levels， the grassland NPP model based on the CSCS has become a new tool for primary productivity assessment and carbon sink calculation of grassland ecosystems. In the future， the following tasks are urgently needed： 1） To improve the quantitative classification system of CSCS subclasses and types； 2） To improve the precision of grassland management based on the CSCS through development of CSCS protocols defining grassland nutrient carrying capacity， and facilitating ecological service value assessment， and other relevant tools.

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