Current issue

• 2020 Vol.36 No.31 Published:05 November 2020

  Effects of Drought on Root Configuration, Active Enzymes and Osmosis in Different Types of Winter Wheat Han Liping, Han Xiaofan, Zhu Yupeng, Guo Weiwei 2020, 36 (31):  1-6.  DOI: 10.11924/j.issn.1000-6850.casb20191100874 Abstract + ( 317 )   HTML ( 10 )   PDF ( 1359KB )   ( 92 ) To study the effects of drought on antioxidant enzymes and osmotic substances of different types of winter wheat roots, we used water-fertilizer wheat cultivar ‘Jimai 22’ (J22) and drought-tolerant wheat cultivar ‘Qingmai 6’ (Q6) as materials to simulate the field environment through PVC soil pillars. Two treatments were normal condition and drought treatment during the full growth period, and then we observed the changes of root morphology, dry matter weight, SOD, MDA and POD enzyme activity of different types of wheat. With the development of wheat, the number of wheat populations, POD activity and soluble sugar content in root system decreased gradually; the SOD activity and proline content in the root system increased first and then decreased; and MDA content gradually increased. The two different types of winter wheat showed different trends under different conditions. The SOD, POD activity and soluble sugar content in the root system of J22 were significantly greater than those of Q6 under water condition. However, in the absence of water, compared with those of J22, the population number, SOD, POD enzyme activity, soluble sugar, and proline content of Q6 increased significantly. Under drought stress, Q6 shows strong antioxidant ability of regulating cell osmotic potential in the root system, thus maintaining water balance and enhancing adaptability to the stress.

  Effects of Different Dosages of Silicon-Calcium-Potassium-Magnesium Fertilizer on Root Development and Tobacco Quality Ma Cunjin, Ren Shiwei, Zheng Lei, Chen Jianqiu 2020, 36 (31):  7-12.  DOI: 10.11924/j.issn.1000-6850.casb20191100817 Abstract + ( 655 )   HTML ( 6 )   PDF ( 1137KB )   ( 83 ) The main objective is to investigate the effect of a new soil conditioner on root development and tobacco quality and explore the fertilizer’s role in improving acidified soil. With ‘NC55’ as the test material, different dosages of silicon calcium potassium magnesium fertilizer gradient (0, 750, 1500, 2250 kg/hm2) treatment were set up in field to determine the agronomic indexes and root morphology and root physiological activity indexes by systematic sampling according to different organs of the plant. Experimental results showed that: the addition of silicon calcium potassium magnesium fertilizer improved the root development and tobacco quality within the range of gradient treatment. It showed that the root was stronger, the agronomic characters were significantly improved, tobacco quality and economic benefits were improved, and the chemical composition was more coordinated. With the increase of the dosage of silicon calcium potassium magnesium fertilizer, all the tested indexes showed a trend of rising first and then decreasing. Among them, the treatment dosage of 1500 kg/hm2was the best. Compared with the treatment without the application of silicon calcium potassium magnesium fertilizer, the morphological index of root increased by 25.06%, the physiological activity of root increased by 28.62%, the potassium content of leaves increased by 0.35 percentage points, the potassium content of leaves decreased by 0.35 percentage points, the output value increased by 3486.88 yuan/hm2, the average price increased by 1.23 yuan/kg, and the proportion of topped tobacco increased by 6.9 percentage points. But the dosage should be adjusted according to the soil pH and the specific acidification degree.

  Advances in Enzyme Properties and Applications of Sulfate-reducing Bacteria Yan Liang, Zhao Hui 2020, 36 (31):  13-19.  DOI: 10.11924/j.issn.1000-6850.casb20191100879 Abstract + ( 670 )   HTML ( 12 )   PDF ( 1373KB )   ( 82 ) Two different metabolic pathways of assimilative sulfate reduction and dissimilating sulfate reduction were summarized, and the enzymatic properties of two key enzymes, adenosyl sulfate reductase and sulfite reductase, were outlined. It is pointed out that the sulfate-reducing bacteria could reduce soil heavy metal pollution in agricultural fields by their own metabolic characteristics, promote the growth of crops, and degrade lactate in liquor to increase caproic acid and decrease lactic acid, and could also be used in microbial fuel cell, the degradation of polycyclic aromatic hydrocarbons and other fields. At the same time, sulfate-reducing bacteria have the disadvantage of corroding metals, and analysis has shown that metal ions with strong inhibition on the self-repair mechanism of sulfate-reducing bacteria could be screened out or genetically modified to reduce the harm of metal corrosion.

  The Seedling Growth and Physiological Characteristics of Tsuga longibracteata Under Different Treatments of Fallen Wood You Xiuhua, Bai Jing, Liu Juncheng, Liu Jinshan, Cai Changtang, Chen Yan, Li Ning 2020, 36 (31):  20-27.  DOI: 10.11924/j.issn.1000-6850.casb20200200123 Abstract + ( 292 )   HTML ( 4 )   PDF ( 1345KB )   ( 37 ) Taking the fallen wood of Tsuga longibracteata with high decay class (Ⅲ,Ⅳ,Ⅴ) as the substrate and covering for seed germination of T. longibracteata, and the effects of fallen wood substrate on seed germination and seedling growth of T. longibracteata were discussed to provide new approaches for the regeneration of T. longibracteata. In the study, the fallen wood of T. longibracteata with diameter >20 cm and decay grades Ⅲ~Ⅴwere selected as experimental materials. The fallen wood of different grades and yellow loam were divided into 2:8, 5:5, 8:2, 1:0 and CK (control, only yellow loam) according to the mass ratio, and the effects of fallen wood as substrate on the germination of T. longibracteata seeds were discussed. The effects of fallen wood covering on seed germination of T. longibracteata were studied by using different grades of fallen wood to cover seeds with 2.5, 5, 7.5, 10 mm and CK (control, only covered with cotton sand). The results showed that the fallen wood matrix had a certain effect on the germination and seedling growth of spruce seeds. (1)Seed germination rate and seedling root length of grade III and grade V fallen wood treated with wood: soil=5:5 were significantly higher than those of other proportioning treatments. (2)The germination rate of T. longibracteata was significantly higher when the ratio of wood to soil was 8:2, while the ratio of wood to soil was 5:5 significantly affected the root length and leaf length of T. longibracteata seedlings. For each decay class (Ⅲ, Ⅳ, Ⅴ) of fallen wood in the wood: soil=1:0, the CAT activity, PPO activity and SOD activity of T. longibracteata seedlings were significantly higher than those of the control group (CK); class V of fallen wood had significant effect on POD activity of T. longibracteata seedlings. (3)The germination rate of T. longibracteata seeds was significantly higher than that of the control group (CK) under the treatment of 7.5 mm covering with grade III fallen wood, and the root length of seedlings under the treatment of 5 mm covering was significantly higher than that of the control group (CK); the fallen wood of different decay class (Ⅲ, Ⅳ, Ⅴ) of 5 mm covering had significant effect on the leaf length of T. longibracteata seedlings; the germination rate of T. longibracteata under class Ⅲ fallen wood covering was better than that of other classes, but there was no significant difference with that of the control group (CK).

  Effects of Maturity Stage on Fruit Quality and Aroma Components of ‘Jinyan’ Kiwifruit Chen Cheng, Wang Yi, Yang Yong, Yan Yongqi 2020, 36 (31):  28-36.  DOI: 10.11924/j.issn.1000-6850.casb20191100865 Abstract + ( 421 )   HTML ( 4 )   PDF ( 1321KB )   ( 68 ) To explore the effects of maturity stage on fruit quality, type and relative contents of volatile components, ‘Jinyan’ kiwifruit (Actinidia chinensis) was taken as the experimental material. The first sampling time was 110 days after flowering, followed by sampling every 10 days for a total of 6 times (harvest Ⅰ-Ⅵ). The appearance quality and inherent quality of fruit were measured immediately after harvest. The inherent quality of fruit was measured at the edible stage, and aroma components were analyzed by solid phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS) at the same time. The results showed that the later the harvest time, the heavier the fruit was. Besides, the soluble solid content increased with the prolongation of fruit harvest time. However, the firmness of fruit harvested at Ⅵ stage dropped sharply compared with the earlier periods. The fruit harvested at Ⅴ stage had the lowest total acid content after ripening, and the ratio of soluble solid content to total acid and the total ascorbic acid content were the highest. Meanwhile, the analysis of aroma components showed that the types and the relative content of esters were also the highest. The results showed that the fruits were suitable to be harvested at Ⅴ stage for best taste and flavor, and the soluble solids content was around 7.5%, the total acid content was around 1.3%, and the ratio of soluble solid content to total acid was around 5.5.

  Effects of Different Treatments on the Cutting Propagation of Passiflora edulis Zhang Tianxiang, Niu Xianqian 2020, 36 (31):  37-41.  DOI: 10.11924/j.issn.1000-6850.casb20191200963 Abstract + ( 459 )   HTML ( 5 )   PDF ( 1180KB )   ( 51 ) The paper aims to study the cutting experiment of Passiflora edulis, identify the key factors affecting the cutting effect of P. edulis, and optimize the best combination of cutting treatment, so as to provide references for the cutting propagation of P. edulis. Three factors and three levels orthogonal design were used to study the effects of stem segment location, NAA concentration and cutting matrix on the cutting effect of P. edulis. Queuing score and formula score were used to analyze the survival effect of cutting, and the best combination of treatment groups for cutting propagation of P. edulis was selected. Cutting position had the greatest influence on the survival rate of P. edulis, while NAA concentration and cutting matrix had relatively small influence. The influence on root number and average root diameter was cutting position> cutting matrix> NAA concentration, and the influence on average root length, new vine length and new leaf number was cutting position> NAA concentration> cutting matrix. The results showed that the cutting position was the most important factor affecting the cutting effect of P. edulis, followed by cutting matrix, and the effect of NAA concentration was the least. The best combination for cutting of P. edulis was A2B3C3 treatment. The cutting effect of P. edulis was the best when the middle semi-lignified stem segments were used as cuttings, soaked in 300 mg/L NAA solution for 20 minutes, and peat mixed matrix (peat: yellow soil= 1:1) was used as the cutting medium.

  The Cadmium and Lead Tolerance of Six Species of Melastoma Plants During Germination Liu Xiaozhou, Zhang Xinjian, Yi Huilin, Zhou Renchao, Tan Guangwen 2020, 36 (31):  42-48.  DOI: 10.11924/j.issn.1000-6850.casb20191200934 Abstract + ( 406 )   HTML ( 5 )   PDF ( 1515KB )   ( 46 ) The paper aims to explore the tolerance of cadmium and lead of six species of Melastoma plants at the germination stage, and to provide a reference for screening cadmium-resistant and lead-resistant Melastoma plants for remediation of heavy metal polluted soil. The seeds of 6 Melastoma species were used as experimental materials, the germination test was carried out under the stress treatment of cadmium concentration (calculated as Cd2+) of 0, 5, 10, and 50 mg/L, and lead concentration (calculated as Pb2+) of 0, 200, 500, and 1000 mg/L. The germination rate, germination index, vigor index, hypocotyl length and radical length of Melastoma seeds during germination stage were determined under different gradients of cadmium and lead stress respectively. The membership function method and cluster analysis were used to evaluate and classify the cadmium and lead tolerance of the 6 species of Melastoma plants. The germination rate, germination index, vigor index, hypocotyl length and radical length of the 6 species of Melastoma plants showed a downward trend with the increase of cadmium and lead concentrations. Cadmium and lead stress could inhibit the growth of radical more than the hypocotyl growth. There were differences in cadmium and lead tolerance among the 6 species of Melastoma plants. It is found that Melastoma malabathricum, Melastoma candidum and Melastoma ‘Tianjiao’ have strong cadmium resistance and lead resistance, while Melastoma sanguineum, Melastoma ‘Yuncai’ and Melastoma ‘Chaoqun’ have poor cadmium resistance and lead resistance by comprehensive value of membership function and cluster analysis. Melastoma malabathricum, Melastoma candidum and Melastoma ‘Tianjiao’ have strong resistance to cadmium and lead, and can be used as pioneer plants for ecological restoration of soils polluted by cadmium and lead.

  Effects of Organic Waste Substrates on Growth of Potted Jasminum sambac Kang Kaili, Wang Pu, Jin Jing, Liang Jing 2020, 36 (31):  49-53.  DOI: 10.11924/j.issn.1000-6850.casb20191100876 Abstract + ( 414 )   HTML ( 5 )   PDF ( 1185KB )   ( 44 ) To screen organic culture substrates for garden flowers, cassava residue, wormcast, pine bark, coconut coir were used as raw materials to make 5 substrates by volume ratio. Cultivation experiment was carried out to study the effects of the substrates with different mixing proportions on the growth of Jasminum sambac. The principal component analysis was used to analyze the effects of different substrates. The results indicated that compared with garden soil: peat: perlite=6:2:2 (CK), wormcast: peat: perlite=6:2:2 (T2) and cassava residue: peat: perlite=6:2:2 (T3) had an evident advantage in promoting stem diameter, branch number, chlorophyll content, bud number and biomass of J. sambac, and the plants grew well. T2 and T3 could improve the soluble sugar content to enhance cold tolerance of J. sambac, and T3 increased the root activity of J. sambac significantly. Through principal component analysis of 12 growth indexes, the total score of T3 was the highest, and T3 could be recommended as a substrate formula for J. sambac.

  The Introduction Performance of White Bayberry Varieties in Linhai Zhejiang Jiang Xin, Yan Liju 2020, 36 (31):  54-58.  DOI: 10.11924/j.issn.1000-6850.casb20191200959 Abstract + ( 416 )   HTML ( 5 )   PDF ( 1273KB )   ( 158 ) In order to optimize and adjust the variety structure of bayberry and select excellent white bayberry variety suitable for planting in Linhai, an investigation was carried out on several introduced white bayberry varieties and two local white bayberry varieties, and the indexes such as phenology, fruit characters, storability and resistance to twig blight disease were comprehensively evaluated. The results showed that there were significant differences in the performance of the nine white bayberry varieties introduced in Linhai, and the ‘Shui-jing-tou’ variety showed early maturity, relative resistance to twig blight disease, and superior fruit characters, which could be used as a good early maturing white bayberry variety for introduction and promotion.

  Study on the Summer Growth of Rhododendron lapponicum in Chengdu Plain Chen Rui, Hu Ju, Xian Xiaolin 2020, 36 (31):  59-64.  DOI: 10.11924/j.issn.1000-6850.casb20191200942 Abstract + ( 560 )   HTML ( 5 )   PDF ( 1370KB )   ( 77 ) To improve the introduction and cultivation of Rhododendron lapponicum, varieties that suitable for planting in Chengdu plain were selected. Growth index of the whole plant (crown width, plant height, ground diameter, tillering ability), branches (number of branches, longest branch length, single branch thickness, the number of leaf at the longest branch), leaf (leaf length, leaf width, leaf thickness), summer branches length and heat damage index were evaluated of 11 species of R. lapponicum introduced in this study. The results showed that the 11 varieties of R. lapponicum introduced could adapt to the summer growth in Chengdu plain to a certain extent, among which ‘Royal’ was the most suitable, the increasing of its crown width, plant height, ground diameter, the longest branch length, single branch thickness, the leaf length and the leaf width reached 131.43%, 155.07%, 53.79%, 103.65%, 26.66%, 21.51%, and 27.34%, respectively. The heat injury index of ‘Cheer’ was 0, the lowest. In addition, ‘Pink Honey’, ‘Red Overflowing’ also had good performance. Therefore, ‘Royal’, ‘Pink Honey’, ‘Red Overflowing’, and ‘Cheer’ are able to adapt to the summer growth at Chengdu plain, and could be further promoted.

  Pollution of Plastic Film Residue in Xinjiang Under Different Agricultural Practice Systems Liu Xiaowei, Yin Tao, Li Yuanqiao, Lv Jun, He Wenqing 2020, 36 (31):  65-70.  DOI: 10.11924/j.issn.1000-6850.casb20191100833 Abstract + ( 344 )   HTML ( 4 )   PDF ( 1150KB )   ( 48 ) To reduce residual plastic film (PF) pollution, the effects of different agricultural practice systems on residual PF pollution were studied. Through the combination of artificial sampling and questionnaire survey, the residual amount of PF, the current situation of PF recovery and the treatment of residual PF in different farmlands of Xinjiang Production and Construction Corps (PCC) and local areas were studied. The results showed that in northern Xinjiang, there was no significant difference in the residual amount of PF between PCC and local farmland. In southern Xinjiang, the residual amount of PF in local farmland was significantly higher than that in PCC farmland, which was 38.93 kg/hm2(P<0.05) higher. In eastern Xinjiang, the residual amount of PF in PCC farmland was significantly higher than that in local farmland, which was 162.60 kg/hm2(P<0.05) higher. In PF recovery, the PCC and the local areas mainly adopted the way of picking up again when ploughing and only cleaning the soil surface. In the treatment of residual PF, PCC mainly used landfill or incineration after collection, while local farmers used landfill, incineration, placing on the road and sell after collection. Different agricultural practice systems could lead to different amounts of residual PF in farmland.

  Effects of the Microhabitat Formed by Introduced Hippophae rhamnoides on Plant Community and Soil in Desert Land of Northwest Sichuan Province Du Yulong, Tu Weiguo, Vladimirov Dmitrii 2020, 36 (31):  71-76.  DOI: 10.11924/j.issn.1000-6850.casb2020-0146 Abstract + ( 375 )   HTML ( 5 )   PDF ( 1251KB )   ( 169 ) Microhabitat is wildly used to restore deserted ecosystem, but little research has been done on microhabitat restoring alpine-cold desert land. The study set a research in the desert land of northwest Sichuan, Hippophae rhamnoides was introduced from Russia to build single plant and mass plants microhabitat to restore alpine desert. Vegetation types, biodiversity, soil bulk density, water content, pH, organic carbon, total nitrogen, total phosphate, micro biomass carbon, nitrogen and phosphate were studied after three years of formed microhabitats to analyze the effect of microhabitats on vegetation community and soil ecosystem. The results showed that microhabitats increased covers of brush and herb community, mass plants microhabitat enriched biodiversity of the herb community significantly and the amounts of ecological plants, and microhabitat did not change the dominate species of herb community. Microhabitat did not influence soil bulk density, pH and soil water content. Mass plants microhabitat increased soil organic to 5.55 g/kg, total nitrogen to 0.35 g/kg and total phosphate to 0.69 g/kg, and increased soil microbial biomass. However, the soil of alpine desert land was still barren and needed a long time to be restored. Thus, mass plants microhabitat formed by H. rhamnoides has a better function of restoring than single plant microhabitat, and could be used to restore alpine-cold desert land.

  Spatial and Temporal Variability Characteristics and Driving Mechanism of Land-use in Songliao River Basin from 1990 to 2015 Wu Mingwan, Zang Chuanfu, Fu Jiayi 2020, 36 (31):  77-85.  DOI: 10.11924/j.issn.1000-6850.casb20190900690 Abstract + ( 311 )   HTML ( 5 )   PDF ( 2343KB )   ( 156 ) To explain the spatial and temporal change characteristic and driving mechanism of land-use in Songliao River Basin from 1990 to 2015, the authors used ArcGIS space analysis, land-use type transfer matrix and SPSS correlation analysis and factor analysis, analyzed the change of land-use with the statistics of social economic and climate. The results showed that the land-use types in the Songliao River Basin changed significantly from 1990 to 2015. The land-use area followed the order of woodland> cultivated land> grassland> unused land> water area> urban and rural construction land, and the change of land-use area followed the order of cultivated land> grassland> woodland> unused land> water area> urban and rural construction land. The mutual transformation was obvious between cultivated land, woodland, grassland and unused land in 1990 to 2000, the construction land was expanding rapidly. The woodland and high-coverage grassland decreased by 12.6 and 17.4 thousand km2 respectively, but the dry land increased by 22.5 thousand km2. The main driving factors of land-use change were economic development and population growth. This study quantified the driving factors on the foundation of basin area, which could provide theoretical guidance for land-use resource management and formulation of ecological restoration plans.

  Enlightenment of Japan’s Environmentally Conserved Cultivated Land Agricultural System on Cultivated Land Protection in China Su Chang, Yang Zisheng 2020, 36 (31):  86-91.  DOI: 10.11924/j.issn.1000-6850.casb20191200954 Abstract + ( 305 )   HTML ( 6 )   PDF ( 1231KB )   ( 46 ) To solve the problem of long-term extensive management of China’s agriculture, and to study the cooperative protection system of cultivated land and ecological civilization in China, the literature research method and inductive deduction method were used to analyze the cooperative system of cultivated land agriculture under the representative of national environmental conservation agriculture in East Asia. The results showed that, Japan’s farmland agricultural environmental protection payment system, ecological compensation market certification system, and farmland legal system guarantees are established based on the principle of ecological compensation and have been tested in practice to effectively improve the market participation and farmers’ independent input. In conclusion, China has made unremitting efforts to promote the rational use of farmland, but still needs to go ahead in fields of setting a fallow system for the coordinated protection of cultivated land ecology, establishing an ecological compensation system based on local conditions, and accelerating the establishment of a special fund for the collaborative protection of farmland ecology.

  Population Dynamics and Occurrence Regularity of Lissorkoptrus oryzophilus in Leshan Rice Area, Sichuan Yang Chunlin, Li Honghao, Mu Chengjun, Yang Ziwei, Deng Jingmei 2020, 36 (31):  92-96.  DOI: 10.11924/j.issn.1000-6850.casb20191100807 Abstract + ( 275 )   HTML ( 6 )   PDF ( 1261KB )   ( 46 ) To provide a basis for quarantine and control of Lissorkoptrus oryzophilus in Leshan rice area, the population dynamics and occurrence regularity were studied by a field investigation, and the correlation between the damage degree of adults and the number of larvae was analyzed by linear regression. The results showed that L. oryzophilus had one generation a year in Leshan. The migration period of overwintering adults to rice field was not consistent, and its spawning period was long. The larva development, pupation and eclosion period were very irregular, and the cross phenomenon of each insect state was obvious. The overwintering adults of L. oryzophilus were mainly distributed in 0-5 cm shallow soil of slopes and shade within 10 m from the rice field, and the amount of overwintering adults under the shade were the largest. In early spring, the average temperature was over 12℃, and the overwintering adults gradually recovered and fed on surrounding host plants. The survey showed that the epidemic regions covered 5 counties, 73 towns in Leshan, and the infested area was more than 8 thousand hm2.

  Soybean Variety Resource Resistant to Cercospora sojina Race 7: Mining of Elite Alleles Jiang Hongjiao, Zhao Huiyan, Lin Chunyu, Liang Xiaoyu, Ma Shumei, Wang Yang 2020, 36 (31):  97-102.  DOI: 10.11924/j.issn.1000-6850.casb2020-0021 Abstract + ( 335 )   HTML ( 8 )   PDF ( 3470KB )   ( 43 ) The objective is to explore the elite allele of soybean variety resource resistant to Cercospora sojina race 7, and provide genetic information and carrier materials for breeding soybean varieties resistant to C. sojina. In this study, 202 commercial soybean varieties were used as the experimental materials, and the disease resistance to race 7 of C. sojina was identified. The whole genome scanning was used by SSR markers. Association analysis for soybean varieties’ resistance to C. sojina was performed by GLM and MLM model. The results showed that a total of 12 loci were detected by GLM and MLM model, which were significantly associated with the resistance to C. sojina race 7. The rate of explanation on the phenotype of related marker ranged from 2.00% to 15.47%. 20 positive alleles were revealed, among which Satt549-263(18.88) was the largest positive allele in the phenotypic effect value of C. sojina, and ‘Hefeng 29’ was the carrier material. The second one was Satt372-291(17.92), and the carrier material was ‘Hefeng 34’. The information of elite alleles and carrier materials could provide evidence for cross design for pyramiding elite alleles and marker-assisted selection in breeding of varieties resistant to C. sojina.

  Difference of Pathogenicity of Plasmopara viticola in Jiangsu and Zhejiang Zhang Mei, Guo Xia, Wu Bin, Jiang Shanshan, Wang Shengji, Yang Wanhai, Xin Xiangqi 2020, 36 (31):  103-109.  DOI: 10.11924/j.issn.1000-6850.casb2020-0080 Abstract + ( 442 )   HTML ( 8 )   PDF ( 1593KB )   ( 42 ) To clarify the pathogenic differentiation of Plasmopara viticola in different regions of Jiangsu and Zhejiang, this study used single-spot separation method and leaf disc inoculation method to obtain different single-spot strains of P. viticola and determine their pathogenicity. The results showed that 80 strains of P. viticola were pathogenic, and the disease index of more than half of the strains in both provinces was between 40 and 60. The pathogenicity cluster analysis showed that the strains of the two provinces could be clustered into three types of strong, medium and weak pathogenicity. Jiangsu had the strong pathogenic strain as the dominant strain, and Zhejiang had the medium pathogenic strain as the dominant strain. The pathogenicity analysis of the strains in the same province found that the strains of Shushan Jiangsu and Yongfu Zhejiang were significantly stronger pathogenic than those of other regions in the same province, while the strains of Xinfang Jiangsu and Shangqian Zhejiang were the weakest pathogenic compared with those of other regions in the same province. At the same time, the phylogenetic tree of the strains was constructed, and the results showed that the pathogenicity of the strains with the same homology was different, and the rDNA-ITS sequences were also different among the strains with the same pathogenicity. In summary, the grape downy mildews causal agent P. viticola in Jiangsu and Zhejiang have pathogenic differentiation, and the pathogenicity differentiation has no correlation with the genetic relationship of the strains, but the pathogenicity differences of the strains in different regions of the same province have a certain correlation with geographical sources.

  Evaluation of Inoculation Method of Citrus Yellow Vein Clearing Virus and Identification of Resistance of Main Cultivars Fan Zhonghan, Hu Rongping, Chen Qinghua, Chen Qingdong, Li Honghao 2020, 36 (31):  110-114.  DOI: 10.11924/j.issn.1000-6850.casb2020-0208 Abstract + ( 268 )   HTML ( 3 )   PDF ( 1712KB )   ( 37 ) At present, there is no effective method to prevent and cure Citrus yellow vein clearing virus (CYVCV), which has a fast spreading speed and serious harm. The determination of inoculation transmission intensity, and the planting and breeding of resistant varieties can provide an important basis for the prevention and control of CYVCV. In this study, CYVCV was inoculated into 6 different Citrus varieties by grafting, juice friction and injection to determine the infection intensity, and determine the resistance of the varieties to CYVCV. The test results showed that: (1) the grafting morbidity rate and disease index were the highest, reaching 87.5% and 40.27, in addition, the affected plants showed typical symptoms of CYVCV, with severe yellowing, severe yellow vein and shrinkage, and leaf curling; the incidence rate and disease index of injection were 41.67% and 18.05, and the incidence rate of juice friction and disease index were low, 4.17% and 1.39, respectively, showing that CYVCV was a kind of citrus virus disease with high infectivity of grafting; (2) after inoculation of CYVCV, the incidence and disease index of ‘Yulik’ reached 83.33% and 52.78, respectively, its yellowing symptom was serious, had more serious yellow vein, and slight curl and crinkle. The results of the determination of resistance to CYVCV showed that the medium resistance to CYVCV was found in ‘Harumi’, ‘Tacopon’, ‘Daya’, ‘MingRijian’; ‘Sugar orange’ was S; ‘Yulik’ was HS. This study can provide reference for the early detection, prevention and control of citrus yellow vein disease, and the cultivation and disease resistance breeding of citrus.

  Corn Price Prediction Based on Time Series SVR Model Zhang Baowen, Wang Chuan, Yang Chunying, Wang Laigang 2020, 36 (31):  115-120.  DOI: 10.11924/j.issn.1000-6850.casb20191200938 Abstract + ( 684 )   HTML ( 11 )   PDF ( 1359KB )   ( 84 ) The study aims to establish a short-term corn price forecasting model by using time series and support vector regression (SVR) theory, to provide technical support and decision-making basis for corn monitoring and early warning. Based on the non-linear characteristics of corn price series fluctuations, this study took the monthly data of Henan Province from January 1, 2010 to June 30, 2019 as the research object, and combined a chaotic time series with SVR theory, to study a kind of short-term corn price prediction model. The price sequence was processed by the phase space reconstruction method, the model was trained with the reconstructed data, and the grid cross validation (GridSearchCV) was used to optimize the research model. A corn price prediction model was obtained based on time series support vector regression. By analyzing the prediction results of the research model, it is showed that the prediction value of the research model is closer to the true value, and its average relative error (MRE) and root mean square error (RMSE) is 0.006 and 20.57, respectively, which are superior to the prediction results of the traditional support vector regression model, with more accuracy.

  The Patent Development Trend in Global Maize Molecular Breeding Kong Lingbo, Wang Jingjing, Lin Qiao, He Wei, Yang Xiaowei 2020, 36 (31):  121-129.  DOI: 10.11924/j.issn.1000-6850.casb20191200949 Abstract + ( 302 )   HTML ( 6 )   PDF ( 1977KB )   ( 118 ) The paper aims to reveal the development trend of global maize molecular breeding and provide references to related practitioners in China in terms of scientific research or industrialization. The annual number of patents, life cycle of patent technology, major priority and publication country/region, major patentees, technology terms distribution in global maize molecular breeding were analyzed by using methods of bibliometric analysis, experts consultation and investigation research. To clarify typical enterprise’s technical history, the patent technology roadmap of Dupont was drawn based on the relationship among patent citations. The terms of patent titles and abstracts were calculated by emergency indicator calculation to explore emerging technology. The results show that the global maize molecular breeding is in a steady development stage. The largest number of important maize molecular breeding technologies comes from the United States, which is also the most valued technology market. The number of Chinese patents ranks the second in the world, but the patent quality and the awareness of technology layout overseas need to be improved. Multinational enterprises with complete technological system are the main force for technological innovation. Transgenic technology is the most widely used breeding technology at present. There are some emerging technologies in this field that deserve attention, such as doubled haploid, molecular marker-assisted selection, haploid induction, etc. It is suggested that China should further support maize molecular breeding and capture technology gaps sensitively to enhancing patent quality and technological competitiveness. At the same time, technical layout in the international market should be actively promoted.

  New Characteristics, New Trends and Enlightenment of US Dairy Industry Zhang Chao, Jiang Yahui, Shao Dafu, Dong Xiaoxia, Dai Peng, Peng Hua 2020, 36 (31):  130-139.  DOI: 10.11924/j.issn.1000-6850.casb2020-0453 Abstract + ( 487 )   HTML ( 4 )   PDF ( 1396KB )   ( 136 ) The U.S. dairy industry has a long history of development, and its long-term accumulated rich experience in production, consumption and even circulation trade has a certain reference value for the revitalization of China’s dairy industry. This paper analyzes the new characteristics of dairy production, price, consumption, trade and other aspects of the U.S. dairy industry since 2000, combs the supporting policies and their changing trends. The study found that in recent years, the number of dairy farms in the United States has dropped sharply, and has been concentrated in the north and the west. Large scale pastures with more than 500 cows have become the mainstream. The number of dairy cows increased. Technological advances have pushed the yield of dairy cows to 10 tons, and the output of fresh milk is close to 1 million tons. A pricing mechanism for milk composition based on grading pricing has been continuously improved. The price of fresh milk has been running at a low level in the past five years and recovered rapidly in 2019. Dairy processing industry is concentrated in leading enterprises. Cheese is the main processing product. The consumption of dairy products increased year by year, with the annual per capita consumption reaching 292.90 kg. Cheese is the main growth point and the growth rate is accelerated. The trade fluctuation of dairy products has increased. The export destinations are concentrated in North America, East Asia and Southeast Asia. The products are mainly milk powder, cheese and whey. The U.S. dairy industry support policy covers the production, consumption, trade and other aspects of the industrial chain. The functions of each policy are complementary and coordinated, forming a strong policy joint force and comprehensive efficiency. The experience and practice of dairy industry of the United States in terms of industrial organization, operation mechanism and policy support have important enlightenment on promoting and improving the interest linkage mechanism of the Chinese dairy industry, optimizing the formation mechanism of fresh milk price, improving the supporting policy system of dairy industry and cultivating the consumption habits of dairy products.

  The Establishment of Agricultural Periodical Group: On the Perspective of Dissemination of Agricultural Science and Technology Knowledge Liu Xinyong, Lin Lingna, Ke Wenhui 2020, 36 (31):  140-143.  DOI: 10.11924/j.issn.1000-6850.casb20191200917 Abstract + ( 280 )   HTML ( 2 )   PDF ( 1230KB )   ( 42 ) To promote the dissemination of agricultural scientific and technological knowledge, and to make scientific and technological journals bigger and stronger, in view of the lack of dissemination ways of agricultural scientific and technological knowledge, this paper put forward suggestions on the integration of journal resources to establish agricultural professional journal groups, and made a preliminary discussion on the selection of journals in groups, and the construction and operation of journal websites. The agricultural professional periodical group has the advantages of comprehensive industry knowledge, sustainable update, free sharing and flow platform. On the basis of innovating the dissemination mode of agricultural scientific and technological knowledge, the sustainable development of the periodical group could be realized through advertising operation.

  Study on Allogynogenetic Gibel Carp ‘CAS Ⅴ’ in Paddy Field Cultivation Fan Haiping, Xue Lingzhan, Yang Xiaoyan, Zhong Quanfu, Huang Derong, Zhang Shuxing, Chen Bin 2020, 36 (31):  144-147.  DOI: 10.11924/j.issn.1000-6850.casb20191100884 Abstract + ( 457 )   HTML ( 6 )   PDF ( 1175KB )   ( 55 ) To evaluate the efficacy of allogynogenetic gibel carp ‘CAS V’ in paddy field cultivation, the experiments with feeding and unfeeding cultivation mode were carried out in Wuyishan. The growth performance and production of fish were measured, the survival rate, specific growth rate and production index and input-output ratio were analyzed. The results showed that, after 62 days’ paddy field cultivation, the production, survival rate, weight gain rate and specific growth rate of allogynogenetic gibel carp ‘CAS V’ in the feeding mode were 2.17, 1.47, 1.98 and 1.60 times of those of the unfeeding mode respectively, and the average size and condition factor were significantly higher than those of unfeeding mode (P＜0.05). Under the experimental conditions, the unit profit of the feeding mode of paddy field cultivation was 9817.50 yuan/hm2, which was 2.23 times of that of the unfeeding mode. Therefore, the income of allogynogenetic gibel carp ‘CAS V’ of feeding mode is higher than that of unfeeding mode, but more efforts should be done to improve the efficiency of feed utilization and reduce labor cost to raise the economic benefits.

  The Development of Agricultural Science and Technology in Shaanxi for a Century Su Yi, Liu Wei 2020, 36 (31):  148-158.  DOI: 10.11924/j.issn.1000-6850.casb2020-0167 Abstract + ( 345 )   HTML ( 1 )   PDF ( 1417KB )   ( 75 ) Based on the review of the background and environment of agricultural sci-tech development in Shaanxi at different historical periods in the past 100 years, features such as the development impetus, the essence, scope and development targets were analyzed. The study summarizes the achievements of agricultural sci-tech development in Shaanxi, namely, the setting-up of agricultural sci-tech service system, finding out various approaches to breed and popularize new varieties, promoting agricultural industry, building up policy and talent environments for agricultural sci-tech development, and changing the traditional concepts and practices about agriculture. The experience and enlightenments are also concluded in this study, that is, the development of agricultural science and technology is significant for solving various contradictions in agriculture, and it is also an effective way to realize agricultural modernization and a significant measure for safe agricultural production. It needs to be pointed out that the development of agricultural science and technology should be in accordance with the needs of our country and its vast population. In addition, the study emphasizes the problems existing in agriculture development in Shaanxi, such as the relatively low transformation rate of sci-tech achievements, rigid system and mechanism, insufficient support from provincial government, unreasonable personnel structure at grassroots’ level. Finally, the study puts forward that scientific research should be demand-oriented, provincial funds should be established , sci-tech service should be paid, agricultural sci-tech organizations should be empowered more rights for personnel management, and the functions and initiatives of main bodies of market should be given a full play, thus promoting the stable development of agricultural sci-tech in the whole province.

  The Cohesive Mechanism Between Capital Flow to Rural Areas and Endogenous Rural Development in Northwest Minority Regions: A Case Study of Tianzhu Tibetan Autonomous County in Gansu Province Zhang Yanhong, Lv Leili 2020, 36 (31):  159-164.  DOI: 10.11924/j.issn.1000-6850.casb20191100836 Abstract + ( 225 )   HTML ( 2 )   PDF ( 1227KB )   ( 40 ) This paper reviews the significance of business capital going to the countryside for the development of agriculture and rural society. The questionnaire survey in Tianzhu Tibetan Autonomous County in Gansu Province was used to analyze the real needs of local farmers for participating in grassroots affairs, agricultural development services, local organizations and obtaining external development resources. The results shows that local farmers have a strong impetus for these needs, so attracting capital to the countryside is one of the strategies to promote the development of this region. In addition, the paper proposes some cohesive devices of capital going to the countryside and endogenous rural development from the aspects of improving the rural investment climate, developing characteristic industries, and protecting the rural eco-environment.