The grain yield and amino acid content of maize variety Zhengdan958 were determined in a 13-year long-term experiment. The results showed that there were 17 kinds of amino acids. The content of glutamic acid was the highest, the content of cystine and methionine were the lowest. The nitrogen fertilizer significantly increased grain yield and amino acid content of maize. The grain yield of organic nitrogen was lower than that of chemical nitrogen when nitrogen rate was 60 kg/ha. There was no significant difference in grain yield between organic nitrogen and chemical nitrogen when nitrogen rate were 120-360 kg/ha. The grain yield of organic nitrogen was significantly higher than that of chemical nitrogen when nitrogen rate were 420-600 kg/ha. Within the range of 0-600 kg/ha, the higher nitrogen rate could get higher amino acid content and the amino acid content of chemical nitrogen was higher than that of organic nitrogen. The optimum total amino acid content could be obtained by organic nitrogen 118.5-600 kg/ha and chemical nitrogen 91.9-600 kg/ha. Long-term application of organic fertilizer nitrogen 120-420 kg/ha and chemical fertilizer nitrogen 120-300 kg/ha could achieve the synergistic improvement of grain yield and amino acid.
Based on the basic idea of the event study method, this paper constructed a framework for analyzing effectiveness of grain market. According to the relevant data from November 2008 to August 2020, VAR and BEKK models were used to analyze the effectiveness and changes of corn market before and after the market-oriented reform of the purchase and storage system. The study found that after the implementation of the market-oriented acquisition policy, the transmission of price information in China’s corn spot market, upstream and downstream of the industrial chain and domestic and foreign markets has been more unobstructed, the effectiveness of the corn market has been improved, and the goal of policy reform has been preliminarily achieved. To consolidate the effect of market-oriented acquisition policy and prevent abnormal fluctuations in the domestic market caused by international market factors, it should be oriented to enhance the ability to ensure food security, enhance the influence of China’s future market, improve supporting measures, detail the subsidy standard, and reduce the impact of market-based purchase on the grain industry.
Under the integration of water and fertilizer under shallow subsurface drip irrigation in Liaohe town,Tongliao city,Inner Mongolia,DK159 was taken as the research subject and 60 000 plants/ha（D1,CK,Farmers’conventional planting density） and 90 000 plants/ha（D2） and 45 mm(I 45 ),90 mm(I 90 ),180 mm(I 180 ),270 mm(I 270 ),360 mm(I 360 ),450 mm(I 450 ,CK),the effects of planting density and irrigation amount on maize yield and water use efficiency（WUE） were studied at 6 irrigation levels.The results showed that under the irrigation amount of 360 mm,the highest yield and the higher WUE were obtained.The highest yield and the higher WUE were obtained from 60 000plants/ha under 270 mm irrigation.Compared with conventional treatment(D1-I 450 ),the yield of treatment of D1-I 270 was not significantly decreased,while the irrigation amount was decreased by 40.0%,evapotranspiration was decreased by 19.7%,and WUE was increased by 25.1%.Compared with the traditional production method(D1-I 450 ),treatment of D2-I 360 can increase the yield by 20.5%,reduce evapotranspiration by 7.9% and increase WUE by 30.9%.To conclusion,under the condition of water and fertilizer integration under drip irrigation,increasing planting density can significantly improve maize yield and water production efficiency.
The leaves of maize B73 etiolated seedling were isolated and obtained by enzymatic. The PEG-Ca 2+ mediated protoplast cell transformation was optimized, and the effects of PEG concentration and plasmid dosage on the transient conversion efficiency were analyzed. The method of electric shock transformation was explored, and then the influence of voltage and shock time on transformation efficiency was analyzed. Meanwhile, the subcellular localization system for maize mesophyll protoplasts was established using fluorescent protein to fusion localization signal. The possibility of this transient expression system was further verified by overexpressing the ZmDHDPS gene in maize mesophyll protoplast cells. The protoplast cells obtained by enzymatic were analyzed by FDA staining and the result show that about 95% cell was vitality. In the PEG-Ca 2+ mediated transient transformation method, the conversion efficiency reached 51.28% when PEG concentration was 40% and plasmid increased to 25 μg. In the electric shock transformation method, the conversion efficiency is 32.66% when the voltage is 350 V and the shock time is 5 ms. By fusion the nuclear localization signal NLS with the eGFP gene into maize mesophyll protoplast cells,eGFP was successfully localized to the nucleus. The DsRed2 protein was successfully localized in the chloroplast by fusing the chloroplast localization gene ZmMSH1 with the DsRed2 gene. Overexpression ZmDHDPS samples were detected by the qRT-PCT and Western Blot technique, and cellular free lysine content in protoplasts was detected significantly increased.
Flowering time is an important adaptive trait and is a target trait in maize breeding. Mapping quantitative trait locus/loci（QTL） controlling flowering time is the basic work for improving maize flowering time. In order to map the QTL controlling maize flowering time, an F 2:3 population was constructed by crossing maize inbred lines Huangzaosi and 1462, the population was evaluated for days to tasseling（DTT） and days to anthesis（DTA）, and genotyped with high-density SNP markers. The result showed that DTT and DTA had strong correlation, and both traits showed normal distribution. A total of five QTL controlling the stage of male twitching were detected using compound interval mapping with WinQTLcart 2.5 software, located on chromosomes 3, 5, 6, 7 and 9, with contributions ranging from 6.19% to 26.39%. For DTA, 4 QTLs were also detected, located on chromosomes 3, 5, 6, and 7, and the phenotypic variances explained by these QTL ranged from 7.48% to 28.28%. These QTLs mainly showed partially dominance or over-dominance. To find candidate genes underlying three major QTL（explaining＞10% phenotypic variance）, RNA sequencing analysis was performed using V6-stage shoot tips of the parental lines. A total of 21 differentially expressed genes were found in the confidence interval of the major QTL, and might contain the candidate genes for maize flowering time.
Based on the micro survey data in Northeast China, this paper constructed a treatment effect model to analyze the impact of the adjustment of planting structure on the total household income and its composition, and discussed the different influence among farmers with different income by quantile regression method. The results showed that the adjustment of planting structure decreased household income through the reduction of agriculture income and transfer income, which decreased by 4.982%, 3.587% and 3.754%, respectively. In addition, the impact is obviously heterogeneous due to different level of household income, and the middle-income cannot make up for the income loss caused by the adjustment of planting structure. The training of agricultural technology and the utilization of machinery have a positive effect on the family income. Based on the research conclusions, three policy implications are put forward: firstly, to rationally guide farmers to adjust their planting structure and improve the relative income of changing crops; secondly, to improve the quality of rural labor force, promote the development of socialized agricultural services; thirdly, foster new types of business entities such as large farmers to increase the production capacity of small farmers.
Two-year field experiment was conducted to investigate the effects of reduced application of controlled-release N fertilizer（CRU） compared with farmer conventional fertilization on maize yield, its components, N absorption and utilization. The experiment was set up five treatments, including no N fertilizer（N0）, farmer conventional fertilization（FP）, 80% CRU（CRU1）, 70% CRU（CRU2）, and 60% CRU（CRU3）. The results showed that CRU1and CRU2 treatments increased significantly maize yield（P＜0.05） than FP treatment. The two-year average yield increased by 7.0% and 5.4%, respectively. The maximum and average N accumulation rates of maize under CRU1and CRU2 treatments were increased by 9.6%, 6.5% and 7.9%, 6.2% than FP treatment, and the days of maximum N increase rate appeared 7.2 d and 5.0 d earlier, respectively. Compared with FP treatment, reduced application of CRU significantly improved REN, AEN, and PFPN（P＜0.05）. REN and PFPN significantly increased with increasing of the reduction ratio of CRU. While AEN increased at first and decreased later, and the highest value was found under CRU2 treatment. 30% reduction of CRU（193 kg/ha） can achieve simultaneous improvement of maize yield and N use efficiency in this condition.
Simple sequence repeats（SSR） are abundant in eukaryotic genomes and are often randomly and uniformly distributed throughout the whole genome. SSR markers are widely used in animal and plant gene mapping,population genetic diversity analysis, genetic linkage map construction, fingerprint map construction, germplasm identification, molecular marker-assisted selection and other directions. With the publication of large numbers of whole genome sequences, the sequence information available in databases such as NCBI has grown dramatically.However, in conventional molecular biology research, the traditional small-scale marker development model is still continuing, and the markers developed are very limited due to low efficiency. Combining MISA scripts, Primer3 and e-PCR software to search SSR locus, design primers, and to analyze the specific amplification, and calculate their length differences, high-density SSR markers in maize genome were successfully developed. Finally, through primer synthesis, PCR amplification and agarose gel electrophoresis, the reliability of the developed marker was verified by conventional methods of molecular biology.
During the 2019 and 2020 growth season, Sukenuo 1501, Sukenuo 12, Sukehuanuo 2008, Sukenuo11, Suyunuo 5, and Wannuo 2000 were chosen as experimental materials to analyze the difference of grain yield and grain filling characteristics in Southern Area, which would support breeding high-yield and high-quality waxy maize variety. The results showed that grain yield and yield components were similar in two years. Grain number and grain weight per ear were higher in higher-yield varieties（Sukenuo 12, Sukenuo 1501, Wannuo 2000 and Sukehuanuo 2008） than those in lower-yield varieties（Suyunuo 5 and Sukenuo 11）. The grain yield was significantly positively correlated with ear length, ear grains and 100-kernel fresh weight. The 100-kernel fresh weight was significantly positively correlated with the maximum filling rate and average filling rate. The number of grains per ear was correlated with the effective grain filling period, maximum grain filling rate and the growth at maximum grain filling rate. Therefore, the selection of higher filling rate and growth at maximum filling rate could be used for higher-yield varieties of waxy maize.
To explore the effect of the interaction between vermicompost and salt stress on the stomatal characteristics and photosynthetic characteristics of maize, five treatments were set with maize as the experimental material. Under the salt stress, the proportions of vermicompost were 0, 10%, 20%, and 40%, respectively. The changes of earthworm manure on the stomatal characteristics and photosynthetic characteristics of maize under salt stress were analyzed with the treatment without vermicompost and NaCl solution as the blank control. The results showed that the addition of vermicompost could significantly increase the stomatal length, stomatal area, and stomatal perimeter of maize leaves under salt stress. At the same time, the length and perimeter of stomata on the abaxial surface also increased significantly with the addition of vermicompost. The spatial distribution of stomata on adaxial and abaxial surfaces of maize leaves became more regular after adding vermicompost. The net photosynthetic rate, intercellular carbon dioxide concentration and stomatal conductance of maize seedlings treated with vermicompost were significantly higher than those treated with salt stress, and the water use efficiency of maize seedlings was increased. The addition of vermicompost can also effectively increase the maximum photochemical transformation efficiency of maize seedling leaves under salt stress, reduce the relative conductivity and alleviate the damage of salt stress to maize.
In this study, different varieties were selected, low and high planting densities were adopted, and the changes in yield and mechanical harvest quality of spring and summer maize were analyzed. The results showed that the kernel number per ear and grain weight of spring maize and summer maize decreased after densification. However, densification significantly increased the number of ears, and then significantly increased the yield by the average of 10.5% in spring sown maize and 14.4% in summer sown maize, respectively. The grain broken rate and loss rate of spring sown and summer sown maize under higher density treatment were significantly decreased by 0.9% and1.1%, respectively, and the loss rate decreased by 1.5% and 1.2%, respectively; while, the effect of densification on impurity rate was not significant. Significant linear correlations were found among grain moisture, the crushing force of grain compression and grain broken rate. Reducing grain water content and increasing crushing force of compression could significantly reduce grain broken rate. Interestingly, the increase in density significantly reduced the grain moisture and increased crushing force of compression at maize harvest. Therefore, it is suggested that the planting density of spring maize and summer maize in Hubei province could be appropriately increased.
In order to clarify the reasons for the growth of maize yield per unit area and the change of total factor productivity in China for a long time, this paper calculated the total factor productivity of maize from 2003 to2019 based on Solow residual method and stochastic frontier method, and decomposed the contribution of growth rate of maize yield per unit area and total factor productivity. The analysis results showed that, from 2003 to 2019,China’s maize yield per unit area increased by 28%, in which the contribution rates of labor input, machinery cost,seed use, fertilizer application and total factor productivity growth were-0.8%, 22.5%,-3.8%, 6.1% and 75.9%, respectively. From 2003 to 2019, the fluctuation of total factor productivity increased, and the cumulative increase calculated by the residual method and stochastic frontier production function method reached 13.7% or 18.7%. Technological progress and technological efficiency improvement played a decisive role in the growth of total factor productivity of maize production, and their contribution rates were 68.8% and 32.3% respectively.With the strong driving effect of total factor productivity, the growth of maize yield per unit area in China has shifted from input-oriented to efficiency-oriented growth. Factor input tends to saturation, but there is still room for the improvement of total factor productivity, which is reflected in the improvement of seed innovation, mechanical transformation and upgrading,and the improvement of scale efficiency through service scale.
This paper systematically describes the harvest, silage processing, feeding value and economic benefits of HMC, as well as the potential and prospect of developing HMC silage in China. Compared with direct harvesting and crushing of corn kernels, HMC silage can reduce by 25%-30% of the cost, and has the same energy and protein as dry corn. The feeding effect shows that net energy lactation and starch digestibility increase by 5%-10%and by 30%-35%, respectively, when HMC silage is used. Furthermore, the wrapped HMC can be stored safely for2 to 3 years. Focusing on the main problems of drying, storage and transportation of corn in the main corn producing areas of Northeast China and HuangHuaiHai, the developing HMC will have great development potential and market application prospects, which can effectively alleviate the contradiction between supply and demand of corn, and strengthen feed supply capacity and security in China.
The maize variety Zhengdan958 was used as the experiment material.Three treatment concentrations of DEHP（diethylhexyl phthalate） were set at C1（50 mg/kg）,C2（100 mg/kg）,and C3（150 mg/kg） in addition to the control group（CK）.The growth of seedlings,chlorophyll concentration,photosynthetic characteristics and antioxidant enzyme activities were measured.The results showed that the inhibitory effect on the growth and development of maize seedlings increased with the increasing DEHP concentration;the chlorophyll concentration,net photosynthetic rate（P n ） and transpiration rate（T r ） in leaves decreased significantly;the concentration of carbon dioxide（C i ） between cells increased significantly;and the maximum photochemical efficiency（F v /F m ） and photosynthetic performance index(PI ABS ) of PSⅡshowed a descending trend.The activities of ribulose carboxylase（Ru BP carboxylase）and phosphoenolpyruvate carboxylase（PEP carboxylase） decreased significantly.The activity of superoxide dismutase（SOD） increased significantly.The activity of ascorbate peroxidase（APX） decreased significantly.The activity of peroxidase（POD） showed a trend of increasing and then decreasing,reaching maximum value when the concentration of DEHP was 50 mg/kg.
Maize genome and other databases were used to search for calmodulin family genes. The CaM gene family was identified, and then the basic protein characteristics of the family members, such as gene structure, isoelectric point, molecular weight, subcellular localization and protein conserved domain were analyzed. The expression levels of these genes in different tissues and under drought stress were also analyzed. In addition, qRT-PCR was used to detect the expression levels of five representative CaM genes under drought treatments. The results showed that a total of 14 CaM genes were identified, which could be divided into four subfamilies based on the 3’-UTR sequence and three isoforms based on the amino acid sequence of proteins. The gene structures of them are very conserved; the molecular weight of most family members was about 16.8kD, and the isoelectric point is between4.10 and 4.30. The conserved domain of this family composed of 3 to 4 EF hand domains. Most of them localized in cytoplasm and nucleus. The expression of Zmcal4, Zmcal5 and Zmcal6 genes were very low in all tissues, and the expression of most members of CaM gene family was inhibited by drought. The expression of Zmcal3-1, Zmcal3-2,Zmcal3-3 and Zmcal3-4 could be restored to the control level after rewatered, which suggested that these genes might be involved in drought stress response. The result of q RT-PCR showed that drought inhibited the expression of CaM gene, and the expression level of CaM gene decreased gradually with drought treatment.
An incomplete diallel cross design was used to analyze the breeding potential of 4 Lvda Red Cob inbred lines, 6 parental inbred lines from 3 main hybrid lines of Jilin province were selected as the test lines. A total of 24 crosses were created with Xianyu335 as the control. The combining ability and heterosis of germplasm of Lvda Red Cob were analyzed in these traits including yield, ear, agronomic characters, and comprehensive resistance.The results showed that the general combining ability of E28, LD61, and Dan340 decreased plant height and ear height, and 4 lines increased the resistance to Curvularia leaf spot, big spot, gray spot, and stem rot. The general combining ability of Dan340 and Dan598 increased yield, and the special combining ability extended the growth stage and increased the number of green leaves at harvest, while E28 and LD61 showed the opposite. The analysis of yield combining ability showed that yield was significantly correlated with total combining ability values and general combining ability values of mother parental lines, and the correlation coefficient with total combining ability was greater. The results of heterosis analysis showed that Dan598 had the best heterosis value, and the 3 paternal lines PH4CV, Chang7-2, and PD752B were more closely related to the tested line.
以郑单958为供试品种,设不覆膜(T0)、出苗后揭膜(T1)、第二水前揭膜(T2)、第三水前揭膜(T3)、第四水前揭膜(T4)和不揭膜(T5)处理,测定玉米生长指标,研究揭膜时期对滴灌玉米生长及产量的影响.研究表明,不同时期揭膜对玉米的生长影响不一致,在拔节期和大喇叭口期揭膜对玉米株高、茎粗和叶面积指数影响较小;对在抽雄期至成熟期株高、茎粗和叶面积影响较大,其中T3处理株高、茎粗和叶面积指数均显著高于T0处理.适时揭膜有利于提高玉米产量,其中,T3处理实收产量最高,较T0、T5处理分别增产25.46％和7.63％.将玉米实收产量(y)与揭膜时间(x)进行拟合,得出拟合方程为y=-0.352 9x2+58.677x+12 074,R2=0.819 8;最高理论产量为14 513.07 kg/hm2,最佳揭膜时间介于第三水和第四水之间.因此,在本试验条件下,北疆地区滴灌玉米最佳揭膜时间应在第三水至第四水之间,即六月底至七月初.
Through two-year field trials with five nitrogen fertilizer levels were set,and Xianyu 35（XY335） and Limin 33（LM33） as the test varieties,which systematically monitor the populations yield composition,nitrogen absorption,distribution and transportation characteristics.The yield of maize grains grew first,then dropped when nitrogen fertilizer was increased.Among them,the yield with N3 treatment was the greatest,reaching 14 354 kg/ha.The nutrient accumulation after flowering and contribution of nutrient accumulation to grain increased with increasing nitrogen application,and difference in nitrogen accumulation between XY335 and LM33 was mainly after flowering,XY335 had better yield performance than LM33,and plant nutrient remobilization to grain had higher efficiency.The one-variable quadratic equation y=-0.013x~2+9.915 1x+12 186,R~2=0.888 9 is produced and the best economic fertilization quantity is 277.3 kg/ha,corresponding yield is 13 936 kg/ha.Comprehensive consideration of soil fertility and climatic conditions showed that a yield level of 14 000 kg/ha of spring maize could be achieved at nitrogen fertilizer application of 280 kg/ha in black soil region in central northeast China.Reasonable nitrogen fertilizer management could help transfer dry matter to grains,while also increasing nitrogen absorption and transfer efficiency in the plant’s latter stages of silking,resulting in crop yield increase.
The nine inbred lines were used as materials to establish the basic population MCO-0 of southwest spring maize, which was improved by cross test and progeny identification. The population yield and yield traits, ear traits and plant type traits of different generations were analyzed. The results showed that MCO-0 was used as the basic population, and after a round of improvement, the main target characters of MCO-2 population including yield per plant, rows per ear, grains per row, anthesis-silking interval（ASI）, etc. were all improved, while ear length, axis diameter, growth period, etc. were negative gains. After a round of improvement of MCO-2, the plant height, ear height, ASI, etc. were increased, while the ear length, ear diameter, number of grains per row, etc. were negative gains. After a round of improvement of MCO-2, the plant height, ear height, ASI, etc. were increased, while the length of ear, the thickness of ear, the number of grains per row, and the number of rows per ear were decreased.Compare with MCO-1, the main target traits of MCO-3 yield per plant, bald head length and ASI were all increased, and some of the other traits were increased or decreased in some rounds.
The wild-type and CzVelB strains were used as test strains, biological, inoculation test and the activities of toxin and cell wall degrading enzyme were analyzed. The results showed that compared with the wild-type,there was no significant difference between knockout transformants in the growth rate, but the spore production and spore germination of the knockout transformants decreased obviously, and the germination process lagged 1h. The pathogenicity of transformants was significantly decreased, including the disease index and lesion size. Toxin assays results showed that it had a certain pathogenic effect on leaves, but the mutant was lower than that produced by the wild-type. CzVelB and wild-type strains produced 5 cell wall degrading enzymes, the CWDEs activity of C. zeaemaydis was affected after CzVelB knocked out. Cellulase（Cx） and Pectin methyl-galacturonase（PMG） played a role in the early stages of infection（12 h）. Polygalacuronic acid trans-eliminase（PGTE） played a part in the late stage of infection（72 to 96 h）. CzVelB regulates the pathogenicity of C.zeae-maydis mainly by affecting the activity of PGTE.
