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.
