In order to reveal the diversity characteristics of endophytes in different species and different organs,the correlation between endophyte community structure and host species and organ types was preliminarily clarified.The stems,leaves and leaf sheaths,which were respectively collected from the plants of the foxtail millet blast-susceptible varieties Shawan millet and Jigu 22 and the foxtail millet blast resistant varieties Xiaoqinggu and Shiliuzi,were used to carry out the endophytic diversity by high-throughput sequencing based on the 16S rDNA V3—V4 region.There were certain differences in endophyte species composition between susceptible and resistant varieties.In all tested samples,the dominant groups at the phylum level were Proteobacteria and Actinobacteriota.Bacteroidota,Chloroflexi,Myxococcota,Firmicutes followed.Alpha diversity analysis showed that the susceptible varieties(Shawan millet,Jigu 22)had higher abundance of endophyte in leaves.PCoA analysis revealed that the organ type had a greater impact on the endophyte community structure than the variety.Species composition analysis showed that the susceptible varieties Shawan millet and Jigu 22 contained endophytic flora that were significantly different from those of Xiaoqinggu and pomegranate(resistant to foxtail millet blast).The susceptible varieties(Shawan millet,Jigu 22)contained Entotheonellaeota phylum in leaves,while resistant varieties had Hydrogenedentes phylum in leaf sheaths.It clarified that the diversity and community structure of endophytes in different organs and millet varieties susceptible and resistant to foxtail millet blast were different,and organ types had a greater impact on the community structure of endophytes than varieties.

The SiPRR73 gene was cloned from Yangu 11 using RT-PCR technology,and through analyzing tissue-specific expression,responsive features of SiPRR73 to different photoperiods,photo-thermal combinational treatments and five abiotic stress treatments,the regulation mode of photoperiod and temperature on SiPRR73,and the responsive pattern of SiPRR73 to abiotic stresses in foxtail millet were explored. The results showed that totally 2 928 bp cDNA sequence of SiPRR73 was obtained from Yangu 11,which included 2 283 bp CDS region,encoding 760 amino acids. The SiPRR73 proteins of C4 crops including Panicum miliaceum,Panicum hallii,Sorghum bicolor and Zea mays showed relatively close relationship with SiPRR73. The second parietal leaf was the highest expression tissue of SiPRR73,but the expression level at root,stem and panicle tissues was relatively lower. The expression level of SiPRR73 was higher at light period than that at dark period under both short-day and long-day conditions,and during the whole vegetative growth phase,SiPRR73 showed higher expression level under long-day compared to short-day,which indicated that the expression of SiPRR73 was induced by light and controlled by photoperiod. The temperature determined expression peak number of SiPRR73 and the photoperiod determined occurrence time of expression peaks,so temperature and photoperiod participated in regulating of SiPRR73 expression mutually. PEG and low temperature stresses induced SiPRR73 expression totally,NaCl induced SiPRR73 expression at early stress stage,but inhibited it at later stress stage. Fe stress inhibited SiPRR73 expression at early stage,but induced it at later stage. ABA stress caused the close responsive feature of SiPRR73 to NaCl. This study indicated that SiPRR73 showed light-dependent expression feature,and photoperiod and temperature regulated SiPRR73 by interaction pattern,suggesting that SiPRR73 participated in adaptability regulation process to different photo-thermal conditions and might play a certain role in coping with drought,low temperature,ABA,NaCl and Fe stresses in foxtail millet.

In order to understand the function of SibHLH19 in foxtail millet,the CDS sequence and promoter sequence of SibHLH19 gene were separately cloned with the leaf cDNA and genomic DNA from resistance material Shilixiang as template by PCR.Promoter cis-acting elements and biological characteristics were analyzed using bioinformatics online tools.Then the expression patterns of SibHLH19 in different tissues and during the process to rust resistance were surveyed by qRT-PCR,respectively.Lastly the prokaryotic expression characteristics for the gene were detected by SDS-PAGE,laying a theoretical foundation for further research on SibHLH19 gene function and disease resistance mechanism.The results showed that the CDS sequence of the SibHLH19 transcription factor was 843 bp in length,encoding a total of 280 amino acids,the predicted protein molecular weight was 29.97 ku.The theoretical isoelectric point was 5.85,and the encoded protein chemical formula was C₁₂₉₆H₂₀₇₁N₃₉₇O₄₀₀S₁₁,containing a bHLH conserved domain,belonging unstable hydrophilic protein.The largest element of the protein's secondary structure was random coils,and the smallest element was a β-turn.Evolutionary analysis showed that SibHLH19 had the higher homology to the amino acid sequences of Panicum miliaceum (RLM85279.1),Panicum hallii (PUZ71581.1)and Panicum virgatum (XP_039835205.1),and had the lowest homology with Triticum aestivum(KAF7059972.1)and Aegilops tauschii subsp.strangulata (XP_040244423.1).The analysis of the promoter cis-acting elements showed that there were multiple response elements such as hormones and stresses in the promoter region of the SibHLH19 gene.Tissue expression analysis showed that the gene was mainly expressed at the seedling stage with the highest expression in the aboveground part,and was almost no expression at the booting stage.Within 24 hours of the response to the biotic stress of rust disease in foxtail millet,the SibHLH19 gene expression was up-regulated at 8 and 16 h in the disease resistance response,while its expression was only slightly up-regulated at 16 h and down-regulated at the rest of the time points in the susceptible response.It was speculated that SibHLH19 played a positive regulatory role in the resistance response to rust disease in foxtail millet.The constructed prokaryotic expression vector pET30a-SibHLH19 could express the SibHLH19 fusion protein with an apparent molecular weight of about 44 ku after being induced by 0.1 mmol/L IPTG.

In order to explore the suitable nitrogen application,the influence of dry matter and nutrient element accumulation and distribution under different N application levels on buckwheat was studied. Field experiment was conducted under different N application rates N₀,N₁,N₂,N₃ and N₄(0,30,60,90,120 kg/ha). The results showed that buckwheat dry matter first increased and then dropped with the increment of nitrogen application rate. When the nitrogen application rate was N₂,the buckwheat dry matter reached the highest. But when the nitrogen application rate was N₃,the seeds dry matter and distribution rate reached the highest. The results also showed that seeds nitrogen,phosphorus and potassium contents first increased and then dropped with the increment of nitrogen application rate.When the nitrogen application rate was N₃,the seeds nitrogen,phosphorus and potassium contents reached the highest. The seeds nitrogen,phosphorus and potassium distribution rate increased with the increment of nitrogen application rate,but it decreased in stems and leaf. The amounts of nutrients which needed for the formation of 100 kg seeds of buckwheat were N 7.09 kg,P₂O₅ 4.15 kg,K₂O 8.74 kg and the rate was 1.00:0.59:1.24.The production efficiency of N,P₂O₅,K₂O first increased and then dropped with the increment of nitrogen application rate. When the nitrogen application rate was N₃,the production efficiency of N,P₂O₅,K₂O reached the highest.With the increase of the amount of nitrogen fertilizer, the dry matter production efficiency of nitrogen and phosphorus first increased, then decreased, and then increased. The dry matter production efficiency of potassium gradually increased, and the production efficiency of N₄, nitrogen, phosphorus and potassium dry matter reached the highest level. Considering the buckwheat dry matter and nutrient element under the experimental conditions,N application rate of 90 kg/ha identified to be the suitable amount.

In this research,a field orientation experiment on sorghum-maize rotation was conducted.The effects of different fertilization conditions on the growth,nutrient,soil enzyme activity and microbial activity of sorghum was studied.The experimental results showed that different fertilizer could significantly increase the jointing stage of sorghum plant height,stem diameter,number of pieces and index pages visible leaf area,as well as sorghum yield and grain weight per spike (P<0.05).Each processing production order of IF+M+S > IF+M > M+S > IF > CK,compared to the control,the range of yield increase of sorghum in different fertilization levels were 80.6%-120.7%,respectively,reaching a significant level,and among which IF+M+S treatment was the best.All values of inorganic fertilizer treatments were slightly higher than that of no fertilization treatment. The organic fertilizer treatment increased the soil nutrients and organic matter content of sorghum, compared with the inorganic fertilizer treatment. The total N, available P, available K, organic matter of IF+M+S treatment were 1.95, 10.36, 2.01, 1.83 times of CK, respectively (P<0.05). Soil enzyme activity of fertilization treatments in different growth periods was higher than no fertilization (CK),in which the most was the treatment of IF+M+S,activity of alkaline phosphatase in jointing stage and harvest stage,urease in harvest stage,invertase in jointing stage,flowering stage and harvest stage were all significantly higher than that of inorganic fertilizer treatment (P<0.05).The application of organic fertilizer or application combined with inorganic fertilizer could improve the soil microbial community functional diversity and the capability of utilizing carbon sources.And the treatments containing organic fertilizer and straw manure were more conducive to improve soil microbial diversity than other organic fertilizer treatments.

In order to study the physiological response and difference of nitrogen metabolizing enzyme activity in leaves of different forage oats in Horqin Sandy Land. The forage oats of Muwang and Tianyan No.1 were applied with 0 (CK), 100, 200, 300 kg/ha pure nitrogen in the proportion of 15%, 40%, 25% and 20% at tillering, jointing, heading and flowering stages. The activities of glutamate synthase (GOGAT), glutamine synthetase (GS), nitrate reductase (NR), glutamic oxaloacetic transaminase (GOT), glutamic pyruvate transaminase (GPT) were measured in flag leaf, inverted two leaf and converse third leaf during the filling period, and the differences of nitrogen metabolizing enzyme activities and their relationship with hay yield of different forage oat varieties under nitrogen application rate were analyzed. The results showed that the hay yield of Muwang and Tianyan No.1 reached the maximum at 200,300 kg/ha nitrogen levels, respectively;The activities of GOGAT, GS, NR, GOT and GPT in the leaves of Muwang and Tianyan No.1 forage oats increased first and then decreased with the increase of nitrogen application, and the enzyme activity was the strongest under N₂₀₀ nitrogen application (except for GOT activity of converse third leaf under N₃₀₀ treatment).Except for GS activity of the third leaf of N₁₀₀ treatment and GPT activity of the second leaf in different nitrogen treatments, GOGAT, NR, GS, GOT and GPT enzyme activities of Muwang were higher than those of Tianyan No.1. This indicated that nitrogen assimilation ability of forage oat variety Muwang was stronger than that of Tianyan No.1.Therefore, in Horqin Sandy Land, the suitable amount of topdressing nitrogen fertilizer for planting Muwang was 200 kg/ha, while for planting Tianyan No.1, topdressing nitrogen fertilizer of 300 kg/ha could obtain higher hay yield. GOT and GPT activities were the key enzymes for screening forage oat varieties with high nitrogen use efficiency.

In order to alleviate the continuous cropping obstacle of millet,provide a reference for optimizing millet planting mode,millet continuous cropping(Si)was named as control(CK),millet-corn(Si-Zm),millet-potato-corn(Si-St-Zm),millet-corn-soybean(Si-Zm-Gm)and millet-soybean-potato(Si-Gm-St)were used to analyze the effects of different rotation patterns on the physiological indicators,photosynthetic characteristics,agronomic characters,yield and downy mildew incidence rate during the critical millet growth periods.The results showed that compared with CK,in the Si-St-Zm,Si-Zm-Gm and Si-Gm-St rotation patterns,the activeness of superoxide dismutase,peroxidase and polyphenol oxidase in millet flag leaves were significantly increased,with the largest increases of 45.55%,41.55% and 109.09%,respectively.In the Si-Zm-Gm and Si-Gm-St rotation patterns,millet plant height,stem thickness,root length and root branch number were significantly increased,with the largest increases of 30.48%,30.50%,31.76% and 13.79%, respectively.In addition,compared with CK,under the Si-Gm-St rotation system,the H₂O₂ and MDA content in the millet flag leaves were significantly decreased,with the maximum reductions of 18.78% and 47.29%, respectively;and the stomatal conductance,net photosynthetic rate,transpiration rate and relative chlorophyll content were significantly improved by 31.94%-101.43%,35.74%-234.00%,16.44%-46.97% and 24.15%-66.16%,respectively;with millet ear length,1000-grain weight and yield increased by 14.90%,17.09% and 10.58%,respectively;and millet downy mildew incidence rate significantly reduced by 12.33%.In short,compared with CK,the Si-Gm-St rotation system significantly increased the activeness of SOD,POD and PPO,and improved photosynthetic efficiency in millet flag leaves,meanwhile,the millet yield and disease resistance enhanced.Therefore,compared with Si-Zm,Si-St-Zm and Si-Zm-Gm rotation patterns,Si-Gm-St rotation system has the best effect on alleviating continuous cropping obstacles,which can provide a reference for optimizing millet planting system.

In order to explore the effective methods for the identification of drought tolerance of foxtail millet during the entire growth period,select the identification indices of drought tolerance of foxtail millet,and speed up the process of drought tolerance breeding of foxtail millet,a field experiment was conducted using a randomized incomplete block design(alpha-lattice design)and repeated thrice in 2019—2020. Each experiment consisted of 30 foxtail millet genotypes treated under drought stress(DS)and normal water supply(CK). The agronomic traits and drought tolerance coefficient(DC)of the genotypes were assessed during the entire growth period. Combined analysis of variance showed that soil water environment had significant effects on 1000-grain weight,and extremely significant effects on the other indices. Genotype had significant effects on spike weight and grain weight per plant,and extremely significant effects on the other indices. Besides,the interaction between genotype and soil water environment extremely significantly affected the growth traits of foxtail millet,but not yield traits(except 1000-grain weight). Under drought stress,the characteristic value of each index decreased in varying degrees compared with CK,and the sensitivity of each index to drought stress was different. The results of t test showed that the effect of drought stress was significant(except 1000-grain weight). GGE biplot explained 71.15% of the total variation of data.The drought tolerance coefficient of each index was correlated in different degrees,in which the drought tolerance coefficients of plant height,spike length,stem and leaf dry weight and top second leaf area were significant positive correlation,and that of spike weight per plant,grain weight per plant,kernels per spike and yield were also significant positive correlation. The drought tolerance of foxtail millet could be reflected by different agronomic traits. According to the distance from ideal drought-tolerant varieties and ideal drought-tolerant evaluation indices,the drought tolerance and evaluation indices of foxtail millet materials were ranked. Taixuan 26,Chaogu 62,Chaogu 13 and other materials had strong drought resistance,plant height and spike weight per plant could be used as indices for drought tolerance identification in foxtail millet. GGE biplot provided an objective and effective new visual identification method for the breeding of drought resistant foxtail millet varieties.

In order to clarify the change rule of photosynthetic characteristics and the best fertilization method in different growth stages of sweet sorghum under different fertilization treatments, the field experiment was conducted to study the stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr), net photosynthetic rate (Pn), chlorophyll (SPAD), water use efficiency (WUE) and yield of New Sorghum No.3 under 8 different fertilization treatments, including CK, NK, NP, PK, NPK, M (organic fertilizer), NPKM and 1.5NPKM.The results showed that the changes of Pn, Gs, WUE and SPAD value in sorghum leaves under different fertilization treatments were the same at different growth stages, showing a trend of first increasing and then decreasing, and peaking at grain filling stage. The variation trend of Tr and Ci from flowering stage to maturity stage decreased first and then increased, and reached the lowest value in grain filling stage. At the same growth stage, the photosynthetic characteristics of different fertilization treatments were different, and the photosynthetic characteristics of leaves were affected by fertilization treatments. The Tr, Gs and Ci values of NPKM fertilization treatment at maturity stage were higher than those of other treatments, which were 3.64 mmol/(m²·s),328 mmol/(m²·s),439 μmol/mol, respectively. The correlation analysis showed that Pn of NPKM treatment at flowering stage was significant positively correlated with Tr and WUE, while Pn of NPK treatment was positively correlated with Gs and Ci. The biological yield of all fertilization treatments was significantly higher than CK, among them the biological yield of NPKM treatment reached 94.81 t/ha. The biological yield of NPKM increased 97.95%, 26.65%, 20.24%, 19.57%, 15.16%,14.98% and 11.74% respectively compared with CK, M, 1.5 NPKM, NK, PK, NPK and NP. Fertilization affects the photosynthetic parameters of the leaves of New Sorghum No.3 and was conducive to increasing yield. Therefore, it is feasible to use high photosynthetic efficiency breeding to improve biological yield. In order to alleviate the obstacle of continuous cropping of sweet sorghum, different proportion of fertilizer should be adopted. In a word, NPKM is the best fertilization mode to improve photosynthetic conditions and maximize yield, so it is preliminarily confirmed that NPKM is the best fertilization mode to promote the growth and development of continuous cropping sorghum in arid area.

The purpose of this study was to reveal the intercropping advantage of sorghum-soybean intercropping system. Field experiments were conducted in 2018 and 2019 in Fenyang of Shanxi Province. This study included nine treatments, sole-higher sorghum Jinza 22 (G1), sole-lower sorghum Jinza 34 (G2), sole-soy bean(D), 2 rows sorghum and 2 rows soybean(2G1:2D, 2G2:2D), 2 rows sorghum and 3 rows soybean(2G1:3D, 2G2:3D), 2 rows sorghum and 4 rows soybean (2G1:4D, 2G2:4D). Sorghum and soybean yield, land equivalent ratio, water and nutrient use efficiency of different sorghum-soybean intercropping treatments were investigated. The results showed that the 1 000-grain weight and spike weight of sorghum in intercropping system were no significant difference than that of sole sorghum. However, the pods number of soybean had significant difference between different treatments. Compared with sole-soybean(D), the pods number of soybean in 2G1:2D, 2G2:2D, 2G1:4D, 2G2:4D decreased by 37.89%, 32.16%, 22.46%, 21.51%, respectively. The land equivalent ratio (LER) and water equivalent ratio (WER) in the all intercropping system were more than 1, indicating that there were some advantages in land and water use. The nutrient advantage of intercropping system was due largely to a higher total nitrogen accumulation than that of the sole system. Compared with 2G2:2D, the average LER, WER, total nitrogen accumulation of 2G1:2D increased by 8.91%, 8.30%, 4.56%, respectively.The average LER, WER, total nitrogen accumulation of 2G1:4D increased by 10.17%, 9.14%, 4.35%, respectively, than that of 2G2:4D. In the sorghum Jinza 22 and soybean intercropping system, the LER, WER, total nitrogen, phosphorus and potassium accumulation of 2G1:4D were the highest among the intercropping treatments. In conclusion, the LER, water and nitrogen use efficiency by sorghum-soybean intercropping could be improved, and the intercropping advantages of higher sorghum Jinza 22 and soybean were more obvious than that of lower sorghum Jinza 34 and soybean, and the 2G1:4D intercropping system was the suitable combination under the experimental condition.

To study the effects of salt stress on growth and physiological characteristics of sorghum at different growth stages(elongation, flowering, and maturity), two sorghum varieties with different salt tolerances, Gaoliangzhe(salt tolerance) and Henong No.16(salt sensitive), were planted at four salt treatment levels(CK:0 g/kg, S3:3 g/kg, S5:5 g/kg, S7:7 g/kg). Moreover, the two varieties were compared under different salt treatment levels, plant morphology, root morphology, leaf photosynthetic characteristics and antioxidant enzyme activities at different growth stages. The results showed that with increasing salt treatment concentration, the antioxidant enzyme activity and relative chlorophyll content(SPAD) of the two varieties increased first and then decreased. The antioxidant enzyme activity reached the maximum value under S3 or S5 treatment, and there were significant differences between the maximum and CK. With the increase of salt treatment concentration, the malondialdehyde(MDA) of the two sorghum varieties increased significantly, which S7 treatment was significantly higher than CK. Under the same treatment, the antioxidant enzyme activity of salt-tolerant varieties(Gaoliangzhe) was higher than that of salt-sensitive varieties(Henong No.16), but the content of MDA was lower than that of salt-sensitive varieties. The photosynthetic capacity of the two varieties was significantly affected by salt stress. In elengation, S7 treatment significantly reduced the Pn of Gaoliangzhe, and Ci of the two varieties under S7 treatment was higher than that of CK. Under salt stress, the growth of the sorghum aerial portion and underground portion of sorghum were affected. The basal stem diameter, total length of root, root surface area, number of root tips, and number of root branches for two varieties reached the maximum under S3 treatment. And basal internode length, plant height, total length of root and root volume reached the lowest value under S7 treatment. In addition, grain fat content and grain starch content in two sorghum varieties decreased under salt stress.The grain tannin content was significantly higher than CK in low-salt (S3, 3 g/kg). In general, low-salt can promote the growth of sorghum, while medium-salt (S5, 5 g/kg) and high-salt (S7, 7 g/kg) conditions have a significant inhibitory effect on sorghum growth. And Gaoliangzhe is more salt-tolerant than Henong No.16.

In order to study the tolerance of heterologously overexpressed Atvip1 gene in sorghum to defense saline-alkali stress and the corresponding growth, NaHCO₃:Na₂CO₃ of 5:1 solution with 75 mmol/L and pH 9.63 was used in sorghum at the stage of three leaves and one heart. The root growth index, chlorophyll content, antioxidant enzyme activity and MDA content were measured at 0, 4, 12, 24, 72, and 120 h of stress. The results indicated that the heterologous overexpression of Atvip1 gene could alleviate the damage of saline-alkali stress on the growth of sorghum seedlings, increase the root surface area and root volume, the number of root tips and branches, and also cause the browning of sorghum main roots to appear later and mild symphonys, and the earlier and more lateral roots occurrence. The new leaves could still be normally extended at 72 h and present little effect on the growth of aboveground. Overexpression of Atvip1 gene could increase the activity of O₂^-· resistance, decrease the content of MDA and enhance the activities of antioxidant enzymes in transgenic sorghum roots. SOD, CAT and GR had obvious effects at 4-12 h during the early stage of stress, respectively. All enzymes played roles during the middle of stress at 24-72 h. CAT and GSH-PX played important roles at the later stage of stress at 120 h. On the base of differential transcriptome analysis of saline-alkali stress, COG analysis of differentially expressed genes(DEGs) showed that defense mechanisms accounted for a relatively large proportion during various periods, and 42 DEGs related to antioxidant enzymes were obtained. Heterologous overexpression of Atvip1 gene can improve the resistance of transgenic sorghum to saline-alkali stress by alleviating the effects on photosynthesis, growth and development, reducing the damages of reactive oxygen species and membrane damage.

Tillering is an important trait related to yield in many crops,and is the same for yield improvement of foxtail millet. However, the genetic mechanism of tillering in foxtail millet (Setaria italica) remains largely unknown. To accelerate mapping of relevant QTLs or genes, a restriction site-associated DNA sequencing (RAD-seq) approach, MSTmap and WinQTLCart 2.5 were employed to identify QTLs responsible for tillering in two F₂ populations called Cross AJ (543 F₂ individuals) and Cross HC (131 F₂ individuals). A total of six QTLs including qAJTN1, qAJTN5, qAJTN7-1,qAJTN7-2, qAJTN7-3 and qAJTN9, were identified in Cross AJ, explaining 0.7%-9.8% of the phenotypic variance, and two QTLs including qHCTN5 and qHCTN7 were identified in Cross HC, explaining 1.4%-8.3% of the phenotypic variance. Of which qAJTN1, qAJTN5, qAJTN7-2, qAJTN9 and qHCTN5 were newly identified QTLs, and qAJTN7-1, qAJTN7-3 and qHCTN7 were consistent with previous reports. Meanwhile, we screened the insertions and deletions in the QTL regions compared with the reference genome, insertion-deletion (InDel) markers linked with tillering were developed. These results of this study will facilitate the revelation of the genetic mechanism of tillering and molecular marker-assisted breeding of foxtail millet.

In order to explore the effect of plastic film mulching on the growth and yield of millet, clarify the mechanism of plastic film increase production, and provides theoretical basis for the whole film dibbling technology in the summer crops, a study on influence mechanism of film mulching on growth development and yield had been conducted. The test using spit plot experiment design was executed in Shijiazhuang luancheng Qiema experimental station, 2015. The main plot had two treatments, respectively is plastic mulch and no plastic mulch. The split plot had three varieties, respectively is Jigu 19, 36 and 38. Under the condition of plastic mulch and no plastic mulch, the morphological characteristics, yield and its traits, flag leaf SPAD values and flag leaf net photosynthetic at heading stage millet rate were studied. Results show that:compared with no plastic mulch, the sum area of top three leaves increased 12.83-26.36 cm², chlorophyll SPAD value increased 8.2%-17.1%, net photosynthetic rate increased 34.9%-34.9%, and yield increased 7.3%-10.8%. Yield performance of Jigu 36 was better than Jigu 19 and Jigu 38, and yields of three varieties (especially Jigu 38) were improved by film mulching. Yield had a significantly positive correlation with 2nd top leaf area, net photosynthetic rate, leaf area and the top three leaves area. Flag leaf area was positively correlated with grain weight per ear and ear length. Therefore, the growth and developing physiological stage of top leaves (especially 1st top leaf), film mulching affected the growth of ear and increased millet yield eventually.

To realize rational and effective use of N fertilizer in brewing sorghum,a field trial with a brewing sorghum variety Jinza 22 was conducted to study the effects of different N fertilizer rates (0,75,150,225,300,450 kg/ha)on yield of brewing sorghum and nitrogen use efficiency.The results showed that nitrogen application increased effectively grain yield and net profit of sorghum in the range of 0-450 kg/ha N applied,but grain yield increased and then decreased with the increased of nitrogen application.The relationship between yield and N fertilizer rates could be expressed as y=-0.037x²+17.759x+5 874.41 (R²=0.878 1).With the increased of N application,N partial factor productivity and N fertilizer use efficiency significantly decreased,N absorption efficiency gradually reduced and N use efficiency had a largely down trend.The highest yield and net profit were obtained by the N treatment of 225 kg/ha (N₂₂₅).Compared with the treatment of no nitrogen application,yield of N₂₂₅ was increased extremely significantly with the rate of yield increased of 37.64%,N agronomic efficiency of 9.96 kg/kg,N partial factor productivity of 36.42 kg/kg,N fertilizer use efficiency of 38.70% and N balance of 3.07 which kept roughly the N balance.Comprehensive analysis of the indicators,N fertilizer application rate of 225 kg/ha is the optimum level for high-yield,high-income and relative high-N use efficiency of sorghum variety Jinza 22 under the experimental condition.

In order to explore the role of RPM1 in sorghum disease resistance,a sorghum SbRPM1 gene was obtained from sorghum smut resistant variety SX44B by homologous cloning method.The bioinformatics analysis results showed that the total length of the cDNA of SbRPM1 gene was 2 802 bp,encoding 933 amino acids,and its protein had a theoretical molecular weight of 106.1 ku and an isoelectric point of 7.11,which was a hydrophilic protein.The SbRPM1 protein had no transmembrane structure,and its subcellular localization was in the cytoplasm.Conservative domain analysis showed that SbRPM1 protein contained RX-CC-like,NB-ARC and LRR domains,and belonged to CNL proteins in the NLRs family.Phylogenetic analysis showed that SbRPM1 protein was most closely related to the RPM1 protein of Miscanthus lutarioriparius.The expression pattern of SbRPM1 gene was detected by Real-time quantitative PCR,and the results showed that the expression of SbRPM1 gene was higher in leaves and inflorescence,followed by roots,and the lowest in stem.The expression of SbRPM1 gene was significantly up-regulated at 24—72 h in disease-resistant varieties after inoculation with Sporisorium reilianum pathogen,suggesting that this gene could be induced by S.reilianum and played an important role in sorghum disease resistance.In this study, the CDS sequence of the SbRPM1 gene was cloned for the first time in sorghum, and the structure, nature and expression of the gene were characterized.

The study provided a molecular marker technology to identify the waxy foxtail millet,which could be used to utilize the excellent waxy resources of foxtail millet and to breed the waxy varieties.Firstly,through the iodine solution detection of the F₃ seeds endosperm from F₂ constructed from the hybridization of waxy foxtail millet,Shilixiang,and non-waxy foxtail millet,Yugu 1.Results showed that the ratio of plant numbers with dark blue and brownish red endosperm was 3:1,indicated that the waxy phenotype was a recessive trait controlled by a single gene.Then using waxy genotyping primers,the genomic DNA of Shilixiang was amplified by PCR and the products were sequenced.The results showed that the waxy trait was controlled by a Ⅳ type waxy gene,namely a TSI-2 transposon was inserted into the first intron of the starch synthase gene (Si006103m).Therefore,the InDel molecular markers,waxy-TSI2/int1 and waxy-int1-1F/4R,were developed based on the gene sequence of Si006103m,and then the genomic DNA of foxtail millet was amplified by them.If there was an product with 984 bp amplified by the waxy-TSI2/int1 primer and no product with 540 bp amplified by the waxy-int1-1F/4R primer,the material was identified as a waxy foxtail millet containing the type Ⅳ waxy gene.Furthermore,we identified 2 waxy materials controlled by the Ⅳ type waxy gene from 100 foxtail millet resources using two pairs of waxy primers.Therefore,the InDel markers can be used to accurately identify the Ⅳ type waxy gene from foxtail millet.

Mitogen-activated protein kinase kinase (MAPKK or MKK) plays an important role in plant growth,development and stress responses.In order to identify MAPKK genes related to rust resistance in foxtail millet and provide candidate genes for the study of rust resistance mechanism and disease-resistant molecular breeding of foxtail millet,the members of MAPKK gene family (SiMKKs) in foxtail millet were identified and analyzed at the whole genome level by bioinformatics methods.Real-time PCR was used to detect the expression level of SiMKKs gene in different tissues,under the stress of rust fungus and exogenous hormone treatment.Excel,MEGA and DnaSP were used to analyze the variation sites and haplotypes of the SiMKKs gene related to rust resistance in 70 re-sequenced foxtail millet varieties,and the excellent rust-resistant haplotypes were identified based on phenotype analysis.The results showed that a total of 10 SiMKKs were identified in foxtail millet,which were distributed on 5 chromosomes.The number of exons ranged from 1 to 11,and the encoded protein contained 331-523 amino acids.The SiMKKs were divided into 4 groups.Groups A and B contained S/T-X₅-S/T motif,while SiMKKs in groups C and D did not have this motif.Conserved Motif 1-Motif 6 existed in all SiMKK proteins.The promoter region of each SiMKK gene contained 1 to 3 biotic stress-related cis-acting elements,such as defense and stress response,methyl jasmonate(MeJA) response,salicylic acid(SA) response and elicitor activation.Except SiMKK10-1 and SiMKK10-3,the other 8 SiMKK genes were expressed with different degrees in different tissues,and under rust infection,SA and MeJA treatments.The highest expression of SiMKK4,SiMKK5 and SiMKK10-2 were in roots at booting stage,and the highest expression of SiMKK6-1 and SiMKK6-2 were in stems at booting stage.The expression of SiMKK4 was up-regulated in the resistant response and down-regulated in the susceptible response within 24 h after inoculation,and its expression was related to disease resistance.The expression of SiMKK4 was up-regulated within 16 h and then down-regulatedafter SA and MeJA treatments,and showed continuous changes during SA treatment.In addition,the expression patterns of the remaining 7 SiMKK genes in SA and MeJA treatments were also consistent.The coding region of SiMKK4 gene contained 7 haplotypes and Hap_1 was the dominant haplotype,and no key variation sites related to disease resistance were found.In summary,the expression of SiMKK4 is identified to be associated with resistance to rust disease in foxtail millet,and SiMKK4 may participate in the early disease resistance response of foxtail millet through SA and MeJA signaling pathways.

In order to study the variation pattern of wax powder content in different types of Sorghum,the colorimeter method based on the principle of chromatic aberration in physics was used for the first time to measure the wax powder content.The results showed that there were significant differences among different types of Sorghum varieties,and even if different genotypes in the same type of Sorghum germplasm.The top,middle and bottom stems of Forage Sorghum contain high,low and high content of wax powder,respectively.And the content of wax powder in the middle stem was most closed to the average value of mixed wax powder and could be used as representative content of the whole plant.The starting time and duration of the different types of Sorghum varieties transfering into each growth stage varied significantly,and the accumulated amount of wax powder in the same growth stage was also different.The tendency of wax powder contents in terms of different growth stages among different types of Sorghum varieties were slightly different:in Forage Sorghum,heading stage > flowering stage > filling stage > wax ripeness stage > complete ripeness stage,while in Sweet Sorghum,filling stage > heading stage > flowering stage > wax ripeness stage > complete ripeness stage.And the wax powder content in the flowering stage represented the average value of the whole growth period.The diurnal changes of wax powder content followed a monopeak curve,and wax powder content reached the peak value around 13:00.Some wax powder contents were negatively correlated with the stem brix in Sorghum.The study showed that there were significant differences in different types of Sorghum wax powder and the content changed regularly.The results above provided a scientific reference for breeding high wax Sorghum varieties to improve resistance.

To reveal the diversity characteristics of endophytic bacteria in different cultivars and organs,and clarify the correlation between endophytic bacteria community structure and host varieties,organ types and disease resistance and susceptible characteristics.Six different varieties of foxtail millet,Jigu 22,Honggu,Longgu No.11 and Xiaoqinggu,Shiliuzi and Nenxuan 16,which were resistant (susceptible) to Fusarium head blight,were selected as materials.The leaves,roots,stems,leaf sheaths and mature spikes of foxtail millet,were taken respectively.DNA was extracted for PCR amplification of 16S rDNA V3—V4 region,and Miseq library was constructed for high-throughput sequencing.Microbial diversity was analyzed by Major biological cloud platform.There were certain differences in endophyte species composition between susceptible and resistant varieties,the dominant populations of endophytes were Proteobacteria and Actinobacteriota,followed by Bacteroidota and Firmicutes,Myxococota and Chloroflexi were lower relative abundance followed by Gemmatimondota and Fusobacteriota.Alpha diversity analysis showed that the resistant cultivars had higher panicle community richness at leaf and maturity spikes and higher panicle diversity at leaf,root and maturity spikes.The susceptible varieties had higher richness of root and stem community and higher diversity of stem and leaf sheath;PCoA analysis showed that organ type had more effect on endophytic community structure than variety.Species composition analysis showed that the diversity of endophytic flora in foxtail millet was affected by different varieties and different parts,and the species of endophytic flora in different parts were quite different.The diversity of endophytic flora between susceptible cultivars Xiaoqinggu,Shiliuzi and Nenxuan 16 and resistant cultivars Jigu 22,Honggu and Longgu No.11 was quite different.The resistant cultivars had NB1-j in leaf sheath stage,and the ears had Acidobacteriota in mature stage.The study showed that the diversity and community structure of endophytic bacteria were affected by different organs and varieties of the foxtail millet,and the organ types had more influence on the community structure of endophytic bacteria than varieties.

Analysis of the expression pattern of florigen gene (Hd3a)under different photoperiod conditions,aims at revealing the role of florigen gene that played in photoperiod-regulated flowering process of foxtail millet. First,a SiHd3a gene sequence(Seita.4G067600,named SiHd3a)on Chr.4 of foxtail millet was obtained by bioinformatics method and according to the transcribed sequence of Seita.4G067600,a pair of specific primers were designed successfully. Then the total RNA of millet land race Huangmaogu was extracted and after reverse transcription the cDNA sequence of SiHd3a gene was obtained by RT-PCR technology. The cDNA sequence was 792 bp which included a 537 bp CDS region that coding 178 amino acids. The molecular weight,isoelectric point of SiHd3a protein were 19.74 ku and 6.82 respectively,which was preliminarily judged as a hydrophilic protein. The proportion of irregular curl was the highest in protein secondary structure(43.26%),following it were extended chain(β-sheet,29.21%),α-helix(16.29%)and β-turn(11.24%). Subcellular localization analysis showed that SiHd3a protein was located in the cytoplasm and intercellular substance. Phylogenetic analysis based on Hd3a protein sequences showed that there was a close relationship between foxtail millet and crown,maize,sorghum,but a distant relationship between foxtail millet and rice. Semi-quantitative PCR showed that under short-day condition, SiHd3a gene gave a circadian rhythm expression pattern,with two expression peaks at six am,and twelve am respectively. While under long-day condition, SiHd3a gene gave almost stable expression level in 24 hours. It could be speculated that the diurnal expression pattern difference of SiHd3a gene between long-day and short-day might be the cause leading to photoperiod sensitivity of foxtail millet.

In order to further study the Na⁺/H⁺ antiporter roles of vacuole membrane in salt tolerance of plants,the salt-tolerant tartary buckwheat variety Chuanqiao No.1 was used as materials,and the NHX gene was obtained by homology cloning,which named FtNHX1,and registered in GenBank,the landing number was KY438929. Sequence analysis showed that the open reading frame of FtNHX1 was 1 662 bp,encoding 553 amino acids,with predicted molecular weight of 61.24 kDa and isoelectric point of 5.15. Phylogenetic tree analysis showed that FtNHX1 was closely related to AtNHX1,OsNHX1 and TaNHX1,with 60.22%,58.95% and 57.30% amino acid homology rates. Quantitative real-time PCR analysis showed that the relative expression of FtNHX1 gene in roots,stem base and leaf of tartary buckwheat was significantly increased with the concentration increasing of NaCl stress,and that increased the most under NaCl stress of 150 mmol/L,which was increased by 254.10%,311.35% and 256.18% respectively in contrast with control. The average expression of FtNHX1 gene in roots and stem base and leaf of tartary buckwheat was increased by 109.46%,145.67% and 155.94% in contrast with control under NaCl stress,and that in stem base and leaf was very higher,indicating that the expression of FtNHX1 gene in tartary buckwheat was obviously induced and regulated by salt stress,and there was a close relationship between the FtNHX1 gene and the salt tolerance of tartary buckwheat.

Cloning a male sterility gene from foxtail millet male sterility material 1066A, analyzing the mutation sites between sterility gene and fertile gene, which could provide foundation for exploring molecular mechanism of male sterility, breeding multi-purpose male sterility materials by marker assisted selection method. A putative male sterility gene was cloned from 1066A based on the complete foxtail millet genome sequence data and location results of predecessors to explore mutation sites leading to sterility,which could provide foundation for uncovering male sterility mechanism at molecular level and breeding multi-purpose male sterility materials by marker assisted selection method.Firstly,a male sterility gene with total length of 5 027 bp (coded 479 aa,Si015780m.g) was found on chromosome 6 of foxtail millet cultivar Yugu 1 by bioinformatics method,and the gene was in the same genome region as that located by molecular markers. Two pairs of specific primers were designed according to male sterility gene sequence of Yugu 1 to amplify corresponding male sterility gene of 1066A (a male sterility material).Totally 2 561 bp gene sequence was obtained after assembling of two amplification fragments,which contained part code region downstream of the gene.After sequence alignment of part coding regions and putative protein sequences of male sterility gene from Yugu 1,Zhanggu and 1066A,three mutation sites including two single base substitutions and one base insertion were found in coding region of male sterility gene from 1066A.Two base substitutions led to Ile (402) and Leu (403) from protein of Yugu 1 and Zhanggu were replaced by Val and Ile from protein of 1066A,and one base insertion led to premature translation termination of protein from 1066A when reached the 466th aa.Of the three mutation sites, two aa substitutions had limited effect on function of coding protein,so we suggested that premature translation termination of protein from 1066A male sterility gene would be the reason for its sterility phenotype.This study provided foundation for uncovering molecular mechanism of male sterility in foxtail millet.