Table of Content

12 July 2019, Volume 45 Issue 7

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REVIEW

Biosynthesis and signaling of ethylene and their regulation on seed germination and dormancy

SONG Song-Quan,LIU Jun,XU Heng-Heng,ZHANG Qi,HUANG Hui,WU Xian-Jin

Acta Agronomica Sinica. 2019, 45(7):  969-981.  doi:10.3724/SP.J.1006.2019.84175

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Seed germination, a key ecological and agronomic trait, is determined by both internal and external cues that regulate the dormancy status and the potential for germination in seeds, and plays a critical role during the subsequent growth, development and production of plants. Dormancy is the temporary failure of seed germination under favorable conditions. Ethylene is a simple gaseous phytohormone with multiple roles in regulation of metabolism at molecular, cellular, and whole plant levels. It influences performance of plants under optimal and stressful environments by interacting with other signaling molecules. In the present paper, we mainly summarize ethylene biosynthesis and signaling, the role of ethylene in seed germination and dormancy release, and the interaction of ethylene with phytohormone abscisic acid and gibberellin, and propose some scientific problems to be required to investigate further in order to provide an idea for explaining the molecular mechanism of seed germination and dormancy regulated by ethylene.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Comprehensive evaluation of green super rice varieties based on nonlinear principal component analysis

JI Long,SHEN Hong-Fang,XU Chun-Chun,CHEN Zhong-Du,FANG Fu-Ping

Acta Agronomica Sinica. 2019, 45(7):  982-992.  doi:10.3724/SP.J.1006.2019.82057

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Application of green super rice (GSR) is regarded as one of the important ways to realize sustainable development of rice production, and has become a major goal of the rice breeding around the world. However, there are few literatures on comprehensive evaluation of GSR varieties. The GSR concept is the development of varieties with insect and disease resistance, high N- and P-use efficiency, drought resistance, high grain yield and superior quality. Based on the GSR concept, we establish a comprehensive evaluation index system of GSR varieties in four dimensions, including technical indicators, economic indicators, ecological indicators and social indicators. This index system should shed light on a new perspective for evaluation of crop varieties, variety breeding as well as the application and extension of new crop varieties. Further, a nonlinear principal component analysis, namely logarithmic principal component analysis, was introduced into the comprehensive evaluation of GSR varieties. Based on field experimental data with a comparative analysis by different methods, we revealed that the logarithmic principal component analysis is feasible and reasonable for comprehensive evaluation of GSR varieties.

Transcriptome analysis of the peanut transgenic offspring with depressing AhPEPC1 gene

PAN Li-Juan,CHEN Na,Ming-CHEN Na,WANG Tong,WANG Mian,CHEN Jing,YANG Zhen,WAN Yong-Shan,YU Shan-Lin,CHI Xiao-Yuan,LIU Feng-Zhen

Acta Agronomica Sinica. 2019, 45(7):  993-1001.  doi:10.3724/SP.J.1006.2019.84122

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Phosphoenolpyruvate carboxylase is considered as a key enzyme to control the ratio of protein to lipid of oilseeds. In this study, the antisense expression of the peanut PEPC isoform 1 (AhPEPC1) gene increased the lipid content by 5.7%-10.3% compared with the non-transgenic control. The high-throughput sequencing technology — RNA-Seq was used to analyze whether the inhibitory expression of AhPEPC1 gene in peanut affected the function of other genes. The results showed that 110 genes were differentially expressed, of which 25 genes were up-regulated and 85 genes were down-regulated. KEGG enrichment analysis was performed on 110 differentially expressed genes, among which 34 genes were successfully obtained KEGG annotation, and two genes (Aradu.M0JX8 and Aradu.FE0Z7) were down-regulated in the biosynthesis pathway of amino acids. Fifteen DEGs between non-transgenic control and transgenic peanut seeds were selected to analyze the gene expression levels using qRT-PCR. The results of qRT-PCR agreed well with most findings from RNA-seq analysis. This research might resolve to some extent the molecular mechanisms of AhPEPC1 gene regulating oil content of peanut seeds.

Cloning and expression analysis of sugarcane lipoxygenase gene ScLOX1

SUN Ting-Ting,WANG Wen-Ju,LOU Wen-Yue,LIU Feng,ZHANG Xu,WANG Ling,CHEN Yu-Feng,QUE You-Xiong,XU Li-Ping,LI Da-Mei,SU Ya-Chun

Acta Agronomica Sinica. 2019, 45(7):  1002-1016.  doi:10.3724/SP.J.1006.2019.84143

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LOX, which belongs to the lipoxygenase superfamily, is an important factor for fat oxidation and widely involved in the regulation of plant growth and development and the resistance to external stimuli. In this study, based on sugarcane (Saccharum spp.) transcriptome database, we first cloned a full-length cDNA sequence of ScLOX1 gene (GenBank accession number: MK106188) from ROC22 bud by RT-PCR. Bioinformatics analysis showed that the cDNA length of ScLOX1 gene was 2813 bp which had a 2664 bp length of open reading frame, encoding 887 amino acids. The theoretical isoelectric point, instability coefficient, and average hydrophilicity of the ScLOX1 protein were 6.23, 39.77, and -0.437, respectively. There were no signal peptide and transmembrane structure, but the PLAT_LH2 and lipoxygenase active sites in ScLOX1 protein. The similarity of amino acid sequences between ScLOX1 and Sorghum bicolor LOX (XP_002466613.1) was 95.96%. The protein encoded by ScLOX1 gene was predicted to be an acid-stable, hydrophilic, and non-secreted protein which belongs to the type I non-traditional 9-LOX. qRT-PCR results showed that ScLOX1 was specifically expressed in sugarcane bud tissue. The expression level of ScLOX1 gene was transiently increased in the smut-resistant sugarcane variety Yacheng05-179 but significantly decreased in the smut-susceptible sugarcane variety ROC22 after inoculated with Sporisorium scitamineum. When leaves of Nicotiana benthamiana were transiently overexpressed ScLOX1 gene and inoculated with tobacco pathogens Fusarium solani var. coeruleum and Ralstonia solanacearum, respectively, the results of phenotypic observation, 3,3’-diaminobenzidine (DAB) staining and expression analysis of tobacco immune-related genes revealed that the overexpression of ScLOX1 gene could enhance the defense of N. benthamiana to the F. solani var. coeruleum, but had no significant difference with the control on the defense effect against R. solanacearum. In addition, the expression level of ScLOX1 was down-regulated by methyl jasmine and salicylic acid, but up-regulated by abscisic acid, sodium chloride and polyethylene glycol. The above results provide references for further study on the function of sugarcane ScLOX1 gene.

Ectopic expression of S-adenosylmethionine decarboxylase (GhSAMDC1) in cotton enhances salt tolerance in Arabidopsis thaliana

TIAN Wen-Gang,ZHU Xue-Feng,SONG Wen,CHENG Wen-Han,XUE Fei,ZHU Hua-Guo

Acta Agronomica Sinica. 2019, 45(7):  1017-1028.  doi:10.3724/SP.J.1006.2019.84142

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Transgenic Arabidopsis thaliana (GhSAMDC1) was used to study the effect of overexpression of GhSAMDC1 on salt tolerance of Arabidopsis thaliana seedlings, Contents of endogenous polyamines, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and chlorophyll, ion permeability, antioxidant enzymes (SOD, CAT, POD) activities and expression levels were investigated under salt stress. The overexpression of GhSAMDC1 decreased the content of endogenous putrescine (Put) and increased spermidine (Spd) and spermine (Spm) contents in Arabidopsis thaliana. Under salt stress, the expression levels of spermidine synthase (AtSPDS1, AtSPDS2) and spermine synthase (AtSPMS) in transgenic lines were significantly higher than those in wild type, the contents of Spd and Spm were further increased, and the contents of H₂O₂, MDA, chlorophyll, and ion permeability were obviously decreased. Compared with the wild type, Transgenic lines had no remarkable difference in peroxidase (POD) activity, but significantly higher superoxide dismutase (SOD) and catalase (CAT) activities, with the same change trend as their expression levels. Therefore, GhSAMDC1 increased the contents of Spd and Spm of transgenic plants by increasing the expression of genes related to Spd and Spm synthesis under salt stress, Spd and Spm directly or indirectly increased the activity of enzymes related to antioxidant system, and enhanced the salt tolerance of Arabidopsis thaliana by scavenging H₂O₂ and other reactive oxygen species.

Cloning and functional analysis of ZmGRAS31 gene in maize

YIN Long-Fei,WANG Zhao-Yang,WU Zhong-Yi,ZHANG Zhong-Bao,YU Rong

Acta Agronomica Sinica. 2019, 45(7):  1029-1037.  doi:10.3724/SP.J.1006.2019.83070

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The GRAS gene family is a kind of plant-specific transcription factor reported in many plants. To figure out the function of maize GRAS family under stress, we obtained ZmGRAS319 (AC: NC_024462) gene from maize (Zea mays) root. Sequence analysis showed that the coding sequence (CDS) of ZmGRAS31 was 1422 bp encoding a protein of 473 amino acids with molecular weight of 51,700.38 Da and an isoelectric point of 4.73. Bioinformatics analysis revealed that ZmGRAS31 had a conserved domain unique to the GRAS transcription factor family and poor hydrophilicity, but no transmembrane structure. Transient expression of maize protoplasts indicated that ZmGRAS31 was localized in the nucleus. Real-time quantitative PCR analysis showed that the expression of ZmGRAS31 was up-regulated in maize seedlings under low temperature, dehydration, high salinity and drought conditions. The root length of the ZmGRAS31 overexpression transgenic Arabidopsis plants was longer than that of wide type under different concentrations of NaCl treatments. Therefore, our data suggested that ZmGRAS31 might be involved in abiotic stress response.

Characteristics of oil components and its relationship with domestication of oil components in wild and cultivated soybean accessions

CHEN Ying,ZHANG Sheng-Rui,WANG Lan,WANG Lian-Zheng,LI Bin,SUN Jun-Ming

Acta Agronomica Sinica. 2019, 45(7):  1038-1049.  doi:10.3724/SP.J.1006.2019.84114

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In this study, 58 soybean accessions composed of wild, semi-wild and cultivated soybean were used to analyze the oil and fatty acid contents by the NIRs and GC methods. Their genetic diversity and domestication were also analyzed based on 32 pairs of SSR markers. There was a significant difference in oil content and fatty acid compositions between wild and cultivated soybeans. The oil content of cultivated soybean (an average of 20.8%) was significantly higher than that of wild soybean (an average of 10.49%). As regards fatty acid compositions, the content of oleic acid in cultivated soybean (an average of 28.5%) was significantly higher than that of wild soybean (an average of 14.37%), on the contrary, the content of linolenic acid was lower. In cultivated soybean, the oil content positively correlated with oleic acid content (r = 0.85 ^**), and negatively correlated with other fatty acids. Moreover, the oleic acid content had a negative correlation with all other fatty acids, especially, with linoleic acid (r = -0.90 ^**) and linolenic acid (r = -0.89 ^**). Similar clustering results were observed in the clustering and principal component analysis based on oil compositions and SSR molecular markers showing that the soybean accessions were clustered into two main subgroups of wild and cultivated soybean, and semi-wild soybean distributed into both subgroups. Therefore, we suggest that contents of oil and fatty acid compositions are related with the domestication level in soybean, and may be used as a reference index for the evolutionary classification in soybean.

Genetic analysis and fine mapping of white stripe leaf mutant wsl1 in rice

MO Yi,SUN Zhi-Zhong,DING Jia,YU Dong,SUN Xue-Wu,SHENG Xia-Bing,TAN Yan-Ning,YUAN Gui-Long,YUAN Ding-Yang,DUAN Mei-Juan

Acta Agronomica Sinica. 2019, 45(7):  1050-1058.  doi:10.3724/SP.J.1006.2019.82054

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A white stripe leaf mutant wsl1 was obtained from the recombinant inbred lines derived from the cross of Oryza sativa var. japonica Nipponbare and Oryza sativa L. subsp. indica R1128. The mutant wsl1 showed white striped leaves and albino veins firstly at the seedling stage and then through the whole growth period. Agronomic traits such as plant height, number of spikelets per panicle, flag leaf length and heading date were significantly increased, while the seed setting rate decreased significantly in the mutant. Compared with wild type R1128, the chlorophyll a, chlorophyll b, and carotene contents of mutant leaves obviously decreased. Microscope observation indicated there were significantly decreased normal chloroplast and a large number of abnormal chloroplasts in mutant. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive nuclear gene. WSL1 was mapped on the short arm of chromosome 1, between markers M1-54 and M1-70, with physical distance of about 89.7 kb. There were eight new open reading frames in the candidate region. Among them LOC_Os01g02080 encodes a peptide-based prolyl cis-trans isomerase, GO (Gene Ontology) classification showed that it might be related to thylakoid formation.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Location- and quantity-based effects of mepiquat chloride application on cotton plant-type

ZHAO Wen-Chao,DU Ming-Wei,LI Fang,TIAN Xiao-Li,LI Zhao-Hu

Acta Agronomica Sinica. 2019, 45(7):  1059-1069.  doi:10.3724/SP.J.1006.2019.84162

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The plant growth regulator mepiquat chloride (MC; 1,1-dimethyl piperidinium chloride) has been successfully and worldwide used in cotton production. It has been known that MC application time decides its effect location and MC application rate decides its effect strength. However, there were less detailed information on the location- and quantity-based effects of MC on cotton stem and branches. In the present field study, MC was respectively applied at early squaring stage, after peak squaring stage, before peak blooming stage, after peak blooming stage and post-topping stage with a range of rates. We monitored plant height at three days interval during MC valid period, and measured all internodes of stem and fruiting branches prior to harvest. Under the condition of topping in late July, the overall effectiveness scope of MC (across different application times) on main stem ranged from the fourth internode below the uppermost node (named as N) to the sixth internode above N node. In terms of the effectiveness scope of MC on fruiting branches, it covered the 11 fruiting branches below N node and five branches above N node. In addition, the influenced internodes in most fruiting branches below N node were more than those above N node. When we overlaid the effectiveness scopes of MC application after peak squaring and before peak blooming, the effect was covered almost all internodes of both main stem (above the node of the first fruiting branch) and fruiting branches. Moreover, we found that there was not always a good linear relationship between MC rate and its effective strength. Besides application time and rate, the location- and quantity-based effects of MC may depend on temperature, rainfall, plant biomass and source-sink relationship.

Effects of whole soil-plastic mulching with hole-sowing on soil temperature, moisture and yield of buckwheat in aridlands

FANG Yan-Jie,ZHANG Xu-Cheng,YU Xian-Feng,HOU Hui-Zhi,WANG Hong-Li,MA Yi-Fan

Acta Agronomica Sinica. 2019, 45(7):  1070-1079.  doi:10.3724/SP.J.1006.2019.81089

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To provide a theoretical basis for exploring a high-yield and high-efficiency technique for buckwheat (Fagopyrum tataricum [L.] Gaertn.) in semiarid areas of China, we carried out long-term field experiments (2015 to 2017) at the Dingxi Experiment Station of Gansu Academy of Agricultural Sciences in the Loess Plateau of northwestern China. Two planting patterns, namely whole field soil-plastic mulching with hole-sowing (FMS), and hole-sowing on bare soils (CK), were set to investigate the effects of FMS on soil temperature, moisture, yield and water use efficiency (WUE) of buckwheat. Compared with CK, FMS advanced seedling stage of buckwheat 2.0 to 2.7 days earlier, branching stage 2 to 3 days earlier, and budding stage 0 to 1.7 days earlier, and extended the filling stage 4.7 to 7.0 days longer. FMS increased soil water storage (SWS) of 0 to 300 cm layer in normal (2015) and dry years (2016) by 2.91% (16.9 mm) and 5.79% (25.59 mm) (P < 0.05), respectively. However, no significant difference was found between them in the wet year of 2017. FMS increased average soil temperature (T_s) in 0-25 cm layer by 2.27℃ and 2.20℃ in normal and wet years, respectively. While in dry year with higher temperature, FMS lowered Ts during branching to filling stages. Similarly, FMS appreciably decreased seasonal mean T_s of 0 to 25 cm layer compared with CK. At maturity, FMS increased dry matter weight (DM) by 13.46% to 137.87%, leaf area index (LAI) by 16.22% to 52.55%, plant height by 12.78% to 48.91%, grain weight per plant by 33.39% to 60.90%, and grain plumpness rates by 8.48% to 9.14%. On average, FMS increased crop water consumption in 0 to 300 cm soil layer by 3.89% during the three consecutive years, but the difference was not significant (P > 0.05). Nevertheless, FMS increased yield by 7.26% to 95.25%, and WUE by 7.59% to 87.08% (P < 0.05). The results demonstrated that the high-yield and high-efficiency of FMS were more significant during drier years. In conclusion, FMS could increase SWS prior to sowing, decrease T_s during high-temperature periods, prolong filling stage, and markedly increase LAI and DM, resulting in the promoted the development of plants, and the significantly enhanced yield and WUE of buckwheat.

Effects of S3307 on the photosynthesis and yield of mung bean at R1 and R5 stages under waterlogging stress

YU Qi,FENG Nai-Jie,WANG Shi-Ya,ZUO Guan-Qiang,ZHENG Dian-Feng

Acta Agronomica Sinica. 2019, 45(7):  1080-1089.  doi:10.3724/SP.J.1006.2019.84160

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Waterlogging stress is one of the main abiotic stresses during the growth and development of crops. It is of great significance to explore the mechanisms for improving the flood resistance and waterlogging resistance cultivation of mung bean under waterlogging stress. In this experiment, the effects of uniconazole (S3307) on physiology, photosynthesis and yield of mung bean leaves under waterlogging stress were investigated in pot culture with different flood resistance mung bean varieties Lufeng 2 and Lufeng 5 from 2017 to 2018. Under the stress of waterlogging at different growth stages, the chlorophyll content (SPAD) and photosynthetic characteristic parameters of mung beans leaves were significantly decreased, malondialdehyde (MDA) content was significantly increased. The yield reduction rate of mung beans under the stress of waterlogging was 24.70%-33.63% at the beginning bloom (R1 stage), and 18.07%-28.87% at the beginning seed (R5 stage). Both mung bean varieties showed that the effect of waterlogging stress at R1 stage was greater than that at R5 stage, and the flood resistance of Lufeng 2 was stronger than that of Lufeng 5. After S3307 sprayed, SPAD, net photosynthetic rate (P_n), transpiration rate (T_r), and stomatal conductance (G_s) in the leaves of mung beans could be significantly increased and MDA content could be significantly decreased. The remission rate of mung beans under waterlogging stress was 28.91%-52.34% at R1 stage, and 13.77%-27.36% at R5 stage. The results showed that S3307 sprayed on the leaf surface could effectively alleviate the physiological function and photosynthetic capacity of mung bean leaves under the stress of waterlogging, thus reduce the yield reduction, but there were differences in the regulatory response of mung bean varieties to S3307 in different waterlogging periods.

Effects of air drying density on membranous lipid peroxidation and quality of cigar tobacco leaf

ZHAO Song-Chao,LI Yi-Fan,LIU Bo-Yuan,ZHAO Ming-Qin

Acta Agronomica Sinica. 2019, 45(7):  1090-1098.  doi:10.3724/SP.J.1006.2019.84134

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In order to understand the influence of different drying density on membranous lipid peroxidation level and cigar tobacco leaf quality, an experiment was conducted with three treatments (stem distance of 10 cm, stem distance of 20 cm, stem distance of 30 cm) of drying system to measure the temperature and humidity of drying room, tobacco leaf water content, malondialdehyde (MDA) content, antioxidant enzyme activity, polyphenol and the chemical compositions. The level of peroxidation in the treatment of 20 cm was the lowest, and had no significant correlation with the temperature and humidity in the drying room, but correlated with the water content. The activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and polyphenol content in leaves were the highest under the drying density of 20 cm, indicating that the drying density of 20 cm was conducive to the improvement of antioxidant enzyme activity, polyphenol content, and antioxidant capacity of tobacco leaves. The activity of polyphenol oxidase (PPO) was highest at the drying density of 10 cm and the chemical components were coordinates in the treatment of 20 cm. Therefore, the air-curing density with a length of 20 cm is conducive to increasing antioxidants, reducing the damage caused by membranous lipid peroxidation and improving the quality of tobacco leaves.

Generation and application of high temporal and spatial resolution images of regional farmland based on ESTARFM model

CHEN Meng-Lu,LI Cun-Jun,GUAN Yun-Lan,ZHOU Jing-Ping,WANG Dao-Yun,LUO Zheng-Qian

Acta Agronomica Sinica. 2019, 45(7):  1099-1110.  doi:10.3724/SP.J.1006.2019.81065

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Multi-temporal remote sensing images are important data sources for agricultural phenology, growth, and yield monitoring. However, visible light images are vulnerable to cloud and rain, and there is a lack of high temporal and spatial resolution data in reality, the remote sensing image fusion methods have become particularly important. ESTARFM (Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model) is used to synthesize high spatial-temporal resolution images in small areas. The adaptability and application of the algorithm in different agricultural growing areas in China have not yet fully developed. In this paper, the large area application test analysis was performed in the Hebei, Heilongjiang, and Xinjiang. Based on MODIS and Landsat images, we used ESTARFM to generate Landsat images with high spatial-temporal characteristics, which were compared with the real Landsat images. The application of ESTARFM algorithm in NDVI was performed for crop growth monitoring in Xinjiang. In conclusion ESTARFM can perform better image prediction in three different regional conditions, generate 30 m multi-temporal NDVI with good spatial resolution in Xinjiang, and monitor the growth of crops.

RESEARCH NOTES

Genetic analysis of plant height related traits in Ricinus communis L. with major gene plus polygenes mixed model

CUI Yue,LU Jian-Nong,SHI Yu-Zhen,YIN Xue-Gui,ZHANG Qi-Hao

Acta Agronomica Sinica. 2019, 45(7):  1111-1118.  doi:10.3724/SP.J.1006.2019.84127

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In this study, plant height related traits in Ricinus communis L. were analyzed using the mixed major gene plus polygenes genetic model with two groups of six-generation populations (P₁, P₂, F₁, B₁, B₂, and F₂) derived from the cross YC2×YF1. The results revealed that the plant height was controlled by a pair of major gene and polygenes. The major-gene heritability in B₁, B₂, and F₂ populations was 37.05%/49.57% (group I/group II), 30.51%/34.48%, and 43.98%/43.64%, respectively. The bearing height of primary raceme and the node number of main stems were all controlled by two pairs of major genes and polygenes, with the importance of major-gene genetic components in the order of epistasis >dominance >additive. In the three generations the heritability of major genes conferring the bearing height of primary raceme was 67.91%/92.72%, 86.89%/92.13%, and 60.18%/66.87%, respectively, and that of major genes conferring the node number of main stem were 91.83%/91.50%, 35.22%/63.37%, and 85.76%/94.58%, respectively. As for the length of main stem internode, it was fully controlled by polygenes, the heritability was 47.64%/47.64%, 38.87%/38.87%, and 25.25%/52.71%, respectively. The above genetic models explained the positive transgressive inheritance of plant height, the bearing height of primary raceme and the length of main stem internode as well as the similar performance to the low value parent of the node number of main stem in F₁ generation. It suggested that the bearing height of primary raceme and the node number of main stem should be used as indirect selection indexes for plant height at early stage and the node number of main stem of lower value parent should not be too little in high yield breeding.

Effects of different photoperiod conditions on agronomic traits of foxtail millet

JIA Xiao-Ping,QUAN Jian-Zhang,WANG Yong-Fang,DONG Zhi-Ping,YUAN Xi-Lei,ZHANG Bo,LI Jian-Feng

Acta Agronomica Sinica. 2019, 45(7):  1119-1127.  doi:10.3724/SP.J.1006.2019.84128

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One hundred and sixty foxtail millet materials were selected to investigate heading stage, plant height, leaf number, panicle length, panicle diameter, branch number per panicle, kernel number per branch, panicle weight, grain weight per panicle and 1000-grain weight under short-day (Hainan), middle-day (Henan), long-day (Jilin), three different photoperiod conditions in two consecutive years. The multiple factor variance analysis and multiple comparisons were performed by SPSS software (19.0 version) to explore the effects of photoperiod on the ten traits, and evaluate the photoperiod sensitivity of 160 foxtail millet materials. There were highly significant differences in heading stage, plant height, leaf number, panicle length, panicle diameter, branch number per panicle, kernel number per branch, panicle weight, grain weight per panicle (P < 0.01), and significant difference in 1000-grain weight (P < 0.05) among three photoperiod conditions. Five traits (heading stage, plant height, leaf number, panicle length, branch number per panicle) had increasing tendency with the prolonging of day time. The variety had extremely significant effect on all of the ten traits (P < 0.01), and the year had extremely significant effect on the nine traits except for 1000-grain weight (P < 0.01). The interaction between photoperiod and variety showed extremely significant effect on all of the ten traits (P < 0.01), and that between photoperiod and year had extremely significant effect on the remaining nine traits except for heading stage (P < 0.01). The interaction between year and variety showed extremely significant effect on plant height, leaf number, panicle length, panicle diameter, panicle weight, grain weight per panicle, branch number per panicle and kernel number per branch (P < 0.01). The varieties with low or moderate sensitivity to photoperiod exhibited no clear regional characteristics. While most of the materials with strong sensitivity to photoperiod were landrances mainly from spring millet regions. The very insensitive material (Xiaozaogu) and the very strong sensitivity materials (Huhehaotedamaogu, Rangu, Honggaigu, Qiegu, Er’baigu and so on) screened out in this study provide a foundation for breeding cultivars insensitive to photoperiod and carrying out studies about formation mechanism of photoperiod sensitivity in foxtail millet.

Effects of glycinebetain on photosynthesis and biomass accumulation of island cotton seedlings under saline alkali stress

YAN Qing-Qing,ZHANG Ju-Song,DAI Jian-Min,DOU Qiao-Qiao

Acta Agronomica Sinica. 2019, 45(7):  1128-1135.  doi:10.3724/SP.J.1006.2019.84117

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Xinhai 35 and Xinhai 48 varieties were used to study the effects of glycinebetain on photosynthesis, biomass accumulation and the role in the growth and development of sea island cotton seedlings under salt alkali stress, which will provide a reference for the application of glycinebetain in the salt alkali cultivation of island cotton. The concentration of saline alkali was 0, 120, 180, 240 mmol L ^-1, and the concentration of glycinebetain was 0, 30, 60 mmol L ^-1. With the increase of saline alkali concentration, island cotton seedling plant height, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), plant fresh and dry weight accumulation showed a significant downward trend, but after glycinebetain spraying, the growth, photosynthesis and biomass accumulation of sea island cotton seedlings were improved in different degrees. Under the same saline alkali concentration, the above indices of island cotton seedlings increased first and then decreased with the increase of glycinebetain concentration. Under the same glycinebetain concentration, the promotion degree of each index of island cotton seedlings showed a continuous downward trend with the increase of salinity and alkali concentration. Under 120 mmol L ^-1 saline-alkali concentration, spraying 30 mmol L ^-1 glycinebetain had a significant effect on improving the photosynthetic performance, thereby increasing the plant height and biomass accumulation of island cotton seedlings, which was more effective in Xinhai 35 than in Xinhai 48. Therefore, in the cultivation of saline alkali soil (0-120 mmol L ^-1), foliar application of glycinebetain (30 mmol L ^-1) can significantly improve the growth and photosynthesis of island cotton.