Table of Content

12 February 2023, Volume 49 Issue 2

Previous Issue    Next Issue

REVIEW

Molecular mechanisms of somatic embryogenesis in plants

HAN Bei, SUN Si-Min, SUN Wei-Nan, YANG Xi-Yan, ZHANG Xian-Long

Acta Agronomica Sinica. 2023, 49(2):  299-309.  doi:10.3724/SP.J.1006.2023.24103

Abstract ( 779 )   HTML ( 117 )   PDF (289KB) ( 636 )   Save

Figures and Tables | References | Related Articles | Metrics

Plant cell totipotency refers to that each cell has all the genetic information of the plant, and in vitro tissues or cells has the potential to develop into a whole plant under appropriate culture conditions. Somatic embryogenesis is the most efficient way to reflect the totipotency of plant cells. It has broad application prospects in the fields of artificial seeds, haploid breeding, asexual reproduction, and germplasm preservation, and its mechanism is also a hotspot in basic research. In recent years, with the development of technology and in-depth research, the molecular regulation mechanism of plant somatic embryogenesis has made important progress. Plant somatic embryogenesis is the result of the expression and regulation of a series of genes in spatiotemporal order. In this review, we systematically reviewed the roles of hormones and stress signal transduction, embryonic development related transcription factors, extracellular proteins, and epigenetic regulation in somatic embryogenesis, and prospected future research priorities and directions in this field.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Fine mapping of qPRO-20-1 related to high protein content in soybean

YANG Shuo, WU Yang-Chun, LIU Xin-Lei, TANG Xiao-Fei, XUE Yong-Guo, CAO Dan, WANG Wan, LIU Ting-Xuan, QI Hang, LUAN Xiao-Yan, QIU Li-Juan

Acta Agronomica Sinica. 2023, 49(2):  310-320.  doi:10.3724/SP.J.1006.2023.24015

Abstract ( 442 )   HTML ( 59 )   PDF (1041KB) ( 441 )   Save

Figures and Tables | References | Related Articles | Metrics

Protein content is a crucial quality trait of soybean, which is controlled by multiple genes. It is of great significance to locate soybean protein content-related loci and mine candidate genes for directional breeding of soybean varieties with high protein content. In this study, an F₂ population consisting of 265 individual plants was constructed by crossing the excellent variety Heinong 88 as the female parent with the high-protein germplasm P73-6B as the male parent. The genotypes of F₂ population were identified by using high-density SNP chip of “ZDX1” and the physical map was constructed. Combined with the protein content phenotypic data, the initial mapping interval of a 2.46 Mb QTL was located on chromosome 20 using the IciMapping 4.2 software. Using 11 polymorphic SSR markers screened out, the mapping range was narrowed from 2.46 Mb to 100.8 kb. Adding four SNP markers (Gm20_28349696, Gm20_30805913, Gm20_31341532, and Gm20_31483719), the interval was further reduced to 95.8 kb. The relative expression levels of the four genes contained in the interval in nine different tissues in both databases Phytozome v13.1 and PPRD RNA-seq yielded two candidate genes (Glyma.20g081800 and Glyma.20g082000). These results provide a theoretical basis for soybean protein content gene cloning and protein regulation mechanism research, as well as elite material and molecular marker for breeding high protein soybean.

Genome editing of BnaMPK6 gene by CRISPR/Cas9 for loss of salt tolerance in Brassica napus L.

ZHANG Wen-Xuan, LIANG Xiao-Mei, DAI Cheng, WEN Jing, YI Bin, TU Jin-Xing, SHEN Jin-Xiong, FU Ting-Dong, MA Chao-Zhi

Acta Agronomica Sinica. 2023, 49(2):  321-331.  doi:10.3724/SP.J.1006.2023.24013

Abstract ( 393 )   HTML ( 42 )   PDF (5159KB) ( 529 )   Save

Figures and Tables | References | Related Articles | Metrics

Brassica napus L. is an important oil crop. MPK6 (Mitogen-Activated Protein Kinases 6) is activated by various stresses to control plant stress tolerance, which is the key gene in response to abiotic stresses. However, the function of MAPK6 in B. napus stress tolerance is still unclear. Gene structure and protein sequence analysis showed that MPK6gene structures were similar, and all proteins had the same STKc_TEY_MAPK domain in Brassica. To explore the potential role of BnaMPK6, the BnaMPK6 mutants were generated by CRISPR/Cas9 genome editing technology. Two quadruple mutants, cr-bnampk6-13-1 and cr-bnampk6-49-1, were obtained. cr-bnampk6 mutant lines were hypersensitive to salt treatment (100 mmol L^-1 and 150 mmol L^-1), the growth of the mutant was strongly inhibited after salt treatment, and the plant height and fresh weight were significantly lower than those of wild-type plants, but there was no significant difference in root length. In addition, reactive oxygen species (ROS), malondialdehyde (MDA), and free proline were more accumulated in cr-bnampk6 mutant lines. In conclusion, these results revealed that BnaMPK6 gene positively regulated salt tolerance in B. napus, providing theoretical and technical supports for genetic improvement of salt tolerance in Brassica napus.

Genetic analysis of photosensitivity divergence among hybrids derived from rice sterile line Xiangling 628S

CHEN Sai-Hua, PENG Sheng, YOU Yi-Wen, ZHANG Lu-Yao, WANG Kai, XUE Ming, YANG Yuan-Zhu, WAN Jian-Min

Acta Agronomica Sinica. 2023, 49(2):  332-342.  doi:10.3724/SP.J.1006.2023.22015

Abstract ( 339 )   HTML ( 25 )   PDF (835KB) ( 408 )   Save

Figures and Tables | References | Related Articles | Metrics

Xiangling 628S is a high quality thermosensitive male sterile line of two-line hybrid rice, whose hybrids have high-quality rice and is suit for light-cultivation, large-scale, and mechanized planting, and 40 new hybrid rice varieties have been approved and widely used. However, its hybrids had strong photosensitivity when it crossed with a large majority of mid-late cultivars, and headed late or even not heading under long-day (LD) conditions, which limited its application in the Yangtze River area. To explore the genetic mechanism of photosensitivity divergence among different hybrids, several key photosensitive loci in Xiangling 628S and its restorer lines were analyzed by allelism tests combined with sequence analysis. The results showed that Xiangling 628S had recessive e₁e₁, Se-1^eSe-1^e and dominant Hd5^kHd5^k, E₂E₂, E₃E₃, and EF-1^tEF-1^t, showing weak photosensitivity. The photosensitivity divergence in different hybrids was closely correlated with E₁ (Ghd7) locus in restorer lines, but not with Se-1 (Hd1) and Hd5 (DTH8). Finally, we developed two functional molecular markers for genetic identification of E₁ and Se-1 loci in restorer lines, which would speed up the selection of weak/non-sensitive hybrids of Xiangling 628S. Our study provides important theoretical guidance and technical supports for the utilization of Xiangling 628S in breeding, as well as hybrid breeding with other sterile lines.

Analysis of heterotic groups and heterosis patterns of sorghum in early- maturing area

CHEN Bing-Ru, YU Miao, GE Zhan-Yu, LI Hong-Kui, HUANG Yan, LI Hai-Qing, SHI Gui-Shan, XIE Li, XU Ning, YAN Feng, GAO Shi-Jie, ZHOU Zi-Yang, WANG Nai

Acta Agronomica Sinica. 2023, 49(2):  343-353.  doi:10.3724/SP.J.1006.2023.24035

Abstract ( 339 )   HTML ( 22 )   PDF (830KB) ( 313 )   Save

Figures and Tables | References | Related Articles | Metrics

The division of heterotic groups can play an important guiding role in broadening the genetic basis of parents, improving breeding efficiency and developing breakthrough new hybrids. In this study, we used the whole genome resequencing technology to scan the whole genome of 55 parent lines of dominant hybrids lines in spring sowing early maturing region for more than 40 years, analyzed their population structure, estimated genetic distance, divided heterosis groups, and analyzed heterosis patterns of dominant hybrid lines. The results showed that the genetic distance of 55 germplasm were 0.704, with a range of 0.627-0.927, and the average polymorphism information content (PIC) was 0.2935, range from 0.1 to 0.5. Fifty-five parents’ lines were classified into 4 heterotic groups that Durra, Kafir/Durra, Russia/Kafir, Kaoliang by the population structure and principal components analysis. Meanwhile, heterosis models of 76% hybrids of 25 main release hybrids from 1973-2014 years were Kafir/Durra × Kaoliang. The sterile line of main release hybrids was derived from Kafir and durra groups from abroad, and the restorer lines were derived from the Kaoliang group produced in China. The heterotic groups divided in this study clarified the genetic basis of sorghum parents’ lines in early- maturing area in China, which provided a scientific basis for the improvement of parental lines and the innovation of heterotic patterns.

Function analysis of OsPIN5c gene by CRISPR/Cas9

YANG Xiao-Yi, WANG Hui-Hui, ZHANG Yan-Wen, HOU Dian-Yun, ZHANG Hong-Xiao, KANG Guo-Zhang, XU Hua-Wei

Acta Agronomica Sinica. 2023, 49(2):  354-364.  doi:10.3724/SP.J.1006.2023.22002

Abstract ( 469 )   HTML ( 37 )   PDF (7118KB) ( 294 )   Save

Figures and Tables | References | Related Articles | Metrics

Polar auxin transport (PAT) plays a key role in plant growth and development, and auxin efflux carriers PIN-FORMED (PIN) are the crucial proteins controlling PAT. Although the functions of some OsPIN genes have been reported, the function of OsPIN5c gene is still unclear. In this study, the target site was designed at the first exon of OsPIN5c and the recombinant CRISPR/Cas9 vector of OsPIN5c was constructed. Twenty-four independent transgenic rice lines were obtained by transformation using Nipponbare (Oryza sativa L. ssp. japonica) as the materials. PCR product sequencing indicated that 15 lines were identified as mutants and the corresponding mutation rate was 62.5%, the mutation type were biallelic heterozygous mutations. Three independent ospin5c homozygous mutants were further obtained in T₁ generation lines and named as ospin5c-1, ospin5c-2, and ospin5c-3, respectively. Sequence alignment analysis showed that the three types of mutations resulted in frame-shift mutation and premature translation termination, which were shortened from 398 amino acid (aa) in wild-type (WT) plants to 109 aa, 106 aa and 250 aa, respectively. Transmembrane helices (TMH) indicated that the TMH of these three mutation proteins were disappeared totally. Protein structure demonstrated that the helix of three mutation proteins were obviously reduced than the native OsPIN5c protein. Phenotype structure indicated that, compared to the WT, the shoot height, root length and adventitious root number were significantly decreased in ospin5c mutants at seedling stage. Tissue-specific analysis showed that OsPIN5c was highly expressed in roots, and OsPIN genes (OsPIN1a and OsPIN5b), OsYUC genes (OsYUC1, OsYUC4, OsYUC6, and OsYUC7) were up-regulated significantly in ospin5c mutants. The gravitropism response of ospin5c mutants was partially inhibited. In conclusion, three ospin5c homozygous mutants were obtained via CRISPR/Cas9 technology and the function of OsPIN5c was investigated in this study, providing the potential gene resources for crop genetic improvement by using OsPIN5c gene.

Construction of rice mutants by gene editing of OsNAC2d and their response to drought stress

LI Zhao-Wei, MO Zu-Yi, SUN Cong-Ying, SHI Yu, SHANG Ping, LIN Wei-Wei, FAN Kai, LIN Wen-Xiong

Acta Agronomica Sinica. 2023, 49(2):  365-376.  doi:10.3724/SP.J.1006.2023.12076

Abstract ( 450 )   HTML ( 31 )   PDF (4552KB) ( 230 )   Save

Figures and Tables | References | Related Articles | Metrics

The main objective of this study is to explore the biological function of transcription factor OsNAC2d and its effect on drought resistance in rice. The sequence of OsNAC2d was firstly edited in japonica variety Zhonghua 11 through the CRISPR/Cas9 technology. The agronomic traits of osnac2d mutants were investigated in normal field cultivation, and the growth status and relative expression level of OsNAC2d genes were performed in the young mutant seedlings under the drought condition. There was the higher expression level of OsNAC2d in grain, leaf, and anther than those in root and stem, and the relative expression of OsNAC2d was enhanced by drought stress. Six homozygous T₂ osnac2d lines were identified in two editing target sites of OsNAC2d genomic sequence through the nucleotide sequencing technology. There was no significant difference between osnac2d mutants and wild type in the agronomic traits including plant height, effective panicle number per plant, panicle length, grain number per panicle, seed setting rate, 1000-grain weight, and grain yield per plant. Under the drought condition, the growth of roots and seedling of osnac2d mutants were depressed, and the biomass of roots and above-ground were also decreased. Meanwhile, the relative expression of OsNAC2d in the osnac2d mutant retained as extremely low level as those in the normal cultivating condition. However, the relative expression of OsNAC2d in wild type was enhanced by drought stress, and the growth and biomass accumulation of wild type were not evidently hindered by drought stress. These results indicated that OsNAC2d positively regulated the drought response in rice. The osnac2d mutants in this present study provided a precious genetic resource for deeply revealing the biological function of OsNAC2d and its fine regulating mechanism in response to drought stress.

Genome-wide association study and candidate genes predication of yield related ear traits in maize

YIN Fang-Bing, LI Ya-Nan, BAO Jian-Xi, MA Ya-Jie, QIN Wen-Xuan, WANG Rui-Pu, LONG Yan, LI Jin-Ping, DONG Zhen-Ying, WAN Xiang-Yuan

Acta Agronomica Sinica. 2023, 49(2):  377-391.  doi:10.3724/SP.J.1006.2023.23021

Abstract ( 473 )   HTML ( 29 )   PDF (9665KB) ( 319 )   Save

Figures and Tables | References | Related Articles | Metrics

Ear traits directly affect the final yield of maize, and the analysis of its genetic mechanisms can provide useful guidance for yield enhancement in maize. In this study, 733 maize inbred lines were planted in randomized block designs under two environments, and three yield-related traits, kernel row number (KRN), ear length (EL), and ear diameter (ED), were investigated. Genotyping was performed using MaizeSNP3072 chip and FarmCPU (fixed and random model circulating probability unification) model was used to conduct genome-wide association study (GWAS). 16, 13, and 24 single nucleotide polymorphism (SNP) loci significantly associated with the three traits were identified, and the values of phenotypic variation explained (PVE) for single locus were 0.01%-7.08%, 0.01%-5.34%, and 0.07%-4.34%, respectively. Further, six, two, and five high confidence (HC) SNPs that were repeatedly detected in multiple environments for KRN, EL, and ED were retrieved, among which two SNPs were simultaneously associated with KRN and ED traits, and one KRN HC-SNP and three ED HC-SNPs were firstly reported in this study. By searching 200 kb regions around the 11 HC-SNPs loci, 33 important candidate genes were identified, including a known gene PIN1a regulating ear development via auxin polar transport located in the confidence interval of chromosome 9 SNP marker PZE-109003046. Other candidate genes encoded transcription factors, hormone (such as auxin, gibberellin, and ethylene) pathway related proteins, DNA methylation, and protein phosphorylation related proteins, which might regulate ear traits by different mechanisms. The 11 HC-SNPs and 33 important candidate genes detected in this study can provide valuable information for further cloning of functional genes and reveal the molecular regulatory mechanisms and marker-assisted selection for ear trait in maize.

Cloning and functional analysis of TaRPP13-1B gene related to powdery mildew resistance in wheat cultivar Brock

LIU Xiao-Ying, ZHANG Chi, WANG Xue-Qing, YANG Chen-Xiao, WANG Guang-Yu, BIAN Yun-Di, FANG Fang, WANG Ying, WANG Zhen-Ying

Acta Agronomica Sinica. 2023, 49(2):  392-401.  doi:10.3724/SP.J.1006.2023.21003

Abstract ( 384 )   HTML ( 23 )   PDF (4822KB) ( 182 )   Save

Figures and Tables | References | Related Articles | Metrics

Powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a severe wheat disease in China. Cloning and pyramiding of different resistance genes to improve crop disease resistance is one of the most cost-effective methods. In this study, TaRPP13-1B on chromosome 1B, which encodes the CC, NB-ARC, and LRR domains, was isolated from common wheat. The relative expression level of TaRPP13-1B in Brock and BJ-1 fluctuated after Bgt inoculation, but the average expression levels were always higher than the susceptible wheat Jing 411. The function of TaRPP13-1B was elucidated by virus-induced gene silencing (VIGS) and overexpression transgenic technique. Silencing of TaRPP13-1B resulted in decreased disease resistance in Brock. Overexpression of TaRPP13-1B improved disease resistance in the transgenic wheat seedlings of Jinqiang 5 cultivar. The above results demonstrated that TaRPP13-1B was involved in the defense response of wheat to powdery mildew, which provided valuable genetic resources for breeding of resistant varieties.

Role of calmodulin gene (HcCaM7) and its protein acetylation is involved in kenaf response to abiotic stress

HUANG Zhen, WU Qi-Jing, CHEN Can-Ni, WU Xia, CAO Shan, ZHANG Hui, YUE Jiao, HU Ya-Li, LUO Deng-Jie, LI Yun, LIAO Chang-Jun, LI Ru, CHEN Peng

Acta Agronomica Sinica. 2023, 49(2):  402-413.  doi:10.3724/SP.J.1006.2023.24031

Abstract ( 257 )   HTML ( 11 )   PDF (14764KB) ( 327 )   Save

Figures and Tables | References | Related Articles | Metrics

Calmodulin (CaM) is a kind of calcium-dependent regulatory proteins involved in plant growth and development, stress tolerance, and other biological processes. In the previous study in kenaf acetylome, our team found that the protein acetylation modification calmodulin protein7 (CaM7) was involved in the regulation pollen development in kenaf. In order to explore its specific mechanism, we cloned the calmodulin gene HcCaM7 from kenaf P3B binuclear anther by using the PCR cloning way. Its maximum open reading frame (ORF) was 450 bp, encoding a protein containing 149 amino acids with a molecular weight of 16.85 kD. Subcellular localization revealed that HcCaM7 was mainly located in cytoplasm and cell membrane. Silencing HcCaM7 by virus induced gene silencing technique caused growth inhibition in kenaf. Furthermore, the protein HcCaM7mut with acetylation modification site was successfully obtained in vitro and the expression of HcCaM7 without acetylation modification was successfully induced. Acetylation of HcCaM7 protein significantly promoted NADK (NAD kinase) activity, indicating HcCaM7 acetylation involved in its functional regulation. The recombinant bacteria containing HcCaM7 protein and HcCaM7mut protein were detected in NaCl (400 mmol L^-1 and 500 mmol L^-1 NaCl), drought (400 mmol L^-1 and 600 mmol L^-1 mannitol) and heavy metals (30 μmol L^-1 and 50 μmol L^-1) by dot plate method. The results showed that the survival rate of recombinant bacteria containing HcCaM7 protein was significantly higher than that of empty control bacteria, in addition, the survival rate of recombinant bacteria containing acetylated HcCaM7mut protein was further improved. The results indicated that HcCaM7 protein could enhance the abiotic stress resistance of E.coli, and the effect of acetylation modification was better. Therefore, HcCaM7 gene regulated the growth and development of kenaf and abiotic stress resistance, and acetylation modification could promote the role of HcCaM7 protein.

Identification and expression analysis of PIN-LIKES gene family in sugarcane

PAN Jie-Ming, TIAN Shao-Rui, LIANG Yan-Lan, ZHU Yu-Lin, ZHOU Ding-Gang, QUE You-Xiong, LING Hui, HUANG Ning

Acta Agronomica Sinica. 2023, 49(2):  414-425.  doi:10.3724/SP.J.1006.2023.24022

Abstract ( 409 )   HTML ( 28 )   PDF (4922KB) ( 503 )   Save

Figures and Tables | References | Related Articles | Metrics

PILS (PIN-LIKES) is a newly reported auxin efflux carrier, which is involved in the polar transport of auxin. In this study, bioinformatics analysis indicated that 11 SsPILS genes and 4 ScPILS genes were identified from the Saccharum spontaneum genomic and the sugarcane cultivars transcriptomic data. 11 SsPILS gene family members were located at 6 chromosomes, and had 5-11 introns, respectively. Phylogenetic tree analysis showed that these PILS from S. spontaneum was clustered into 3 different branches and had highly homologous with PILS from Oryza sativa. The transcriptomic data revealed that, ScPILS1c, the ortholog of SsPILS1c, was differentially expressed in the sugarcane cultivars under Sorghum mosaic virus and Sporisorium scitamineum stress. ScPILS1c (NCBI accession number: OM258732), cloned by RT-PCR, had 1332 bp in length, containing a 1233 bp complete open reading frame and encoding 410 amino acids residues. The isoelectric point, instability coefficient, and average hydrophobicity value of ScPILS1c were 6.17, 39.31, and 0.689, respectively. The ScPILS1c was predicted as a stable acid hydrophobicity protein. The secondary structure of ScPILS1c protein was mainly composed of α-helix (48.54%) and random coils (35.37%) and was highly consistent with the prediction of tertiary structure. The qRT-PCR demonstrated that the relative expression of ScPILS1c was tissue-specific and the highest expression was observed in epidermis while the lowest in pith. ScPILS1c was significantly induced by H₂O₂ treatment and Sporisorium scitamineum infection. Transient expression on Nicotiana benthamiana leaves suggested that ScPILS1c was localized on cell membrane. This study provides a reference for further research on the structure and function of PILS gene in sugarcane.

Cloning and function analysis of a HaLACS9 gene in Helianthus annuus L.

YANG Jia-Bao, ZHANG Zhan, ZHOU Zhi-Ming, LYU Xin-Hua, SUN Li

Acta Agronomica Sinica. 2023, 49(2):  426-437.  doi:10.3724/SP.J.1006.2023.14251

Abstract ( 320 )   HTML ( 24 )   PDF (6864KB) ( 250 )   Save

Figures and Tables | References | Related Articles | Metrics

Long-chain acyl-coenzyme A (CoA) synthetase (LACS) catalyzes the formation of acyl-CoAs from free fatty acids, which plays important roles in lipid metabolism in plant. Here, a LACS family gene named HaLACS9 was screened and cloned from sunflower (Helianthus annuus L.). Homologous protein comparison showed that HaLACS9 had conserved LACS domains and had higher homology with Arabidopsis thaliana, Lactuca sativa, and Cynara cardunculus LACS9 proteins. Subcellular localization prediction indicated that HaLACS9 was localized in the chloroplast. The promoter region of HaLACS9 gene contained a large number of hormone and stress responses related elements. The qRT-PCR revealed that HaLACS9 gene was ubiquitously expressed in sunflower organs, and the highest expressed in seeds at 10 days after flowering. The transcription levels of HaLACS9 were induced by drought, salt, ABA, and GA₃ treatments in sunflower roots, stems, and leaves. The relative expression pattern of HaLACS9 at seed developmental stages in sunflower was higher at the early seed developmental stages, related to sunflower seed oil rapid accumulation periods. The relative expression of HaLACS9 was gradually decreased at late stages of seed development and the slow accumulation rate of oil. HaLACS9 was proved to have the synthetase activity of acyl-CoA in complementation test of deficient yeast mutant and prefers to activate oleic acid substrate. It was speculated that HaLACS9 participated in the regulation of sunflower seed lipid biosynthesis and abiotic stress responses.

Evaluation method of late spring coldness tolerance in wheat

LIU Fang-Fang, WAN Ying-Xiu, CAO Wen-Xin, LI Yao, ZHANG Qi-Qi, LI Yan, ZHANG Ping-Zhi

Acta Agronomica Sinica. 2023, 49(2):  438-446.  doi:10.3724/SP.J.1006.2023.21011

Abstract ( 436 )   HTML ( 30 )   PDF (3993KB) ( 461 )   Save

Figures and Tables | References | Related Articles | Metrics

Sensitivity to late spring coldness can result in considerable yield loss in wheat, and the breeding cold-resistant cultivar becomes an important breeding objective. In order to investigate the suitable treatment conditions for late spring coldness tolerance and to establish an evaluation method for the resistance to late spring coldness in wheat, six cultivars with different late spring coldness tolerance were used for different temperature treatments at different developmental stages based on the dead stem rate. The optimum treatment conditions had been revealed and validated with 120 varieties (lines). The results showed significant differences in the dead stem rate was observed at anther connective formation phase (ACFP) under -6℃ after 6 h stress treatment, which was the most suitable treatment condition for the identification of resistance to late spring coldness. Furthermore, the variation in late spring coldness tolerance among 120 wheat varieties (lines) could be effectively distinguished from the treatment conditions. Cluster analysis demonstrated that the 120 wheat varieties (lines) can be divided into five categories in the resistance to late spring coldness: highly resistant, resistant, moderately resistant, susceptible, and highly susceptible. The established evaluation standard of late spring coldness in wheat will provide technical support for the identification and breeding of resistant wheat varieties in late spring coldness.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of staged potassium application on grain yield and nitrogen use efficiency of winter wheat under reduced nitrogen conditions

ZHANG Xiang-Yu, HU Xin-Hui, GU Shu-Bo, Lin Xiang, YIN Fu-Wei, WANG Dong

Acta Agronomica Sinica. 2023, 49(2):  447-458.  doi:10.3724/SP.J.1006.2023.21013

Abstract ( 351 )   HTML ( 30 )   PDF (804KB) ( 564 )   Save

Figures and Tables | References | Related Articles | Metrics

In order to explore the effect of potassium fertilizer application on the yield and nitrogen use efficiency of winter wheat in different stages, and to determine the high-yield and efficient potassium fertilizer operation plan for winter wheat under the condition of nitrogen reduction, the high-yield and strong-gluten winter wheat variety Gaoyou 5766 was selected as the test materials in this experiment. During the growing season, a two-factor randomized block design was used to set three nitrogen application levels [conventional nitrogen application rate (240 kg hm^-2, N1), nitrogen application rate reduced by 20% (192 kg hm^-2, N2), and nitrogen application rate reduced by 40% (144 kg hm^-2, N3)] and two potassium fertilizer application schemes [all potassium fertilizers applied at the sowing stage (K1) and potassium fertilizer applied in stages (50% was applied at the sowing stage and 50% was applied at the jointing stage, K2)]. The results showed that under the same potassium fertilizer application scheme, the grain yield of N2 treatment was not significantly different from that of N1 treatment, and the grain yield of N3 treatment was significantly lower than that of N1 treatment, with a decrease of 9.0%-11.6%. Under the same nitrogen application rate, potassium application by stages could significantly improve grain yield and nitrogen use efficiency of winter wheat. Compared with K1 treatment, K2 treatment significantly inhibited the leaching of nitrate nitrogen into deep soil layers, increased nitrogen accumulation in winter wheat plants, and increased flag leaf photosynthetic rate and nitrate reductase activity, grain filling rate, the number of grains per spike, and 1000-grain weight. Grain yield and nitrogen use efficiency increased by 21.7% and 20.2% under the conventional nitrogen application rate, by 26.9% and 26.2% under the N2 level, and by 25.2% and 21.1% under the N3 level, respectively. The grain yield, nitrogen uptake efficiency, nitrogen use efficiency, and nitrogen partial productivity of N3K2 treatment were significantly higher than those of N1K1 treatment. The above results showed that potassium application in stages could greatly improve the grain yield and nitrogen use efficiency of winter wheat under different nitrogen application rates. Using the nitrogen application rate of 192 kg hm^-2 combined with potassium application in stages, the grain yield and nitrogen uptake efficiency of winter wheat were the highest, and the nitrogen use efficiency and nitrogen partial productivity also reached a high level. It is a high-yield and efficient nitrogen-potassium fertilizer application scheme.

Effects of density on population quality and yield of peanut with different plant types under the mode of single-seed precision sowing

LIU Jun-Hua, WU Zheng-Feng, DANG Yan-Xue, YU Tian-Yi, ZHENG Yong-Mei, WAN Shu-Bo, WANG Cai-Bin, LI Lin

Acta Agronomica Sinica. 2023, 49(2):  459-471.  doi:10.3724/SP.J.1006.2023.24041

Abstract ( 421 )   HTML ( 40 )   PDF (523KB) ( 404 )   Save

Figures and Tables | References | Related Articles | Metrics

In order to clarify the effect of planting density on the population quality of peanut with different plant types under the mode of single-seed precision sowing, this experiment were carried out with two plant-types (erect big peanut variety “Huayu 22” and semi-creeping big peanut variety “Huayu 9513”), three densities (75,000 plants hm^-2, 150,000 plants hm^-2, and 225,000 plants hm^-2). Yield, photosynthetic product accumulation and distribution, leaf area index, plant characteristics and grain leaf ratio were studied. The results were as follows: (1) With the increase of density, the pod yield of “Huayu 22” increased, while that of “Huayu 9513” increased first and then decreased, in addition, the optimum planting density of “Huayu 9513” was lower than that of “Huayu 22”. (2) The population dry weight of “Huayu 22” increased with the increase of density during the growth period, and the greater the density, the smaller the increase range. While the population dry weight of “Huayu 9513” increased with the increase of density at seedling stage, increased first and then decreased with the increase of density after flower pegging stage, and the dry weight of D2 density was the largest. With the increase of density, the distribution proportion of dry matter in roots increased and that in fruit needles decreased; “Huayu 9513” and “Huayu 22” had the probably same dry weight at harvest stage, while the distribution proportion of dry matter to pods was less, and the economic coefficient and grain to leaf were lower. The leaf area index and leaf area duration of peanut increased with the increase of density at the early growth stage, and the increase of “Huayu 9513” was higher than that of “Huayu 22”. The leaf area index and leaf area duration of “Huayu 9513” was not significantly different from that of “Huayu 22” before pod setting stage, however from pod setting stage to harvest stage it was significantly higher than that of “Huayu 22”. (3) The number of lateral branches and fruit branches per plant decreased with the increase of density in the harvest period, while that of the population increased with the increase of density. (4) The correlation analysis showed that there were positive or significant positive correlation between peanut pod yield and dry matter accumulation after pod setting stage, especially dry matter accumulation at pod fulling stage, leaf area duration, plant dry weight, and leaf area index at harvest stage. In conclusion, density showed different effects on the population quality of peanut with different plant types, erect peanut “Huayu 22” showed good density tolerance and the optimum density was higher, while semi-creeping peanut “Huayu 9513” showed poor density tolerance. The optimum density of “Huayu 9513” was lower.

Effect of different times of spraying chemical regulator on the canopy structure and grain filling characteristics of high planting densities

XU Tong, LYU Yan-Jie, SHAO Xi-Wen, GENG Yan-Qiu, WANG Yong-Jun

Acta Agronomica Sinica. 2023, 49(2):  472-484.  doi:10.3724/SP.J.1006.2023.23028

Abstract ( 401 )   HTML ( 20 )   PDF (634KB) ( 440 )   Save

Figures and Tables | References | Related Articles | Metrics

A proper canopy structure ensures that the productive functions of the crop community are fully utilized, the spraying chemical regulator is one of the most important measures to shape the crop canopy, among which the selection of chemical control period is very crucial. The maize variety Xianyu 335 was used as the experimental material, field experiments were conducted with three treatments with two planting densities at 60,000 plants hm^-2 (D₁) and 90,000 plants hm^-2 (D₂) (chemical regulator made of ethephon), T₁₀ (spray chemical regulator at the 10-leaf), T₁₅ (spray chemical regulator at the 15-leaf), and CK (spray water as control). Therefore, it is important to explore the regulation of maize canopy structure and analyze the effect of changing canopy structure on grain-filling characteristics and yield. The results showed that at D₁ density, the chemical regulator treatment had no significant effect on yield; at D₂ density, compared with the CK, yield of T₁₅ increased by 7.3% on average in two years, the number of kernel and the 1000-kernel weight increased by 2.6% and 3.3%, respectively, the number of kernels and the 1000-kernel weight decreased in T₁₀. The upper leaf angle was reduced by 17.5% at T₁₅ and the leaf area at the 14-17 leaf position was reduced, increased the light energy interception at the ear position leaf at 11.5%, and maintained a high net photosynthetic rate (P_n) at milk stage, a significant increase of 51.3% in leaf area index (LAI) at the physiological maturity, delayed the senescence of the lower and middle leaves, increased dry matter accumulation of post anthesis and the transfer amount of dry matter, extended active grain filling period (P), reduced the days of maximum grain filling (T_max) by 0.8 d, increased the weight of maximum grain filling rate (W_max) and maximum grain-filling rate (G_max) by 7.3% and 4.0% respectively and increased average grain-filling rate (V_max) by 6.9%. Compared with D₁, D₂ significantly improved maize canopy structure, increased light energy utilization in maize populations, increased post-flowering dry matter accumulation, and promoted yield. After the chemical regulator treatment, leaf area of the upper leaves (14-17) was negatively correlated with light energy interception in the middle of the canopy, kernel number, 1000-kernel weight, and yield, and the yield was positively correlated with 1000-kernel weight, kernel number, net photosynthetic rate, post-flowering dry matter accumulation, the weight of maximum grain filling rate and the grain-filling rate. In summary, the spraying of the chemical regulator at the 15-leaf stage of high density was effective in improving the upper canopy structure of the population, resulting in a reduction in leaf area and leaf angle to optimize the light conditions of the population, and enhanced photosynthetic capacity at the late of grain filling, increased grain-filling rate, and it can achieve efficient utilization of light energy and synergistic increase in yield.

Difference between bidirectional reflectance factor and directional-hemispherical reflectance factor spectra and its effect on the estimation of leaf chlorophyll content in wheat

WANG Xue, WANG Wen-Hui, LI Dong, YAO Xia, ZHU Yan, CAO Wei-Xing, CHENG Tao

Acta Agronomica Sinica. 2023, 49(2):  485-496.  doi:10.3724/SP.J.1006.2023.21005

Abstract ( 280 )   HTML ( 6 )   PDF (1228KB) ( 460 )   Save

Figures and Tables | References | Related Articles | Metrics

Bidirectional reflectance factor (BRF) and directional-hemispherical reflectance factor (DHRF) spectra are two common types of reflectance measurements. However, most studies ignored the differences between BRF and DHRF spectra and their effects on the estimation of leaf chlorophyll content (LCC) while monitoring the biochemical parameters of crops. In this study, we collected leaf-level data from field trials of winter wheat with different varieties, densities, and nitrogen rates. We calculated the vegetation indices (VIs) and wavelet coefficients (WCs) based on BRF and DHRF spectra and then established their relationships with LCC. Finally, we evaluated the ability of VIs and WCs in reducing the differences between BRF and DHRF spectra, and their effects on LCC estimation. Results were as follows: (1) changes in BRF and DHRF were consistent with the variation of LCC, but there were significant differences between the two types of spectra, and the reflectance in BRF was higher than that in DHRF. (2) To some extent, the use of either VIs or WCs could eliminate the influence of the differences between BRF and DHRF spectra. For example, the Normalized Differential Red Edge Vegetation Index (NDRE) and the Red Edge Chlorophyll Index (CI_red-edge) could reduce this effect (R²=0.930), but the performance of wavelet coefficients were better than those of NDRE and CI_red-edge (R²=0.995). (3) The performance of VIs and WCs based on DHRF data was better than that of BRF data for LCC estimation. NDRE was the best among all VIs evaluated (DHRF: R²=0.957; BRF: R²=0.938; All: R²=0.892). Furthermore, the WC at the fourth scale of 765 nm [WF(4, 675)] was better than NDRE (DHRF: R²=0.985; BRF: R²=0.971; All: R²=0.973), and it had a stronger ability to eliminate the influence of the spectral differences on LCC estimation than NDRE (WF (4, 675): R²=0.973; NDRE: R² = 0.892). In summary, there was a difference between BRF and DHRF data, and this difference could not be ignored directly. To some extent, the use of suitable VIs and WCs can eliminate the difference and improve the accuracy of LCC estimation. This study determined the differences between BRF and DHRF spectra of the same leaf samples of winter wheat, which provided a theoretical basis for establishing a unified model across BRF and DHRF spectra and improving the accurate estimation of LCC at the canopy level.

Effects of nitrogen application and harvest time on grain yield and nitrogen use efficiency of summer maize under different rainfall years

LIU Meng, ZHANG Yao, GE Jun-Zhu, ZHOU Bao-Yuan, WU Xi-Dong, YANG Yong-An, HOU Hai-Peng

Acta Agronomica Sinica. 2023, 49(2):  497-510.  doi:10.3724/SP.J.1006.2023.23014

Abstract ( 309 )   HTML ( 14 )   PDF (2646KB) ( 412 )   Save

Figures and Tables | References | Related Articles | Metrics

To investigate the effects of nitrogen application and harvest time on summer maize grain filling and dehydration, yield formation, and nitrogen use efficiency in thermal resource restricted area in the North China Plain, we adopted a two-factor randomized block area experiment design, one factor was nitrogen application rate per hectare [0 kg (N0), 120 kg (N120, 2021), 180 kg (N180), 240 kg (N240), 300 kg (N300), 360 kg (N360), and 450 kg (N450, 2020)], and another factor was harvest time [normal harvest (NH) and delayed harvest (DH)]. Dry matter accumulation (DM), grain filling and dehydration processes, grain yield (GY) and its components, nitrogen partial factor productivity (PFPN), and agronomic nitrogen utilization efficiency (ANUE) were investigated. Compared to the dry year (2020), DM, grain weight (GW), a%, respectively, resulting in GY, PFPN, and ANUE significantly reduced by 31.4%-58.3%, 27.2%-30.0%, and 2.9%-18.0%, respectively. Compared with N0, nitrogen application significantly enhanced DM, and GW were 14.6-82.1 mg grain^-1 higher than N0, while the maximum grain filling rate (G_max) and its weight increment (W_max) were enhanced by 0.2-3.4 mg (grain d)^-1 and 10.4-44.1 mg grain^-1, meanwhile the time reaching G_max (T_max) were earlier by 0.4-7.0 d. The GY of nitrogen application treatments were dramatically raised by 51.5%-169.5% than N0, and in the N240 level it was the optimized nitrogen application. Compared with that of N180/N120, with the increase of nitrogen application rate, the PFPN and ANUE in two years were significantly reduced by 11.7%-57.9% and 2.5%-54.9%, 19.9%-52.6% and 4.9%-37.0%, respectively. Compared with NH treatment, the DM and GW of DH treatment were increased significantly by 0.8%-55.7% and 3.4%-79.3%, and dramatically reduced grain moisture content to 22.0%-27.9% at harvest stage. The GY, PFPN, and ANUE of DH treatment were remarkable higher than NH treatment by 10.6%-18.5%, 4.4%-26.8%, and 1.5%-48.6%, respectively. The linear plus platform model showed that the highest GY of DH treatment obtained to 12.0×10³ kg hm^-2 and 7.0×10³ kg hm^-2, which were significantly higher than NH by 11.3%-12.6%, whereas the optimal nitrogen application rate were reached to 247 kg hm^-2 form 200-210 kg hm^-2, increased by 13.9%-22.9%. In conclusion, in thermal resource restricted area in the North nd ear grains number (EGN) under rainy year (2021) were significant decreased by 16.3%-81.5%, 2.1%-28.1%, and 44.7%-47.4 China Plain, the nitrogen application rate could reduce to 200 kg hm^-2 and GY stabilized above 6.0×10³-10.5×10³ kg hm^-2 under normal harvest time, meanwhile the nitrogen application rate could optimized to 240 kg hm^-2 and achieved higher GY above 8.0×10³-12.0×10³ kg hm^-2 with higher PFPN and ANUE at 19.2-49.6 kg kg^-1 and 15.2-20.8 kg kg^-1 levels under delayed harvest. In conclusion, the results revealed that the theoretic support for reduced summer maize grain moisture content, achieving the production goal as grain machine harvesting, nitrogen reduction, high yield and high nitrogen use efficiency of summer maize in the North China Plain.

High-yielding population agronomic characteristics of middle-season indica hybrid rice with different panicle sizes in the middle and lower reaches of the Yangtze River

TAO Shi-Bao, KE Jian, SUN Jie, YIN Chuan-Jun, ZHU Tie-Zhong, CHEN Ting-Ting, HE Hai-Bing, YOU Cui-Cui, GUO Shuang-Shuang, WU Li-Quan

Acta Agronomica Sinica. 2023, 49(2):  511-525.  doi:10.3724/SP.J.1006.2023.22010

Abstract ( 354 )   HTML ( 23 )   PDF (3993KB) ( 263 )   Save

Figures and Tables | References | Related Articles | Metrics

To clarify the mechanism of yield and common characteristics of high-yielding cultivars of middle-season indica hybrid rice with different panicle sizes in the middle and lower reaches of the Yangtze River, the field experiments were conducted in 2019 and 2020 at Shucheng Agricultural Science Institute, Anhui province. 120 middle-season indica hybrid rice cultivars were classified into three panicle types by spikelets per panicle [large panicle size (LPS, 193-270), middle panicle size (MPS, 167-191), small panicle size (SPS, 108-166)], and their yield and yield components, growth period, daily yield, leaf area index, biomass, and panicle structure were compared. The results showed that rice yield varied across the cultivar types, irrespective of the panicle type. Cluster analysis revealed that it could be further divided into three yield types (high-yield, middle-yield, and low-yield). High daily yield was a common indicator of high yield among different panicle cultivars, LPS was associated with the increasing leaf area index, while MPS and SPS might be associated with the promoting light energy conversion efficiency. There were extremely different ways of producing high yields among panicle types, except daily yield. In yield components, the yield increasing of LPS mainly relied on the effective panicles, the spikelets per panicle, and 1000-grain weight; MPS was the effective panicle and the grain filling rate; and SPS was the effective panicle, the spikelets per panicle and the grain filling rate. This difference of panicle types was related to the classification method and the grain filling disorders of large panicle size rice. In terms of biomass, LPS and MPS cultivars were dependent on increased biomass to improve yield, but SPS high-yielding cultivars were dependent on the higher harvest index. There were no significant differences in the distribution of branches and panicle length among different yield types under each panicle type. Principal component analysis revealed that LPS high-yield cultivars were mainly characterized by higher daily yield, higher biomass, higher grain weight, more panicles, and higher leaf area index; MPS high-yield cultivars exhibited higher daily yield, more panicles, and higher biomass. However, SPS high-yield cultivars had higher daily yield, higher harvest index, more balance between panicle and spikelets, and higher grain filling rate. In general, the common indicators of LPS high-yield cultivars were daily yield 107.0 kg hm^-2 d^-1, biomass 20.2 t hm^-2, effective panicle 229.8 m^-2, leaf area index 6.1; MPS high-yield cultivars were daily yield 95.3 kg hm^-2 d^-1, effective panicle 253.9 m^-2, biomass 19.5 t hm^-2; and SPS high-yield cultivars were daily yield 79.6 kg hm^-2 d^-1, harvest index 61.0%, effective panicle 239.0 m^-2, grain filling rate 84.6%. In addition, high-yield nitrogen fertilizer management should be targeted according to the different panicle size cultivars.

Effects of intercropping with watermelons on cane yields, soil physicochemical properties and micro-ecology in rhizospheres of sugarcanes

XIAO Jian, WEI Xing-Xuan, YANG Shang-Dong, LU Wen, TAN Hong-Wei

Acta Agronomica Sinica. 2023, 49(2):  526-538.  doi:10.3724/SP.J.1006.2023.24050

Abstract ( 315 )   HTML ( 17 )   PDF (1747KB) ( 431 )   Save

Figures and Tables | References | Related Articles | Metrics

To provide theoretical basis for developing sugarcane intercropping cultivation system, cane yields, total economic benefit, soil physicochemical properties and bacterial community structure in rhizospheres of sugarcane intercropping with watermelon were analyzed. Based on traditional and modern high-throughput sequencing techniques, cane yields, total economic benefit, soil physicochemical properties and bacterial community structure in rhizosphere of sugarcanes between monoculture (CK) and sugarcane intercropping with watermelons (TM) were analyzed. Compared with CK, the contents of soil organic matter (SOM), total nitrogen (TN), phosphorus (TP) and potassium (TK), and the contents of available nitrogen (AN), phosphorus (AP) and potassium (AK) were all not significantly altered in sugarcane intercropping with watermelons system. Meanwhile, soil bacterial diversity, richness and soil bacterial functions were also not significantly changed in sugarcane intercropping with watermelons system. In addition, although some soil dominant bacterial phyla, such as Actinobacteria and other could be enriched, but Planctomycetes and Bacteroidetes also lost in rhizospheres of sugarcanes in TM treatments also lost. Meanwhile, Acidothermus, Bradyrhizobium, norank_o__SC-I-84, Bryobacter, Streptomyces, norank_f__DA111, Candidatus_Solibacter, Acidibacter and norank_f__Acidobacteriaceae__Subgroup_1_ were the unique soil dominant bacterial genera in rhizospheres of sugarcanes in CK. By contrast, Micromonospora, norank_f__Anaerolineaceae, unclassified_f__Micrococcaceae, norank_o__JG30-KF-CM45, norank_f__Elev-16S-1332, norank_c__Actinobacteria, Luedemannella, unclassified_f__Intrasporangiaceae, norank_f__ Nitrosomonadaceae, unclassified_f__Nocardioidaceae, norank_c__S085 and Defluviicoccus were the specific soil dominant bacterial genera in rhizospheres sugarcanes in TM treatment. Moreover, there were no significantly different in the functions of soil bacteria in rhizospheres of sugarcanes between TM and CK treatments, suggesting that soil bacterial functions in rhizospheres of sugarcanes did not significantly alter by intercropping with watermelons. In comparison with sugarcane monoculture, cane yields and total economic benefit all could be improved. In addition, soil physicochemical properties and soil bacterial diversity, richness and functions in rhizospheres of sugarcanes could not be significantly improved by intercropping with watermelons. However, the compositions of soil bacterial communities were altered, such as Micromonospora, enriched as the unique soil dominant bacterial genera in rhizospheres of sugarcanes intercropping with watermelons. All the above results showed that not only cane yields and total economic benefit could be improved but also soil physicochemical properties were not decreased. Furthermore, soil bacterial functions also were not significantly deteriorated, just the compositions of soil bacterial communities were partly altered by intercropping with watermelons. The stress resistance properties of sugarcanes could be improved by intercropping with watermelons for some benefit bacteria, such as Micromonospora enriched in rhizospheres of sugarcanes under sugarcane/watermelon intercropping systems.

Effects of potassium application rate on NPK uptake and utilization and grain yield in summer maize (Zea mays L.)

SONG Jie, WANG Shao-Xiang, LI Liang, HUANG Jin-Ling, ZHAO Bin, ZHANG Ji-Wang, REN Bai-Zhao, LIU Peng

Acta Agronomica Sinica. 2023, 49(2):  539-551.  doi:10.3724/SP.J.1006.2023.13067

Abstract ( 360 )   HTML ( 39 )   PDF (646KB) ( 393 )   Save

Figures and Tables | References | Related Articles | Metrics

Field experiments were conducted at Dongping Agricultural Science Institute, Tai’an city, Shandong province from 2019 to 2020, using Denghai 605 (DH605) as the experimental material. To study the effects of K application on summer maize grain yield, nutrient uptake and transportation, and utilization under continuous multi-year straw return conditions, five K₂O application rates of 0 kg hm^-2 (K₀), 150 kg hm^-2 (K₁), 225 kg hm^-2 (K₂), 300 kg hm^-2 (K₃), and 375 kg hm^-2 (K₄) were set under uniform N and P fertilizer rates (N 225 kg hm^-2 and P₂O₅ 110 kg hm^-2). The results showed that K application significantly increased grain yield with the highest increase at 225 kg hm^-2 in both years, 13.64% and 15.27% in 2019 and 2020, respectively. K application significantly increased maize leaf area index, biomass and the intensity of dry matter transfer to the ears, promoted plant uptake of N, P and K, and increased maize N, P and K accumulation and the proportion of N and P accumulation after flowering, but the efficiency gain decreased when the K application was less than 225 kg hm^-2. With the increase of K application, the nutrient transport of maize increased and then decreased, with the highest amount of nutrient translocation and the contribution rate of nutrient translocation at 300 kg hm^-2. The nutrient harvest index, apparent utilization efficiency of N, P, and K, and agronomic utilization efficiency of K remained at a high level when K application rate was at 225 kg hm^-2, and the fertilizer utilization efficiency decreased significantly when K application rate exceeded 300 kg hm^-2. The appropriate amount of K application promoted the shoot growth of summer maize, increased biomass accumulation, significantly improved the uptake efficiency and plant N, P, and K accumulation of summer maize, optimized post-flowering nutrient accumulation and distribution, and improved the contribution of nutrient translocation to the formation of grain yield, thus improving the grain yield and nutrient utilization of summer maize. Considering the factors of grain yield, nutrient accumulation and transport, and fertilizer utilization, the K application rate of 225 kg hm^-2 was suitable for this experiment.

RESEARCH NOTES

Screening of different dropping formulations about mepiquat chloride and their effects on cotton growth and development

LOU Shan-Wei, GAO Fei, WANG Chong, TIAN Xiao-Li, DU Ming-Wei, DUAN Liu-Sheng

Acta Agronomica Sinica. 2023, 49(2):  552-560.  doi:10.3724/SP.J.1006.2023.24034

Abstract ( 275 )   HTML ( 11 )   PDF (2263KB) ( 236 )   Save

Figures and Tables | References | Related Articles | Metrics

The drop method of mepiquat chloride is an important research field in cotton. In order to explore the new sustained-release dropping formulation and its effect on cotton regulation, the following experiments were carried out. The dropping formulations were screened by pot cultivation with five kinds (H1, H2, H3, H4, and H5) of dripping application form, and common mepiquat chloride (S) and water as the control (CK). To investigate the screening of different dosage forms and the effect of regulating cotton agronomic characters and yield, two concentration levels of low and high (90.0 g hm^-2 and 180.0 g hm^-2) were set in the field. The results showed that under pot conditions, the uniformity of five different formulations of mepiquat chloride was basically above 66%, and the seedling growth rate greatly affected by the variety mostly between 40% and 70%. Plant height was reduced by 32%-41% and 24%-35%, respectively, and there was significantly different in plant height after 25 days. Under field conditions, treatment S had the best height control effect, CK increased the fastest, and all treatments had better height control effects at high concentrations of sustained-release mepiquat chloride and were significantly different from CK. At low concentrations, plant height of H5 was 61.0 cm. The effect was similar to S and had no significant difference, and other treatments had no significant difference with CK. Cotton plant width, stem diameter, the number of leaves in main stem, and the number of fruit branches were 26.0-35.0 cm, 9.5-11.5 mm, 13-14 pieces, and 7-8 sets, respectively, which had no significant difference with CK and S. The new type of sustained-release mepiquat chloride could promote bud initiation and increase boll numbers. By June 28 (peak flowering stage), the total number of flowers and bolls in two concentration levels of H1 were 12.7 and 11.5 per plant, respectively, which were 2.0 and 0.8 higher than that of S. The final yield of all treatments at low concentration was higher than that of high concentration. And the yield of H5 was the highest (7267.26 kg hm^-2), which was 40% and 33% higher than CK and S, respectively, followed by H1. In conclusion, dropping formulations of H1 and H5 control plant height, shape plant type and yield performance was better, and further related experimental research can be carried out.

Effects of GsERF6 overexpression on salt-alkaline tolerance in rice

CAI Xiao-Xi, HU Bing-Shuang, SHEN Yang, WANG Yan, CHEN Yue, SUN Ming-Zhe, JIA Bo-Wei, SUN Xiao-Li

Acta Agronomica Sinica. 2023, 49(2):  561-569.  doi:10.3724/SP.J.1006.2023.22008

Abstract ( 320 )   HTML ( 23 )   PDF (7138KB) ( 188 )   Save

Figures and Tables | References | Related Articles | Metrics

Ethylene response factors (ERFs) are a family of plant specific transcription factors that play important roles in abiotic stress. Bioinformatic analysis revealed that GsERF6, a Glycine soja ERF transcription factor that positively regulated salt-alkaline tolerance, shared high sequence identity with homologous ERF proteins with one highly conserved AP2 domain in rice. To explore the effect of GsERF6 overexpression on the salt-alkaline tolerance in rice, we transformed GsERF6 into rice and obtained two homozygous transgenic lines via PCR and RT-PCR. Phenotypical and physiological assays indicated that, compared with the wild type rice under 200 mmol L^-1 NaHCO₃ treatment, the survival rate, relative water content, the activities of SOD, POD, and CAT, the soluble sugar and proline contents, were significantly increased, while ROS accumulation was significantly decreased in GsERF6 overexpression lines. The qRT-PCR showed that transcript levels of OsP5CS2 and OsLEA14 were significantly up-regulated in GsERF6 transgenic line after 40 mmol L^-1 NaHCO₃ treatment for 6 hours. In summary, GsERF6 overexpression in rice contributed to ROS scavenging, osmotic regulation, and activation of stress responsive genes, thus improving the salt-alkaline tolerance of transgenic rice.

Comprehensive evaluation of drought resistance of wheat varieties based on synergy of different developmental stages

MENG Yu, TIAN Wen-Zhong, WEN Peng-Fei, DING Zhi-Qiang, ZHANG Xue-Pin, HE Li, DUAN Jian-Zhao, LIU Wan-Dai, GUO Tian-Cai, FENG Wei

Acta Agronomica Sinica. 2023, 49(2):  570-582.  doi:10.3724/SP.J.1006.2023.21008

Abstract ( 395 )   HTML ( 37 )   PDF (1108KB) ( 465 )   Save

Figures and Tables | References | Related Articles | Metrics

Screening of drought resistance identification indicators and establishment of evaluation models can provide a basis for the selection and optimization of drought-resistant wheat varieties. Taking 23 winter wheat varieties mainly promoted in Huanghuaihai wheat area as the test materials, setting two treatments of drought and full irrigation, measuring 12 morphological and physiological parameters of wheat at the jointing, booting, flowering, and grain filling stages, and calculating drought resistance coefficient for each morphological and physiological trait. Principal component analysis, membership function method, grey relational degree method, cluster analysis, and stepwise regression analysis were used to comprehensively evaluate the drought resistance of wheat varieties. The results showed that under drought stress, the variation range of traits at booting and filling stages was relatively large (7.4%-41.7%), while the variation range of traits at jointing and flowering stage was relatively small (9.63%-31.63%). The correlation analysis revealed that there was a significant or extremely significant correlation between the measured agronomic parameters at each growth stage. Further, principal component analysis was used to convert the 12 trait parameters into 6 mutually independent comprehensive indicators at jointing, booting, and flowering stages, and 5 mutually independent comprehensive indicators at filling stage, and the cumulative contribution rate reached 89.03%, 88.69%, 87.68%, and 85.83% for above four stages, respectively. The membership function method was introduced to calculate the comprehensive drought resistance evaluation value (SD value) for each growth stage, and the quantitative relationship between SD value and yield drought resistance index (DRI) was analyzed, and the fitting precision of the simulation equation were the highest 0.744 at anthesis and the lowest 0.679 at filling. In order to better integrate the information of drought resistance at different stages, the first four parameters with the highest correlation with SD value at each stage were selected through the grey correlation degree and combined to form an evaluation index system for the whole growth period. The principal component and membership function analysis were carried out again to calculate the comprehensive evaluation value of drought resistance based on whole growth stages (MD), and this derived MD value can explain 87.8% of DRI variation, which represented an 18.1% increase over determinative coefficient of the best single stage. According to MD value, the varieties can be divided into four categories, moderate drought resistance, moderately weak drought resistance, weak drought resistance, and extremely weak drought resistance. A comprehensive evaluation mathematical model (R²=0.995) for the whole growth stage was established through the stepwise regression analysis, and the plant height and leaf water content at jointing, proline, plant height, and chlorophyll a at booting, chlorophyll a and soluble sugar at anthesis, and proline and leaf water content at filling were selected as a set of screening indicators. This study provides the theoretical guidance and information support for the early selection of drought-resistant material of wheat and the identification and promotion in suitable areas.