Table of Content

12 July 2024, Volume 50 Issue 7

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REVIEW

Carbon emission reduction in dry sloping land in Southwest China

WANG Xie, YANG Qin, LIU Yu-Chi, LI Qin, YANG Qin, CHEN Guan-Tao, YUE Li-Jie, ZHANG Jian-Hua, CHEN Xin-Ping, LIU Yong-Hong

Acta Agronomica Sinica. 2024, 50(7):  1635-1646.  doi:10.3724/SP.J.1006.2024.32029

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The agricultural ecosystem is both a carbon source and a carbon sink, with strong potential for carbon sequestration and thus makes significant contributions to the global carbon cycle. The traditional small-scale and fragmented agricultural production pattern on dry slopes in the southwestern region have brought great uncertainty to regional carbon emissions. Exploring the characteristics of carbon emissions and reduction pathways on dry slopes in the southwest is of great significance for improving the environment and enhancing the potential of regional agricultural production. This study systematically summarized the production processes of major greenhouse gases (CO₂, N₂O, CH₄) in the agricultural ecosystem of dry slopes in the southwestern region of China. We discussed the effects of new materials and technologies application for carbon sequestration and emission reduction on dry slopes, and proposed carbon sequestration and emission reduction strategies for dry slopes in the future. (1) Given the significant differences in regional resources, industrial foundation, production scale, management methods, and ecological functions in dry slopes in the southwestern mountainous areas, suitable carbon sequestration and emission reduction measures and monitoring systems should be developed based on the specific agricultural production conditions of the region. The aim was to explore the carbon emission process and its underlying mechanisms in the context of global warming, and comprehensively enhanced the resilience of regional agricultural production to climate change. (2) Considering the high crop replanting index and fragmented spatial distribution of crops in the southwestern mountainous areas, agricultural production methods should be improved and industrial spatial layout should be optimized based on national strategies and local plans, aiming for an agricultural ecosystem with low carbon emission and high productivity. (3) As carbon emission reduction on dry slopes in the southwestern mountainous areas was a complex process, it was currently necessary to optimize and combine mature emission reduction technologies, carbon sequestration products, and carbon sequestration models in a targeted manner based on the actual structure and functional needs of regional agricultural production in the foreseeable future. This would form comprehensive carbon sequestration and emission reduction plans. In summary, this review hoped to provide a comprehensive and effective reference for further research on the carbon source and carbon sink characteristics of the agricultural ecosystem in dry slopes in the southwestern region, as well as for rational adjustment of farmland management measures.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Effects of high light stress on photosynthesis and physiological characteristics of wheat with maize C₄-type ZmPEPC+ZmPPDK gene

FANG Yu-Hui, QI Xue-Li, LI Yan, ZHANG Yu, PENG Chao-Jun, HUA Xia, CHEN Yan-Yan, GUO Rui, HU Lin, XU Wei-Gang

Acta Agronomica Sinica. 2024, 50(7):  1647-1657.  doi:10.3724/SP.J.1006.2024.31077

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To study the photosynthetic and physiological response of maize C₄-type PEPC (phosphoenolpyruvate carboxylase gene) and PPDK (pyruvate phosphate double kinase gene) dual-gene wheat to high light, the ZmPEPC + ZmPPDK wheat lines PCK30 and PCK60 and their wild type control material (WT) were used as experimental materials. The relative expression levels of exogenous genes in transgenic wheat were identified. The photosynthetic enzyme activity, chlorophyll content, gas exchange parameters, chlorophyll fluorescence parameters, active oxygen content, and antioxidant enzyme activity of transgenic wheat were measured under normal light intensity (NL) and high light stress (HL) at heading and grain-filling stages. The results showed that the two transgenic lines expressed the PEPC and PPDK genes efficiently at the transcriptional level. The enzyme activity of PEPC, PPDK, NADP-ME, and Rubisco of transgenic wheat was significantly higher than WT under NL or HL stress at different stage, and the increase of WT was more obvious under HL stress. Compared with NL stress, the chlorophyll content of transgenic wheat and WT decreased significantly under HL stress, but the decrease of transgenic lines was smaller, and the chlorophyll content of transgenic lines was significantly higher than WT under HL stress. Under two treatment stresses, the net photosynthetic rate (P_n) of PCK30 and PCK60 was significantly higher than WT, and the higher range was more obvious under HL stress. The increases were 15.26% and 17.57% at heading stage and 13.41% and 15.82% at grain-filling stage, respectively. The variation trend of stomatal conductance, F_v/F_m and q_p was consistent with P_n, while the variation trend of intercellular carbon dioxide concentration was opposite to P_n. The content of reactive oxygen species and malondialdehyde produced by transgenic lines under HL stress was significantly lower than WT, while the trend of antioxidant enzymes was opposite. In two consecutive years of field plot yield experiments, PCK30 and PCK60 were 8.37% and 10.16% higher than WT on average. The overexpression of PEPC and PPDK in wheat enhanced the endogenous photosynthetic enzyme, photochemical efficiency, and antioxidant enzyme activities of wheat, enhanced the stability of leaf cell membrane under high light stress, protected the photosynthetic apparatus, and maintained a high photosynthetic efficiency, thus improving the tolerance of transgenic wheat to high light stress.

Establishment of large fragment knockout in pea genome by CRISPR/Cas9 technology

HUANG Shu-Xian, LIU Rong, LI Guan, SHU Qin, XU Fei, ZONG Xu-Xiao, YANG Tao

Acta Agronomica Sinica. 2024, 50(7):  1658-1668.  doi:10.3724/SP.J.1006.2024.34196

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Pea is one of the main food legumes in the world and has been paid more and more attention due to its rich nutritional value and good ecological value. CRISPR/Cas9 as a new biology breeding tool has been widely used in many crops, however, its usage in pea is very limited. In this study, we successfully achieved large fragment deletion of the Psat01G0240600-T1, Psat03G0303300-T1, and Psat03G0304700-T1 genes in “Zhongwan 6” variety by CRISPR/Cas9 technology. The large fragment knockout ratio was 24.1%, 13.0%, and 3.6%, respectively. Further analysis revealed that there were significant differences in editing efficiency among different target sites and large fragment deletion depend on the specific target site with the lower editing efficiency between the two target sites. In this study, we explored the application of CRISPR/Cas9 by using the hairy root system in pea and achieved large fragment knockout for the first time in pea, which is of great significant for the research of peas.

QTL mapping and KASP marker development of grain quality-relating traits in two wheat RIL populations

BI Jun-Ge, ZENG Zhan-Kui, LI Qiong, HONG Zhuang-Zhuang, YAN Qun-Xiang, ZHAO Yue, WANG Chun-Ping

Acta Agronomica Sinica. 2024, 50(7):  1669-1683.  doi:10.3724/SP.J.1006.2024.31073

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We utilized a 55K single-nucleotide polymorphism (55K SNP) array and diversity array technology (DArT) to identify QTLs for grain protein content (GPC), wet gluten content (WGC), and sedimentation value (SV) in two F₆ recombinant inbred lines derived from Avocet/Chilero and Avocet/Huites. Sixty-eight QTLs were identified related to grain protein content, wet gluten content, and settlement value, explaining 3.60%-22.53% of the phenotypic variances. Fourteen QTLs were found to be present in multiple environments, located on chromosomes 3A(2), 4D, 5D(2), 6A(8), and 7B, respectively. Additionally, seven QTLs clusters were detected on chromosomes 3A, 3D, 4B, 5D, 6A(2), and 7B, respectively. Two stable QTL clusters, C3A and C6A.2, identified in the physical intervals of 9.32-60.01 Mb and 38.47-82.95 Mb, respectively, were significantly associated with grain protein content and wet gluten content. These clusters accounted for 6.55%-14.21% and 3.83%-22.53% of the phenotypic variances for grain protein content, wet gluten content, and sedimentation value. Meanwhile, a total of 16 candidate genes associated with grain protein content were predicted within the two stable QTL clusters. Moreover, two KASP marker, CGPC-6A-KASP-1 and CGPC-6A-KASP-2, were developed based on the candidate genes. The findings of this study provide support for the identification of new QTL and KASP markers that can contribute to the genetic improvement of grain quality-related traits in wheat. These results also offer valuable insights for marker-assisted breeding in wheat.

Developing new rice lines with ultrashort-duration, long-grain, and fragrance

PEI Fa-Jing, ZHANG Wen-Xuan, ZHANG Xiao, WANG Xin-Yu, PENG Shao-Bing, MI Jia-Ming

Acta Agronomica Sinica. 2024, 50(7):  1684-1698.  doi:10.3724/SP.J.1006.2024.32044

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Developing high-quality and ultrashort-duration rice varieties is of great significance for improving the multiple cropping index in the middle and lower reaches of Yangtze River to ensure our food security. In this study, the ultrashort-duration rice line CPPC09-180-28-1-5 was used as the recipient parent. The high-quality variety Xiangyaxiangzhan which carrying the fragrance gene fgr and the grain length gene GW7 was used as the donor parent. Three new breeding lines carrying homozygous fgr and GW7 genes were bred with high-quality and ultrashort-duration, via hybridization, backcrossing and genome-wide marker-assisted selection. Fragrance identification, main agronomic characters, and grain quality analysis of the new breeding lines were carried out. The new lines carrying fgr and GW7 genes had obvious fragrance. The grain length of the new lines was significantly increased compared with the recipient parent CPPC09-180-28-1-5, resulting in better grain quality. The whole growth period of the new lines was about 85-98 days, which was basically consistent with the recipient parent CPPC09-180-28-1-5. The new lines could be planted as early or late rice in the rice area of the middle and lower reaches of the Yangtze River to improve the multiple cropping index. In addition, plant height, 1000-grain weight, and yield per plant of the new breeding lines were significantly reduced compared with the recipient parent CPPC09-180-28-1-5, indicating that the introgression of two chromosome fragments carrying target genes in this study has a significant effect on the main agronomic traits of CPPC09-180-28-1-5. This study provides the germplasm resources and strategies for breeding high grain quality and ultrashort-duration rice by the molecular breeding.

Identification and evaluation of atrazine tolerance of soybean germplasm resources at germination stage and screening of excellent germplasm

LI Xiao-Fei, GAO Hua-Wei, GUANG Hui, SHI Yu-Xin, GU Yong-Zhe, QI Zhao-Ming, QIU Li-Juan

Acta Agronomica Sinica. 2024, 50(7):  1699-1709.  doi:10.3724/SP.J.1006.2024.34198

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Laboratory bioassay is a common method to identify crop herbicide tolerance, which was widely used in soybean, cotton, and other crops to study the tolerance of glyphosate, chlorsulfuron and other herbicides, but there are few reports on laboratory bioassay method and soybean tolerance to atrazine. In this study, the effects of atrazine on the germination stage of soybean were evaluated, and the changes of germination potential, germination rate, germination index, vitality index, and root length of soybean under atrazine stress were analyzed. A laboratory bioassay method was established for the atrazine tolerance of soybean, and 3.5 mL L^-1 was determined as the appropriate concentration for screening atrazine tolerance of soybean at germination stage. The tolerance of atrazine to 159 soybean germplasms at germination stage was identified. The results showed that the relative coefficient of variation of each index was the relative atrazine stress rate, the relative bud length, the relative germination index, the relative vitality index, the relative germination potential, and the relative germination rate. According to the T-value cluster analysis, the tested germplasm was divided into 4 atrazine tolerance grades, and 9 high-tolerant, 50 medium-tolerant, 70 low-tolerant, and 30 sensitive germplasm were identified. Nine germplasm, including soybean, fancy bean, Kenfeng 13, and Nannong 99-6, had excellent tolerance to atrazine. This study provides the theoretical basis, material and technical support for the selection of parents, the selection of progeny and the mining of genes related to atrazine tolerance in soybean.

Construction of SNP high-density genetic map and localization of QTL for β-glucan content in oats

HAN Li, TANG Sheng-Sheng, LI Jia, HU Hai-Bin, LIU Long-Long, WU Bin

Acta Agronomica Sinica. 2024, 50(7):  1710-1718.  doi:10.3724/SP.J.1006.2024.31060

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β-glucan is the main functional component of oats for health care, and improving its content is of great significance to the production of high-quality oats. In this study, in order to promote the effective utilization of high β-glucan oat germplasm resources and the discovery of related genes, a genetic linkage map containing 21 linkage groups and 5032 bin markers was constructed by using resequencing technology with the 223 RIL8 populations derived from the high β-glucan variety Xiayoumai and the low β-glucan resource Chi38. The total length of the map was 2045.09 cM, and the average plot distance was 0.42 cM. The β-glucan content of RIL populations in four environments was determined by standard enzyme method and near infrared method. Combined with the determination results, QTL analysis of β-glucan content was performed by complete interval mapping method. The results showed that the β-glucan content of RIL populations was normally distributed under different environmental conditions, and there were superparent descendants. The coefficient of variation of β-glucan content in the four environments ranged from 9.06% to 16.63%. Seven QTLs related to β-glucan content in oat were detected by QTL mapping, distributed on 2D, 3D, 4C, and 4D chromosomes, with the highest contribution rate of 14.73%. The same QTL was detected in two environments with a marker interval of Chr4C_mark8361257-Chr4C_mark8384831. The results of this study provide an important theoretical basis for molecular marker-assisted breeding of oat β-glucan.

QTL mapping for flavonoid content and seed color in foxtail millet

QIN Na, YE Zhen-Yan, ZHU Can-Can, FU Sen-Jie, DAI Shu-Tao, SONG Ying-Hui, JING Ya, WANG Chun-Yi, LI Jun-Xia

Acta Agronomica Sinica. 2024, 50(7):  1719-1727.  doi:10.3724/SP.J.1006.2024.34186

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Foxtail millet (Setaria italica L.) is an important grain crop in northern China. The grain is rich in nutrients and many kinds of flavonoid, which plays an important role in growth and quality formation. At present, there are few studies on the regulatory mechanisms of flavonoid synthesis and seed color formation in foxtail millet. The quantitative trait loci (QTL) analysis of flavonoid content and seed color traits in foxtail millet laid a foundation for fine mapping, cloning, and functional study of key genes for flavonoid synthesis, and it also provided technical support for revealing the mechanism of flavonoid synthesis and metabolism in foxtail millet and cultivating millet varieties rich in flavonoid. In this study, a recombinant inbred line (RIL) population consisting of 150 families was used as the experimental materials, which was constructed using a red seed-color high-flavonoid variety Jinmiaohongjiugu and a yellow seed-color low-flavonoid variety Yugu 28 as the parents. The related traits of seed color and flavonoid content were analyzed at maturity stage in foxtail millet. At the same time, composite interval mapping (CIM) was used to locate and analyze QTL for seed color and flavonoid content, and the candidate genes within the QTL confidence intervals were predicted. Correlation analysis showed that flavonoid content was significantly positively correlated with seed color. A total four and eleven QTL associated with flavonoids content and seed color were located on chromosomes 1, 2, 5, 6, 7, 8, and 9, respectively, and individual QTL phenotypic contribution rate was 2.01%-29.25%, six major QTLs were identified, qSC1-2 and qFLA1-1, qSC7-1 and qFLA7-1, qSC9-3, and qFLA9-1 were co-localized QTL under both two traits. Through gene prediction and functional annotation, five candidate genes related to flavonoid synthesis and metabolism in the confidence interval of QTL were screened, indicating that the genes related to flavonoid synthesis, metabolism, and utilization were most probably to regulate the expression of these genes. 15 QTL were clustered on seven chromosomes, respectively, and five candidate genes related to flavonoid synthesis and metabolism were screened based on gene functional annotation, indicating that different QTL loci were involved in the common genetic mechanism, and the pyramiding breeding of beneficial genes such as flavonoid synthesis and metabolism could be carried out through molecular marker-assisted selection.

Core germplasm identification of proso millet in spring sowing area of Northeast China using fluorescent microsatellite markers

DING Yi-Bing, XIN Xu-Xia, FENG Zhi-Zun, GUO Juan, CAO Yue, CHEN Xi-Ming, WANG Xiao-Dan, CAO Xiao-Ning, SANTRA Dipak K, CHEN Ling, QIAO Zhi-Jun, WANG Rui-Yun

Acta Agronomica Sinica. 2024, 50(7):  1728-1739.  doi:10.3724/SP.J.1006.2024.34183

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Rich germplasm resources are the basis of new varieties breeding and industrial development in proso millet. In this study, 190 core germplasms of proso millet in spring sowing area of northeast China were used as the experimental materials. PCR amplification and capillary electrophoresis were performed using the previously constructed SSR markers labeled with fluorescence at the 5° end. According to the fragments detected by capillary electrophoresis, “0/1” was used to represent without of the fragments, and ID Analysis 4.0 was used to distinguish them. PopGene, PowerMarker, MEGA, Structure, and NTSYS were used for genetic diversity analysis. The results showed that 190 materials could be distinguished by three fluorescent SSR (RYW3, RYW6, RYW28) marker combinations. A total of 73 alleles were detected, with an average of 24.3333. The effective number of alleles (N_e) was 5.4728 (RYW3)-15.8922 (RYW6), with an average of 9.6469. The Shannon diversity index (I) was 2.0851 (RYW3)-2.9457 (RYW6), with an average of 2.4896. The observed heterozygosity (H_o) was 0.7529 (RYW6) - 0.9574 (RYW28), with an average of 0.8876. The expected observed heterozygosity (H_e) was 0.8194 (RYW3) - 0.9398 (RYW6), with an average of 0.8765. The Nei’s gene diversity index (Nei) was 0.8173 (RYW3)-0.9371 (RYW6), with an average of 0.8741. The polymorphism information content (PIC) was 0.8656 (RYW3)-0.9722 (RYW6), with an average of 0.9198. Based on UPGMA, 190 resources were divided into three groups. Based on the genetic structure of Structure (K = 3), the core collection of proso millet was divided into three groups. The proso millet was derived from four provinces in northeast China (Heilongjiang, Jilin, Liaoning, and the part of Inner Mongolia). Based on principal component analysis, the materials were divided into four groups, which was consistent with their geographical origin. The DNA molecular identification cards of 190 core collections of northeast proso millet were constructed using online two-dimensional code technology (https://cli.im/).

Screening and functional identification of chlorogenic acid regulatory factors in potato

ZHOU Hong-Yuan, YANG Hui-Qin, LUO Wei, SHI Zhen-Ming, MA Ling

Acta Agronomica Sinica. 2024, 50(7):  1740-1749.  doi:10.3724/SP.J.1006.2024.34185

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Potato is the third largest food crop in the world. Chlorogenic acid is the most important phenolic compound in potato, and also one of the material basis of potato insect resistance and disease resistance. However, excessive chlorogenic acid can affect the taste of tuber, therefore, breeding varieties with high chlorogenic acid content in the ground part and low chlorogenic acid content in tuber flesh can well meet the needs of potato disease resistance and quality taste. In order to clarify the molecular regulation mechanism of chlorogenic acid in potato, we used the promoter sequence of StHQT, a key enzyme for chlorogenic acid synthesis, as bait to screen the yeast single hybridization library, and identified the transcription factor StAHL of an AT-hook gene family. Further, the bioinformatic characteristics, the relative expression patterns, and subcellular localization of protein products of StAHL were systematically analyzed, and the transcriptional activity between StAHL and StHQT promoters was verified by yeast single hybridization and double luciferase report experiments. The results showed that StAHL gene expression was not tissue specific, but relatively high in roots and flowers. StAHL protein products contained two conserved domains, AT-Hook and DUF296, and were localized in the nucleus. StAHL proteins acted directly on StHQT promoter sequences and inhibited transcriptional activity. This suggests that StAHL may inhibit the accumulation of chlorogenic acid in potato by inhibiting StHQT expression. The results laid a foundation for revealing the molecular mechanism of chlorogenic acid biosynthesis in potato, and provided a molecular target for the breeding practices in potato.

Functional analysis of flax LuWRI1a in response to drought and salt stresses

LI Wen-Juan, WANG Li-Min, QI Yan-Ni, ZHAO Wei, XIE Ya-Ping, DANG Zhao, ZHAO Li-Rong, LI Wen, XU Chen-Meng, WANG Yan, ZHANG Jian-Ping

Acta Agronomica Sinica. 2024, 50(7):  1750-1761.  doi:10.3724/SP.J.1006.2024.34171

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The AP2/ERF family of transcription factors is involved in the regulation of plant responses to biotic and abiotic stresses. Previously, we cloned LuWRI1a, a WRINKLED1 homologous gene from flax. Protein sequence analysis showed that LuWRI1a contained two AP2 DNA-binding domains and belonged to the AP2/ERF transcription factor family. The cis-acting elements of LuWRI1a were analyzed that pLuWRI1a was found containing multiple abiotic stress elements in response to light, drought, low temperature and hormones. In this study, the flax cultivar Longya 10 and LuWRI1a overexpression transgenic pure lines were used as the experimental materials, and salt stress and drought stress treatments were simulated with 200 mmol L^-1 NaCl nutrient solution and 25% PEG nutrient solution. The results showed that the relative plant height, primary root length, lateral root number, and leaf number of transgenic plants were elevated after salt and drought stress treatments. The activities of three antioxidant enzymes were significantly higher than the control, while MDA content was lower. The relative expression levels of the abiotic stress-responsive genes, LuAREB, LuDREB, LuLEA, and LuNCED, were up-regulated. By exploring the biological function of LuWRI1a under adversity stress, it was found that LuWRI1a enhanced flax tolerance by resisting the inhibition of flax growth by salt stress and drought stress, enhancing the scavenging ability of reactive oxygen species, reducing the oxidative damage of membrane lipids, and activating the expression of adversity stress response genes. In summary, LuWRI1a may be a multifunctional gene, which was not only involved in fatty acid synthesis and metabolism pathway, but also may be involved in plant abiotic stress signaling pathway. This study provides a new genetic resource for the improvement of stress-tolerant varieties of flax.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of an integrated dryland tillage and soaking pattern on the reducing substances in rice field and early growth of machine transplanted rice

CHENG Shuang, XING Zhi-Peng, TIAN Chao, HU Qun, WEI Hai-Yan, ZHANG Hong-Cheng

Acta Agronomica Sinica. 2024, 50(7):  1762-1775.  doi:10.3724/SP.J.1006.2024.32053

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There were some problems in rice-wheat rotation areas, such as low quality of rice field soil preparation, and the accumulation of reducing substances was not conducive to the early growth of mechanically transplanting rice. We explored the feasibility of applying an integrated dry tillage and soaking pattern to promote high-quality early growth of machine transplanted rice. The experiment was carried out in the experimental base of Sihong county, Suqian city, Jiangsu province from 2021 to 2022. Three tillage patterns were conducted, namely integrated dryland tillage + soaking pattern (Treatment 1, T1), dryland rotary tillage + soaking + paddy rotary tillage pattern (Treatment 2, T2), and soaking + paddy rotary tillage pattern (Treatment 3, T3). The redox potential of paddy soil, the content of reducing substances in different soil layers, and the root and shoot traits of machine-transplanted rice at early growth stage were determined. The result showed that the soil redox potential of T1 was the highest, which was 19.3%-24.7% and 31.6%-41.1% higher than that of T2 and T3 at the lowest point, respectively. Different tillage patterns significantly affected the contents of total reducing substances, active reducing substances, ferrous ions, and divalent manganese ions in 0-5 cm and 5-10 cm soil layers. Among them, compared with the mean values of T2 and T3, the content of active reducing substances in the 0-5 cm and 5-10 cm soil layers of T1 decreased by 31.9%-37.6% and 22.6%-23.5%, respectively, and the content of ferrous ions decreased by 30.5%-40.3% and 25.3%-27.3%, respectively. This result was mainly related to the fact that T1 significantly reduced the soil bulk density of 0-5 cm and 5-10 cm soil layers and increased the total soil porosity of the same soil layers. Root traits (root total number, root dry weight, and root oxidation capacity) and above-ground indexes (tiller number, dry matter accumulation) of T1 were the highest, followed by T2, and T3 was the lowest. Compared with the mean values of T2 and T3, the total root number, root dry weight, root oxidation force, the number of tillers, and the dry matter accumulation of T1 increased by 9.6%-32.9%, 19.5%-53.8%, 27.3%-34.7%, 9.0%-15.4%, and 30.7%-44.7%, respectively. Correlation analysis indicated that the early high-quality growth of machine-transplanted rice under T1 was mainly due to the reduction of reducing substances within the 0-5 cm soil layer, especially the significant reduction of active reducing substances and ferrous ions (P < 0.05). In conclusion, the application of the integrated dryland tillage and soaking pattern can help to reduce the content of rice field reducing substances and promote the early high-quality growth of machine transplanted rice in rice-wheat rotation areas.

Effects of soil conditioners on soil salinity content and maize yield in coastal saline-alkali land

HAN Xiao-Chen, ZHANG Gui-Qin, WANG Ya-Hui, REN Hao, WANG Hong-Zhang, LIU Guo-Li, LIN Dian-Xu, WANG Zi-Qiang, ZHANG Ji-Wang, ZHAO Bin, REN Bao-Zhao, LIU Peng

Acta Agronomica Sinica. 2024, 50(7):  1776-1786.  doi:10.3724/SP.J.1006.2024.33069

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In order to provide the theoretical basis for the selection of suitable soil conditioners for summer maize field in coastal saline-alkali land, we analyzed the effects of different types of soil conditioners on soil salt content of 0-10 cm, 10-20 cm, 20-30 cm, and 30-40 cm layers of summer maize fields in coastal saline-alkali land, root morphology, and grain yield of maize. In 2022-2023 maize growth seasons, the experiments were conducted in coastal saline-alkali summer field at Binzhou, Shandong province. The experiments were designed with the completely random block experimental design, with no soil conditioner as the control (CK), three different types of soil conditioners treatments: silica-calcium-potassium-magnesium conditioner (T1), silica-calcium-potassium -magnesium zeolite conditioner (T2), and silica-calcium-potassium-magnesium polymer (PAM) conditioner (T3) were set up for studying the effects of different types of soil conditioners on soil salt content of 0-40 cm layer, root morphology, leaf area index, biomass of shoot, nitrogen accumulation amount of shoot and grain yield in maize. The results indicated that, at V6 stage, compared with CK, the total salt content and Na⁺ content of 20-30 cm soil layer in T1 and T3 treatments decreased by 6.88% and 23.00%, 28.82%, and 17.44%, respectively, but the HCO₃^- content of 20-30 cm soil layer increased by 10.97% and 5.66%, respectively. At R1 stage, compared with CK, the total salt content and Na⁺ content of 10-40 cm soil layer in T2 treatment decreased by 9.07% and 14.11%, respectively. The HCO₃^- content of 10-40 cm soil layer increased by 21.35%. The decrease of soil total salt content was beneficial for the growth of root and shoot. Compared with CK, at R1 stage, the average root length per plant of 0-40 cm soil layer was increased by 17.56%, 74.83%, and 33.53% in T1, T2, and T3 treatments, respectively. The average root surface per plant was increased by 33.35% and 27.44% in T2 and T3 treatments, respectively. The average root dry weight per plant were increased by 14.58% and 11.93% in T2 and T3 treatments, respectively. Compared with CK, T1, T2, and T3 treatments significantly increased the leaf area index, shoot biomass, and nitrogen accumulation, thus increasing the grain yield of summer maize. Compared with CK, the grain yield of T1, T2, and T3 treatments were increased by 3.81%, 8.22%, and 4.72% in 2022, and by 8.08%, 18.88%, and 15.95% in 2023, respectively. In conclusion, in the conditions of our experiments, silica-calcium-potassium-magnesium zeolite conditioner effectively reduced soil salt content at R1 stage in maize, alleviated salt stress, promoted root and shoot growth, increased shoot nitrogen accumulation and biomass, and thus significantly increasing grain yield in maize, which was the best soil conditioner for improving summer maize growth in saline-alkali coastal land.

Effects of alternate wetting and drying irrigation and different nitrogen application levels on photosynthetic characteristics and nitrogen absorption and utilization of japonica rice

FU Jing, MA Meng-Juan, ZHANG Qi-Fei, DUAN Ju-Qi, WANG Yue-Tao, WANG Fu-Hua, WANG Sheng-Xuan, BAI Tao, YIN Hai-Qing, WANG Ya

Acta Agronomica Sinica. 2024, 50(7):  1787-1804.  doi:10.3724/SP.J.1006.2024.32056

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Soil water potential and nitrogen nutrients are the important factors affecting photosynthetic characteristics in leaves and nitrogen absorption and utilization of rice (Oryza sativa L.). Little is known, however, how synergistic the two factors under alternative wetting and drying irrigation (AWD) can be in terms of nitrogen metabolism enzyme activity, grain yield, and nitrogen use efficiencies. A field experiment was conducted using a super rice variety of Nanjing 9108 with five nitrogen levels, namely, no nitrogen applied (N0), 90 (N1), 180 (N2), 270 (N3), and 360 kg hm^-2 (N4), and two irrigation regimes, namely, conventional irrigation (CI) and AWD over two years. Our results revealed significant interaction between irrigation and nitrogen levels. At the same nitrogen levels, the content of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid, net photosynthetic rate, the activities of superoxide dismutase, catalase, nitrate reductase, glutamine synthetase, and glutamic acid synthetase at main growth stages were higher in AWD than those in CI. Furthermore, the activities of nitrate reductase, glutamine synthetase, glutamic acid synthetase, and glutamate dehydrogenase in roots of rice were also increased, but the activities of peroxidase, endopeptidase, and the content of malondialdehyde in leaves were lower. AWD treatment increased grain yield by an average of 10.4% compared with CI, and also enhanced nitrogen transport capacity, nitrogen transport efficiency, nitrogen absorption, utilization efficiency, and partial productivity of nitrogen fertilizer. AWD coupled with N3 had the highest yield and nitrogen use efficiency; this treatment was the optimal water-nitrogen interaction management model in this study. These results suggest that adopting AWD with an appropriate nitrogen rate promotes nitrogen metabolism in roots and leaves and improves photosynthetic characteristics of leaves, thereby synergistically increasing grain yield and nitrogen use efficiency in rice.

Effects of nitrogen application levels on the accumulation, distribution of nitrogen, phosphorus and potassium, and the corresponding yield of Cyperus esculentus in sandy soil

CAO Zi-Qi, ZHAO Xiao-Qing, ZHANG Xiang-Qian, WANG Jian-Guo, LI Juan, HAN Yun-Fei, LIU Dan, GAO Yan-Hua, LU Zhan-Yuan, REN Yong-Feng

Acta Agronomica Sinica. 2024, 50(7):  1805-1817.  doi:10.3724/SP.J.1006.2024.34187

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The effects of different nitrogen fertilizer application levels on dry matter and nutrient accumulation, distribution and yield of Cyperus esculentus under sandy soil conditions were evaluated, which provided a theoretical basis for the rational application of nitrogen fertilizer in Cyperus esculentus under sandy soil conditions. A field experiment was conducted with four nitrogen application levels: no nitrogen (N0), low nitrogen (N1), medium nitrogen (N2), and high nitrogen (N3). The effects of different nitrogen fertilizer application levels on dry matter and nutrient accumulation, distribution and yield of Cyperus esculentus ‘Zhongyousha 1’ were explored. The results showed that the dry matter accumulation in stems, leaves, roots, and tubers of Cyperus esculentus showed an increasing with the development of growth. Before the tuber formation period, Cyperus esculentus was mainly based on the vegetative growth of the above-ground stems and leaves. After the tuber formation period, the growth centre gradually shifted to the underground tubers, and the proportion of dry matter accumulation and distribution in the tubers was as high as 43.34%-51.00% at harvest stage. The dry matter accumulation and distribution ratio of tubers at N2 level in two years were higher than those at other levels, which were 17.50% and 4.00% higher than those at other nitrogen levels, respectively. Cyperus esculentus had a large demand for nitrogen and potassium, and less phosphorus. The accumulation of nitrogen, phosphorus, and potassium in Cyperus esculentus was the order: tuber > stem and leaf > root, and tuber became the final storage organ of nitrogen, phosphorus, and potassium in Cyperus esculentus. The cumulative absorption of nitrogen, phosphorus, and potassium in Cyperus esculentus under N2 level had been at a high-level during growth period, especially the distribution ratio of nitrogen, phosphorus and potassium in tubers at maturity stage reached 47.09%, 65.82%, and 56.40%, respectively. Under the N2 level, compared with other nitrogen application levels, the above-ground biomass, under-ground biomass, 1000-grain weight, and tuber yield of Cyperus esculentus were higher than other levels, and increased by 5.57%, 7.40%, 15.83%, and 18.12% on average, respectively. Therefore, under the cultivation conditions of low sandy soil fertility level, 150 kg hm^-2 nitrogen fertilizer was more suitable for Cyperus esculentus.

Effect of chlorophyll degradation rate in seed on key quality of rapeseed oil

YAN Zi-Heng, WANG Xian-Ling, SHAO Dong-Li, GAO Geng-Dong, NING Ning, JIA Cai-Hua, KUAI Jie, WANG Bo, XU Zheng-Hua, WANG Jing, ZHAO Jie, ZHOU Guang-Sheng

Acta Agronomica Sinica. 2024, 50(7):  1818-1828.  doi:10.3724/SP.J.1006.2024.34117

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The chlorophyll in rapeseed seed is one of the key factors hindering the production of high-quality rapeseed oil. The higher chlorophyll content in rapeseed oil is not only make it poor in appearance, but also cause rapid photooxidation reaction. Therefore, it is of great significance to improve the appearance and nutritional quality of rapeseed oil by increasing the degradation rate of chlorophyll at seed ripening stage. In order to provide the theoretical and technical support for the production of high-quality rapeseed oil raw materials, a natural population consisting of 281 cultivars and breeding lines from different regions was used in a two-year field experiment in Wuhan, to investigate the chlorophyll degradation rate of rapeseed seeds, and the appearance and nutritional quality of oil, besides analysing the internal relationship between chlorophyll degradation and 1000-seed weight, oil content, oil colour, and its antioxidant capacity. The results showed that there were significant differences in chlorophyll degradation rate among different strains, and there was wide variation among the tested population materials. Correlation analysis showed that there was no significant correlation between chlorophyll degradation rate and 1000-seed weight and oil content of seed, but significantly negative correlation with the chlorophyll content of rapeseed oil. The chlorophyll content of rapeseed oil was positively correlated with the red value, yellow value, and peroxide value, while negatively correlated with antioxidant capacity of rapeseed oil. For the category with fast chlorophyll degradation rate, rapeseed oil had lighter colour, lower peroxide value, higher total phenol content, and antioxidant capacity. Compared to slow chlorophyll degrading strains, the activity of protochlorophyllide oxidoreductases (POR) enzyme was lower at 40 days after anthesis, whereas pheophorbide an oxygenase (PAO) enzyme activity was higher at 53 days after anthesis in the seeds of fast chlorophyll degrading strains, indicating that seed chlorophyll content was lower and its degradation rate was faster in seeds at the late stage of seed maturation.

Analysis of water requirement and water surplus/deficit characteristics of winter rapeseed in Yangtze River Basin

XIE Xiong-Ze, XIE Jie, CHU Qian-Mei, YIN Yu-Feng, YU Xiao-Hong, WANG Dun, FENG Peng

Acta Agronomica Sinica. 2024, 50(7):  1829-1840.  doi:10.3724/SP.J.1006.2024.34190

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Based on the daily meteorological data of 129 cities in 11 provinces and 2 municipalities in the Yangtze River Basin for nearly 20 years, the effective precipitation and water requirement of winter rapeseed during the whole growth period and various growth stages were calculated by empirical formulas, the improved HS data model recommended by Food and Agriculture Organization (FAO), and crop coefficients. Furthermore, the water surplus/deficit index and the frequency of droughts and waterlogging disasters over multiple years were analyzed. The results indicated that the effective precipitation during various growth stages of winter rapeseed in the Yangtze River Basin had a decreasing belt-like distribution from southeast to northwest. Specifically, the plains around Poyang Lake and Dongting Lake, as well as Hangzhou-Jiaxing-Huzhou Plain, had abundant effective precipitation, while the effective precipitation in the coastal areas of the middle and lower reaches of the Yangtze River mainstream was moderate. Conversely, the effective precipitation was relatively low along the line from Qinling Mountains to Huaihe River, in Sichuan Basin, and on Yungui Plateau. The water requirement during various growth stages exhibits a distribution pattern of high in the southwest, moderate in the southeast, and low in the northwest. Among them, the water requirement was the highest in Yunnan Province, moderate in the plains of the middle and lower reaches of the Yangtze River, and the lowest in the areas along the line from Qinling Mountains to Huaihe River, in Sichuan Basin and Guizhou province. The spatial distribution characteristics of water surplus/deficit over multiple years indicated moderate water supply in the coastal areas of the middle and lower reaches of Yangtze River mainstream, insufficient water supply along the line from Qinling Mountains to Huaihe River, in Sichuan Basin, and on Yungui Plateau. The temporal evolution characteristics of water surplus/deficit indicated that droughts are more frequent at seedling stage in the upper reaches of the Yangtze River, with the occasional occurrences of waterlogging disasters, while waterlogging disasters were more frequent in the middle and lower reaches, with the occasional occurrences of droughts. At other growth stages, droughts were frequent in the upper reaches, while both droughts and waterlogging disasters were frequent in the middle and lower reaches. To ensure appropriate water supply at various growth stages of winter rapeseed in Yangtze River Basin, it was recommended to focus on adequate irrigation in the upper reaches at seedling stage and timely drainage in the middle and lower reaches. At other growth stages, sufficient irrigation should be emphasized in the upper reaches, timely irrigation in the cities on the northern bank of the mainstream in the middle and lower reaches, and timely drainage in the cities on the southern bank of the mainstream in the middle and lower reaches, aiming to promote high and stable yields of winter rapeseed in Yangtze River Basin and ensure a stable supply of domestic rapeseed raw materials.

Effect of phosphorus application on yield, quality, light temperature physiological characteristics, and root morphology in summer peanut

YANG Qi-Rui, LI Lan-Tao, ZHANG Duo, WANG Ya-Xian, SHENG Kai, WANG Yi-Lun

Acta Agronomica Sinica. 2024, 50(7):  1841-1854.  doi:10.3724/SP.J.1006.2024.34161

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Phosphorus (P) application status on the yield, quality, phosphorus accumulation dynamics, physiological characteristics of light and temperature, and root morphology of summer peanuts were explored to provide theoretical support for the efficient and scientific application of P in peanuts. Field experiment was conducted in Wen county, Henan province from 2021 to 2022. Five P (P₂O₅) fertilization treatments (0, 30, 60, 90, and 120 kg hm^-2) were applied using variety “Yuhua 22” as the experimental material. The yield and quality indicators of summer peanut pods were measured at mature stage, leaf SPAD value, canopy photosynthetic effective radiation, and canopy temperature were determined at seedling stage, flowering-pegging stage, pod-setting stage, and pod-filling stage, respectively. Plant samples were collected to analyse P accumulation and root morphology. Results showed that the “linear + platforms trends” were observed between P rates and peanut pods yield in both years and the optimal P application rates were 94 kg hm^-2 and 95 kg hm^-2, respectively. P application increased yield by 23.68% on average. The contents of crude protein, oil and amino acid in grain at maturity had a trend of “first increasing and then stabilizing” with the increasing P application rates. Compared with no P application (0 kg hm^-2), the average increasing rate of crude protein, oil and amino acid contents in grain with P application of 90 kg hm^-2 was 11.06%, 3.89%, and 11.58%, respectively. The P accumulation amount of summer peanuts was fitted by nonlinear regression through the Logistic equation, and it was concluded that P application treatments increased the maximum amount of P accumulation (Y_m) by increasing the maximum accumulation rate (V_m) and the average accumulation rate (\bar{V}) of P and prolonging the rapid accumulation period (Δt) and the active accumulation period (T_aas). Applying proper amount of P increased the absorption and accumulation of P in each part and promoted the distribution of P to pod. The maximum, minimum, and mean temperatures of the summer peanut canopy all decreased significantly with the increases of P rates. Peanut leaf SPAD values and canopy photosynthetically active radiation (APAR) and fractions (FPAR) significantly increased with P application of 90 kg hm^-2. Total root length, average root diameter, root volume, and root surface area of the ploughing layer in summer peanuts were increased by an average of 48.50%, 16.25%, 37.80%, and 21.88%, respectively, in P application treatments. Phosphorus fertilizer recovery efficiency and partial factor productivity decreased gradually with the increase of P application, and agronomic efficiency showed a trend of increasing first and then decreasing. Reasonable phosphorus application can significantly increase the yield and quality of summer peanuts, promote the accumulation and utilization of phosphorus, and improve the physiological performance of light and temperature at reproductive stage. The recommended P application rate for summer peanuts under the conditions of this experiment was 90 kg hm^-2.

RESEARCH NOTES

Interaction between calmodulin-like ScCML13 of sugarcane and SCMV movement protein P3N-PIPO

YU Quan-Xin, YANG Zong-Tao, ZHANG Hai, CHENG Guang-Yuan, JIAO Wen-Di, ZENG Kang, LUO Ting-Xu, HUANG Guo-Qiang, WANG Lu, XU Jing-Sheng

Acta Agronomica Sinica. 2024, 50(7):  1855-1866.  doi:10.3724/SP.J.1006.2024.34191

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Calmodulin-like (CML), one of the calcium signal receptor proteins unique to plants, is involved in plant growth and development and in response to environmental signal transduction. However, the response of CML to Sugarcane mosaic virus (SCMV) infection in sugarcane (Saccharum spp. hybrid) has not been reported. In the present study, a CML gene was cloned from a Badila (S. officinarum) and designated as ScCML13. The open reading frame (ORF) of ScCML13 gene is 519 bp in length and encodes a protein with 172 aa in length. Bioinformatics analysis showed that ScCML13 was a stable hydrophilic lipoprotein in with no transmembrane domain and contains 4 Ca²⁺-binding EF-hand domains. Phylogenetic tree analysis showed that the ScCML13 protein differentiated in monocotyledon and dicotyledon plants and in monocotyledonous C₃ and C₄ plants. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) experiments indicated that ScCML13 interacted with P3N-PIPO, the movement protein of SCMV. Subcellular localization assays demonstrated that ScCML13 was localized to the endoplasmic reticulum and nucleus, whereas the co-localization assays showed that ScCML13 interfered with the localization of SCMV-P3N-PIPO to plasma membrane or plasmodesmata. The RT-qPCR showed that ScCML13 gene was mainly expressed in sugarcane leaves, but relatively low in internodes and roots. The ScCML13 gene was significantly up-regulated at 2 h upon SCMV infection, and then down-regulated to the levels compared with the control group, while up-regulated at the later stage of infection.

Application analysis of chloroplast markers on rapid classification in maize germplasm

WANG Rui, SUN Bo, ZHANG Yun-Long, ZHANG Ming-Qi, FAN Ya-Ming, TIAN Hong-Li, ZHAO Yi-Kun, YI Hong-Mei, KUANG Meng, WANG Feng-Ge

Acta Agronomica Sinica. 2024, 50(7):  1867-1876.  doi:10.3724/SP.J.1006.2024.33063

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The chloroplast marker has high genetic conservation and is not affected by nuclear gene recombination, making it suitable for the classification and management of maize germplasm resources. Based on the Maize6H-60K chip, candidate markers for chloroplast grouping were obtained and 3549 maize germplasm resources were classified into five groups: B, D, H, C, and T. Twenty-nine specific chloroplast group panels (VCP) were selected and KASP primers were designed by the comparison of genotype information. A rapid group analysis algorithm compatible with chip and KASP platform was developed, which was consistent with the cluster analysis. Five group-specific markers were selected using sequential analysis to rapidly detect the germplasm resources, and a new efficient method for rapid grouping of maize germplasm resources was established, reducing the detection volume by 95%. This method provides a new efficient way to classify and manage maize germplasm resources.

Effects of waterlogging at jointing stage on starch particle size distribution and pasting properties of soft wheat

CHEN Juan, YANG Ting-Ting, YAN Su-Hui, YONG Yu-Dong, ZHANG Shi-Ya, LI Wen-Yang

Acta Agronomica Sinica. 2024, 50(7):  1877-1884.  doi:10.3724/SP.J.1006.2024.31072

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The objective of this study is to clarify the effect of waterlogging at jointing stage on starch particle size distribution and pasting properties in soft wheat. Under field conditions, from 2021 to 2023, the soft wheat varieties Huachengmai 1688 and Quanmai 725 were selected as the test materials, and two treatments of control (CK) and waterlogging (WL) were conducted. The waterlogging treatment was carried out for 10 consecutive days at jointing stage of wheat to study the effect of waterlogging at jointing stage on the starch particle size distribution and viscosity parameters of soft wheat and their relationship. The results showed that, compared with the control, waterlogging stress at jointing stage reduced wheat yield by reducing spike number, grain number per spike, and 1000-grain weight. The wet gluten content and protein content of grains were significantly reduced, and the starch content was significantly increased. Waterlogging stress at jointing stage inhibited the production and growth of B-type starch in wheat endosperm, and significantly reduced the volume, surface area, and the number percentage of B-type starch granules, mainly affecting 2.8-10.0 μm starch granules. The volume and surface area percentage of A-type starch granules increased significantly, mainly affecting 10.0-22.0 μm starch granules. Waterlogging stress had no significant effect on the percentage of A-type starch granules. After waterlogging stress, the peak viscosity, trough viscosity, final viscosity, breakdown, and setback of wheat increased significantly. In conclusion, waterlogging stress at jointing stage changed the starch particle size distribution of wheat. By reducing the proportion of B-type starch granules, increasing the proportion of A-type starch granules and the viscosity parameters such as peak viscosity were increased, and finally the yield and quality of wheat were affected.