Table of Content

12 January 2021, Volume 47 Issue 1

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REVIEW

Review of biochar structure and physicochemical properties

ZHANG Wei-Ming, XIU Li-Qun, WU Di, SUN Yuan-Yuan, GU Wen-Qi, ZHANG Hong-Gui, MENG Jun, CHEN Wen-Fu

Acta Agronomica Sinica. 2021, 47(1):  1-18.  doi:10.3724/SP.J.1006.2021.02021

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As a new emerging technology, biochar and its applications have been rapidly developed in recent years. However, due to large differences in carbonization materials and processes, it is difficult to compare or even contrast the results of biochar application studies, thus hindering the development of biochar applications to some extent. For this reason, our paper focuses on the key factors restricted the function of biochar, namely, the structure as well as physical and chemical properties of biochar, and then systematically presents the main research advances in recent years from the following perspectives of biochar such as definition, formation, structure, elemental composition, and other main physical-chemical properties, and property controlling-technologies. The paper analyses and summarizes the common and differential characteristics of biochar structure and physical and chemical properties and clarifies the relevant basic perspectives, statuses, trends, and consensus on the structure and properties of biochar. The structure and fundamental physical and chemical properties of biochar are believed to be the most important factors affecting the roles, function, and effects of biochar. They also determine the application field, scope, amount, objective, and direction of biochar. Therefore, the modification technology or optimal regulation technique is the key to develop the efficacy advantage, potential and values of biochar. By further combining the research and application of biochar, the basic principles and development directions of biochar physicochemical property research in the future focusing on the physical and chemical properties of biochar are evaluated from cycle and sustainable development of resources and material perspectives. This paper aims to provide the basis and reference for the development of basic scientific science and application technology studies on biochar.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Overexpression of TaJRL53 enhances the Fusarium head blight resistance in wheat

CHEN Tong-Rui, LUO Yan-Jun, ZHAO Pan-Ting, JIA Hai-Yan, MA Zheng-Qiang

Acta Agronomica Sinica. 2021, 47(1):  19-29.  doi:10.3724/SP.J.1006.2021.01050

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Jacalin-related lectins (JRLs) are a group of plant lectins with jacalin protein domain, which play important roles during plant response to biotic and abiotic stress. According their carbohydrate binding specificities, the JRLs were described as two types: galactose-binding acalins (gJRLs) and mannose-binding jacalins (mJRLs). Previous studies have shown that TaJRL53 encodes a protein with Jacalin and Dirigent domains and can be up-regulated by Fusarium graminearum infection. Wheat FHB induced by this pathogen is a disastrous disease, which not only reduces the grain yield, but also contains deoxynivalenol and other toxins, which seriously affect the health of human and livestock. To dissect the gene’s function in FHB resistance, we silenced and overexpressed the TaJRL53 in wheat respectively. As a result, attenuating TaJRL53 increased susceptibility to Fusarium graminearum. And susceptible wheat transformed with TaJRL53 over-expression showed higher Fusarium head blight resistance, the number of diseased spikelets (NDS) and length of diseased spike rachis (LDR) of transgenics wheat with TaJRL53 overexpression were significantly reduced than those of wild type. After Fusarium graminearum infection, the expression of ROS synthesis pathway, JA synthesis and signaling pathways marker genes, and disease related genes in TaJRL53 over-expression transgenic plants were higher than those in non-transgenic control. These results suggest that TaJRL53 enhanced the FHB resistance in wheat through regulating ROS synthesis pathway and JA signal transduction pathways. This study enhanced the understanding of wheat JRLs family genes’ function and laid a foundation for the mechanism dissection of TaJRL53 resistant to FHB in wheat.

Function study of cotton GbSTK gene in regulating flowering and Verticillium wilt resistance

CUI Jing, WANG Zhi-Cheng, ZHANG Xin-Yu, KE Hui-Feng, WU Li-Qiang, WANG Xing-Fen, ZHANG Gui-Yin, MA Zhi-Ying, ZHANG Yan

Acta Agronomica Sinica. 2021, 47(1):  30-41.  doi:10.3724/SP.J.1006.2021.04090

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Cotton is an important cash crop, and achieving disease resistance as well as early maturity is an important breeding goal. However, the molecular relationship between disease resistance and early maturity of cotton is still a research gap. In previous study, we identified a GbSTK gene response to V. dahliae that could enhance Verticillium wilt resistance in transgenic Arabidopsis. In this study, we found that GbSTK was more highly expressed in resistance and/or tolerant varieties than in susceptible varieties. Knocking down of GbSTK expression in Nongda 601 showed that the silenced plants displayed serious disease symptoms, with disease index from 27.5 (tolerant) to 63.2 (susceptible), suggesting that GbSTK positively regulates cotton Verticillium wilt resistance. More interesting, we found that GbSTK could promote the development of Arabidopsis. At the flowering time point, the average number of rosette leaves in transgenic lines was 7.5, significantly less than the mock plants, and the transgenic plants bloomed five to seven days earlier than the control. The FT and SOC1 gene, regarded as marker genes in Arabidopsis flowering signaling pathway, maintained higher expression level in transgenic lines than in the mock, indicating that GbSTK could accelerate flowering via regulating FT and SOC1 gene expression. We also obtained 30 candidate proteins that could interacted with GbSTK via yeast double hybrid test, which helped to further revealing the molecular regulatory network of GbSTK. Taken together, we first identified a functional gene that could improve disease resistance and early flowering, which would provide a reference for genetic improvement of cotton disease resistant and early maturity.

Genetic diversity and population structure analysis by SNP and InDel markers of cassava in Brazil

SUN Qian, ZOU Mei-Ling, ZHANG Chen-Ji, JIANG Si-Rong, Eder Jorge de Oliveira, ZHANG Sheng-Kui, XIA Zhi-Qiang, WANG Wen-Quan, LI You-Zhi

Acta Agronomica Sinica. 2021, 47(1):  42-49.  doi:10.3724/SP.J.1006.2021.04067

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As a typical tropical crop, cassava (Manihot esculenta Crantz) has the characteristics of drought resistance, barren resistance, high biomass and so on. In addition to being used for food and forage, it can also be used for production, processing and starch extraction. Due to highly heterozygous cassava genome, breeding is more difficult. Enriching the genetic diversity of cassava germplasm, comprehensively evaluating its genetic background and traits, and discovering superior alleles that control excellent traits are of great significance for cassava breeding in the future. In order to analyze the genetic diversity, genetic relationship and population structure of cassava germplasm in Brazil, 7946 SNPs and 1997 InDels molecular markers were used. Population structure analysis was performed by ADMIXTURE software, and principal component analysis was performed by GCTA software. Brazilian cassava was divided into nine subgroups, and was roughly consistent with the results of cluster analysis using PHYLIP. Among them, subgroup 1, subgroup 2, subgroup 4, subgroup 6, and subgroup 8 could be clustered together respectively, while the samples of other subgroups could be roughly clustered, and there was a certain cross between the samples. The genetic diversity of cassava germplasm in Brazil (0.274) was higher than the genetic diversity level of cassava germplasm in China and Nigeria. Subgroup 5 of Brazil cassava had a relatively high genetic diversity (0.29). The genetic differentiation of subgroups was low (the genetic differentiation vary from 0.03 to 0.15), but higher than domestic cassava germplasm. The genetic distance between cassava accessions varied from 0.084 to 0.297, with the average of 0.228. The results of this study can provide a basis for subsequent association analysis to identify great alleles and introduction.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Physiological characters and gene mapping of a dwarf and wide-leaf mutant osdwl1 in rice (Oryza sativa L.)

HUANG Yan, HE Huan-Huan, XIE Zhi-Yao, LI Dan-Ying, ZHAO Chao-Yue, WU Xin, HUANG Fu-Deng, CHENG Fang-Min, PAN Gang

Acta Agronomica Sinica. 2021, 47(1):  50-60.  doi:10.3724/SP.J.1006.2021.92069

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Plant height is one of the important factors affecting rice lodging. The semi-dwarf rice varieties possess high level of lodging resistance, and could reduce yield loss and improve grain quality. Thus, it is very important to study the molecular and physiological mechanism of dwarf formation in rice. In this study, a stable hereditary dwarf and wider-leaf mutant osdwl1 was obtained from ⁶⁰Co γ-radiated indica restore line Zixuan 1, and its morphological and physiological characteristics, cytological observation, genetic analysis and gene mapping were investigated. Under field condition, the mutant osdwl1 exhibited dwarf and wider-leaf after the tillering stage due to shorter length of the parenchyma cells, and its panicle length and all internodes length were significantly shorter compared with wild type plants at mature stage. Paraffin sections and scanning electronic microscopy (SEM) observation revealed that the number of small vascular (SV) bundles and the distance between SVs increased significantly, resulting in wider-leaf blade in osdwl1. Moreover, the number of microhairs on the abaxial and adaxial epidermis were also increased significantly in osdwl1. In addition, starting at the 3-4 leaf seedling stage, yellowing was visible at the upper middle parts of old leaves in osdwl1. Physiological analysis and transmission electron microscopy (TEM) observation indicated that the lamellar structure of chloroplast was distorted and began to collapse in some mesophyll cells, which led to the reduction of total chlorophyll contents, net photosynthetic rate and F_v/F_m ratio of the second and third leaves from top in osdwl1 at the heading stage. Relative to the wild type plants, the soluble protein content, catalase (CAT) and superoxide dismutase (SOD) activities were significantly decreased, which in turn resulting in the accumulation of H₂O₂ and O₂^-, and a steady increase of malondialdehyde (MDA) contents in the mutant leaves. Genetic analysis and gene mapping showed that osdwl1 was controlled by a single recessive nuclear gene, located in a region of 333 kb between SSR marker RM19297 and the InDel marker ID269-2 on the short arm of chromosome 6. The results would further facilitate the cloning and functional analysis of OsDWL1 gene.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Screening of germplasm resources and QTL mapping for germinability under submerged condition in rice (Oryza sativa L.)

SUN Zhi-Guang, WANG Bao-Xiang, ZHOU Zhen-Ling, FANG Lei, CHI Ming, LI Jing-Fang, LIU Jin-Bo, Bello Babatunde Kazeem, XU Da-Yong

Acta Agronomica Sinica. 2021, 47(1):  61-70.  doi:10.3724/SP.J.1006.2021.02030

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Screening of germplasm resources, exploiting and utilization of genes conferring tolerance to hypoxia are the key to breeding new cultivars adapted to direct seeding. In order to evaluate the germinability of germplasm resources under submerged condition in a simple and efficient way, 191 japonica germplasm resources released from different years and regions were screened, 12 japonica varieties with high germinability under submerged condition were found. Among them, Lianjing 15, a japonica variety, showed stable and high tolerance to hypoxia. Using a F_2:3 population derived from Lianjing 15 and Huanglizhan (HLZ, a highly susceptible indica rice variety), four quantitative trait loci (QTL) conferring tolerance to hypoxia, namely qGS1, qGS3, qGS9, and qGS10 were identified under simulated field environment, and they explained 70.9% of the total phenotypic variation. Among them, qGS1, qGS3, and qGS10, were repeatedly detected in different years, accounting for 19.2%-24.0%, 12.6%-14.7%, and 19.1%-20.5% of the total phenotypic variation, respectively. The germplasm resources and QTL found in our study would provide innovative resources for breeding rice cultivars with high germinability under submerged condition, and would also provide a theoretical basis for breeding varieties adapted to direct seeding.

Identification and gene localization of a novel rice brittle culm mutant bc17

JIANG Hong-Rui, YE Ya-Feng, HE Dan, REN Yan, YANG Yang, XIE Jian, CHENG Wei-Min, TAO Liang-Zhi, ZHOU Li-Bin, WU Yue-Jin, LIU Bin-Mei

Acta Agronomica Sinica. 2021, 47(1):  71-79.  doi:10.3724/SP.J.1006.2021.02025

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A brim culm mutant bc17 (brittle culm 17) was obtained by irradiating wyj7 (Wuyunjing 7) with heavy ions. The brittle traits of the mutant were only found in the stalks and not in the leaves. The brittleness of the culm began to appear after heading stage, while it became more obvious as rice grew from heading stage to maturity stage. The growth and development of the mutant were affected, the plant height of the mutant was significantly lower than that in the wild type, and tiller number and seed setting rate were also lower than in the wild type. Compared with wild type, the cellulose content in bc17 culms and leaves decreased by 22.7% and 18.67%, while the hemicellulose content increased by 45.76% and 31.36%, respectively. The breaking resistance and tensile force of bc17 were significantly lower than those of wild type, indicating that the mechanical strength of the culm changed. The thick-walled cells of bc17 culms had larger pores, looser structures, and fewer cells. The fragile characteristics of bc17 were controlled by a single recessive nuclear gene. The bc17 gene was located in the 162 kb region of chromosome 7 by map-based cloning. Bioinformatics analysis indicated that it might be a novel gene related to rice brittle culm. These findings provided an important material support for the research on the molecular mechanism of cell wall synthesis in rice.

Establishment of DNA molecular fingerprint of applied core germplasm in jute (Corchorus spp.)

GUO Yan-Chun, ZHANG Li-Lan, CHEN Si-Yuan, QI Jian-Min, FANG Ping-Ping, TAO Ai-Fen, ZHANG Lie-Mei, ZHANG Li-Wu

Acta Agronomica Sinica. 2021, 47(1):  80-93.  doi:10.3724/SP.J.1006.2021.04022

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It is important to construct and study the applied core collection in order to promote jute genetic breeding and explore excellent genes. In this study, the applied core collection in jute, including 61 accessions divided into 16 application-oriented features, such as high yield, high quality, disease resistance and so on, was established based on the field performance from 300 jute germplasm. 12 fluorescent core primers were screened from 46 pairs of core primers. Fluorescence labeled capillary electrophoresis was used to analyze the polymorphism of these 12 pairs of primers, and a total of 140 polymorphism sites were detected. The precise DNA molecular ID cards were constructed by the combination of the 12 core primer pairs from the data coded in the form of numbers and English letters. Bar code and quick response code DNA molecular were established and can be quickly scanned and recognized by electric gadget. These results could be beneficial to increase the application efficiency and rapid molecular identification in jute germplasm resources.

Cloning of sugarcane ScCRT1 gene and its response to SCMV infection

ZHANG Hai, CHENG Guang-Yuan, YANG Zong-Tao, WANG Tong, LIU Shu-Xian, SHANG He-Yang, ZHAO He, XU Jing-Sheng

Acta Agronomica Sinica. 2021, 47(1):  94-103.  doi:10.3724/SP.J.1006.2021.04156

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Calreticulin (CRT) is widely expressed in eukaryotes. As a molecular chaperone and a Ca²⁺ binding protein, CRT is involved in many biological pathways such as the regulation of calcium homeostasis, calcium-dependent signaling, endoplasmic reticulum quality control, plant growth and development, immunity and response to stress. However, the response of CRT of sugarcane (Saccharum spp. hybrid) challenged by Sugarcane mosaic virus (SCMV) has not been reported. In this study, a CRT gene was cloned from the noble cane cultivar Badila (S. officinarum) and designed as ScCRT1. ScCRT1 had an open reading frame (ORF) length of 1281 bp and encoded 426 amino acids. Bioinformatics analysis showed that ScCRT1 was a stable hydrophilic protein and possesses a signal peptide at the N-terminal, a typical transmembrane domain, and a typical endoplasmic reticulum location signal at the C-terminal. The secondary structure of ScCRT1 was composed of mostly random coils. Phylogenetic tree analysis indicated that ScCRT1 belonged to the CRT1/CRT2 subtype and was divergent between monocotyledons and dicotyledons. Subcellular location assays showed that ScCRT1 was mainly located in the endoplasmic reticulum. Real-time quantitative PCR analysis showed that ScCRT1 gene was extensively expressed in different tissues of sugarcane, with the highest expression in leaf roll and the lowest expression in the 8th internode. ScCRT1 gene was up regulated in the early stage of SCMV infection, but down regulated with time going. ScCRT1 interacted with the 6K2 from SCMV as confirmed by yeast two hybrid and bimolecular fluorescence complementation assays. Based on these foundlings, we speculated SCMV interfered the calcium homeostasis by the interaction of 6K2 with ScCRT1, thereby facilitating viral infection of sugarcane.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of low temperature in spring on fertility of pollen and formation of grain number in wheat

GAO Yun, ZHANG Yu-Xue, MA Quan, SU Sheng-Nan, LI Chun-Yan, DING Jin-Feng, ZHU Min, ZHU Xin-Kai, GUO Wen-Shan

Acta Agronomica Sinica. 2021, 47(1):  104-115.  doi:10.3724/SP.J.1006.2021.01031

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Grain yield and the number of grains per ear of wheat decreased under the low temperature after jointing stage. In order to explore the physiological reasons of the decrease of grains number per ear by low temperature in spring, the spring wheat variety Yangmai 16 and the semi-winter wheat variety Xumai 30 were used as tested varieties to analyze the effects of low temperature in spring on the fertility of pollen and the formation of grain numbers at the appearance of the penultimate leaf stage (5℃/-3℃, day/night), booting stage (8℃/-1℃, day/night), and anthesis stage (12℃/4℃, day/night). The results showed that low temperature at the appearance of the penultimate leaf stage and booting stage resulted in abnormal metabolism of starch and protein in the anther both at the binuclear and tri-nuclear pollen stages and delayed degradation of the tapetum. The low temperature at the booting stage caused abnormal meiosis of pollen mother cells, abnormalities in chromosome pairing, which affected the formation of male gametophyte. The abortion rate of pollen was more significantly increased under low temperature at the appearance of the penultimate leaf stage than that at the booting stage, and it was the minimum at anthesis stage. The abortion rate of pollen in Xumai 30 was higher than that in Yangmai 16. The low temperature at three stages had significant effects on the number of spikelets, the number of fertile spikelets and the number of grains per spikelet. The effect of low temperature at the appearance of the penultimate leaf stage on grains number per spikelet was the most significant. There was a significant positive correlation between the number of grains per spike and pollen fertility, which was affected by abnormal meiosis, delayed degradation of the tapetum, and undersupply of nutriment for anther development. Therefore, the decline of pollen fertility caused by low temperature in spring is the main reason for the decrease of grains number per spike.

Effects of calcium application on the structural diversity of endophytic bacterial community in peanut roots under acidic red soil cultivation

ZHANG Wei, HONG Yan-Yun, LIU Deng-Wang, ZHANG Bo-Wen, YI Tu-Yong, LI Lin

Acta Agronomica Sinica. 2021, 47(1):  116-124.  doi:10.3724/SP.J.1006.2021.04087

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Peanut is an important economic crop and calcium-loving crop in China. In order to explore the effect of calcium application on the diversity of endophytic bacteria in peanut roots planted in acid red soil, the genomes of endophytic bacteria in peanut roots of different treatments and different growth stages were deeply sequenced by 16SrRNA gene V3-V4 region, and the root microbial community structure of peanut plants planted in acid red soil and control was analyzed. The results showed that Klebsiella and Enterobacter were the dominant genera with high relative abundance in the endophytic bacterial community from all sample groups. The relative abundance of Pseudomonas and Lysinibacillus were significantly higher than that from the control group, while the relative abundance of Ralstonia decreased significantly in the calcium application groups during the pod-pin stage at P ≤ 0.05. The interaction network analysis showed that the connection of root endophytic bacterial in calcium application group was relatively close. We reasonably inferred that the composition of peanut root endophytic bacterial community was affected by calcium application and plant growing development. Calcium application could change the community structure and improve the ability of peanut to cope with external stress. This study may lay a foundation for improving the quality of acid soil and improving the disease resistance of peanut by applying calcium in the future.

Effects of chemical fertilizer reduction with organic fertilizer application under water deficit on photosynthetic characteristics and yield of cotton

FENG Ke-Yun, WANG Ning, NAN Hong-Yu, GAO Jian-Gang

Acta Agronomica Sinica. 2021, 47(1):  125-137.  doi:10.3724/SP.J.1006.2021.04077

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Fixed position experiments were conducted in 2017 and 2018, and split plot arrangement with the main treatment for full irrigation (W₁) with irrigation amount was 4800 cubic meters per hectare and deficit irrigation (W₂) was 2400 cubic meters per hectare, and the secondary treatment including treatments without fertilization (CK), single application of chemical fertilizer (CF), 75% chemical fertilizer with 25% organic fertilizer (M₁), 50% chemical fertilizer with 50% organic fertilizer (M₂), and 25% chemical fertilizer with 75% organic fertilizer (M₃). The effects of chemical fertilizer reduction and organic fertilizer application on photosynthetic characteristics and yield of cotton were studied to provide theoretical basis for rational utilization of organic fertilizer and reduction of chemical fertilizer input under water deficit. Under deficit irrigation, leaf area index (LAI), net photosynthetic rate (P_n), stomatal conductance (G_s), above-ground dry matter accumulation and seed yield of cotton were all lower than that under full irrigation, while irrigation water productivity (IWP) and intercellular CO₂ concentration (C_i) were higher. The chemical fertilizer reduction combined with application of organic fertilizer could effectively improve the LAI after the full squaring stage, improve P_n and G_s of cotton in all stage, promote the accumulation of vegetative and reproductive organs dry matter, improve its transfer to the reproductive organs, improve the IWP and seed yield, and also increase the moisture content of soil surface in the period of full boll stage and boll opening stage. The effects among different organic fertilizer treatments on LAI, P_n and seed yield were all presented as M₁ > M₂ > M₃, and under the treatment of M₁, the average seed cotton yield of two years increased compared with CF and CK by 6.9% and 62.1% respectively. Whereas, the effects under deficit irrigation were presented as M₂ > M₁ > M₃, and the two years’ average seed yield increased by 19.9% and 79.3% respectively compared with CF and CK under M₂. Chemical fertilizer reduction and organic fertilizer application were beneficial to increase the yield of seed cotton under water deficit, and alleviate the influence of water deficit on cotton growth and development, M₂ (50% fertilizer +50% organic fertilizer) was the best treatment.

Effects of tillage depth on soil hydrological characteristics and potato yield on northwest Loess Plateau

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

Acta Agronomica Sinica. 2021, 47(1):  138-148.  doi:10.3724/SP.J.1006.2021.04065

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The subsoiling can break the plough pan and optimize soil hydrological characteristics. However, the study on the effects of tillage depths on soil water characteristics, potato water consumption and yield, is insufficient. The field experiment was conducted with three tillage depths of 15 cm (TT), 40 cm (VRT), and 60 cm (VRT6), to investigate the effect of tillage depths on the yield and water utilization of potato in semiarid rain-fed area in 2016 and 2017 on northwest Loess Plateau. The parameters of soil bulk density, soil hydrological properties, potato SPAD (soil and plant analyzer development) value, leaf area index (LAI), and tuber yield were measured. The soil bulk density, and increased saturation moisture, capillary moisture and field water capacity of VRT6 treatment compared with VRT and TT were decreased in 40-60 cm and 0-60 cm profile, respectively. Water consumption of VRT6 treatment was significantly increased in pre-squaring stage, resulting in the decrement of soil water storage in 0-100 cm profile by 22.3 mm and 49.0 mm in 2016, and 43.9 mm and 56.6 mm in 2017. Water consumption in pre-squaring stage of VRT6 was significantly increased by 42.2 mm and 38.3 mm compared with VRT and TT treatment in 2017, respectively. Based on the excessive water consumption in pre-flowering period, the LAI of VRT6 was significantly higher than TT in whole growth period, than VRT in post-squaring period, and the SPAD value was higher than VRT in expanding stage in 2017, which indicated that the vigorous growth was subsistent in VRT6 treatment. The tuber yield of VRT6 were significantly higher than TT, but it significantly decreased in 2017 compared to VRT, and the water use efficiency (WUE) of VRT6 were significantly decreased by 61.2%-67.5% and 41.0%-53.5%, as compared with VRT and TT. Consequently, the suitable tillage depth for potato cultivation was 40 cm in semiarid area, which could optimize the soil hydrological properties and potato water consuming process, and relieved the drought stress efficiently, resulting in significantly higher tuber yield and WUE.

Grain filling and dehydrating characteristics of maize hybrids with different maturity

WANG Rong-Huan, XU Tian-Jun, CHEN Chuan-Yong, WANG Yuan-Dong, LYU Tian-Fang, LIU Yue-E, CAI Wan-Tao, LIU Xiu-Zhi, ZHAO Jiu-Ran

Acta Agronomica Sinica. 2021, 47(1):  149-158.  doi:10.3724/SP.J.1006.2021.93008

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Suitable variety arrangement according to the natural ecological conditions, maturity, grain filling and dehydrating characteristics and yield potential of maize hybrid is an important approach for realizing higher maize yield, quality and photothermal resource utilization. Thirteen hybrids widely planted in maize production with three maturity types [medium-early maturity (MEM), medium maturity (MM) and medium-late maturity type (MLM)] were selected to clarify the grain filling and dehydrating characteristics for different maturity hybrids, by investigating the dynamic changes of grain filling and moisture content. The results showed that yield, grain filling and dehydrating characteristics differed significantly between different maturities and hybrids. Average yield level showed MLM (13,813.0 kg hm^-2) > MM (12,970.4 kg hm^-2) > MEM (10,729.0 kg hm^-2), with MLM was 28.7% and 6.5% higher than that of MLM and MM type, respectively. Average grain filling rate showed MEM (0.034 g 100-grain^-1 ℃^-1) > MM (0.031 g 100-grain^-1 ℃^-1) > MLM (0.027 g 100-grain^-1 ℃^-1), average dehydrating rate after physiological maturity (PM) showed MM (0.027% ℃^-1 d^-1) > MEM (0.025% ℃^-1 d^-1) > MLM (0.018% ℃^-1 d^-1). Average grain filling rate and dehydrating rate after PM of MEM representative hybrid Jingnongke 728 were 38.5% and 112.5%, 28.6% and 54.5%, 28.6% and 13.3% higher than those of representative hybrid Zhengdan 958, Xianyu 335 and Nonghua 101 for three maturity type; the yield of Jingke 968 was the highest (14,813.0 kg hm^-2), average grain filling rate and dehydrating rate after PM was7.7% and 18.8% higher than the same maturity hybrid Zhengdan 958. Yield level was significantly or extremely significantly correlated with grain filling period, corresponding accumulated temperature, average grain filling rate and 100-grain weight; grain moisture content at harvest stage was significantly correlated with grain filling period and corresponding accumulated temperature, but negatively significantly correlated with dehydrating rate before and after PM; there were no significant correlation between dehydrating rate before and after PM with average grain filling rate. Maturity, grain filling and dehydrating characteristics were all important factors for higher maize yield, quality and photothermal resource utilization. This study indicated that maize grain filling and dehydrating characteristics differed significantly between different maturity types and hybrids. Maturity, grain filling and dehydrating characteristics should be well considered for variety arrangement in maize production in order to achieve higher maize yield, quality and photothermal resource utilization.

Application study of crop yield prediction based on AquaCrop model in black soil region of Northeast China

CUI Ying, LIN Hong-Hong, XIE Yun, LIU Su-Hong

Acta Agronomica Sinica. 2021, 47(1):  159-168.  doi:10.3724/SP.J.1006.2021.03016

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Northeast black soil area is the production area of maize and soybean in China. In order to optimize the agricultural management and forecast crop yield with AquaCrop model, we use OAT (one factor at a time) method to analyze the sensitivity of the model parameters based on the experiment and field observation data, and to validate the model after calibrated the high sensitivity parameters. The results of sensitivity analysis showed that the yields of maize and soybean were both extremely sensitive to the reference harvest index (HI₀) and the parameters of canopy growth and root growth. The difference was that maize was more sensitive to the canopy decline coefficient (CDC), while soybean was more sensitive to the shape factor for water stress coefficient for canopy expansion (Pexshp). Maize was more sensitive to the maximum effective rooting depth (Z_x) because of its deep root, while soybean was more sensitive to the shape factor describing root zone expansion (Rexshp) because of its short roots. Maize was extremely sensitive to the crop coefficient before canopy formation and senescence (Kc_Tr,x) and the normalized water productivity (WP^*) due to the large water demand, while soybean was only generally sensitive. After calibrated the high sensitivity parameters with experiment data, the regression coefficient of simulated yield and measured yield of maize increased from 0.34 to 0.89, and the regression coefficient of simulated yield and measured yield of soybean increased from 0.80 to 0.88. Furthermore, the validation results of field observation data indicated that the determination coefficients (R²), the root mean square error (RMSE), the normalized root mean square error (NRMSE) and the model efficiency (ME) of the AquaCrop model of maize and soybean were 0.775 and 0.779, 1.076 t hm^-2 and 0.299 t hm^-2, 0.097 and 0.178, 0.747 and 0.730, respectively. The calibrated AquaCrop model can accurately simulate the yield of corn and soybean in the black soil area of Northeast China, and is useful for yield prediction and optimal management.

RESEARCH NOTES

Effects of phosphorus application on phosphorus uptake and utilization of sweet corn

YAN Xiao-Jun, YE De-Lian, SU Da, LI Fang, ZHENG Chao-Yuan, WU Liang-Quan

Acta Agronomica Sinica. 2021, 47(1):  169-176.  doi:10.3724/SP.J.1006.2021.03013

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Understanding the phosphorus (P) absorption mechanism is the premise for high P utilization and high crop yield. In this study, the effects of different P rates (0, 37.5, 75, 150, and 300 kg hm^-2, expressed as P0, P1, P2, P3, and P4, respectively) on sweet corn yield, biomass and P accumulation and tissue distribution, P transportation and P utilization were studied using a two-year P gradient positioning field experiment. Our results showed that P application significantly increased the fresh ear yield of sweet corn, but the yield difference among different P application rates (P1-P4) was not significant from 2018 to 2019 compared with P0 treatment. P application significantly increased the biomass and P accumulation of sweet corn plants at jointing, silking and fresh eating stages, respectively. In addition, P accumulation in grain was not significant different, which accounting for 42% of plant P accumulation. With P application, the contribution rate of P assimilation to the ear P accumulation was 57.3%-93.0% after anthesis, while the fresh ear yield per P accumulation, P physiological efficiency, agronomic efficiency, recovery efficiency and partial productivity decreased with P rates. Considering the yield and utilization efficiency of phosphate fertilizer, the supply of 37.5 kg hm^-2 of phosphate fertilizer can meet the needs of high yield and efficient utilization of phosphate fertilizer in sweet corn in this experiment.

Remote sensing monitoring on maize flood stress and yield evaluation at different stages

SUI Xue-Yan, LIANG Shou-Zhen, ZHANG Jin-Ying, WANG Meng, WANG Yong, HOU Xue-Hui, ZHANG Xiao-Dong

Acta Agronomica Sinica. 2021, 47(1):  177-184.  doi:10.3724/SP.J.1006.2021.03011

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In order to set up remote sensing monitoring and evaluation technology of maize flood stress and loss, a simulation experiment with different flood stress degrees was developed at different stages. Chlorophyll content, canopy spectral reflectance and coverage were monitored in vivo, and yield level was tested finally. The results showed that chlorophyll content decreased under flood stress at jointing and filling stages. The decreasing extend was significant at jointing stage and the value of maximal relative change reached -56.30%. There was little influence on chlorophyll at silking stage. Flood stress could reduce the coverage, especially at jointing stage, the most serious treatment was only 46.33%, followed by silking stage and filling stage. Flood stress reduced production at last, and the reduction was more serious in the early stage than in the later stage. There was a negative correlation between reflectance and flood stress degree at jointing stage and silking stage. It was extremely significantly difference at near infrared platform bands and significantly at green peak bands. There was no significant positive correlation between reflectance and flood stress degree at filling stage. Reflectance and spectral indexes with extremely significant correlation can be used to monitor flood. Two models with DSIPI were set up to evaluate flood loss at jointing and silking stage separately.