Table of Content

01 September 2022, Volume 55 Issue 17

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Effects of Seedlings Enriched with Zinc on Cadmium Accumulations and Related Transporter Genes Expressions in Different Rice Cultivars

JIANG XiaoTing,HUANG GaoXiang,XIONG XiaoYing,HUANG YunPei,DING ChangFeng,DING MingJun,WANG Peng

Scientia Agricultura Sinica. 2022, 55(17):  3267-3277.  doi:10.3864/j.issn.0578-1752.2022.17.001

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【Objective】 Rice seedlings enriched with zinc (Zn) is a new method to antagonize cadmium (Cd) within rice, studying the various effects and underlying mechanisms among different rice cultivars is useful to provide a basis for the application of this method. 【Method】 Hydroponic and pot experiments were conducted to test the effects of the Zn enrichment in four cultivars including the Wuyunjing21, Zhejingyou1578, Huanghuazhan, and Huiliangyousimiao. Dynamics of Zn accumulation in different cultivars, and variations of Cd uptake and transport in rice tissues were investigated. Furthermore, the expressions of the Cd-related transporter genes of the root were analyzed to explore the underlying mechanisms responsible for the various effects in different cultivars. 【Result】 Results showed that the Zn cultivation didn’t affect the growth of all rice seedlings. Zn accumulations varied obviously among different cultivars, the Zhejingyou1578 had the highest Zn level (230 μg Zn per plant), followed by the Wuyunjing21 (124 μg Zn per plant), the Huanghuazhan and Huiliangyousimiao had the low levels (85.1-95.0 μg Zn per plant). Zn enrichment greatly influenced the expression of Cd-related transporters in the Zhejingyou1578, the OsZIP7 was down-regulated by 48.7% and OsZIP1 was up-regulated by 81.3%. The expressions of the OsIRT1 and OsZIP7 in the Wuyunjing21 were also down-regulated by 35.9% and 35.0%, respectively, and the OsZIP1 was up-regulated by 31.1%. However, the Cd-related transporters in the Huanghuazhan and Huiliangyousimiao were insensitive to Zn enrichment. As a result, Zn enrichment significantly reduced Cd concentrations in the root and shoot by 26.7% and 36.7% of the Wuyunjing21, and 32.0% and 40.0% of the Zhejingyou1578 with a 12.0% inhibition on the Cd transport, respectively. Furthermore, brown rice Cd were reduced by 37.5%, 36.7% and 25.3% in the Wuyunjing21, Zhejingyou1578, and Huanghuazhan, respectively, while no difference occurred in the Huiliangyousimiao, revealing various effects on reducing Cd among different cultivars induced by the Zn enrichment. Correlation analysis showed that the brown rice Cd was negatively correlated with the shoot Cd which was negatively correlated with the root and shoot Zn, revealing a significant antagonism between Zn and Cd within rice. However, the root and shoot Zn were negatively correlated with the OsZIP7 and OsIRT1 and positively correlated with the OsZIP1 expression, indicating that the Zn enrichment within seedlings influenced the brown rice Cd mainly through regulating the expressions of the OsZIP1, OsZIP7 and OsIRT1. 【Conclusion】 The regulations on Cd-related transporters through Zn enrichment were varied among different cultivars, and the Zhejingyou1578 and Wuyunjing21 were more sensitive, so that the reductions of brown rice Cd were higher than other cultivars.

Leaf Stomatal Close and Opening Orchestrate Rhythmically with Cell Wall Pectin Biosynthesis and Degradation

ZHANG XiaoPing,SA ShiJuan,WU HanYu,QIAO LiYuan,ZHENG Rui,YAO XinLing

Scientia Agricultura Sinica. 2022, 55(17):  3278-3288.  doi:10.3864/j.issn.0578-1752.2022.17.002

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【Objective】 Comparing on differential expression proteins between stomatal closing and opening at different leaf stomata-densities, it is to be revealed how pectin metabolism regulates stomata closing and opening. The result will play an essential role in understanding how stomata functions to environment adaptation.【Method】 Vectors, either over- or inhibiting-expression of StEPF-2 (Solanum tuberosum EPIDERMAL PATTERNING FACTOR 2) in vivo were constructed. The fusing genes were transformed into Solanum tuberosum cultivar Kexin 1. Transgenic potato lines, either rise or lower at leaf stomatal density were generated. Gene and protein expression profiles of leaves at various stomatal densities were assayed via RNA-seq and iTRAQ. Comparing differentiation expression proteins, pectin metabolic enzymes driving stomatal movement under light and darkness were identified and confirmed by the Pulldown and LC-MS/MS. A pectin metabolism pathway regulating stomatal movement was to be proposed.【Result】 At least 14 protein families, driving stomata closing and opening involved in pectin metabolism of the guard cell wall during stomatal mature. Five protein families were detected and confirmed only in the stomatal-closed leaves under darkness, including polygalacturonase inhibitor proteins (PGIP) and rhamnose synthase (RHM) for RG side-chain biosynthesis. Four protein families, polygalacturonase (PG), pectate lyase-like (PLL), pectinmethylesterase (PME) and α-galactosidase (AGAL) were identified only in leaves at various stomatal densities under light. Additionally, five protein families were concurrently identified in both leaves of stomata closing and opening, including pectinacetylesterase (PAE) and subtilase (SBT). 【Conclusion】 Under light, PMEs catalyze pectin demethylesterification, afterwards, pectin was exo- and endo-hydrolyzed by PG, PLL and AGAL. Pectin losing structure was split under turgor, results in stomatal opening. Reversely, under darkness, PGI inhibited pectin hydrolysis. Pectin side-chain biosynthesis was promoted by RHM. Therefore, stomata kept closing due to structurally-complete pectin with voluntary expending function.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Effects of Deep and Layered Application of Reduced Chemical Nitrogen Fertilizer on Water, Nutrient Utilization and Yield of Spring Wheat in Rain-Fed Arid Area

HOU HuiZhi,ZHANG XuCheng,YIN JiaDe,FANG YanJie,WANG HongLi,YU XianFeng,MA YiFan,ZHANG GuoPing,LEI KangNing

Scientia Agricultura Sinica. 2022, 55(17):  3289-3302.  doi:10.3864/j.issn.0578-1752.2022.17.003

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【Objective】 The field experiment was conducted from 2018 to 2020, in order to determine the optimized fertilization amount and methods of spring wheat, and to improve yield and water use efficiency on rain-fed area of northwest China. 【Method】 The spring wheat (Longchun 35) was selected as test material. Three fertilization depths with nitrogen reduction application included shallow application (PM-N), deep application (PMD), and layered application (PMA), and the control was traditional nitrogen shallow application (PM). The soil water content in 0-300 cm profile, aboveground biomass, leaf SPAD value, canopy temperature and leaf area index (LAI) in different growth stages, as well as grain yield of wheat were recorded. The soil water storage (SWS), periodical evapotranspiration (ET), water use efficiency (WUE), plant nitrogen accumulation (PNA) and nitrogen partial productivity (PFPN) were calculated to understand the effects of the deeper and layered application of chemical fertilizer on nutrient and water utilization from the aspect of soil moisture, canopy development and grain yield. 【Result】 PMA and PMD significantly regulated the process of water consumption during the growth period of spring wheat. From seedling to jointing stage, the water consumption in 0-300 cm profile of PMA and PMD increased by 11.8-20.4 mm and 15.1-25.4 mm compared with PM, respectively, and increased by 10.7-14.6 mm and 9.3-20.0 mm compared with PM-N, respectively. From heading to filling stage, the water consumption increased by 15.1-39.8 mm and 16.5-26.5 mm compared with PM, increased by 18.1-48.7 mm and 19.5-35.4 mm compared with PM-N, respectively. Correspondingly, the average SPAD value, LAI and biomass during the growth period of spring wheat of PMA and PMD were increased by 7.2% and 4.2%, 23.0% and 19.4%, 34.6% and 17.8% compared with PM, respectively, and increased by 7.6% and 5.4%, 17.7% and 10.8%, 38.5% and 23.4% compared with PM-N, respectively. However, the canopy temperature of PMA after jointing, and that of PMD after heading was decreased by 8.5% and 4.5% compared with PM, respectively, and decreased by 8.6% and 4.8% compared with PM-N, respectively. The grain number was increased by 4.3% and 4.0% compared with PM, respectively, and increased by 4.8% and 4.2% compared with PM-N, respectively. The spike number was increased by 10.1% and 6.2% compared with PM, respectively, and increased by 11.0% and 7.8% compared with PM-N, respectively. The yield, WUE, PNA and PFPN of PMA and PMD were increased by 10.5% and 5.1%, 11.8% and 6.2%, 48.0% and 35.7%, 38.2% and 31.3% compared with PM, respectively, and increased by 15.7% and 10.0%, 14.1% and 8.0%, 51.8% and 40.4%, 15.7% and 10.0% compared with PM-N, as compared with PM-N, respectively. The yield, WUE and PFPN of PMA were increased by 5.2%, 4.8% and 5.2% compared to PMD, respectively. The significant difference of the indices between PM-N and PM were not observed, except the PFPN of PM-N was significantly increased by 21.0% compared to PM. 【Conclusion】 While the amount of chemical N application was reduced from 150 kg·hm^-2 to 120 kg·hm^-2, both PMD and PMA could increase the grain yield, nitrogen and water utilization, which should be widely extend on the northwest loess plateau.

Effects of Nitrogen on Nitrogen Accumulation and Distribution, Nitrogen Metabolizing Enzymes, Protein Content, and Water and Nitrogen Use Efficiency in Winter Wheat Under Heat and Drought Stress After Anthesis

RU Chen,HU XiaoTao,LÜ MengWei,CHEN DianYu,WANG WenE,SONG TianYuan

Scientia Agricultura Sinica. 2022, 55(17):  3303-3320.  doi:10.3864/j.issn.0578-1752.2022.17.004

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【Objective】 The diurnal variation of temperature was simulated based on the growth chamber, this study aimed to investigate the effects of nitrogen (N) on dry matter accumulation, N accumulation and distribution, activities of N metabolism-related enzymes, protein content, yield, and water and N use efficiency of winter wheat plants under heat, drought and combined stress.【Method】 The experiments were carried out based on growth chambers with Xiaoyan 22 as test material. The experiment consisted of three blocks, in which two temperature treatments (high temperature: H; suitable temperature: S) were assigned as the main plot, two watering treatments (drought: D; sufficient water supply: F) were arranged split-plot, and three N supply levels (low N: N₁; medium N: N₂; high N: N₃) were arranged split-split plot to form a completely randomized block design to investigate the response of the growth and physiological characteristics, yield, and water and N use efficiency in wheat plants to heat, drought stress and different N applications.【Result】 Heat, drought and combined stress resulted in the decrease in ADW (aboveground dry weight) and ANA (aboveground nitrogen accumulation). At maturity, the ANA of N₃ supply under HD and SD was higher 7.26% and 6.82% than that under N₁ supply, respectively. Heat, drought and combined stress resulted in the increase in NRR, and the average NRR of three N supplies under HD increased by 38.21% compared with the control, while increasing N supply further expanded this increasing effect. Heat, drought and combined stress led to decrease in N distribution rate of panicle at maturity, especially combined stress. PY decreased significantly when exposed to heat, drought and combined stress. Compared with the control, the decrease of PY under drought stress conditions (7.37%) was more obvious than that under heat stress conditions (3.94%). Under individual and combined stress treatments, PY was significantly increased under N₂ supply. Furthermore, GS and NR activities decreased under individual heat and drought stress, which were significantly increased under regulation of N₂ supply. The NR and GS activities of N₁ supply under HD were 23.81% and 23.07% higher than that of N₃ supply, respectively. Compared with the control, the reduction in grain number per spike, 1000 grain weight and yield under drought stress conditions was greater than that under heat stress. N₂ supply had an obvious positive effect on these parameters of the two stress treatments, and WUE_g and WUE_b were significantly improved under N₂ supply. Adequate water supply under N₂ had 19.09% and 19.44% higher NUE_g than drought and combined stress under N₃, respectively. This indicates adequate water supply under medium N could effectively alleviate the decrease of NUE_g induced by drought and heat stress. The increase of NUE_g and NUE_b might be attributed to increase of GS and NR activities by appropriate N supply. Principal component analysis indicated that TGW and ADW of wheat were more closely related to yield under stresses conditions.【Conclusion】 The results showed that combined effect of drought and heat stress was more detrimental than individual stresses. Under individual heat and drought stress, an appropriate N supply could increase the activities of N metabolism enzymes and maintain higher N metabolism capacity, improve GNA and PY, and would be much more beneficial to increasing grain yield, water and N use efficiency in wheat production. However, when wheat was subjected to the combined stress after anthesis, compared with low N supply, increasing N supply had a restrictive effect on wheat yield formation as well as water and N utilization capacity, while N supply should be appropriately reduced.

Study on Critical Nitrogen Dilution Model of Winter Wheat Spike Organs Under Different Water and Nitrogen Conditions

ZHAO XiaoHui,ZHANG YanYan,RONG YaSi,DUAN JianZhao,HE Li,LIU WanDai,GUO TianCai,FENG Wei

Scientia Agricultura Sinica. 2022, 55(17):  3321-3333.  doi:10.3864/j.issn.0578-1752.2022.17.005

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【Objective】 The spike organ becomes the growth center after anthesis in wheat, so ensuring sufficient nitrogen nutrition in spike organ is the basis of grain yield and protein quality formation. The accurate diagnosis of spike nitrogen nutrition is of great significance for predicting wheat yield and quality. 【Method】 Zhoumai 27 and Yumai 49-198 were used as wheat materials, and three irrigation treatments under field conditions (W0: rain-fed, W1: single irrigation at jointing, W2: irrigation at jointing and anthesis) and five nitrogen application levels (0 (N0), 90 kg·hm^-2 (N6), 180 kg·hm^-2 (N12), 270 kg·hm^-2 (N18) and 360 kg·hm^-2 (N24)) were set in this experiment. The dry matter and nitrogen content data of wheat spike organs at different filling periods were collected for constructing critical nitrogen dilution (Nc) curve of spike organs under different irrigation conditions, and the wheat grain yield and protein content were measured at maturity stage. 【Result】 Under the same irrigation condition, the dry matter and nitrogen content of spike organ both increased with the increase of nitrogen application rate. All the relationships between spike critical nitrogen concentration and spike biomass under different irrigation conditions were power exponent, and the different models showed the difference under different irrigation conditions (W0: Nc=2.58 DM^-0.242; W1: Nc=2.92 DM^-0.24; W2: Nc=3.10 DM^-0.231). Nitrogen nutrition index (NNI) increased with the increase of nitrogen application rate under different irrigation conditions, and the suitable nitrogen application rate varied with the irrigation conditions, with 180-270 kg·hm^-2 for rainfed conditions and about 270 kg·hm^-2 for irrigation conditions. There was a significant correlation between relative yield (RY) and NNI, which was expressed as linear + platform characteristics. The NNI values of gaining the highest relative yield were different under different irrigation conditions, with 1.01 under rainfed condition and 0.97 under irrigated condition. There was a significant linear quantitative relationship between grain protein content and NNI of wheat, and the irrigation led to a decrease in protein content. 【Conclusion】 The spike organ Nc and NNI models established in this study could effectively indicate the changes in wheat spike nitrogen abundance and deficiency under different water and nitrogen conditions, evaluate the yield status in real time, and accurately predict protein content. These results provided the reference and basis for the field and storage management in the later stage of wheat growth.

PLANT PROTECTION

SCAR-PCR Rapid Molecular Detection Technology of Heterodera zeae

CUI JiangKuan,REN HaoHao,CAO MengYuan,CHEN KunYuan,ZHOU Bo,JIANG ShiJun,TANG JiHua

Scientia Agricultura Sinica. 2022, 55(17):  3334-3342.  doi:10.3864/j.issn.0578-1752.2022.17.006

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【Objective】 Corn cyst nematode (Heterodera zeae) is one of the sedentary semi-endoparasitic nematode of Heterodera spp., infects the roots of various gramineae crops. The occurrence and spread of H. zeae will pose a serious threat to corn yield production. The objective of this study is to establish the rapid and accurate molecular detection system for H. zeae from the related cyst nematode species, which will lay a technical foundation for the monitoring, early warning and prevention and control of H. zeae.【Method】 A total of 20 cyst nematode populations of H. zeae related species were collected as the nematode samples, from Henan, Hebei, Gansu, Shandong, Hunan, Guangxi and Beijing. Thirteen random primers containing 10 bases were selected, and RPAD technique was used to analyze the polymorphism of the tested nematode samples. The specific RPAD fragment was screened and transformed to SCAR-PCR primers of H. zeae. PCR was used to test the accuracy of specific primers for H. zeae and the stability, sensitivity and effectiveness of the detection technology system.【Result】 By comparative analysis of the RAPD results, one specific fragment of 468 bp was produced by primer OPA03. The fragment was recovered for sequencing. According to the fragment sequencing information, a pair of specific primers HzF1/HzR1 was designed. The specific primers HzF1 and HzR1 specificity test results showed that, one 393 bp specific fragment was amplified from H. zeae, no target bands were amplified in the other 16 populations of 5 related Heterodera spp. species (H. avenae, H. filipjevi, H. glycines, H. elachista and H. schachtii) and 4 populations of other species (Aphelenchoides besseyi, Ditylenchus destructor, Pratylenchus neglectus, P. coffeae). Furthermore, the 393 bp specific fragment was also amplified from the 6 related Heterodera spp. species mixed DNA. Meanwhile, there were no target bands when the mixed population without H. zeae. The system realized the accurate and stable detection of H. zeae, and the sensitivity and practical range of the established rapid detection technology system were tested. The results showed that the detection system was sensitive to single cyst and single 2nd stage juvenile (J2) of H. zeae. The minimum detection thresholds were 1/2 000 of single cyst or 1/80 of single J2, respectively.【Conclusion】 The SCAR-PCR rapid molecular detection technique established in this study can be used for the rapid detection of single samples and mixed populations of H. zeae. It has sensitive detection ability for both the cysts and the J2 of H. zeae, with strong primer specificity, convenient and stable detection method and high sensitivity.

Effects of ‘Good Quality Standard’ Rice System on Soil Environment of Paddy Field

XIA QianWei,CHEN Hao,YAO YuTian,DA Da,CHEN Jian,SHI ZhiQi

Scientia Agricultura Sinica. 2022, 55(17):  3343-3354.  doi:10.3864/j.issn.0578-1752.2022.17.007

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【Objective】 In view of the fertilizer-pesticide reduction approaches in rice production, the rice good quality standard system (GQS) was developed independently in the early stage. The objective of this study is to analyze the rice yield, rice contaminant content and soil quality characteristics under GQS application, evaluate the effect of applying GQS in agricultural practices, and to provide scientific basis for the reasonable design and timely adjustment of GQS.【Method】 The fixed-point rice growing areas with continuous application of GQS for 1-5 years in Jiangsu and Shanghai were selected. The adjacent areas with conventional rice cultivation system (CCS) were taken as control. The rice samples and soil samples were collected at harvest stage for analysis. The rice yield was measured. The contents of pesticide residues and toxic heavy metals were determined by SGS. Soil fertility was evaluated by using Nemerow index method. The activity of dehydrogenase, urease, and sucrase in soil was determined by using TTC reduction method, indophenol blue colorimetric method, and 3,5-dinitrosalicylic acid colorimetric method, respectively. Soil microbial diversity was analyzed using 16S rDNA high-throughput sequencing.【Result】 Compared with the CCS, the application of nitrogen fertilizer was reduced by 46.8% in GQS with organic fertilizer, EM bacteria agent, foliar fertilizer, and zinc fertilizer as alternatives. The high safety standard of rice in GQS was ensured by using biological agents and chemical pesticides with low toxicity and low residues. Applying GQS significantly increased soil total nitrogen and organic matter content without compromised rice yield and quality. The comprehensive score of soil fertility of the GQS was higher than that of the CCS after 1-4 years of continuous implementation, but the comprehensive score of soil fertility of the GQS was lower than that of the CCS at the fifth year. Applying GQS for two consecutive years resulted in the increase of urease, dehydrogenase and sucrase activity in rice paddy soil than CCS, and it was also found that the diversity and abundance of bacterial community increased in rice paddy soil with the application of GQS. Bacteroidetes and Chloroflexi showed repeated changes in the increasing ratio of soil bacterial richness after the one-year and the five consecutive years application of GQS. Terrimonas and Flavobacterium were the dominant genera. Correlation analysis showed that the abundances of Bacteroidetes and Chloroflexi were positively correlated with soil pH fertility index and total P fertility index after one-year implementation of GQS. Soil pH fertility index was positively correlated with the abundance of Bacteroidetes and Chloroflexi, respectively, after five consecutive years implementation of GQS. In addition, soil dehydrogenase activity was positively correlated with the abundance of Bacteroidetes and Chloroflexi, respectively.【Conclusion】 The application of GQS was helpful for the restoration of rice soil fertility by effectively improving the soil quality and the diversity of soil bacterial community without compromised rice yield and safety.

SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT

Conversion Characteristics of Different Carboxyl-Containing Organic Acids Modified Urea in Calcareous Fluvo-Aquic Soil

ZHANG YingQiang,ZHANG ShuiQin,LI YanTing,ZHAO BingQiang,YUAN Liang

Scientia Agricultura Sinica. 2022, 55(17):  3355-3364.  doi:10.3864/j.issn.0578-1752.2022.17.008

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【Objective】 The conversion characteristics of different carboxyl-containing organic acids modified urea combined with carboxyl groups and other active functional groups in calcareous fluvo-aquic soil were investigated, so as to provide a theoretical basis for the development of high-efficiency nitrogen fertilizers.【Method】 The citric acid (carboxyl group + hydroxyl group), humic acid (carboxyl group + phenolic hydroxyl group/carbonyl group/aldehyde group, etc.), polyglutamic acid (carboxyl group + amino group) and polyacrylic acid (carboxyl group) were added into the molten urea at 0.5% addition amount, to prepare the test fertilizers, exactly, citric acid urea (CAU), humic acid urea (HAU), polyglutamic acid urea (PGAU) and polyacrylic acid urea (PAAU). The treatments of without urea (CK), common urea (U), CAU, HAU, PGAU and PAAU were set up to study the effects of different carboxyl-containing organic acids modified urea on the soil amide nitrogen, NH₄⁺-N, NO₃^--N and soil urease activity by using soil incubation method. The influence mechanism of different carboxy-containing organic acids modified urea in soil conversion was revealed with the results from Fourier transform infrared spectroscopy (FTIR) of U and different carboxy-containing organic acids modified urea.【Result】 (1) Compared with U, the four kinds of carboxyl-containing organic acids modified urea delayed the urea hydrolysis in the soil from 6 h to 2 d. HAU and PGAU had a better performance than other treatments, and their residual amount of soil urea nitrogen increased by 22.3% and 23.7% than that with U, respectively. (2) Compared with the appearing time of NH₄⁺-N content peak treat with U (2 d), HAU application delayed to the appearing time of NH₄⁺-N content peak to the third day. In 6 h-2 d, the average value of NH₄⁺-N content with HAU treatment decreased by 16.9% than that with U, while increased by 3.2% in 3-14 d. (3) Compared with U, four kinds of carboxyl-containing organic acids modified urea significantly increased soil NO₃^--N content in the later period of incubation, and the HAU treatment showed the highest value with an average increase of 17.4 mg·kg^-1 than the U treatment. (4) Compared with U, four kinds of carboxyl-containing organic acids modified urea inhibited soil urease activity in 1-2 d, among which HAU had the strongest inhibitory effect, and the urease activity was reduced by 30.9% compared with U. However, HAU enhanced the soil urease activity in 2-14 d.【Conclusion】 Carboxyl-containing organic acids modified urea could delay the hydrolysis and transformation of urea in the soil by inhibiting urease activity in the early stage of incubation delaying the transformation of NH₄⁺-N to NO₃^--N in the middle stage of incubation, and increase the NO₃^--N content of cultivated soil in the late stage of incubation to reduce nitrogen loss. The above results were mainly attributed to the reaction of carboxyl groups and other active functional groups with urea. The reaction degree with urea was the deepest when the carboxyl group and a variety of active functional groups (phenolic hydroxyl group/aldehyde group/carbonyl group) existed at the same time, which attributed the slow release of urea to the best.

Research on Soybean Irrigation Schedule Based on AquaCrop Model

WANG QiaoJuan,HE Hong,LI Liang,ZHANG Chao,CAI HuanJie

Scientia Agricultura Sinica. 2022, 55(17):  3365-3379.  doi:10.3864/j.issn.0578-1752.2022.17.009

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【Objective】 The aim of this study was to evaluate the applicability of AquaCrop model in the Guanzhong Plain and to explore the optimal irrigation schedule for summer soybean under various precipitation year types. 【Method】 AquaCrop model was calibrated by using field experiment data and then used to simulate soybean yield and water use efficiency under 14 irrigation systems with three different precipitation years from 1961 to 2019.【Result】 The determination coefficient (R²), root mean square error (RMSE), standard root mean square error (NRMSE) and Nash efficiency coefficient (EF) of simulated and measured soybean yield under the highest yield treatment by AquaCrop model were 0.96, 7.15%, 11.03% and 0.94, respectively, which of simulated and measured biomass values were 0.99, 526.04 kg·hm^-2, 14.45% and 0.97, respectively. A good agreement was observed for final yield simulation with the R², RMSE, NRMSE, and EF were 0.97, 49.98 kg·hm^-2, 1.74% and 0.82, respectively. The R² values of the measured and simulated canopy coverage and biomass of each treatment were greater than 0.95, indicating that the AquaCrop model could better simulate the growth and development dynamics and yield of soybean in Guanzhong Plain. Combined with the simulation results of the model, the water requirements of the whole growth period of soybean were 398.2 mm. The water requirements of each growth period were significantly different for three precipitation years. The water requirements in the soybean branch stage were 127.8 mm, the water requirements of flowering and podding stage were 212.6 mm, and those of grain filling stage were 57.7 mm. Combined with the simulation of different irrigation systems for three different precipitation years, it was found that the flowering and podding period stage was the key period of water demand, and the water supply in this growth period affected the final yield of soybean. Simulation resulted showed that no irrigation was needed in wet years. In the normal and dry years, it was recommended to irrigate only 45 mm and 70 mm at flowering and podding stage to achieve the maximum yield of 2 699 kg·hm^-2 and 2 486 kg·hm^-2, and the maximum water use efficiency of 0.74 kg·m^-3 and 0.7 kg·m^-3, respectively. 【Conclusion】 To ensure higher soybean yield and water use efficiency, the soybean irrigation schedule in this region should be determined based on the distribution of different precipitation years, which could be used as a reference for the soybean irrigation system in the Guanzhong Plain region.

Thought of Pollution Comprehensive Prevention and Control System of Non-Point Sources Based on National Food Security

YANG ShiQi

Scientia Agricultura Sinica. 2022, 55(17):  3380-3394.  doi:10.3864/j.issn.0578-1752.2022.17.010

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【Objective】 In this study, in view of food security (FS) in China, the situation of non-point source pollution (NPS) was clearly showed, and NPS technical system and NPS comprehensive prevention and control system were proposed. 【Method】 The grain production and fertilizer application among main nations were compared, including total grain output and fertilizer application, per capita grain and per hectare fertilizer application, ration of fertilizer application and grain productive capacity. Meanwhile, the ration of nitrogen fertilizer and it’s judgment and ration of nitrogen fertilizer based on provincial scale were analyzed, and NPS reduction effects according to two national pollution censuses, trends of NPS reduction in China were deeply investigated, including total amounts and it’s proportion, NPS reduction potential (stockbreeding, plantation, nitrogen reduction and food saving). Based on FS the NPS technical system was constructed, and NPS comprehensive prevention and control system was proposed. 【Result】 (1) The per capita grain was more than 400 kg in 2008, more than 450.0 kg in 2012 and 475.0 kg in 2019 in China, indicating a higher FS created a key safeguard for NPS. (2) The ration of nitrogen application was not high and decreased on national scale, which was 161.1 kg·hm^-2 in 2019 and lay low side of reasonable range. The excessive and inadequate application should be paid attention. (3) At the national scale, the ration of nitrogen fertilizer application 160.0-170.0 kg·hm^-2 could safeguard per capita grain 450.0-500.0 kg in the future. (4) NPS reduction scheme: firstly, the dung should be all returned to field, and the pollutant emission should be close to zero, and the Ⅴ class water from NPS should be basically eliminated. Secondly, TN and TP emission from plantation should be reduced to 4.0×10⁵-4.5×10⁵ t and 4.0×10⁴-5.0×10⁴ t, respectively. Thirdly, the saving food and decreasing food waste could create the favorable condition for field fertilizer, emission and stress reduction, rehabilitation and FS. The key elements of NPS technical system based on FS were suitable fertilizer application, soil conservation and crop production, and a good and harmonious system should set up by agricultural machinery, farmland irrigation and water conservancy, clean stockbreeding, intelligence techniques, standards, laws and regulations to form farming system with local and watershed characters, then which had an extensive application. 【Conclusion】 NPS comprehensive prevention and control system was composed of scientists, agricultural producers and government to form the trinity, which should motivate scientist initiative, agricultural producer enthusiasm and government functions to carry out the double security of national food and environment in China in the future.

HORTICULTURE

Understanding and Thinking About Some Problems of Fruit Tree Germplasm Resources and Genetic Breeding

CHEN XueSen,WANG Nan,ZHANG ZongYing,MAO ZhiQuan,YIN ChengMiao

Scientia Agricultura Sinica. 2022, 55(17):  3395-3410.  doi:10.3864/j.issn.0578-1752.2022.17.011

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This review summarized the research progress of fruit tree germplasm resources and genetic breeding as well as the understanding and thinking of several issues. The main results were as follows: 1. Although China was the world’s largest fruit tree resource country and the origin and evolution center (one of) of many fruit trees, such as citrus, apple, pear, peach, longan, loquat, banana, kiwi, plum, apricot, jujube and persimmon, the discovery, innovation and utilization of wild germplasm and famous local varieties needed to be further strengthened. 2. According to the source of genetic variation, the fruit tree breeding mainly had two approaches: hybrid breeding and bud sports selection; the first generation of fruit tree hybrids was widely separated, and the genotype with the strongest heterosis was selected for each breeding. It became a new variety through asexual reproduction, and was used for a long time in production. The three hypotheses of dominant, superdominant and epistasis were the main genetic basis of heterosis; the analysis of the main characters of the new varieties of Fuji and Luli apples, Muscat Hamburg grape, and Shannongsu pear and their parents showed that selecting varieties with complementary traits as hybrid parents and selecting varieties with complex genetic background as female parents were important guidelines for the efficient utilization of fruit tree heterosis. Hybrid breeding was to determine the breeding goals according to the variety needs of the industry, to carry out parental selection and matching, and to breed new varieties with complementary parental traits and obvious heterosis. Bud mutation selection was the use of somatic natural mutations and epigenetics to repair and improve the individual traits of the main plant varieties in production; therefore, the organic combination of hybrid breeding and bud sports selection was an important technical approach to solve the variety problem of fruit tree industry. 3. In the face of rural revitalization and the country’s reform of the talent evaluation mechanism of “Persist in evaluating talents based on ability, actual performance and contribution, and overcome the tendency of only education, qualifications, and papers”, this review explained the scientific research ideas and classic cases that agricultural scientists must adhere to “Equal emphasis on technological innovation and the combination of good varieties and methods”.

Screening and Application of Universal SSR Molecular Marker Primers in Actinidia

HU GuangMing,ZHANG Qiong,HAN Fei,LI DaWei,LI ZuoZhou,WANG Zhi,ZHAO TingTing,TIAN Hua,LIU XiaoLi,ZHONG CaiHong

Scientia Agricultura Sinica. 2022, 55(17):  3411-3425.  doi:10.3864/j.issn.0578-1752.2022.17.012

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【Objective】 Based on the whole genome data of kiwifruit, a batch of SSR primers with high polymorphism and strong universality were developed and screened to lay a foundation for genetic diversity analysis and variety identification of kiwifruit germplasm resources. 【Method】 Based on the whole genome sequence of Hongyang kiwifruit, 435 pairs of SSR primers were designed and synthesized, and the allelic variation was detected by fluorescence labeled capillary electrophoresis. Firstly, five kiwifruit germplasm resources with large genetic differences were used to screen the effectiveness of primers. Secondly, 16 kiwifruit germplasm resources from 9 species or hybrid combinations were selected for primer re-screening. Finally, 225 germplasm resources belonging to 51 types of Actinidia in the National Actinidia Germplasm Repository were analyzed by core primers.【Result】 From 435 pairs of primers, 216 pairs of valid primers were initially screened, and 67 pairs of primers distributed on 29 chromosomes were identified as the final core primers after re-screening. Using 67 SSR markers, a total of 842 observed alleles (Na) were detected with 6-18 alleles (mean = 12.57) per locus; the effective number of allele (Ne) ranged from 3.27 (A-Geo-149) to 13.84 (A-Geo-407) with an average of 8.18; the observed heterozygosity (Ho) ranged from 0.60 (A-Geo-073) to 0.93 (A-Geo-158) with an average of 0.77; the expected heterozygosity (He) ranged from 0.72 (A-Geo-149) to 0.92 (A-Geo-101 and A-Geo-158) with an average of 0.85; the polymorphism information content (PIC) ranged from 0.67 (A-Geo-149) to 0.92 (A-Geo-158) with an average of 0.84; the Shannon diversity index (I) range was 1.47 (A-Geo-149) to 2.73 (A-Geo-101) with an average of 2.22. The above results indicated that the polymorphism of primers was very high, so it is suitable for the analysis of genetic relationship and genetic diversity of kiwifruit germplasm resources. The clustering results of 225 germplasm resources could clearly reveal the genetic relationship of Actinidia.【Conclusion】 The selected SSR primers were stable, reliable, polymorphic and universal, which could be used as core primers for germplasm resources identification, fingerprint construction, core germplasm mining and genetic diversity analysis of Actinidia.

FOOD SCIENCE AND ENGINEERING

Research on the Application of a Balanced Sampling-Random Forest Early Warning Model for Aflatoxin Risk in Peanut

GUO Can,YUE XiaoFeng,BAI YiZhen,ZHANG LiangXiao,ZHANG Qi,LI PeiWu

Scientia Agricultura Sinica. 2022, 55(17):  3426-3436.  doi:10.3864/j.issn.0578-1752.2022.17.013

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【Objective】 Peanuts are highly vulnerable to aflatoxin contamination. Based on the Balanced Sampling-Random Forest early warning model for aflatoxin contamination in peanut established previously, this study aimed to analyze the main technical parameters and practical application effects of the model through systematic application research, which could provide a critical technical support for risk prediction of aflatoxin in post-harvest peanuts in China.【Method】 The model was used to predict the aflatoxin contamination risk of 153 main peanut producing cities in China from 2019 to 2020 by selecting the data of one month before the peanut harvest, including one geographical variable (latitude) and three climatic variables (precipitation, average air pressure, and daily average temperature of 8:00-20:00) as the key input parameters of the model. The immunoaffinity chromatography-high performance liquid chromatography-fluorescence detection method was used to determine the aflatoxin content of 2 164 peanuts to obtain the aflatoxin contamination data areas. The accuracy, precision, sensitivity, and false-positive rate of the model were analyzed to clarify the application effect according to the predicted risk and the actual risk of the model. 【Result】 A total of 125 areas were predicted as low-risk areas of aflatoxin, of which 116 areas were consistent with the actual measurement results, but 9 high-risk producing areas were misjudged as low-risk areas (False negative). Meanwhile, 28 areas were predicted as high-risk areas of aflatoxin, of which 15 areas were consistent with the actual measurement results, but 13 low-risk producing areas were misjudged as high-risk producing areas (False positive). Therefore, the accuracy of the model was 85.61%, the false-negative rate was 8.49%, and the false-positive rate was 5.88%. 【Conclusion】 The application of the Balanced Sampling-Random Forest early warning model could predict the risk of aflatoxin contamination in peanuts, which provided the technical support for scientifically guiding the harvesting, storage and utilization in post-harvest peanuts in China, thereby reducing the loss of aflatoxin contamination and guaranteeing the quality and safety of agricultural products.

ANIMAL SCIENCE·VETERINARY SCIENCE

Effects and Mechanisms of Exogenous GABA Against Oxidative Stress in Piglets

YANG ChangPei,WANG NaiXiu,WANG Kai,HUANG ZiQing,LIN HaiLan,ZHANG Li,ZHANG Chen,FENG LuQiu,GAN Ling

Scientia Agricultura Sinica. 2022, 55(17):  3437-3449.  doi:10.3864/j.issn.0578-1752.2022.17.014

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【Objective】 The purpose of this paper is to study the effect of exogenous γ-aminobutyric acid against oxidative stress in piglets, and the possible mediating role of hippocampal neuron γ-aminobutyric acid receptors regulating apoptosis signaling pathways in it, which will provide scientific basis for the application of γ-aminobutyric acid as animal stress regulator. 【Method】 bbbbbBased on the successful establishment of oxidative stress model in piglet and rat hippocampal neurons, the effects of exogenous GABA on piglets under oxidative stress, including oxidative / antioxidant related indexes, growth performance related indexes and GABA receptor in serum and hippocampus, along with the GABA receptor and apoptosis signal pathway related indexes in hippocampal neurons were investigated. 【Result】 The serum MDA levels of piglets in the low, medium, and high concentration GABA feeding groups (LD+OS; MD+OS; HD+OS) were extremely significantly lower than those in the oxidative stress (OS) group (P<0.01), the GSH level was extremely significantly higher than that in the OS group (P<0.01), and the T-AOC level in the HD+OS group was extremely significantly higher than that in the OS group and control group (P<0.01). And the high concentration (100 mg·kg^-1 BW) of GABA more decreased the MDA level and more increased the GSH level in serum of piglets than those of the low concentration (20 mg·kg^-1 BW) and middle concentration (60 mg·kg^-1 BW) of GABA. Therefore, the follow-up study only investigated the anti-oxidative stress effect and mechanism of 100 mg·kg^-1 BW. The daily gains of piglets at 0-7 days, 8-14 days and 0-28 days in the OS group were extremely significantly lower than those in the control group (P<0.01),the daily gains of piglets at 0-7 days, 8-14 days and 0-28 days in the HD+OS group were extremely significantly higher than those in the OS group (P<0.01), the daily gain of piglets aged 15-28 days in the OS group was significantly lower than that in the control group (P<0.05),the daily gain of piglets aged 15-28 days in the HD+OS group was extremely significantly higher than that in the OS group (P<0.01). The above results showed that the 100 mg·kg^-1 BW GABA feeding extremely significantly increased the daily gain of piglets. There was no significant difference in the diarrhea rate of the control group, OS group and HD+OS group in the first, middle and late stages (P>0.05). The MDA level of hippocampus in the OS group was significantly higher than that of the control group and HD+OS group (P<0.01), the T-AOC and GSH levels were extremely significantly lower than the other two groups (P<0.01), which showed that GABA feeding would improve the antioxidant capacity of hippocampus. The levels of GABA_A and GABA_B receptors in the hippocampus of the HD+OS group were extremely significantly higher than those in the control group and the OS group (P<0.01), which showed that GABA feeding increased the levels of GABA_A and GABA_B in hippocampus. The Bcl-2 level in the hippocampus of the OS group was significantly lower than that of the control group (P<0.05), and the Bax and Caspase-3 levels were extremely significantly higher than those of the control group (P<0.01). The Bcl-2 level of the HD+OS group was extremely significantly higher than that of the OS group (P<0.01), the Bax level was extremely significantly lower than that of the OS group (P<0.01), and the Caspase-3 level was significantly lower than that of the OS group (P<0.05). Consistent with this, the Bax and Caspase-3 levels in hippocampal neurons of rats in the OS group, GABA+OS+Picrotoxin group and GABA+OS+CGP54626 group were significantly higher than those in the control group and GABA group (P<0.05), which indicated that GABA alleviated the damage of hippocampal neurons under oxidative stress, and the addition of GABA receptor inhibitors blocked the anti-stress damage effect of GABA. 【Conclusion】 GABA reduced the level of oxidative stress in the hippocampus of piglets. The anti-stress mechanism of GABA could be related to the decrease of the expression of apoptotic protein gene, while GABA_A and GABA_B receptors mediated this process.

Effects of Heat Stress on Ileal Microbiota of Broilers

WANG XueJie,XING Shuang,ZHAO ShaoMeng,ZHOU Ying,LI XiuMei,LIU QingXiu,MA DanDan,ZHANG MinHong,FENG JingHai

Scientia Agricultura Sinica. 2022, 55(17):  3450-3460.  doi:10.3864/j.issn.0578-1752.2022.17.015

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【Objective】 To explore how heat stress influences the composition and structure of intestinal microbiota in broilers, and to provide a basis for alleviating the adverse effects of heat stress. 【Method】 144 broilers ((1 771±40) g, 35 d) were randomly divided into three groups with six replicates and raised in three controlled climate chambers from 35 to 42 days in this study. They were allocated to one of a thermoneutral control group (TC, 21℃, ad libitum), a heat stress group (HT, 31℃, ad libitum), or a pair-feeding group（PF, 21℃, pair-feeding as much as the consumption of the HT birds）. 【Result】 Compared with broilers in TC, the feed intake and body weight gain were significantly decreased and F/G was increased in broilers of HT (P<0.01), the feed intake and body weight gain were also significantly decreased in broilers of PF (P<0.01). The feed intake of broilers in HT was as same as it in PF, but the body weight gain in HT was lower than it in PF, and the F/G was higher (P<0.05), which indicated that the heat stress still decreased the body weight gain of broilers even at the same level of feed intake. Compared with broilers in TC, the core temperature (P=0.079) and serum corticosterone content (P=0.071) have an increasing tendency in broilers of HT, and have similar levels in PF (P>0.05). The richness of species（sobs and Chao1）and diversity indices（Shannon）of samples in the HT and PF group were higher than those in the TC group (P<0.05). There was no significant difference in terms of the diversity estimators of the ileal microbiota between the HT and the PF groups. The PCoA showed that the HT and PF groups were gathered together but were distinctly separated from the TC group. This tendency was also verified by the similarity analysis. Moreover, the feed consumption was significantly correlated with the principal coordinate 1 in the PCoA (R = 0.786, P<0.001), but the body temperature or the serum corticosterone was not correlated with the principal coordinate 1 (P>0.05). Furthermore, 18 differential genera between the HTG and the TC groups were identified by LEfSe analysis (score ≥ 3). The relative abundance of these genera in the PF and HT groups was similar but had significant differences compared with that in the TC group. In addition, among the 50 most abundant genera in the ileal microbiota, the feed consumption was significantly correlated with 30 genera, but the body temperature and serum corticosterone were significantly correlated with only two and no genera, respectively. 【Conclusion】 The core temperature and serum corticosterone content were different, the feed intake was similar between HT and PF, and the composition and community structure of ileal microbiota were similar between those two groups; the core temperature and serum corticosterone content were similar, but the feed intake was different between TC and PF, and the composition and community structure of ileal microbiota were also different between those two groups, these results indicate that the effects of constant heat stress on composition and community structure of ileal microbiota in broilers are related to reduced feed consumption. This conclusion was also proved by the results of correlation analysis.

Effect of Allium mongolicum Regel and Its Extracts on the Growth Performance, Carcass Characteristics, Meat Quality and Serum Biochemical Indices of Captive Small-Tailed Han Sheep

LIU WangJing,TANG DeFu,AO ChangJin

Scientia Agricultura Sinica. 2022, 55(17):  3461-3472.  doi:10.3864/j.issn.0578-1752.2022.17.016

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【Objective】 The aim of this experiment was to investigate the effects of Allium mongolicum Regel and its extracts on the production performance, carcass characteristics, meat quality and serum biochemical indexes of Small Tailed-Han Sheep, and to provide an experimental basis for the development of feed additives for captive sheep. 【Method】 Sixty 3-month-old, male, Small-Tailed Han sheep were selected and allocated into four groups in a randomized block design. There were four treatments with 3 replications each: 1) a basal diet as the control group; 2) the basal diet supplemented with 10 g•lamb^-1•d^-1 Allium mongolicum Regel powder as the AMR group; 3) the basal diet supplemented with 3.4 g•lamb^-1•d^-1 Allium mongolicum Regel water extract as the AWE group; and 4) the basal diet supplemented with 2.8 g•lamb^-1•d^-1 Allium mongolicum Regel ethanol extract as the AFE group. The experiment lasted for 75 days, including a 15-day preliminary feeding period for adaptation and a 60-day experimental feeding period. The production performance of small-tailed Han sheep was measured during experimental feeding period, and the serum biochemical indexes were measured by fasting jugular blood collection at the end of experimental feeding period, followed by slaughter of 2 sheep randomly selected in each replication and carcass characteristics (Hot carcass weight, Carcass yield, perirenal adipose tissue weight, dorsal subcutaneous adipose tissue thickness and firmness) were measured immediately, meat quality was determined by taking Longissimus Dorsi muscle on the left side of the carcass, and fat color was determined by taking perirenal adipose tissue, tail adipose tissue, dorsal subcutaneous adipose tissue, omental adipose tissue. 【Result】 The results showed that: compared to the control group, ① the mean daily feed intake was significantly lower (P=0.001), feed conversion ratio was significantly higher (P=0.039) and mean daily weight gain did not differ (P>0.05) for AFE group; ② the addition of Allium mongolicum Regel powder and water extracts was able to significantly reduce the shear force of lamb compared to the control group (P=0.029); ③ there was no significant difference (P>0.050) in the b^* values of perirenal adipose tissue in other groups, while the b^* values of perirenal adipose tissue (P=0.096) and omental adipose tissue (P=0.087) in the alcohol extract group tended to be higher compared with Allicum mongolicum Regel powder group, while the a^* (P=0.044) and C^* (P=0.021) values were significantly higher than those of Allicum mongolicum Regel powder group; ④ the addition of Allium mongolicum Regel and its extract significantly increased the serum total protein (P=0.006), Allium mongolicum Regel and its alcoholic extract significantly increased the serum albumin (P=0.006), and Allium mongolicum Regel alcoholic extract significantly decreased the serum urea nitrogen (P=0.024). 【Conclusion】 In conclusion, Allium mongolicum Regel and its extracts had no significant effect on carcass characteristics and fat color of captive Small Tailed-Han Sheep. The addition of Allium mongolicum Regel and its alcoholic extract to the diet significantly improved the feed conversion rate of Small-Tailed Han sheep, and Allium mongolicum Regel powder and water extract significantly reduced the shear force of meat. Meanwhile, Allium mongolicum Regel and its alcoholic extract can significantly increase the content of total protein and albumin in serum and promote the absorption of protein of meat sheep.