Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and frag...Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.展开更多
Deep placement of nitrogen fertilizer is a key strategy for improving nitrogen use efficiency. A two-year field experiment was conducted during the early rice growing seasons(March–July) of 2016 and 2017.The experime...Deep placement of nitrogen fertilizer is a key strategy for improving nitrogen use efficiency. A two-year field experiment was conducted during the early rice growing seasons(March–July) of 2016 and 2017.The experimental treatments comprised two rice cultivars: Wufengyou 615(WFY 615) and Yuxiangyouzhan(YXYZ), and three N treatments: mechanical deep placement of all fertilizers as basal dose at 10 cm soil depth(one-time deep-placement fertilization, namely OTDP fertilization);manual surface broadcast(the common farmer practice) of 40% N fertilizer at one day before sowing(basal fertilizer)followed by broadcast application of 30% each at tillering and panicle initiation stages;and no fertilizer application at any growth stage as a control. One-time deep-placement fertilization increased grain yield of both rice cultivars by 11.8%–19.6%, total nitrogen accumulation by 10.3%–13.1%, nitrogen grain production efficiency by 29.7%–31.5%, nitrogen harvest index by 27.8%–30.0%, nitrogen agronomic efficiency by 71.3%–77.2%, and nitrogen recovery efficiency by 42.4%–56.7% for both rice cultivars, compared with the multiple-broadcast treatment. One-time deep-placement fertilization reduced CH4-induced global warming potential(GWP) by 20.7%–25.3%, N2O-induced GWP by 7.2%–12.3%, and total GWP by 14.7%–22.9% for both rice cultivars relative to the multiple-broadcast treatment. The activities of glutamine synthetase and nitrate reductase were increased at both panicle-initiation and heading stages in both rice cultivars following one-time deep-placement fertilization treatment. Larger leaf area index at heading stage and more favorable root morphological traits expressed as larger total root length, mean root diameter, and total root volume per hill were also observed. One-time deep-placement fertilization could be an effective strategy for increasing grain yield and nitrogen use efficiency and lowering greenhouse-gas emissions under mechanical direct-seeded cropping systems.展开更多
In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geo...In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geometry structure.In this study,the airflow flow law of the multi-branch pipeline of the pneumatic system was studied,the mechanism of airflow flow in the multi-branch pipe was analyzed,and it was clarified that the main factors affecting the airflow flow in the pipe,namely,air density,air dynamic viscosity,the total flow rate of the inlet branch pipe,the length of the closed end of the header,the inner diameter of the outlet branch pipe,and the outlet branch pipe spacing.Numerical simulations were carried out using Fluent simulation software to elucidate the cause of multi-branch pipes of uneven distribution of airflow in multi-branch pipes,the empirical equation among these factors and the flow velocity of the outlet branch pipe are established by dimensional analysis method.The bench test results show that the established empirical equations are applicable in the following ranges:0.018 m3/s≤Q≤0.054 m3/s,0.045 m≤d≤0.05 m,0.075 m≤L≤0.125 m,0.7 m≤Y 1≤0.875 m(0.5 m≤Y 2≤0.75 m,0.36 m≤Y 3≤0.45 m),the prediction accuracy can be controlled within 10%of the empirical formula,which can provide a reference for the prediction and optimization design of outlet velocity of the multi-branch pipe.展开更多
Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increas...Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increases in agricultural production costs.This article reviews the research and application progress of mechanized rice direct seeding including direct seeding technologies,precision rice seeding,precision rice seed-metering devices,key supporting agronomy technologies for mechanized rice direct seeding.South China Agricultural University developed precision rice hill-drop drilling(PRHDD)with synchronous furrowing and ridging technology and series machines for paddy that affords remarkable advantages in terms of saving time and labour,higher yield,and higher efficiency.In this approach,pre-germinated seeds are uniformly hill-dropped in the expected positions in puddled soil.It significantly improved the crop growth population and effectively solved the problems of high frequency of disease and pests caused by the irregular distribution of rice seeds with manual broadcasting,and generally reduces seed usage and increases the yield.Therefore,this technology has broad application prospects and great potential for promoting the development of mechanized rice direct seeding in China.展开更多
To meet the requirement of the precision direct-seeding for hybrid rice,this study aimed to design a hill-drop pneumatic central cylinder direct-seeding machine to sow ten rows at a time.A series of orthogonal experim...To meet the requirement of the precision direct-seeding for hybrid rice,this study aimed to design a hill-drop pneumatic central cylinder direct-seeding machine to sow ten rows at a time.A series of orthogonal experiments were conducted to investigate the performance of the cylinder seeder.The influences of the hole diameters,degree of vacuum,and rotational speed of the cylinder were tested on JPS-12 computer-vision seeding test platform,and the rotational speed of 10-50 r/min,diameter of 135 mm and a negative pressure of 1.0-2.0 kPa were employed.Test results showed that the optimal parameter combination was a vacuum of 2.0 kPa and a hole diameter of 2.0 mm(straight hole),with a rotational speed of 30 r/min.The probability of(2±1)seeds in each hole was 95.3%,while the probability of seed-missing hole was 2.0%.A series of field experiments were then conducted to test the seeder performance according to China National Standard Test Methods,and the field test results showed that for the hill-drop pneumatic central cylinder direct-seeding machine,the probability of(2±1)seeds in each hill was 91.6%,while the probability of seed-missing hill was 2.7%.The yield data showed that the average effective panicle had 231.25 ears,the average seed setting rate was 9.92%,the average 1000-grain weight was 22.45 g,and the average yield was 7107.9 kg/hm^(2) that was 26.14%higher than the average yield of rice(5634.9 kg/hm^(2))of Guangdong Province in 2016.The results showed that the hill-drop pneumatic central cylinder direct-seeding machine for hybrid rice could be applied in practical precision rice seeding.展开更多
To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that...To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.展开更多
To adapt to the diversity of hybrid rice and meet its requirements of precision seeding,a rice pneumatic seeder with adjustable seeding rates was designed in this study.The seeder employed an independent vortex pump t...To adapt to the diversity of hybrid rice and meet its requirements of precision seeding,a rice pneumatic seeder with adjustable seeding rates was designed in this study.The seeder employed an independent vortex pump to provide the air source for the seed metering device.According to the requirements of air flow in the seed metering device,a sub-pipeline and a general pipeline were designed.The performances of the two types of pipelines were verified by the air pressure uniformity tests.The results showed that the sub-pipeline can distribute the air pressure more evenly than the general pipeline.The coefficient of variation of the sub-pipeline pressure was less than 5%.Wuyou 1179 hybrid rice was selected as the experimental object.The field seeding tests were carried out with different negative pressures and different numbers of groups of sucking holes as experimental factors.The results showed that the average qualified rate of seeding was 93.35%when only 2 groups of sucking holes were working under the seed sucking negative pressure of 2.0 kPa.The average qualified rate of seeding was 87.21%when 3 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 83.73%when 4 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 79.86%when 5 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The main factors affecting the seeding effect were analyzed and the feasibility of a rice pneumatic seeder with adjustable seeding rates was verified by field tests.The research results can provide a basis for its practical production and application.展开更多
基金This project was financially supported by the National Natural Science Foundation of China(31601244 and 31971843)the Guangdong Provincial Key Field Research and Development Plan Project,China(2019B020221003)the Modern Agricultural Industrial Technology System of Guangdong Province,China(2020KJ105).
文摘Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2019B020221003)National Natural Science Foundation of Guangdong Province(008175187004)National Natural Science Foundation of China(31471442)。
文摘Deep placement of nitrogen fertilizer is a key strategy for improving nitrogen use efficiency. A two-year field experiment was conducted during the early rice growing seasons(March–July) of 2016 and 2017.The experimental treatments comprised two rice cultivars: Wufengyou 615(WFY 615) and Yuxiangyouzhan(YXYZ), and three N treatments: mechanical deep placement of all fertilizers as basal dose at 10 cm soil depth(one-time deep-placement fertilization, namely OTDP fertilization);manual surface broadcast(the common farmer practice) of 40% N fertilizer at one day before sowing(basal fertilizer)followed by broadcast application of 30% each at tillering and panicle initiation stages;and no fertilizer application at any growth stage as a control. One-time deep-placement fertilization increased grain yield of both rice cultivars by 11.8%–19.6%, total nitrogen accumulation by 10.3%–13.1%, nitrogen grain production efficiency by 29.7%–31.5%, nitrogen harvest index by 27.8%–30.0%, nitrogen agronomic efficiency by 71.3%–77.2%, and nitrogen recovery efficiency by 42.4%–56.7% for both rice cultivars, compared with the multiple-broadcast treatment. One-time deep-placement fertilization reduced CH4-induced global warming potential(GWP) by 20.7%–25.3%, N2O-induced GWP by 7.2%–12.3%, and total GWP by 14.7%–22.9% for both rice cultivars relative to the multiple-broadcast treatment. The activities of glutamine synthetase and nitrate reductase were increased at both panicle-initiation and heading stages in both rice cultivars following one-time deep-placement fertilization treatment. Larger leaf area index at heading stage and more favorable root morphological traits expressed as larger total root length, mean root diameter, and total root volume per hill were also observed. One-time deep-placement fertilization could be an effective strategy for increasing grain yield and nitrogen use efficiency and lowering greenhouse-gas emissions under mechanical direct-seeded cropping systems.
基金supported by the National Natural Science Foundation of China(Grant No.52175228)the earmarked fund for the National Key Research and Development program of China(Grant No.2021YFD2000403)+2 种基金the scientific research fund for the Guangdong Laboratory for Lingnan Modern Agriculture(Grant No.NZ2021039)the earmarked fund for CARS-01the earmarked fund for the Guangdong Province Key Field Research and Development Program(Grant No.2020B020210007).
文摘In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geometry structure.In this study,the airflow flow law of the multi-branch pipeline of the pneumatic system was studied,the mechanism of airflow flow in the multi-branch pipe was analyzed,and it was clarified that the main factors affecting the airflow flow in the pipe,namely,air density,air dynamic viscosity,the total flow rate of the inlet branch pipe,the length of the closed end of the header,the inner diameter of the outlet branch pipe,and the outlet branch pipe spacing.Numerical simulations were carried out using Fluent simulation software to elucidate the cause of multi-branch pipes of uneven distribution of airflow in multi-branch pipes,the empirical equation among these factors and the flow velocity of the outlet branch pipe are established by dimensional analysis method.The bench test results show that the established empirical equations are applicable in the following ranges:0.018 m3/s≤Q≤0.054 m3/s,0.045 m≤d≤0.05 m,0.075 m≤L≤0.125 m,0.7 m≤Y 1≤0.875 m(0.5 m≤Y 2≤0.75 m,0.36 m≤Y 3≤0.45 m),the prediction accuracy can be controlled within 10%of the empirical formula,which can provide a reference for the prediction and optimization design of outlet velocity of the multi-branch pipe.
基金The authors wish to acknowledge the funding from National Postdoctoral Program for Innovative Talents(BX201700083)Introduction of the International Advanced Agricultural Science and Technology Program(948 plan)(Project No.2016-X24)+1 种基金Commonweal Project(Project No.201203059)13th Five-year Plan National Key Research Program(Project No.2017YFD0700503-2).
文摘Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increases in agricultural production costs.This article reviews the research and application progress of mechanized rice direct seeding including direct seeding technologies,precision rice seeding,precision rice seed-metering devices,key supporting agronomy technologies for mechanized rice direct seeding.South China Agricultural University developed precision rice hill-drop drilling(PRHDD)with synchronous furrowing and ridging technology and series machines for paddy that affords remarkable advantages in terms of saving time and labour,higher yield,and higher efficiency.In this approach,pre-germinated seeds are uniformly hill-dropped in the expected positions in puddled soil.It significantly improved the crop growth population and effectively solved the problems of high frequency of disease and pests caused by the irregular distribution of rice seeds with manual broadcasting,and generally reduces seed usage and increases the yield.Therefore,this technology has broad application prospects and great potential for promoting the development of mechanized rice direct seeding in China.
基金The authors acknowledge the funding from the Introduction of the National Key Research and Development Program of China(2018YFD0100800)the earmarked fund for China Agriculture Research System(CARS-01-41)+1 种基金International Advanced Agricultural Science and Technology Program(948 plan)(Project No.2016-X24)National Postdoctoral Program for Innovative Talents(BX201700083).
文摘To meet the requirement of the precision direct-seeding for hybrid rice,this study aimed to design a hill-drop pneumatic central cylinder direct-seeding machine to sow ten rows at a time.A series of orthogonal experiments were conducted to investigate the performance of the cylinder seeder.The influences of the hole diameters,degree of vacuum,and rotational speed of the cylinder were tested on JPS-12 computer-vision seeding test platform,and the rotational speed of 10-50 r/min,diameter of 135 mm and a negative pressure of 1.0-2.0 kPa were employed.Test results showed that the optimal parameter combination was a vacuum of 2.0 kPa and a hole diameter of 2.0 mm(straight hole),with a rotational speed of 30 r/min.The probability of(2±1)seeds in each hole was 95.3%,while the probability of seed-missing hole was 2.0%.A series of field experiments were then conducted to test the seeder performance according to China National Standard Test Methods,and the field test results showed that for the hill-drop pneumatic central cylinder direct-seeding machine,the probability of(2±1)seeds in each hill was 91.6%,while the probability of seed-missing hill was 2.7%.The yield data showed that the average effective panicle had 231.25 ears,the average seed setting rate was 9.92%,the average 1000-grain weight was 22.45 g,and the average yield was 7107.9 kg/hm^(2) that was 26.14%higher than the average yield of rice(5634.9 kg/hm^(2))of Guangdong Province in 2016.The results showed that the hill-drop pneumatic central cylinder direct-seeding machine for hybrid rice could be applied in practical precision rice seeding.
基金funding from National key research program(Project No.2017YFD07000700,2017YFD07000704)Commonweal Project(Project No.201203059)+1 种基金National Natural Science Foundation of China(Project No.51105147)Foundation of Guangdong Province of China(Project No.S2011010001948).
文摘To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.
基金The authors are thankful for funding from the National Natural Science Foundation of China under Grant No.31871529,the earmarked fund for the National key research program of China under Grant No.2017YFD07000700,2017YFD07000704,and China Agriculture Research System under Grant CARS-01-41.The authos also acknowledge the anonymous reviewers for their critical comments and suggestions for improving the manuscript.
文摘To adapt to the diversity of hybrid rice and meet its requirements of precision seeding,a rice pneumatic seeder with adjustable seeding rates was designed in this study.The seeder employed an independent vortex pump to provide the air source for the seed metering device.According to the requirements of air flow in the seed metering device,a sub-pipeline and a general pipeline were designed.The performances of the two types of pipelines were verified by the air pressure uniformity tests.The results showed that the sub-pipeline can distribute the air pressure more evenly than the general pipeline.The coefficient of variation of the sub-pipeline pressure was less than 5%.Wuyou 1179 hybrid rice was selected as the experimental object.The field seeding tests were carried out with different negative pressures and different numbers of groups of sucking holes as experimental factors.The results showed that the average qualified rate of seeding was 93.35%when only 2 groups of sucking holes were working under the seed sucking negative pressure of 2.0 kPa.The average qualified rate of seeding was 87.21%when 3 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 83.73%when 4 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 79.86%when 5 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The main factors affecting the seeding effect were analyzed and the feasibility of a rice pneumatic seeder with adjustable seeding rates was verified by field tests.The research results can provide a basis for its practical production and application.
