Grain yield and nitrogen use efficiency of an ultrashort-duration variety grown under different nitrogen and seeding rates in direct-seeded and double-season rice in Central China

Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha–1with a total growth duration of 85 to 97 days across all treatments with N application. Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield. Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates. The moderate N rates of 100–150 and 70–120 kg N ha–1in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR. Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity(INS) between the two seasons. Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.

Effects of Seeding Rate, Water and Fertilizer Coupling on Grass Yield of Forage Millet ( Setaria itlica) in Hebei

The paper was to study the effects of seeding rate,water and fertilizer (N,P,K) coupling on grass yield of forage millet Jigu No.18 (Setaria itlica).A quadratic regression orthogonal rotation combination with five factors was designed in pot experiment.The mathematical model between hay yield of forage millet (Y) and soil moisture content (x_1),N fertilizer (x_2),P fertilizer (x_3),K fertilizer (x_4) and seeding rate (x_5) was established to simulate optimization.The results showed that moisture content,seeding rate,P fertilizer and K fertilizer had important effects on hay yield.Soil moisture content had the biggest impact on yield,followed by seeding rate,P and K fertilizer.The coupling effects of various factors successively were moisture content/seeding rate > K fertilizer/seeding rate > N/P fertilizer > soil moisture/N fertilizer > soil moisture/P fertilizer.Moreover,the mathematical model,Y=20 543.756-565.570x_1- 39.942x_2- 23.102x_3- 38.470x_4- 151.877x_5+ 1.052x_1x_2+ 1.604x_1x_3+ 12.953x_1x_5- 0.173x_2x_3+ 0.737x_4x_5- 2.292x^2_5,was established.The optimum soil moisture and seeding rate were determined as 10% and15 kg/hm^2,respectively.In this scheme,the hay yield was 14 037.151 0 kg/hm^2 and the economic benefit was 13 887.15 yuan/hm^2; the income was increased by 23.68% (3 288.98 yuan/hm^2) compared to the optimal combination in the test.The results provided a theoretical basis and technical support for forage millet production in Hebei Province.

Effects of Seeding Rate and Light on the Seed Yield and Bioactive Ingredient Contents of Vernonia anthelmintica

[Objectives]This study was conducted to investigate the effects of seeding rate and light on the seed yield and active ingredients of Vernonia anthelmintica.[Methods]With V.anthelmintica L.Willd as the research object,the seed yield was determined by staged harvesting combined with the actual cutting and measuring method;and the caffeoylquinic acids(CQA)were used as the characterization indexes,and high performance liquid chromatography was used to determine the contents of 3,4-CQA,3,5-CQA and 4,5-CQA of V.anthelmintica seeds under different seeding rate+light treatments,so as to compare the changes in seed yield and chemical composition of V.anthelmintica under different seeding rates and light factors.[Results]In Moyu County,Hetian and similar areas,the suitable planting rate of V.anthelmintica was in the range of 13.5-15.0 kg/hm^(2).For different harvesting purposes,the optimal seeding rate and light conditions of V.Anthelmintica were different.[Conclusions]The seeding rate and light conditions can be used to interfere with the seed yield and quality of V.anthelmintica.

Effect of Irrigation System, Tillage System, and Seeding Rates on Wheat (<i>Triticum aestivum</i>L.) Growth, Grain Yield and Its Water Consumption and Efficiency

A field trial was conducted at a private farm in AL-Hashimiya district Babylon Governorate—the republic of Iraq during the 2016-2017 and 2017-2018 growing seasons. This study was conducted using two irrigation methods, sprinkler and surface irrigation, for each of them had three Tillage methods (zero-tillage, medium-tillage, deep-tillage) and each tillage system had four seeding rate of wheat yield (120, 180, 240, 300) kg∙ha-1. Results indicated that the consumptive water use was 557.5 and 535.9 mm for surface irrigation and 460.9 and 442.6 mm for sprinkler irrigation in the 2016-2017 and 2017-2018 growing seasons. Sprinkler irrigation significantly increased the flag leaf area with no significant effect on plant height. However, the minimum tillage and seeding rate (240 kg∙ha-1) significantly increased the plant height and flag leaf area in both growing seasons. For the grain yield, the sprinkler irrigation, minimum tillage, and seeding rate (240 kg∙ha-1) also increased the plant height and flag leaf area by 13%, 10, % 11%, 11%, 12%, and 14% in both growing seasons, respectively, through an increased number of spikes/m2, the number of grain spike-1, and 1000-grain weight in both growing seasons, respectively. Interestingly the grain yield was increased by 33% and 32% in both growing seasons under the effects of these three factors altogether, respectively. It can be concluded that these factors act synergistically, resulting in a significant improvement in the wheat grain-yield of, less consumptive water use, and high water use efficiency.

Design and experimental analysis of rice pneumatic seeder with adjustable seeding rate

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.

Effects of AG1 and AG2 QTLs on Nonstructural Carbohydrate and Seed Management Options for Rice Seedling Growth and Establishment under Flooding Stress

Rice(Oryza sativa)plants acquired excess photosynthates in the form of nonstructural carbohydrates(NSCs)in their stems and grain.Despite keen interest in rice NSC,the dynamics of NSC accumulation,translocation and re-accumulation have not yet been well investigated.AG1 and AG2 QTLs associated with flooding tolerance through catalyzing starch into soluble sugar in germinating seeds.Here we conducted three experiments,greenhouse and field to lay the groundwork for large-scale diversity studies on grain NSC and some agronomic traits under direct-seeded rice(DSR)system,using elite lines incorporating AG1,AG2 and AG1-AG2 QTLs into the popular varieties PSB Rc82 and Ciherang-Sub1 along with the donors Kho Hlan On(AG1)and Ma-Zhan Red(AG2).In germinating seedlings,soluble sugars increased,while starch concentration decreased gradually especially in the tolerant checks and AG1-AG2 introgression lines under flooded soil.Soluble sugar accumulation in stem started to increase from the vegetative stage and peaked at the panicle initiation stage then gradually decreased towards the maturity stage.But Sub1-AG lines had higher sugar and starch concentrations at different growth stages than other genotypes in wet season 2016 and dry season 2017.Plant survival rate was positively correlated with the stem NSC at the early vegetative stage(21 days after sowing),and stem NSC was positively associated with plant height at different growth stages.Among the tested seeding rate,the most suitable seeding rate,4 g/m2 with shallow burial depth(0.5 cm),resulted in better seedling establishment,relatively higher seedling vigor index and higher leaf area index under flooding in DSR system.Introgression of AG1-AG2 QTLs had no any negative impact on nonstructural carbohydrate,germination rate,and growth and biomass production.

Effects of Na_4EDTA and EDTA on seeded precipitation of sodium aluminate solution

Na4EDTA and EDTA were adopted as new additives to intensify the seeded precipitation process of sodium aluminate solution. The effects of the two additives at certain concentrations on the seeded precipitation rate of sodium aluminate solution, particle size distribution (PSD) and morphology of precipitated gibbsite were investigated using titration method, particle size analyzer and scanning electron microscope (SEM), respectively. The results show that the two additives can accelerate the seeded precipitation rate of sodium aluminate solution. At relatively high concentration, the facilitative effect of EDTA on sodium aluminate solution is more obvious than that of Na4EDTA. EDTA makes gibbsite particles thinner than Na4EDTA. The Na+ and H+ result in the different effects on the seeded precipitation rate of sodium aluminate solution in spite of the same EDTA anion in the two additives.

Effect of soil surface roughness on emergence rate and yield of mechanized direct-seeded rapeseed based on 3D laser scanning

The quality of seedbed after sowing such as soil surface roughness is one of the key factors affecting the seedling emergence of rapeseed,which ultimately affected crop yield.However,the effect of soil surface roughness on seedling emergence and yield of rapeseed is still unclear.In this study,field experiments at the experimental site of Jianli and Shayang were carried out.Three treatments were designed:relative slow(M1),medium(M2),and fast(M3)forward speed of the unit.Soil surface roughness measured by a 3D laser scanner,seed quantity of the seeder,emergence rate and yield of rapeseed were determined to investigate the soil surface roughness effect on emergence rate and yield of rapeseed.The results showed that as the forward speed of the unit increased,the compartment surface became rougher.Compared with the M1 and M2 treatments,soil surface roughness under the M3 treatment increased by 36.5%and 9.8%,respectively.The actual seed quantity of the seeder under different treatments ranged from 3806.56 to 4158.18 g/hm2.The average error rate of the actual and theoretical seed quantity was less than 5%,which met the operational quality requirements for seeding rapeseed crops.As the forward speed of the unit increased,the actual seed quantity of the seeder gradually increased while the emergence rate and yield of rapeseed decreased.The seed quantity under the M3 treatment increased by 6.9%and 4.7%,while the emergence rate of rapeseed decreased by 3.3%and 2.0%,and the yield decreased by 23.2%and 13.1%,compared with the M1 and M2 treatments,respectively.Correlation analysis indicated that emergence rate and yield of rapeseed were negatively influenced by soil surface roughness.Considering rapeseed emergence rate,seed yield,and economic benefits,the M1 treatment was recommended.But considering the factor that the M1 treatment may reduce the unit operation efficiency,and thus resulting in lower cost of production,M2 could be recommended in actual farming.The results of this study laid a theoretical foundation for analyzing the relationship between the seedbed surface quality and seedling emergence and yield.

Experimental study on performance of pneumatic seeding system

The purpose of this study was to promote the development of large-scale agricultural machines in China and meet the demand of air seeder localization.This study investigated the relationship between the working parameters and the performance of pneumatic seeding system,Cangmai 6004 wheat seed was used.A test platform for pneumatic seeding systems was developed,and then a series of experiments were performed based on the quadratic general rotary unitized design and response surface methodology(RSM).The seeding rate and the air flow rate were selected as affecting factors,coefficient of variation(CV)of evenness of feeding rate between rows and CV of seeding stability of total rows were assigned as the test indexes.Regression models between factors and indexes were established,and finally,an optimal equation based on this pneumatic seeding system were established as well,which can determine the proper air flow rate once the seeding rate was set based on the practical agronomic requirements.For example,when the seeding rate is set as 250 kg/hm^(2),the proper air flow rate of 7.53 m3/min can be obtained.The verification experiment results showed that the predicted working parameters obtained by RSM were feasible,which might provide a theoretical basis for further research of pneumatic seed metering systems.

Design and evaluation of a maize monitoring system for precision planting

To increase the accuracy and real-time performance of on-line assessment of maize planting,a CAN bus based maize monitoring system for precision planting was designed and tested both in laboratory and field.The system was mainly comprised of:(a)seeding rate sensors based on opposite-type infrared photoelectric cell for counting the dropping seeds;(b)a decimeter GPS receiver for acquiring planter position and operation speed;(c)a vehicle monitoring terminal based on ARM Cotex-m4 core chip to acquire and process the whole-system data;(d)a touchscreen monitor to display the planter performance for the operator;and(e)a buzzer alarm to sound a warning when skip and double seeding happened.Taking the applicability,dependability and feasibility of the monitoring system into consideration,the opposite-type infrared photoelectric sensors were selected and their deployment strategies in the 6-port seed tube were analyzed.To decrease the average response time,a distributed information communication structure was adopted.In this information communication mode,collectors were designed for each individual sensor and communicated with sensors through two-wire CAN bus.A sensor together with the designed collector is called a sensor node,and each of them worked individually and took the responsibility for acquiring,processing,and transiting the on-going information.Laboratory test results showed that the random error distribution was approximately normal,and by liner analysis,the system observed value and the true value had as a liner relationship with coefficient of determination R^(2)=0.9991.Series of field tests showed that the seeding rate maximum relative error of the 6-port seed tube was 2.92%,and the maximum root mean square error(RMSE)was about 1.64%.The monitoring system,including sensor nodes,vehicle monitoring terminal and a touch-screen monitor,was proved to be dependable and stable with more than 14 d of continuous experiments in field.