Evaluation of grain breakage sensitivity of maize varieties mechanically-harvested by combine harvester

A high grain breakage rate is the main problem that occurs during mechanical maize harvest in China.The breakage sensitivity of different varieties was significantly different,and the breakage resistance is heritable.Therefore,breakage resistant variety screening can help improve the field production efficiency and provide references for breeding work.In this study,42 varieties of maize were harvested with the same mechanical parameters and the same manipulator on a range of harvest dates at experimental stations in Xinxiang,Henan Province,in 2017 and Changji,Xinjiang Province,in 2018 to determine the sensitivity of grain moisture content on grain breakage rate during machine harvest for different varieties.The integral value of the grain breakage rate curve corresponding to the range of 15%to 30%grain moisture content was used as an index that expressed the sensitivity of maize grains to breakage depending on grain moisture content(BSW).Forty-two varieties were categorized as having weak,intermediate,or strong BSW.Among the same four varieties in the two stations,Lianchuang 825 and Lianchuang 808 were classified as sensitive and fragile varieties,Shandan 650 was classified as an intermediate variety,Zeyu 8911 was divided into weak sensitive and breakage-resistance varieties in Xinxiang and intermediate varieties in Changji.The BSW classification results at the two experimental sites were generally consistent,indicating that breakage sensitivity due to moisture content may be a relatively stable genetic characteristic.This study suggested that the integral method for determining BSW can be used to assess the resistance of different maize varieties to grain breakage during mechanical harvesting.The integral method was used to identify twelve breakage-resistant varieties in Xinxiang Station,and six breakage-resistant varieties in Changji Station.This study provides a method for screening maize varieties that are suited to mechanical grain harvesting and for studying the mechanisms of grain breakage resistance.

Development and application of mechanized maize harvesters

Maize harvesting is one of the most important filed operations of maize production.As the accelerating development of maize industry,mechanized maize harvesting is widely accepted and used by farmers in the world.According to the harvesting methods,maize harvesters could be classified into two types,one is maize-for-grain harvesters,including pickers and grain harvesters,the other is whole plant harvesters,including forage harvesters and combined grain-stover harvesters.Structure characteristics,appropriate areas and relative technologies of those harvesters are described in this paper,i.e.,pickers are suitable for multi-crop areas,Grain harvesters are mainly for one-crop areas when grain moisture content is lower than 25%,combined grain-stover harvesters are applicable in agro-pastoral ecotone,and forage harvesters are capable in large-scaled animal husbandry farming areas where large amount of silage are required.Meanwhile,the future development trend of the different harvesters is predicted.Big horsepower engines,enhanced working efficiency,automation and intelligence are required by large scaled farms.As maize breeding development,more varieties that are suitable for grain harvesting are put into practice,so grain combine harvesters will be popular in future.

Bionic design and performance test of maize grain cleaning screen through earthworm motion characteristics

The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen,and it is easy to accumulate in the front of the screen,which leads to the decrease of screening efficiency.Based on the reverse engineering technology,using the wavy geometry formed during the earthworm(Pheretima guillelmi)moving as a bionic prototype,a bionic screen was designed to make the maize mixture migrate backward rapidly in the front of the screen.The contour curve of earthworm’s head in an axial contracted state was extracted and fitted to obtain its equation.Based on the difference of concave position of the lower surface’s wavy geometry during the earthworm moving,the motion of the bionic screen was divided into four postures,and the conversion between different postures of the bionic screen was realized by the cam drive mechanism.The kinematics simulation of the bionic screen was carried out through ADAMS,and the displacement and velocity of the bionic screen were analyzed.When the feeding mass of the maize mixture was set at 5 kg/s,6 kg/s and 7 kg/s,the test results showed that the time of the maize mixture migrated(TOMMM)in the front of the bionic screen was shortened by 0.18 s,0.71 s,and 1.36 s,respectively,compared with that of planar reciprocating vibrating screen.The total screening time(TST)of the bionic screen was shortened by 1.28 s,1.33 s,and 1.53 s,respectively.The ability of the maize mixture to be migrated backward was improved.This study can provide a reference for the innovative design of the cleaning screen.

Transmission of climate change impacts from temperature change to grain harvests, famines and peasant uprisings in the historical China

Because of the complexity of social responses to climate change,as well as limitations of proxy data concerning interactions between climate change and human responses,the social impacts of past climate change and associated response mechanisms,thus,require further investigation.To shed light on the transmission of climate change impacts within historical Chinese society,we selected 30-year resolution sequences of temperature anomalies in eastern China and 10-year resolution sequences of grain harvest grades,famine indices,and frequencies of peasant uprisings in China over the past 2000 years.Using a food security perspective,we analyzed the impacts of temperature changes historically transmitted through Chinese production,population,and social subsystems,and differences in transmission characteristics between cold and warm units.Our results were as follows.(1)From 210 BC to 1910 AD,temperature changes in China were significantly positively correlated with grain harvest grades(correlation coefficient,0.338),and significantly negatively correlated with famine indices,and frequencies of peasant uprisings(correlation coefficients,-0.301 and-0.277,respectively).The correlation coefficients between famine indices and grain harvest grades or frequencies of peasant uprisings were very low.(2)There was a higher proportion of bumper or normal harvests(86.5%of the total decades),more moderate and mild famines(76%),and a lower proportion of peasant uprisings(33.3%)in the 30-year warm units.Conversely,there was a higher proportion of poor or normal harvests(70.7%),a greater proportion of moderate and severe famines(77.6%),and more peasant uprisings(51.7%)in the 30-year cold units.(3)Of the 23 main transmission pathways extending from temperature change to the social subsystem,13 occurred in cold units,of which 7 had an endpoint of peasant uprisings,and 10 occurred in warm units of which 3 had an endpoint of peasant uprisings.The main transmission pathways that were more likely to be associated with the impacts of temperature change were:Cold→poor harvests→severe famines→more uprisings;cold→poor harvests→moderate famines→more uprisings;warm→bumper harvests→mild famines→no uprisings;warm→bumper harvests→moderate harvests→no uprisings;warm→normal harvests→mild famines→no uprisings;and warm→normal harvests→moderate famines→no uprisings.(4)The transmission of the impacts of temperature change was a complex process.Within this process,famine was most prone to being modulated by human society.In the transmission pathways from the production to the social subsystem,there was a stepwise decrease in the occurrence rate of decades that were probably affected by climate change.In all cold units,10.4%of decades ending in more uprisings were most likely to be associated with the impacts of temperature change.In all warm units,47.9%of decades ending in no uprisings were most likely to be associated with the impacts of temperature change.This research can contribute a better understanding on the past interaction mechanisms and processes within the human-climate-ecosystem complex,as well as a better response to the impacts of the ongoing climate change.

Comparison and analysis of maize grain commodity quality and mechanical harvest quality between China and the United States

Maize is a bulk commodity in international agricultural product trading,and unified and standardized quality inspection standards are the basis of purchase and sales and other trading behaviors.China and the United States are the largest maize producers and consumers in the world,jointly accounting for more than 60%of the world's total production.In this research,the used data were from annual maize harvest quality reports released by the U.S.Grains Council in 2011-2019 and 2987 groups of mechanical grain harvest sample data collected by the Crop Cultivation and Physiology Innovation Team of the Chinese Academy of Agricultural Sciences in 2012-2019,this study compares the quality standards of commercial maize grain in China and the United States,the mechanical harvest quality(which affects the quality of the maize grain commodity),and the status quo of harvesting and storage processes in the two countries.Additionally,this study analyzes the differences in the formulation of mechanical harvest quality standards between China and the United States,as well as the reasons behind these differences,and recommends requirements for the formulation of quality standards for maize production technology and commodities that are in line with the economic conditions and maize-production conditions in China and in line with international standards in order to provide support for the industrialization of modern maize production in China.