Relationship Between Moisture Content And Breakage Of Maize And Prediction Of Suitable Harvest Time

High broken rate is a main factor to affect quality when maize is harvested by grain harvester.The moisture content of maize is an important factor affecting kernel breakage.In 2018,the study conducted various sowing experiments of various cultivars in Beijing and Xinxiang.In this experiment,the relationship between breakage rate and moisture content was tested by grinding method,with finding the moisture content of the lowest broken rate and evaluating the variety resistance to breakage.In the experiment,various cultivars maize grain dehydration dynamic was analyzed and the model of maize grain dehydration was built to predict suitable harvest time of different cultivars in Beijing region.To achieve these goals,there are three methods:?1?Grinding time?X₁?,rotational speed?X₂?,determination of grain mass?X₃?were selected as the investigation factors,by using quadratic general rotary unitized design,was used to optimize the determination method and parameters of the breakage of kernel.?2?The experiment was conducted in Comprehensive Experiment Station of Chinese Academy of Agricultural Sciences located in Henan province and Beijing city.17 maize cultivars were planted in different sowing dates.The dynamics of moisture content were systematically tested,the particle broken rate was carried out simultaneously by grinding method to analyze the correlation between the broken rate and moisture content.To evaluate the susceptibility of different varieties and the variety resistance to breakage,by using the integral values of the broken rate and moisture content quadratic curve of each variety.?3?Statistical maize growth period accumulated temperature in Beijing,the moisture content of combining multiple varieties dynamic test,grain dehydration model was set up,predicted suitable harvest time of different cultivars.There are several results through this experiment:?1?The optimum parameters for the determination of corn kernel breakage were as follows:grinding time 80s,rotational speed 1 200 rpm,and grain mass 30g.Under these conditions,the difference of breakage rate between two maize varieties is 4.07%.?2?The relationship between the moisture content?x?and the broken rate?y?of Beijing samples and Henan samples and the overall samples of the two regions are in line with the quadratic curve?y=ax²+bx+c?.Among them,the fitting equation of 512 samples in two regions is y=0.0796x²-3.3929x+78.779?R²=0.2646,n=512?.It can be seen by the equation fitting that the lowest broken rate is 42.62%,and the corresponding moisture content is 21.31%,then in the 90%confidence interval,the moisture content of the lowest broken rate ranged from 19.7%to 22.3%,which was consistent with the moisture content value of the lowest broken rate in the field.Found at the lowest point of the broken rate,under the condition of low moisture content,the relationship between broken rate and moisture content showed a significant linear negative correlation;under the condition of high moisture content,the relationship between broken rate and moisture content showed a significant linear positive correlation.It can be seen from thee slope and correlation of the fitted curve?y=ax+b?that under the condition of high moisture content of the grain,the fragmentation of the grain is more sensitive to moisture content and the correlation is higher.The varieties with strong fracture resistance were ZD 958 and FK139,the easily broken varieties including LC825,JD 66 and JNK728 in Beijing pilot;in Xinxiang pilot,the varieties with strong fracture resistance were HT1,ZD958and FK139,easily broken varieties including ZY 8911,DK 653 and JNK 728 by using the integral values of the broken rate and moisture content quadratic curve of each variety to evaluate the susceptibility of different varieties.The classification results of the six varieties selected in the two pilots are basically same.?3?It showed that in Beijing region,during normal winter wheat sowing?1st Oct.?,grain moisture content of spring sowing maize such as ZD958,XY335 could drop to 25%reaching the standard,of mechanical grain harvest.And spring maize has a broad seeding time.For summer sowing maize?15th June?,only grain moisture content of early-maturing and fast dehydration cultivars such as Fengken139 and Dika517 could drop to 25%until 1st Oct.Grain moisture content of other 7 cultivars could drop to 25%until 11th Oct.to1st Nov.There are the conclusions from analysis of the results:?1?The optimized method and parameters are stable and feasible.The grinding method is a highly stable detection method,which can be used for the evaluation of breakage susceptibility to moisture content and fracture resistance of variety crushing to further provide support for the selection of crushing resistant maize varieties.?2?In the Beijing region,the winter wheat-summer maize rotation for one year should be changed to spring maize-winter wheat-summer maize rotation for two years.Selecting the cultivars suitable for grain harvest can achieve mechanical grain harvest of spring and summer maize and improve maize planting benefits.