Study On Maize Mechanical Grain Harvest Quality And Grain Dehydration Characteristics Of Spring Maize In Northern Xinjiang

?Objective?(1)The northern Xinjiang is the region with the highest mechanical grain harvesting rate in China.The purpose of this study was to investigate grain mechanical harvesting quality status of spring maize in north of Xinjiang,and to determine the suitable moisture content range for grain harvesting;(2)To study the grain dehydration characteristics of different types cultivars,clear the relationship between the grain moisture content and the accumulated temperature combining the accumulated temperature in the growth period,;(3)Under the conditions of large-scale production,it is necessary to take into account the synergistic increase in production and efficiency.Through the rational allocation of different ripening varieties and sowing dates,it can extend the time for sowing and harvesting machinery,improve the efficiency of the use of machinery and corn production.?Methods?(1)The relationship between and grain moisture content could be built based on the data of grain harvest quality indexes(grain broken rate,impurity rate and yield loss rate)and grain moisture content during the period of grain harvest in north of Xinjiang maize planting areas form 2012-2017 collected by the team(crops and physiology innovation team of chinese academy of agricultural sciences).(2)Through the comparison test of different cultivars during the year of 2015-2017,the dynamic changes of grain moisture content were observed.The cumulative temperature required during the grain filling stage and the grain moisture content at the physiological maturity was regarded as classified indicators and the two-way average method was used to classify the tested varieties into four types.I: the cultivars of more accumulated temperature demand in the grain filling stage and high grian moisture content in the period of physiological maturity;?:the cultivars of more accumulated temperature demand in the grain filling stage and low grain moisture content in the period of physiological maturity;III: the cultivars of less accumulated temperature demand in the grain filling stage and high grain moisture content in the period of physiological maturity;IV: with low accumulated temperature demand in the grain filling stage and low grain moisture content in the period of physiological maturity.(3)The main maize cultivars with three different ripening periods including KWS9384,Xinyu77,and Xinyin M751 were selected to observe the dynamic changes of grain moisture content,establish a pridiction model for grain moisture content based on accumulated temperature(>0?)after pollination,and analyze the sowing and harvesting time of different cultivars under large-scale planting conditions combining with local meteorological data.?Results?(1)The mean grain moisture content of spring maize in Northern Xinjiang was 23.56% at present,and the broken rate,impurity rate and yield loss rate were 5.64%,0.88% and 1.44%,respectively.The average grain broken rate was higher than the national standard of 5%(GBT-21961—2008),the rate of impurity and yield loss were lower than the national standard of 3% and 5%(GBT-21961-2008),The relationship between the grain moisture content and broken rate was quadratic curve function.(2)The grain moisture content in the period of physiological maturity stage II and IV was significantly lower than that of type III and type I,and there was no significant difference of grain moisture content among the four cultivars at harvest.The grain dehydration rate of the four types cultivars before physiological maturity was significantly different(p<0.01),which showed: IV > III > II > I,there was no significant difference in total dehydration rate after physiological maturity,which indicated that the difference of dehydration rate was mainly happening before physiological maturity,the difference of acculurated temperature meeting grain moisture dropped to 28%,25%,and 20% was significant.The correlation analysis showed that there were no significant correlations between the grain moisture content at the physiological maturity or the harvest period and the grain filling rate,but the grain filling rate was positively correlated with the dehydration rate before the physiological maturity,and was significantly negatively correlated with the accumulated temperature during the filling stage,which showed that the filling rate significantly affected the dehydration rate,but did not cause the difference of grain moisture content at physiological maturity.(3)Cultivars with different mature period have different yields and suitable sowing date.The early sowing cultivar KWS9384 had a better sowing date and harvest time,but the yield was lower than that of the late-mature cultivars.The mid-late mature cultivars Xinyu 77 and M751 had high yields,but it needed a longer time met the physiological maturity and dehydration to the appropriate mechanical grain moisture content.Through the combination of early-mature cultivars and late-mature cultivars,the time of sowing and grain mechanical harvesting could be effectively prolonged;the deployment scheme of early-sowing latemature cultivars and late-sowing early-mature cultivars could coordinate the relationship between yield and grain dehydration well.?Conclusion?(1)Grain mechanical harvesting quality was mainly influenced by grain moisture content,the broken rate,the impurity rate and the yield loss rate would increase with the increase of moisture content,the yield loss was mainly caused by the falled ear.(2)The change of grain moisture content was dominated by two key factors to evaluate the suitablity of spring maize cultivars for mechanized grain harvest not only should paid attention to the grain filling characteristics and maturity period,but also the selection of grain dehydration characteristics(3)Through the analysis of the suitable sowing time and appropriate harvest period of different cultivars,the principle of varieties and sowing date configuration under the target of high yield and high efficiency was put forward to maximize machine utilization efficiency and effectiveness under the specific ecological and production conditions,it could provide some ideas for the research and application of the related technology requirements.