Abstract:

Three different types of maize grain harvesters and maize varieties of seven different genotypes were chosen to study the quality of harvested maize grains and the influencing factors, and explore the effects of different harvester types on maize grain harvest quality of different genotypes, so as to provide a basis for the selection of maize harvesters and the popularization of maize machine harvesting technology. According to the data obtained from the test, among the main characteristics of maize varieties with different genotypes, ear height, density, grain number per ear and yield per unit area have significant effects on the crushing rate, loss rate and impurity rate, respectively. The grain moisture content before harvest has extremely significant effect on the crushing rate, but less significant effects on the loss rate and impurity rate. The grain moisture content before harvest of the three types of harvesters is significantly and positively correlated with the crushing rate, but not significantly and positively correlated with the loss rate and the impurity rate. The crushing rate of the grains harvested by the 3 types of harvesters is significantly different, the loss rate is significantly different, but the impurity rate is not significantly different. The grain moisture content before harvest is the main factor affecting the crushing rate, but it does not significantly affect the loss rate and impurity rate. There is no significant interaction and correlation among the crushing rate, loss rate and impurity rate. According to the regression analysis, the grain moisture content before harvest is linearly correlated with the crushing rate, loss rate and impurity rate, and the grain crushing rate of different types of maize harvesters increases with the increase of moisture content before harvest and the loss rate and impurity rate do not increase with the increase of grain moisture content before harvest, the differences of working quality of different types of harvesters are mainly reflected in the influence of grain moisture content before harvest on the crushing rate. Under the condition that the moisture content before harvest is not higher than 25% of the national standard (GB/T 21962-2008), the crushing rate, loss rate and impurity rate of the three types of harvesters can all reach the national standard of 5%, 5% and 3%, respectively. When the crushing rate required by the national standard is no more than 5%, the suitable grain moisture content harvested by Foton 4LZ-8E, Gowang 4LZ-7B and LeiVo 4LZ-8E2 should not be higher than 26.51%, 26.95% and 36.41%, respectively, with an average value of 29.96%. At this grain moisture content level, the loss rate and impurity rate will not be higher than the national standard. That is, if the grain moisture content before harvest is not higher than 30%, the working quality of the harvester can be guaranteed to meet the national standard. Before harvesting, the main components of the harvester should be adjusted to achieve reasonable indexes, and the appropriate harvesting speed or feeding amount should be adopted to achieve the best harvesting quality by comprehensively considering the growth of maize, the grain moisture content, the terrain and other factors.

Key words: maize, self-propelled harvester, crushing rate, loss rate, impurity rate, grain harvesting, harvest quality