Theoretical and experimental research into impact of threshing tools in combine grain harvesters on quality of cereal crop seeds

Abstract

The theoretical and experimental research into the micro-damaging of cereal crop seeds in the process of their harvesting by combine grain harvesters in relation to the strains, forces and stresses imparted to them by the threshing tools has been carried out. The propagation of deformations and cracks in the seeds as well as the nature of their strength and the damage that is sustained, when the critical load is applied, have been investigated. It has been established that the onset of cracks, the direction of their propagation and their quantity in the bodies of grain seeds depends in the majority of cases on the direction of action of the external forces and the specifics of the seeds’ internal biological properties. It has been established that the strength of the grain seed is, apart from the arisen cracks, also under the significant effect of the microtraumas in the germ, endosperm as well as the seed coat and shell. Theoretical calculations have been carried out on the PC and the effect that the drum and rotor threshing apparatus have on the deformation and damage sustained by cereal crop seeds has been substantiated. The said calculations and the obtained graphic relations support the results of the experimental investigations and prove that the macro- and especially micro-damage sustained by the seeds of winter wheat and rye is different, when they are threshed with the use of different types of threshing apparatus, which has a considerable impact on the final quality of the harvested cereal crop seeds. The results obtained in the experimental investigations, field and laboratory tests on the topic of the effect of mechanical loading on the sustained damage and quality of seeds indicate that the damage rate accounted for the work processes of the reaping and postharvest treatment of the cereal crop heaps of different winter wheat varieties with the use of rotor threshing apparatus is 3.1% as compared to the drum threshing apparatus – 6.4%, that is, 2 times lower. The total amount of the seeds with microtraumas collected in the hopper after threshing amounts to 23.0% and 54.0%, respectively, which is a significant difference. Similar results have been obtained in the experimental investigations on the effect of the equipment on the sustained damage and quality of seeds in the cleaning, chemical treatment and sowing of cereal crops.