Optimisation of the seed spacing uniformity performance of a vacuum-type precision seeder using response surface methodology

The objective of this study was to optimise the seed spacing uniformity performance of a precision seeder using response surface methodology (RSM) and to verify the optimum levels of the variables. The variables considered in the study consisted of the vacuum on the seed plate, the diameter of seed holes and the peripheral speed of the seed plate. Cotton seeds were used for sowing and experiments conducted in this study were based on the central composite design (CCD), one of the designs in RSM. Data obtained in the laboratory were divided into three different groups in order to obtain values of the multiple index, quality of feed index and miss index. An additional performance criterion was also proposed and used as an indicator of the sowing performance. This was the root-mean-square deviation from the theoretical seed spacing. The data obtained in the laboratory were then used to develop functions in polynomial form that allowed the calculation of the optimum level of each independent variable considered in the study. The optimum levels of vacuum pressure and the diameter of holes for precision seeding of cotton seeds were found to be around 5.5 kPa and 3 mm, respectively. No optimum value was obtained for the peripheral speed of the seed plate. It was found that the lower the peripheral speed of the plate, the higher is the performance.