Singulation of seeds has been investigated extensively by researchers all over the world and a large number of precision seeding systems with design variations have been developed for different crops. A picking type metering mechanism was developed at CAET, AAU, Godhra, Gujarat, India. The performance of the picking type seed-metering device of a pneumatic planter was investigated under laboratory conditions to optimize the operating parameters for lady's finger seed. The picking of single seed the three operational parameters i.e. hole diameters for the nozzle: 1.0, 1.5, 2.5 and 3.0 mm; forward speed: 0.37, 0.56, 0.83, 1.11 and 1.30 m/s and vacuum pressure: 19.33, 39.32, 43.98, 58.64 and 68.63 kPa were selected for the study. The metering system of the planter was set to place the seed to seed spacing at 300 mm. The response surface methodology (RSM) technique was used to optimize the operational parameters of a precision planter. For optimizing the forward speed, vacuum pressure and nozzle size for developed machine was evaluated by examining the miss index, multiple index, quality of feed index and precision. The data obtained in the experiments were used to develop functions in polynomial form using multiple regression technique. The optimum value was found to be around 0.96 m/s, 36.25 kPa and 2.0 mm of forward speed, vacuum pressure and the holes diameter of nozzle, respectively. The most important variable that governs planting phenomenon is the combination of hole diameter of nozzle and vacuum pressure accounts 89.18 per cent.

Precision machinery is one of the most important technology in the recent decades in respect to judicious use of resources. In precision machinery one of the most important machine is seeding machines because it picks the seed from the hopper and individually placed in field. An effort has been made to optimize the operational (forward speed and vacuum pressure) and design (nozzle diameter) parameters of the precision seed drill. For optimizing the metering mechanism three parameters i.e. nozzle diameters: 2.00, 2.50, 3.00, 3.50 and 4.0 mm; forward speed: 0.27, 0.55, 0.83, 1.11 and 1.38 m/s and vacuum pressure: 19.33, 39.32, 43.98, 58.64 and 68.63 kPa were selected. The seed to seed spacing was 300 mm. The RSM technique was used to optimize the above parameters. The machine was evaluated on the basis performance parameters like miss index, multiple index, quality of feed index and precision. The optimum value for forward speed, vacuum pressure and the nozzle holes diameter was 0.83 m/s, 43.98 kPa and 3.50 mm, respectively. The most important variable that governs planting phenomenon for vegetable pigeon pea seed is nozzle diameter as well as vacuum pressure.