To improve seed vigour in rice, barley and soybean, several methods of presowing treatment, using chemicals and priming in polyethylene glycol solution, were investigated. Gibberellic acid($GA_3$) slightly improved germination of rice, but other chemical treatments showed no beneficial effect on seed vigour. Aged seeds were primed in polyethylene glycol solution then rinsed and germinated with drying back. In general mean germination time increased and percentage germination decreased with in- creasing water potential of the priming solution, but there were no significant effects on spread of germination times. Priming also showed no marked improvement in germination under cold, wet, or osmotic conditions. None of the treatments used was successful in practically improving the seed germination and vigour of the tested crops. However, seed treated with GA$_3$ gave the best overall germination response.