THE EFFECT OF TIME OF APPLICATION AND CHEMICAL FORMULATION OF NITROGEN FERTILISERS ON THE MORPHINE PRODUCTION OF POPPIES (PAPAVER SOMNIFERUM L.) IN TASMANIA

In two field experiments factorial combinations of ammonium sulphate at N1=50, N2=100, N3=150 and N4=200 kg N/ha were band placed with superphosphate at the same four rates of P. 100 kg N increased dry matter yield of poppy heads by 20 – 40% and morphine concentration by about 10% – 20% compared with the general commercial rate of 20 kg N/ha.

Other field experiments have compared the effect of ammonium nitrate at 0, 40, and 80 kg N/ha applied top-dressed 28 days before flowering (early stem elongation), 14 days before flowering and 1 week after flowering. The optimum time of application tended to be 14 days before flowering and yields increased up to the 80 kg N/ha rate. Dry matter yields of capsules were increased by about 10–20%.

A third series of experiments compared the effect of different forms of N : ammonium nitrate, ammonium sulphate, potassium nitrate, calcium nitrate, and urea at 0, 40 and 80 kg N/ha top-dressed 2 weeks before flowering. These comparisons were made under a wide range of irrigation regimes. All ammonium and nitrate forms of N had similar effects on dry matter and morphine and the maximum effect on morphine concentration of capsules occurred at a high rate of irrigation which was continued until a month after flowering.

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