Articles
THE EFFECT OF TIME OF APPLICATION AND CHEMICAL FORMULATION OF NITROGEN FERTILISERS ON THE MORPHINE PRODUCTION OF POPPIES (PAPAVER SOMNIFERUM L.) IN TASMANIA
A series of field experiments investigated the effect of high rates of nitrogen applied either banded at drilling or top-dressed at various times between emergence and flowering.
In addition various chemical formulations of nitrogen fertilizer were compared under a wide range of irrigation regimes.
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.