The effect of delayed harvest and leaching on the morphine concentration of poppy (Papaver somniferum L.) capsules

Abstract

SummaryIn a series of field experiments over four seasons, in the north-west region of Tasmania, poppy (Papaver somniferum L.) capsules were harvested at various intervals after dry maturity (12% moisture in capsules). Reductions in the relative morphine concentration of capsules were closely associated with rainfall after dry maturity. These values ranged from a reduction of 0·92 to 0·82% over 5 weeks with 13 mm of rain to a reduction of 0·95 to 0·31% over 6 weeks with 79 mm of rain.In a simulated leaching experiment ground capsules were leached with 50 mm of water. Morphine was detected in the leachate and after being held for 10 days the morphine concentration of the ground capsules had decreased from 0·56 to 0·22%.Intact capsules from glasshouse grown plants were harvested at 2 weeks (T1, 4 weeks (T2), and 6 weeks (dry maturity T3) after full bloom. At each time of harvest they were immersed in distilled water for four different lengths of immersion time: zero (L0), 6·7 min (L1, 44·8 min (L2), and 300 min (L3). After immersion both the immersion water and the capsules were analysed for morphine. Morphine was readily detected in the immersion water with more at T3 than T2 and the amount of morphine increased as the length of immersion time increased. This latter process was greater at T3 than T2. At both T2 and T3 here was a trend for capsule morphine to decrease as immersion time increased.