Poppy Cultivation in Australia

2014

Poppies (Papaver somniferum L.) were grown in Australia on a very small scale throughout the 19th century by some medical practitioners for the production of opium to be used in their individual practices. This was in the form of tinctures of opium (laudanum), a common item of medical practice in this period (). More comprehensive plans to establish a poppy industry based on opium production were considered in the state of New South Wales (Turner, 1891), however planned production was never brought to fruition at that time.

World War II was the event which gave a strong motivation for the commencement of poppy production based, not on opium, but on dry poppy ‘straw’ (the capsules and a small quantity of stem). Morphine and related derivatives which were normally imported from Northern Hemisphere sources were in very short supply at that time and an experimental programme on the agronomy of P. somniferum was initiated by the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO). Experimental plots were set out in the Australian Capital Territory at Canberra (Loftus Hills, 1945) and in collaboration with State Departments of Agriculture in Tasmania (), Victoria and South Australia. Small areas of semi-commercial production of poppies followed the trials in these Australian states during the war years and a small amount of morphine was extracted.

Poppy production in Australia was not continued in the early post-war period, with supplies of medicinal morphine again being imported from Northern Hemisphere countries. However in the early 1960s an experimental programme of poppy production was commenced in Tasmania by the English pharmaceutical company McFarlane Smith, a subsidiary of Glaxo. The motivation for this resurgence of interest was due to the fact that the major pharmaceutical companies in the Northern Hemisphere drew their supplies mainly from India and Turkey with small amounts from Eastern Europe. Supplies of poppy straw and opium from these traditional areas of production were subject to fluctuation because of the vagaries of weather and production problems. Because of this, a strategy was developed to draw supplies of morphine and related alkaloids derived from dry poppy straw from Australia which is politically stable, has modern agricultural expertise and infrastructure and reliable climatic conditions. In the extraction of morphine from dry poppy straw a modified Kabay process () was used. In addition to a reliable supply of poppy alkaloids, the out-of-season nature of production in the Southern Hemisphere spread the supply of poppy straw and derived pharmaceuticals to complement supplies drawn from the Northern Hemisphere.

In the late 1960s, commercial production of poppies began in the island state of Tasmania with farmers being contracted by Glaxo Australia Pty Ltd (now Glaxo Wellcome). In the early 1970s a second pharmaceutical company, Abbot International, entered the industry in Tasmania using the name of Tasmanian Alkaloids. This latter company is now owned by the large American pharmaceutical company Johnson and Johnson. In 1971, due to a formal agreement between all of the six Australian States, the production of poppies was exclusively restricted to Tasmania. The main reason for this was the isolation of the island state of Tasmania which gave added security against any illegal use of poppy crops.

Poppy production on private farms in Tasmania is administered by a system of licenses issued under the direction of the State controlled Poppy Advisory and Control Board (PACB). Licenses are only issued after farmers have measured up to a stringent range of criteria. Inspectors from the PACB monitor all crops throughout the growing season for any evidence of illegal use and to ensure that crop straw is properly disposed of after harvest to minimize any re-growth problems. Another important function of the PACB is to ensure that production of poppy alkaloids is carried out strictly in accordance with Australia’s international obligation to the 1961 Single Convention on Narcotic Drugs (as amended by the 1972 Protocol). The objective of this Convention is to ensure that the production of poppy alkaloids is restricted to recognized medicinal and scientific needs. This is accomplished by limiting production to expected market demand.

Contracts for the production of poppy crops in Tasmania are made with individual farmers by the two commercial companies Glaxo Wellcome and Tasmanian Alkaloids who supply the seed, organize the drilling, supply cultural advice and harvest the crops. Poppy seed forms a valuable by-product of these operations and is used primarily for culinary purposes. In the 1997-1998 season about 14 000 hectares of poppies were cultivated in Tasmania and the total area which has been used since 1970 has ranged from about 500 to 14 000 ha. The isolation of Tasmania and the stringent security measures have ensured that any illegal use of crops has been minimal. Useful abbreviated general outlines of poppy and alkaloid production in Tasmania have been recorded by Allen and Frappell (1970), Walker (1977), Davies (1985), White (1985), Bremner (1989), Wallis (1994) and Allwright (1995).

Climate and Environment

Poppy growing in Tasmania is carried out in a cool temperate maritime environment. The crop is cultivated from latitude 41°S to 42°30’S with the largest area located in the North West region of the state. Over most of the poppy growing areas of Tasmania, the physical environment is characterized by gently rolling or hilly terrain () with a limited contribution from flat areas. Site Selection

Poppies do not grow well on acid soils in Tasmania () and in selecting sites for commercial crops, efforts are made to obtain locations with a pH of at least 5.7 (). The terrain on the coastal strip in the North West region is generally flatter and more amenable to easier cultivation and harvesting. In addition to the physical environment being more hilly back from the coastal strip, rainfall increases at these higher altitudes and the soil pH generally decreases. Moreover, the incidences of frosts increase and although poppies are generally tolerant to frost at the early stages of growth some cultivars do tend to be susceptible during the stem elongation phase. For all of these reasons the less hilly areas closer to the coast are preferred; in addition is the fact that the logistics of transport of harvested crops to processing and extraction plants is easier. Similarly, the areas of river flats of the Derwent and Coal Rivers in the South of Tasmania have also been chosen for poppy production.

Germplasm And Seed Selection

The poppy ecotypes cultivated in Tasmania are long-day plants which have been specially developed for Tasmanian conditions. These plants have been bred for the basic fundamentals of high capsule yield and high concentration of poppy alkaloids, morphine and codeine in particular. In addition to alkaloid content, factors such as straw length, standing ability and resistance to disease have also been incorporated into the various breeding lines.

A greenhouse experiment was carried out in Tasmania on the effect of seed size on establishment in response to abnormal seedling growth in autumn-sown crops (). A commercial line of seed with a mean 1000 seed weight of 465mg was divided into three categories of ‘small’ (423mg), ‘medium’ (440mg) and ‘large’ (476mg). The 1000 seed weight of the ‘small’ seed was only 11% less than the ‘large’ seed but after 14 days its percentage emergence was 53% less than the ‘large’ seed. The conclusion to this experiment was that size grading of poppy seed was an important contributor to uniform establishment.

The germplasm utilized and the seed selections developed in Tasmania have been the exclusive and independent prerogative of the two contracting pharmaceutical companies, Glaxo Wellcome and Tasmanian Alkaloids. The combination of germplasm and seed selection, climatic environment, soil type and farming techniques have resulted in the alkaloid yields per hectare of Tasmanian poppies being the highest in the world.

Poppy Cultivation in Australia: Plant Cultural Techniques

Poppy Cultivation in Australia: Plant Diseases

Harvesting And Processing

Time of Harvest

In Tasmania poppies are generally harvested when the crop is dry (12% moisture content) and the poppy alkaloids in the latex have formed a dried deposit on the walls of the capsules. Harvesting () is carried out with specialized headers, or more commonly, modified forage harvesters which take the poppy heads and a small quantity of stem (about 15cm). Capsules and seed are then separated in a later operation by sieving. Field experiments in Tasmania have studied the effect of earlier times of harvest on the dry matter and morphine yields of both capsules and stem and leaves (). In a field experiment on krasnozem soil, poppy plants were harvested at weekly intervals commencing ten days after full bloom and continuing until four weeks after dry commercial harvest (about eight weeks after full bloom.

Changes in Dry Matter

The dry matter yield of the total plant and of all the components other than seed gave maximum values two to three weeks after full bloom and then decreased. The decrease in total plant yield between maximum dry weight and commercial harvest (eight weeks after full bloom) was 26% (). The decrease for total capsules was 29% and for stem+leaves 39%. Other work has shown that the individual stem and leaf components both decline to a similar extent over this period (). In contrast to these decreases, the total seed dry matter yield achieved a maximum by four weeks after full bloom and then remained constant at later harvests ().

Changes in Poppy Alkaloids

The morphine concentration of capsules reached a maximum value of 1.1% at six weeks after full bloom and then declined by about 10% at the stage of dry harvest. The morphine concentration of stem+leaves also reached a maximum of 0.1% at six weeks after full bloom but decreased rapidly after this and had halved by dry commercial harvest stage. The compensating factor of decreasing dry matter yield and increasing morphine concentration gave very similar total plant morphine yields at all times of harvest from two to seven weeks after full bloom. The morphine extracted from the whole plant during the period two to seven weeks after full bloom was approximately 50% greater than that obtained from capsules alone at the dry commercial harvest stage ().

Generally then, the morphine content of capsules relative to leaves and stem dictates that it is economical to harvest only capsules in Tasmania. Under average seasonal weather conditions at dry commercial harvest (eight weeks after full bloom) the small decrease (10%) in capsule morphine content from the maximum is more than compensated for by the fact that there is limited need for artificial kiln drying.

In other sequential harvesting field studies in Tasmania, morphine, codeine and thebaine in capsules were assayed at weekly intervals from full bloom for a thirteen-week period (). The changes in morphine were substantially similar to those described above (). Morphine and codeine both reached maximum concentrations about five weeks after full bloom but the thebaine concentration was at a maximum one week after full bloom and decreased by 48% during the second week.

Effects of Rain and Delayed Harvest

Although weather conditions at harvest time are generally good in Tasmania, continued periods of wet weather can occur, causing delays in the harvest. The effect of delayed harvest on the morphine concentration of poppy capsules has been studied in Tasmania (). The morphine concentrations in poppy capsules were measured in four different seasons during which plots of poppies were left for four weeks after the normal time of dry commercial harvest (). Morphine reduction in the capsules increased weekly and the relative reduction between seasons was strongly associated with total rainfall. Similar associations have been drawn in other studies (). In some of these studies overhead irrigation was found to cause reductions in morphine content similar to those experienced as a result of rainfall, with distinct cultivar differences ().

Although significant reductions of morphine in poppy capsules have been associated with rain or overhead irrigation, these reductions may not always be the result of leaching or movement of morphine out of the capsule. Other influences, such as chemical conversions of morphine within the walls of the capsule () and metabolic conversion by capsule fungi (), may also exert an effect. In a study in which intact capsules were immersed in deionized water in a glass receptacle for varying lengths of time up to 300 min, morphine was recovered from the immersion water. However the morphine detected in the immersion water only represented 25% of the actual decline in capsule morphine (). In addition to the effects of rain, the battering of plants against each other — particularly the rubbing of the serrated stigmatic discs present at the top of adjacent capsules — causes removal of the waxy bloom which covers the capsule and this may also aggravate morphine loss (). For all of these reasons every effort is made to harvest commercial poppy crops in Tasmania as soon as they reach the dry commercial harvest stage of 12% moisture in the capsules.

Drying and Storage

In certain unusually wet seasons in Tasmania poppies have been harvested at capsule moisture contents well above 12%. If the moisture content of the capsules is 16% or greater, artificial drying is used in order to prevent the development of moulds and fungi during bulk storage or the possible loss of morphine and other alkaloids by other chemical changes (). The moisture characteristics of the individual components of poppy capsules harvested at various times from green capsule to dry harvest maturity have also been studied in Tasmania (). Generally lateral capsules had a higher moisture content than terminal capsules. Of the capsule components the placentae had the highest moisture contents in both terminal and lateral capsules. Even at seven weeks after full bloom the placentae of the lateral capsules had a mean moisture content of 17.5-20.5%. One of the inferences of this experiment is that if there were a relatively large moisture contribution from the lateral capsules then these may be the cause of damp patches and moulding during bulk storage. However, any attempt to virtually eliminate lateral capsules by the use of high-density strands would predispose the crop to lodging. In addition, at the optimum density of 70 plants/m2 (), a very significant part of the increase in head yield with irrigation is attributable to the effect on the number and yield of lateral capsules. In this situation the occasional possibility of having to resort to artificial drying is outweighed by the economics of the increase in total head yield.

John C.Laughlin, Brian Chung and Bruce M.Beat Tie “Poppy Cultivation in Australia” (1998)