Changes in the capsule of Papaver somniferum between flowering and maturity

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Abstract
SUMMARY: The changes occurring during ripening in the seed and capsule of Papaver somniferum were examined at Oxford in each of the years 1948‐60.The percentage content of dry material in the seed increases at a fairly uniform rate and in average seasons reaches a maximum of 85–90 about 7 weeks after flowering. The dry weight of the seed and the content of oil and protein are maximal at least a fortnight before a minimum water content is attained.The capsule increases very rapidly in size and weight during the first 2 weeks and the volume, fresh weight and dry weight are maximal within 3 weeks of flowering. Subsequently, there is a significant reduction, not only in volume and fresh weight but also in dry weight. When the capsule has a minimum water content the dry weight is 10–15% below the previously recorded maximum. The percentage dry matter content of the capsule shows little increase until 4–6 weeks after flowering; it then falls very rapidly and the maximum percentage value of 80–85 is reached at the same time as in the seed.The dry and ripe capsule readily absorbs or loses water with changes in ambient conditions, whereas the contained ripe seed exhibits little such variation.Morphine is accumulated in the capsule until about 6 weeks after flowering but later the content declines. When conditions during ripening are warm and dry the water content of the seed and capsule is nearly minimal when the morphine content in the capsule is maximal. In wet seasons, more than half of the morphine previously accumulated in the capsule may be lost by the time a minimum water content is reached.Different varieties behave similarly during ripening, but there are marked variations from year to year in the maximum amount of morphine accumulated in the capsule. Although morphine content is usually greater when warm, dry conditions prevail during ripening, there are exceptions, and the complex interrelationships between environment and morphine production need further elucidation.