Studies on the Growth and Development and Morphine Content of Opium Poppy

Abstract

1. An attempt was made to correlate the growth and development and morphine content of Yuma poppy, U.S.D.A. no. 17 (Papaver somniferum L.) grown under usual greenhouse conditions with that of plants grown under controlled temperatures and photoperiods. 2. The concentration of morphine (μg/gm dry weight) in organs of plants first grown on an 8-hour day, then on 18-hour photoperiods at 49-59 days after seed germination, and then transferred to natural daylengths in the greenhouse was greatest in the capsules, while none was detected in the seed. In plants harvested 32, 61, 98, 114, and 126 days after seed germination, the capsules collected at 98 days contained the highest concentration of morphine, while capsules collected at the last harvest contained the greatest amount of morphine (concentration x dry weight). On a whole-plant basis the greatest concentration of morphine was found in plants harvested 98 days after germination, whereas the greatest amount of morphine was found in plants collected after 98 and 114 days. 3. The mean number of nodes produced by plants grown under certain artificial conditions is related to the average dry weight of the capsule. The number of nodes and the dry weight of capsules of plants placed on inductive 18-hour photoperiods 14, 30, 45, or 64 days after seed germination were directly proportional. 4. A relationship was found between the mean number of nodes produced and the following daily photoperiods: 10, 11, 12, 14, 15, 16, 17, 18, or 24 hours. The number of nodes on plants exposed to all photoperiods greater than 15 hours was approximately the same, while that on plants exposed to photoperiods of less than 15 hours was greatest for the 10- and 11-hour photoperiods. 5. The concentration of morphine in capsules and roots of plants grown at 50⚬ or 70⚬ F. in controlled-temperature rooms was greater at the lower temperature, while that in the straw (stems plus leaves) was greater at the higher temperature. The total dry weight of capsules produced by plants grown at 70⚬ was 37% greater than that for plants grown at 50⚬; however, the dry weight of straw and roots of plants grown at the lower temperature was at least 34% greater than that of plants grown at the higher temperature. 6. In thermoperiodicity studies on plants induced to flower at 65⚬ F. with fourteen 18-hour photoperiods, the production of dry weight of shoots (all aerial organs) per day was greater when the day temperature was 65⚬ than at 82⚬, and when the night temperature following these two day temperatures was 48⚬ than when it was 82⚬ or 65⚬. At each of the two day temperatures employed the dry weight of shoots produced was greatest when the night temperature was lower than the preceding day temperature. At high night temperatures the time to flowering was shortened and the rate of flowering and the concentration of morphine increased as compared with effects of the low night temperatures, while height, dry weight, length of peduncle, and area of leaves were greater at the low night temperatures. The total morphine content was apparently increased by low night temperatures if it is assumed that photosynthesis was more limiting during the 82⚬ day than at the 65⚬ day. 7. Inhibition of floral induction at 84⚬ ± 6⚬ F. during the supplemental photoperiod and subsequent dark period occurred in plants exposed to 14, 15, 16, 17, or 18-hour photoperiods for 45 days. Of the total population, 7% flowered, while all remaining plants were vegetative. These predominantly rosette plants, including an 8-hour control, were then grown for 96 days on an 82⚬ day, and on night temperatures maintained at 82⚬, 65⚬, or 48⚬. On a dry-weight basis the intermediate night temperature was most favorable. A possible shift in optimum night temperatures for the production of leaves and leaf size was indicated. 8. The following culture conditions are indicated for the optimal production of morphine in biosynthesis studies: After germination of seeds at 70⚬-80⚬ F., seedlings are grown on an 8-hour day at 60⚬-70⚬, utilizing natural sunlight. Induction of flowering occurs as a result of exposure to fourteen 18-hour days at 60⚬ when thirty to thirty-five leaves have been formed. Floral induction and total leaf number are determined by microdissection. Plants are then transferred to the biosynthesis chamber, which is maintained on an 18-hour day at 60⚬-65⚬. Sunlight is supplemented with artificial illumination from twelve 40-watt G.E. DeLuxe Warm White lamps mounted inside the chamber. Radioactive morphine with a specific activity of 0.5 mc. per gram of carbon has been obtained from Yuma poppies treated in this manner.