Submitted to: Annals Of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/1997
Publication Date: N/A
Interpretive Summary: The U.S. State Department annually estimates yields of opium poppy and other narcotic crops around the world. This is a difficult task because poppy is grown illegally under a variety of conditions and in many locations. To understand how the flowering of opium poppy can be affected by weather variables such as temperature, plants were grown in controlled environments in a range of temperatures. This study was carried out to find out how temperature affected flower initiation and development. Results indicated that flower initiation was not sensitive to temperature, but flower development was. Thus, low temperatures delay flowering mainly because they prolong flower development. Results presented here provide important insights that will make it possible to predict flowering of the poppy crop more accurately anywhere in the world.
Technical Abstract: Flower development in opium poppy (Papaver somniferum L.) has been divided into four phases from emergence to anthesis which mark changes in its sensitivity to photoperiod: a photoperiod-insensitive juvenile phase (JP), a photoperiod-sensitive inductive phase (PSP), a photoperiod-sensitive post-inductive phase (PSPP), and a photoperiod-insensitive post-inductive phase (PIPP). To predict flowering time under field conditions, it is essential to know how these phases are affected by temperature. Plants were grown in artificially-lit growth chambers and received three different temperature treatments: 15/10, 20/15, and 25/20 C in a 12 h thermoperiod. Plants were transferred within each temperature regime from a non-inductive 9-h to an inductive 16-h photoperiod or vice versa at 1-4 d intervals to determine the durations of the four phases. Temperature did not affect the durations of the first two phases (i.e. JP lasted 3-4 d and PSP required 4-5 d). The most significant effect of temperature was on the duration of PSPP which was 28, 20, and 17 d at 15/10, 20/15, and 25/20 C, respectively. The temperature effect on PIPP was small (maximum difference of 3 d between treatments) and the data too variable to indicate a significant trend. Our results indicate that PSPP is the only phase that clearly exhibits sensitivity to temperature.