TEMPERATURE EFFECTS ON GROWTH, PIGMENTATION AND POSTHARVEST LONGEVITYOF PETUNIA FLOWERS

Petunia (Petunia hybrida, cv. 'VR') flowers produced at 32/27 degrees C (day/night) developed from Stage 1, when the corolla is barely visib le, to full anthesis within 4 days, as compared with 9 days for flower s produced at 17/12 degrees C (day/night). However, the flowers produc ed at high temperatures were approximately half the size of the latter at anthesis, owing to differences in both fresh and dry weights. Coro lla pigmentation was enhanced at the lower growth temperatures, owing to higher anthocyanin content. Northern analyses revealed that both gr owth and pigmentation are regulated by temperature at the molecular le vel. In contrast to its beneficial effect on size and pigmentation, gr owth at lower temperatures resulted in a shorter vase life for the cut flowers, which was associated with enhanced ethylene production. Cut petunia flowers were treated with aminooxyacetic acid, silver thiosulf ate or 1-aminocyclopropane carboxylic acid. The results supported our contention that ethylene is indeed involved in the regulation of the g rowth-temperature effects on petunia flower vase life. In this study, petunia did not behave according to the common conception that lower g rowth temperatures lead to better quality cut flowers. (C) 1997 Elsevi er Science B.V.