Temperature effects on growth, pigmentation and post-harvest longevity of petunia flowers

Petunia (Petunia hybrida, cv. 'VR') flowers produced at 32/27°C (day/night) developed from Stage 1, when the corolla is barely visible, to full anthesis within 4 days, as compared with 9 days for flowers produced at 17/12°C (day/night). However, the flowers produced at high temperatures were approximately half the size of the latter at anthesis, owing to differences in both fresh and dry weights. Corolla pigmentation was enhanced at the lower growth temperatures, owing to higher anthocyanin content. Northern analyses revealed that both growth and pigmentation are regulated by temperature at the molecular level. In contrast to its beneficial effect on size and pigmentation, growth 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 thiosulfate or 1-aminocyclopropane carboxylic acid. The results supported our contention that ethylene is indeed involved in the regulation of the growth-temperature effects on petunia flower vase life. In this study, petunia did not behave according to the common conception that lower growth temperatures lead to better quality cut flowers.