Effects of ambient temperature on flower initiation and flowering in saffron (Crocus sativus L.)

Abstract

Saffron is one of the most appreciated and expensive spices in the world and serves as a traditional Chinese medicine in China. Shanghai Chongming Island, as the main production area of saffron in China, has formed a unique "two-segment" cultivation mode since the 1980s. The study evaluated the effects of different temperatures and incubation periods on flower initiation and flowering of saffron. From mid-June, corms were placed in a cultivation chamber without any substrate under 30 °C, −25 °C, and −15 °C, or 25 °C and −15 °C for phased constant temperature treatment, or under 25 °C, 20 °C and 15 °C for continuous constant temperature treatment, respectively. The optimal temperature (between 20 and 25 °C) compared to the natural temperature can effectively promote the initiation time of flower differentiation and shorten the flower differentiation process. Meanwhile, inappropriate incubation temperature, such as constant temperature at 15 °C or 25 °C, results in no flower initiation, or flower interruption and atrophy, respectively. In summary, incubation of corms at a slightly high temperature (about 30 °C) for 2∼3 weeks, then transfer to a suitable temperature (about 25 °C) for 1∼2 months, and final transfer to a lower temperature (about 15∼20 °C) for flowering, which is a suitable temperature condition to promote flowering, can induce saffron to enter in its full flowering stage on early October. These results can provide a theoretical basis for indoor environment conditions to regulate saffron flowering under the “two-segment” cultivation model.