Effects of temperature on the flowering of the saffron crocus (Crocus sativus l.): Induction of hysteranthy

The saffron crocus (Crocus sativus L.), a sterile geophyte propagated by annual replacement corms, is cultivated for its red stigmatic lobes that constitute, after drying, the spice saffron. C. sativus is a subhysteranthous species, i.e., it blooms in autumn shortly after planting, before, concomitantly with, or after leaf appearance. The remainder of its growing season consists of initiation, filling up, and maturation of the daughter corms at the beginning of summer. In the countries where saffron crocus is grown, cultivation is still performed by traditional methods: corm planting, flower harvesting, stigma separation, and corm lifting are carried out manually. These labour-consuming practices greatly contribute to the high price of the spice. The study of the physiological background of the developmental processes in C. sativus was aimed at improving the cultivation methods. It is demonstrated that a controlled temperature regime during corm storage affects flowering and production of daughter corms. Moreover, the combination of corm storage and planting under controlled environmental conditions is shown to promote the hyster- anthous behaviour of the saffron crocus. The application of these methods might make it possible to replace manual picking by mechanical flower harvesting.