GREENHOUSE SAFFRON CULTURE – TEMPERATURE EFFECTS ON FLOWER EMERGENCE AND VEGETATIVE GROWTH OF THE PLANTS

Abstract

The physiology of flower initiation and early flower development of the saffron plant (Crocus sativus L.) is well characterised. However, the optimal conditions for anthesis have not been ascertained. In this work we determined the influence of temperature after flower initiation on flowering and saffron spice production, as well as the influence of the environmental conditions in the greenhouse on plant growth. To this aim, saffron corms which had been stored at 25°C during 105 days, were sprouted at different temperature regimes in growth chambers in the light, with an 16/8 h photoperiod and a photon fluence rate of 20-40 μmol m -2 s -1 . One month after the completion of flowering the plants were transplanted to the open field, and their CO 2 assimilation rates were compared to that of plants coming from corms planted directly in the open. In plants grown at a constant temperature, this parameter, in the range 13-20°C, had no significant effect on the number of sprouts nor that of flowers formed per corm. Flowering occurred earlier at 17°C than at higher and lower temperatures. The flowers formed at 20°C had a wilt aspect. The size of the styles was directly related to temperature and therefore was highest at 20°C. in these plants, however, the styles were difficult to separate from the flower. Growing the plants at a 20/10°C term period hastened flowering and resulted in the formation of normal flowers, but also reduced style size. Growth in the chambers resulted in a 90% reduction of the maximum photosynthetic CO 2 fixation as compared with plants grown in the open. This loss was recovered in part (about 50%) several weeks after transferring the plants to the open field.