IMPROVEMENT OF NATIVE SOUTH AMERICAN PLANTS: HIGH TEMPERATURES AS A TOOL TO OVERCOME PRECIGOTIC BARRIERS IN THE COMPLEX Calibrachoa–Nierembergia

Abstract

The aim of this study was to evaluate the use of high temperatures to overcome prezygotic interspecific incompatibility barriers in crosses between species of Calibrachoa and Nierembergia. The following combinations were evaluated: N. scoparia x C. ovalifolia, N. scoparia x C. caesia, N. linariaefolia x C. thymifolia and N. linariaefolia x C. ovalifolia, using different genotypes. The plants with prepared buds were placed in a stove at 50°C for 5 minutes for N. scoparia and 2.5 minutes for N. linariaefolia. Subsequently, the plants are removed from the oven and pollinated with fresh pollen. The percentage of crosses of pollen tubes to the style and ovary was evaluated. Application of high temperatures in N. scoparia could be a good approach in the combination N. scoparia x C. caesia, because in all cases the amount of pollen tubes in ovary was higher than in the control. For N. linariaefolia results show that, although there is an improvement with this method, no increase of pollen tubes which reached the ovaries. The results of this work allowed generate new knowledge about genera relationships, incompatibility barriers and issues related to the floral biology, which are basic for obtaining hybrids.