Bromeliads have been widely used for potted flowers or landscape decoration for decades, and they are currently considered among the most valuable ornamental plants (Negrelle et al., 2012). Interspecific and intergeneric hybridizations have been made to develop new cultivars in several bromeliad genera, including Aechmea, Guzmania, Neoregelia, Tillandsia, and Vriesea (Parton et al., 2001; Smith, 1983; Vervaeke et al., 2001). Neoregelia cultivars have been popular because of their attractive multicolored foliage, even when the plants are not flowering. Therefore, they have been used in many areas for landscaping and indoor decorations. However, the cultivars that are of interest are hybrids.
Information regarding pollination timing is crucial for successful hybridization because some bromeliads have short-lived flowers and anthesis occurs at a particular time of the day (Foster, 1996; Souza et al., 2016). Foster (1958) stated that most Neoregelia flowers open and last only a few hours. Parton et al. (2001) showed that stigma receptivity was high at anthesis and then became significantly lower in Aechmea. Souza et al. (2016) showed higher stigma receptivity at anthesis for Aechmea, Alcantarea, Ananas, and Vriesea, with the highest receptivity at 0800 hr; receptivity remained until 1200 hr and declined thereafter.
A prefertilization barrier has been reported for interspecific pollination of Aechmea, in which abnormal pollen tubes occur either in the stigma or during penetration of the micropyle (Souza et al., 2017). Prefertilization barriers were observed when the female parents have a longer style than the male parents for hybridization of bromeliads (Parton et al., 2001; Souza et al., 2017; Vervaeke et al., 2001). The cut style technique combined with in vitro culture of the fertilized ovules can lead to the successfully attainment of intergeneric offspring (Vervaeke et al., 2002, 2003). The lack of seed formation in Vriesea and failure of seed germination in Aechmea occur despite fertilization, thus characterizing postfertilization barriers (Parton et al., 2001). Little information is available regarding the fertilization barriers of crossing Neoregelia species and/or cultivars.
The objectives of the present study were to 1) define the conditions for pollination timing, and 2) to observe whether the parental style length can affect seed formation when Neoregelia cultivars are crossed, and if so, if the cut style technique can overcome the fertilization barrier.
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