The Relationship between Flower Age and Seed Production in Hatiora gaertneri and Schlumbergera truncata (Cactaceae)

Abstract

<jats:p>Flowers of two cacti [<jats:italic>Hatiora gaertneri</jats:italic> (Regel) Barthlott `Crimson Giant' and <jats:italic>Schlumbergera truncata</jats:italic> (Haworth) Moran `Eva'] were pollinated at different times between anthesis and senescence to determine the effect of floral age on seed production. Studies were conducted in a growth chamber (20 ± 0.5°C) to minimize temperature effects. Mean flower longevity (time from anthesis to first signs of senescence) was 4.7 days for <jats:italic>S. truncata</jats:italic> and 10.5 days for <jats:italic>H. gaertneri</jats:italic>. Stigmas of both species were receptive to pollination on the day of anthesis. The maximum number of viable seeds per pollinated flower was obtained when flowers of <jats:italic>S. truncata</jats:italic> and <jats:italic>H. gaertneri</jats:italic> were pollinated (respectively) on the second and fourth days after anthesis. For both species, the relationship between floral age and number of viable seeds per pollinated flower was described by a second-degree polynomial. The rate of pollen tube growth in the style was about 1.7 mm·h<jats:sup>–1</jats:sup> for <jats:italic>S. truncata</jats:italic> and about 0.9 mm·h<jats:sup>–1</jats:sup> for <jats:italic>H. gaertneri</jats:italic>. Some senesced flowers of <jats:italic>H. gaertneri</jats:italic> were capable of setting fruit with viable seed. Flowers of <jats:italic>S. truncata</jats:italic> did not set fruit when pollinated during the late phase of flower opening or after they had senesced. Senesced flowers of <jats:italic>S. truncata</jats:italic> failed to set fruit due to an insufficient number of pollen tubes reaching the ovary.</jats:p>

Reproductive challenges related to a complex sexual system in Euphorbia rosescens, a rare endemic herb

“…Euphorbia rosescens did not have significant differences in pollen viability in staminate flowers between male and hermaphrodite cyathia, similar to findings for other species of Euphorbia (Narbona et al, 2005, 2008) and other andromonoecious species (Cuevas & Polito, 2004). Pollen viability is often affected by fluctuations in temperature (Franchi et al, 2007), humidity (Shivanna & Johri, 1985), as reviewed by Pacini and Dolferus (2019), and age of flower since anthesis (Boyle, 2006). Except for potential microsite differences, both male and hermaphrodite inflorescences would have experienced similar temperature and humidity trends.…”