Abstract
Abstract Adenium obesum (Forssk.) Roem. & Schult., popularly known as desert rose, has become a valuable ornamental plant. In floriculture, the production of hybrids is prioritized. Hence, knowledge on floral biology and sexual reproduction of the target species is fundamental. The objectives of this study were: (1) to test sucrose concentrations and temperatures for in vitro germination of A. obesum pollen grains; (2) to identify the effect of temperature on the viability of A. obesum pollen grains; and (3) to evaluate the viability of pollen grains and stigma receptivity in pre-anthesis, at flower opening, and 72 h post-flower opening in three accessions of A. obesum. A significant relationship between temperatures and sucrose concentrations was observed in the in vitro germination test. The highest percentage of in vitro germination of pollen grains, 39.81%, was observed at an estimated temperature of 26.05 °C. Desert rose accessions maintained in biochemical oxygen demand (BOD) chambers at 30 °C during a 16-h light photoperiod showed faster flowering, and temperatures ≥ 25 °C induced pollen grain viability percentages above 69%. Temperature is one of the most important abiotic factors, influencing mainly in pollen germination, pollen tube growing and in efficiency fertilization. The ICA-wd accession stood out and can be considered a pollen donor in artificial pollination. The stigmas of flowers were receptive from a day before flower opening until three days after. The two parameters presented above, stigma receptivity and pollen viability, allow inferences about the appropriate time for successful pollination and subsequent fertilization in desert roses.
Highlights
Adenium obesum (Forssk.) Roem. & Schult, commonly known as desert rose, belongs to the Apocynaceae family, and is native to sub-Saharan Africa (Plaizier, 1980)
This study was aimed at answering the following questions: 1) Is pollen viability in A. obesum influenced by temperature variation during floral development? 2) Do the in vitro pollen grain germination rate and stigma receptivity vary according to the floral development stadium? 3) Is the rate of in vitro pollen germination influenced by variations in sucrose concentration and temperature?
The present study showed that the temperature of 20 °C in a 16-h photoperiod considerably affected pollen viability, and there is evidence that it delayed flower development, caused yellowing of leaves, and increased the abscission of the reproductive structures
Summary
Adenium obesum (Forssk.) Roem. & Schult, commonly known as desert rose, belongs to the Apocynaceae family, and is native to sub-Saharan Africa (Plaizier, 1980). & Schult, commonly known as desert rose, belongs to the Apocynaceae family, and is native to sub-Saharan Africa (Plaizier, 1980) It is a shrub or small tree with a short stem, a thick base (caudex) that serves as a reserve organ, and spiral leaves, normally clustered at the end of twigs (Plaizier, 1980). Similar to other representatives of the family, Adenium spp. flowers have exuberant beauty, marked by morphological complexity They are actinomorphic or slightly zygomorphic; pentamerous, with a rounded or star-shaped corolla, funnel-shaped tube, five stamens with short filaments and long anthers with a sagittate base, forming a cone on the apex of the style (Plaizier, 1980; Colombo et al, 2018). The apocarpous gynoecium gives rise to fruit formed by two polyspermic follicles united by the basal region (Plaizier, 1980; Colombo et al, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
