Temperature as the main factor affecting the reproductive phenology of the dioecious palm Mauritiella armata (Arecaceae)

Abstract

Our research focused on the reproductive phenology of Mauritiella armata, a key veredas species in southeastern Brazil, and aspects of its floral and fruit morphology and sexual system. We observed the reproductive phenological patterns of M. armata for 36 months, and examined the relationships between phenophases and environmental variables to describe its phenological patterns in relation to environmental filters, as well as its floral and fruit morphologies, sexual system (to evaluate dioecy), and the biometry of its reproductive parts. Flowering was observed in the dry season and at the beginning of the rainy season, with fruiting occurring during the rainy season. The reproductive phenophases responded to environmental seasonality, principally temperature in the period immediately preceding the expression of the phenophase, as well as to environmental variations that had occurred up to six months earlier. The dioecious sexual system of M. armata was confirmed, with flowering synchronization between the sexes. The population studied did not exhibit apomixis, having xenogamy as its reproductive system. The staminate inflorescences were larger than the pistillate inflorescences and had greater numbers of flowers, although the pistillate flowers were larger. Wind pollen dispersal was not observed, thereby indicating that this species requires biotic pollination for fruit production.

Sexual and reproductive systems of woody species in vereda are distributed according to the life form and habitat occurrence

“…However, pollen vectors dependence makes these species more susceptible to extinction (Ollerton et al 2011), mainly the veredas plants that depend on cross-pollination, such as the dioecious species M. flexuosa, Mauritiela armata and Tapirira guianensis. Populations of dioecious species require reproductive strategies such as synchrony in the flowering period between staminate and pistillate individuals and pollinating agents (biotic or abiotic), relative frequency of reproductive individuals in the population, or sex ratio, for cross-pollination occur (Bawa 1980;Storti 1993;Avila et al 2022). Species showed a great diversity of mechanisms that favour allogamy, such as hercogamy, dichogamy and secondary presentation of pollen, functional dioecy, in addition to floral attributes used to attract pollinators.…”

“…In this case, M. flexuosa and M. armata, considered key species for their wide distribution along the vereda. These palm species provide resources for pollinators and frugivores, and their fruits that are used by the local fauna and traditional human populations ( Avila et al 2022), presenting an important ecological role in the balance of this ecosystem. Consequently, the floral complexity and reproductive biology of these species, and the relation with the pollinator can affect reproductive success if the pollen vectors become extinct (Darrault & Schlindwein 2005).…”

“…Populations of dioecious species require reproductive strategies such as synchrony in the flowering period between staminate and pistillate individuals and pollinating agents (biotic or abiotic), relative frequency of reproductive individuals in the population, or sex ratio, for cross‐pollination occur (Bawa 1980; Storti 1993; Ávila et al . 2022).…”