Unveiling triggers for flowering in coffee plants: A systematic review of endogenous and environmental factors

JOSE RAUL RENDON SAENZ^1*Carolina Zamorano-Montañez²Juan Carlos García López¹NELSON CEBALLOS²Miguel Alfonso Castiblanco Carranza¹Juliana Vargas López²

• ¹National Research Center of Coffee (CENICAFE), Manizales, Colombia
• ²Universidad de Caldas, Manizales, Colombia

This systematic review (SR) focuses on the triggers of coffee flowering and synthesizes the main findings of scientific publications published over approximately 60 years, with the aim of analyzing the progress of studies on environmental and endogenous factors that promote flowering and prioritizing prospects for future research. Flowering studies in coffee species related to climate, soil or endogenous variables were included, and studies in other crops or phenological stages other than flowering were excluded. For the search, databases of private publishing clusters were consulted, including Science Direct, Taylor and Francis and Springer Link, and a second group of databases considered large indexers was integrated, namely, Dimensions, Web of Science and SciELO, with search dates until October 25, 2024. Of the 706 studies retrieved on environmental factors, 43 met the eligibility criteria, and of a total of 187 studies on endogenous factors, 23 were included. Among climate variables, water stress is essential for coffee flowering; the initiation of flowering can occur after a precipitation event greater than 10 mm. The development of flower buds occurs at average annual temperatures ranging from 17 to 23 °C, with a lower limit of 10 °C and an upper limit of 32 °C. The photoperiod with shortest days (less than 13–14 hours of light) two or three months before flowering determines the induction of flowering at latitudes above 7°N. At the endogenous level, the MADS-box gene family, type II (MIKC), stands out for its function as a regulator of reproductive development, the flower organ identity and flower meristem determination, while the FLOWERING LOCUS C (FLC) gene is related to the regulation of flower induction time. During dry periods, ethylene production decreases in leaves and flower buds; later, when the plants are rehydrated, the ethylene levels increase. Future research should focus on investigating agroclimatic indices such as air vapor pressure deficit and plant physiological and functional traits, such as density and stomatal conductance.