Flowering Percentage in Arabica Coffee Crops Depends on the Water Deficit Level Applied During the Pre-Flowering Stage1

Abstract

Nonuniform flowering leads to uneven ripening of fruits, which impairs harvesting efficiency and the quality of the coffee. The aim of this study was to determine the water deficit level required to break flower bud dormancy of Coffea arabica and to evaluate its effects on gas exchange, photosynthetic pigment levels, coffee yield, and fruit maturation. After a growth period of 18 months in 200 L pots maintained under greenhouse conditions, water deficit treatments were imposed by withholding watering from plants exhibiting at least a 60% rate of "E4 stage" flower buds. When five groups of six coffee plants reached the pre-dawn leaf water potential (Ψwpd) of -0.04, -0.65, -1.43, -1.96, and -2.82 MPa, the leaf gas exchange was measured and leaf disks were collected to quantify the photosynthetic pigment levels, after which, watering was resumed. The rate of opened flowers increased with the reduction of Ypd based on the mathematical model, Y = 67.064 + 20.660 x ln(-Ψwpd). The leaf gas exchange was strongly affected by water deficit levels, without any alterations in the photosynthetic pigment levels. Coffee yield was not affected by the treatments but the ripe stages of cherries increased slightly with the reduction in Ψwpd. The water deficit level applied at the pre-flowering stage determined the percentage of flowering in C. arabica.

Drought and re-watering modify ethylene production and sensitivity, and are associated with coffee anthesis

“…Under tropical Brazilian conditions, coffee flower bud dormancy coincides with the beginning of the dry season in the main coffee producing regions. Moderate water deficit enhances the competence of flower buds to progress to anthesis, which is triggered by rain or irrigation after this period of water restriction (Alvim, 1960;Barros et al, 1978;Crisosto et al, 1992;Magalhaes and Angelocci, 1976;Ronchi and Miranda, 2020). Soil water deficit may stimulate root ACC accumulation (the ethylene precursor) while re-watering stimulates ACC transport to the shoot to induce an ethylene burst (Gómez-Cadenas et al, 1996).…”

Crosstalk Between Ethylene and Abscisic Acid During Changes in Soil Water Content Reveals a New Role for 1-Aminocyclopropane-1- Carboxylate in Coffee Anthesis Regulation

“…In the agroecological conditions of Brazil, coffee anthesis occurs after a short rainy event preceded by a water deficit period during the winter, which is necessary to break the bud “latent state,” associated with endogenous and external factors ( Ronchi and Miranda, 2020 ). One of the most important factors that contribute to flowering under water deficit stress conditions are phytohormones ( Izawa, 2021 ).…”

Crosstalk between Ethylene and ABA during changes in soil water content reveals a role of ACC in coffee anthesis regulation

“…In the agroecological conditions of Brazil, coffee anthesis occurs after a short rainy event preceded by a water deficit period during the winter, which is necessary to break the bud “latent state”, associated with endogenous and external factors (Ronchi & Miranda, 2020). Stress inducing flowering can also be seen in lemon ( Citrus limon L. Burm.…”