Abstract
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.
Highlights
The Cerrado Mineiro region will produce between 4.8 and 5.0 million 60 kg bags of arabica coffee in 2019, which corresponds to 18.5% of the production of the state and 13.24% of the national production (BRASIL, 2019)
Given that one of the objectives of the present study was to determine the minimum level of water deficit necessary to break the dormancy of flower buds, watering was suspended when the percentage of E4 reached 60%
At 18 months after transplantation (MAT), the 30 plants used in this experiment had, on average, 6% of buds in E2 stage, 32% in E3 stage, and 62% in the maturing E4 stage; watering was suspended on the following day
Summary
The Cerrado Mineiro region will produce between 4.8 and 5.0 million 60 kg bags of arabica coffee in 2019, which corresponds to 18.5% of the production of the state and 13.24% of the national production (BRASIL, 2019). Watering just before flowering can induce the uneven development of flower buds (DaMATTA et al, 2007; SILVA et al, 2009; RONCHI et al, 2015), many coffee crops are watered without interruption. Establishing fixed dates to suspend and resume watering, without monitoring the level of water deficit and stage of flwer buds, as proposed by Guerra, Rocha, and Rodrigues (2005), is the most empirical way to apply the water deficit. Establishing fixed dates as a criterion can induce severe water deficiencies in plants (MERA et al, 2011), with irreparable losses in productivity (MERA et al, 2011; FERNANDES et al, 2016; GONZÁLEZ-ROBAINA; CISNEROSZAYAS; MONTILLA, 2017), growth (MERA et al, 2011; SAKAI et al, 2015), and crop longevity
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