Abstract
Agroforestry systems are important forms of sustainable farming, providing several ecosystem services. However, characterization and management of factors such as thermal and light heterogeneity, as well as interactions between trees and coffee plants, are determinants for achieving the desired sustainability. This study aimed to verify whether different distances between Coffea arabica L. and Australian red cedar can change soil and microclimate characteristics and how they alter morphological and physiological attributes of coffee plants over the rainy season and a prolonged drought period (veranico) in Summer. The trial was carried out in the municipality of Barra do Choça, in an area with Australian red cedar trees (Toona ciliata M. Roem), distributed in two hedges, spaced 19.8 × 3 m apart, in a northeast-southwest direction, and coffee plants var. Catucaí Vermelho (3.3 × 0.5 m). Treatments were defined by the distance between the coffee plants and the first row of the Australian red cedar hedge (3.3 m, T1; 6.6 m, T2; 9.9 m, T3; 13.2 m, T4; 16.4 m, T5). Morphology and physiology of coffee plants, soil temperature, incident light on coffee plants, and the allelopathic potential of Australian red cedar leaf extracts were assessed in the wet and dry season of the 2016–2017 Summer. Temperatures fluctuated less in experimental units close to the hedge. The reduced growth of coffee plants close to the hedges was related to self-shading associated with light restriction by the trees. The experiment showed the allelopathic potential of Australian red cedar leaves.
Highlights
According to Peloso et al (2017), when leaves are subjected to water deficit, Relative water content (RWC) decreases; RWC is a good indicator of plant water status
In S1, higher Leaf temperature (LT) and Soil temperature (ST) associated with increased vapor pressure deficit and decreased coffee leaf hydraulic conductance were related to partial stomatal opening and reduction in Ψw (Rodrigues, W.P. et al, 2016)
Environmental variations that occurred in the wet season and veranico in Summer affected the morphology, water relations, temperature, and light incidence in coffee plants associated with Australian red cedar hedges
Summary
Agroforestry systems are important forms of sustainable land use, with activities that may produce substantial environmental benefits, such as reducing the risk of extreme temperatures (Moreira et al, 2018; Coltri et al, 2019), promoting carbon sequestration and biomass accumulation (Meireles et al, 2019), nutrient cycling by means of a higher litter deposition (Galetti et al, 2018), and improving water use efficiency (Moreira et al, 2018; Padovan et al, 2018).Sunlight availability is generally studied by assessing the intensity of incident radiation, using shade net houses as an empirical basis (Dias et al, 2017; Bote et al, 2018; Ribeiro et al, 2019). A tree-based system is characterized by uneven sunlight exposure and fluctuating temperatures throughout the day when compared to crops grown in full sun (Alves et al, 2016; Coltri et al, 2019), and this difference is more pronounced when trees are planted in hedges With this type of tree arrangement, shading is tied to the positioning of the hedges in relation to the solar path as the Earth rotates and orbits the Sun. The hedge orientation determines the different shade lengths over the coffee field, and monitoring the seasons and daytime weather changes is of utmost importance (Moreira et al, 2018)
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