Gas exchange and water status of cacao under intercropping and monoculture with contrasting irrigation levels

Authors

  • Hugo Amancio Sales Silva Instituto Federal de Educação, Ciência e Tecnologia do Pará, Altamira, PA, Brazil https://orcid.org/0009-0008-3213-0973
  • Vivian Dielly da Silva Farias Universidade Federal do Pará, Altamira, PA, Brazil https://orcid.org/0009-0009-9727-3788
  • Andressa Julia Santos Vasconcelos Socio-environmental and Water Resources Institute, Universidade Federal Rural da Amazônia, Belém, PA, Brazil https://orcid.org/0009-0006-9983-1569
  • Israel Alves de Oliveira Socio-environmental and Water Resources Institute, Universidade Federal Rural da Amazônia, Belém, PA, Brazil https://orcid.org/0000-0003-3690-4987
  • Matheus Lima Rua Socio-environmental and Water Resources Institute, Universidade Federal Rural da Amazônia, Belém, PA, Brazil https://orcid.org/0000-0002-5184-0726
  • Miguel Gabriel Moraes Santos Socio-environmental and Water Resources Institute, Universidade Federal Rural da Amazônia, Belém, PA, Brazil https://orcid.org/0009-0001-8221-3143
  • Paulo Jorge de Oliveira Ponte de Souza Socio-environmental and Water Resources Institute, Universidade Federal Rural da Amazônia, Belém, PA, Brazil https://orcid.org/0000-0003-4748-1502

DOI:

https://doi.org/10.1590/1983-21252026v3915239rc

Keywords:

Irrigation. Theobroma cacao. Intercropping.

Abstract

Cacao is of major socioeconomic importance in the Trans-Amazonian region, where irregular rainfall may affect plant physiological performance. This study evaluated gas exchange and water status in seed-propagated cacao grown under intercropping and monoculture systems and subjected to irrigation levels corresponding to 0, 65, 100, and 130% of reference evapotranspiration. The experiment was conducted under field conditions using a split-plot design with five blocks. Leaf water potential (Ψf), net CO₂ assimilation rate (A), stomatal conductance (gs), intercellular CO₂ concentration (Ci), leaf transpiration (E), instantaneous water-use efficiency (WUE), and carboxylation efficiency (CE) were evaluated. During the rainy season, no significant differences in Ψf were observed among treatments, with values ranging from –0.17 to –0.55 MPa, indicating high water availability. During this period, plants grown in monoculture showed higher A, gs, and E due to greater availability of photosynthetically active radiation, whereas WUE was approximately 38% lower in monoculture cacao than in cacao grown in the intercropping system. During the less rainy season, increasing irrigation levels progressively increased Ψf, indicating mitigation of water stress. Mean Ψf was higher in the monoculture system (–0.75 MPa) than in the intercropping system (–1.07 MPa). These results indicate that irrigation is essential for maintaining plant water status during the less rainy season, whereas during the rainy season, the two cropping systems exhibit distinct responses associated with radiation availability and water-use efficiency.

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Published

20-10-2026

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Scientific Article