Abstract

ROMERO-H., Maria Esther; PENA-VALDIVIA, Cecilia B.; GARCIA-N., Rodolfo  and  CAMPOS, Huitziméngari. Effects of soil water restriction on tissue water potential and diurnal and nocturnal acidity changes on Ferocactus histrix y F. pilosus. Polibotánica [online]. 2017, n.44, pp.167-183. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.44.13.

Plants of the Cactaceae family have morphological and physiological characteristics, such as succulent and photosynthetic stems, spines, thick whitish water economy, and crassulacean acid metabolism (CAM), which allows them to adapt to arid environments. Ferocactus histrix is a globose stem cactus and F. pilosus is a columnar one, both species are found in the standard NOM-059-SEMARNAT-2010 official rules, in the category of risk "subject to special protection". Physiology and mechanism of adaptation to adverse conditions of these species is known very little. The aim of the study was to evaluate the effect of irrigation and water restriction on parenchyma and chlorenchyma water potential (ΨA) and on changes in its daytime and nighttime acidity in Ferocactus pilosus y F. histrix plants. The hypothesis was that plants upregulate tissues ΨA and maintain diurnal and nocturnal typical acidity patterns as a CAM plants, regardless of the irrigation suspension. Plants of each species were maintained with or without weekly irrigation for a year. The study was conducted with a completely randomized design. The experimental unit was a plant and four units were assessed every 4 h for 24 h, after 3, 6 and 12 months. ΨA was evaluated in the parenchyma and chlorenchyma tissue as well as acidity of both tissues by titration with NaOH. The parenchyma tissue was the most affected by the lack of irrigation, which after 12 months reached ΨA of -3.23 in F. histrix and -9.29 MPa in F. pilosus. The malic acid content decreased in both tissues and in both species during the year; in chlorenchyma of F. histrix it decreased 45 % in nighttime phase and 33 % in light phase while the parenchyma decreased 35 % in nighttime phase and 28 % in light phase; in chlorenchyma of F. pilosus the decrease was 90.47 % at night phase and 68.18 % in light phase, and 81 % in parenchyma in both phases. The irrigation suspension for 3, 6 and 12 months affected malic acid accumulation differently in the cycle of 24 h Ferocactus tissues, and decreased the synthesis of malic acid as increased time without irrigation. Both species tolerate up to 12 months in this condition and reactivated its growth with further irrigation.

Keywords : Cactaceae; CAM; malic acid; irrigation; Cactaceae; Ferocactus.

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