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sur le développement des zones arides et semi-arides

Titre : Características biofísicas y químicas de plantas MAC en relación con su domesticación, especie y humedad en el suelo.

CHEMISTRY AND BIOPHYSICS CHARACTERISTIC OF CAM PLANTS AS INFLUENCED BY DOMESTICATION, SPECIE AND SOIL HUMIDITY

Auteur : García Nava, Francisca.

Université de soutenance : Colegio de Postgraduados (COLPOS) Consejo Nacional de Ciencia y Tecnología (CONACYT)

Grade : Doctorado en Ciencias, especialista en Botánica 2014

Résumé
The aim of this research was to evaluate 15 variants of nopal belonging to five species of Opuntia in a domesticated gradient defined by morphologic characteristics and seven Agave species (Subgenera Littaea and Agave) of plants grown in a greenhouse and as influenced by the level of watering. The hypothesis was that the biophysics and chemistry characteristics of nopalitos and the Agave leaves are different among the species due to their level of domestication independently of the soil humidity and specie. Experiments were made in a complete randomize design, variable number of treatments, six replications (one plant as an experimental unit). The data were analysed by ANOVA, Tukey multiple mean comparison and principal components. The nopal firmness (from 4.57 to 7 kgf), the soluble content solids (TSS, from 4.8 to 6.5º Brix), the acidity (from 0.6 to 0.85 g malic acid per 100g fresh tissue) and the relative permeability of cellular membrane (from 13.55 to 31 %), were variables among species and increased with the domestication gradient. In contrast, the water potential (ψA, from -0.8 to -1.2 MPa) and the osmotic potential (ψS, from 0.65 to 1.2 MPa) diminished with the domestication gradient. The principal components analysis (PCA) showed that membrane permeability and TSS were the main variables of the nopalitos that contributed to the separation of the species with low (O. streptacantha) and high (O. ficus-indica) domestication level and as a consequence as biological independent entities. The Agave leave firmness (from 0.05 to 0.25 mm), TSS (from 10 and 23 ºBrix), the ψS (from -0.8 to 1.4 MPa), relative permeability of the cell membrane (from 20 and 75 %) and the chlorophyll total content (from 10 an 55 mg per 100 g of fresh tissue) were partially dependent of the soil humidity and specie. The biophysics and physiological modifications of Opuntia follow a pattern defined by the domestication, in contrast with maguey which showed a different pattern to the degree of domestication.

Mots clés :  : Opuntia, Agave, domestication, biophysics characteristics, chemistry characteristics, maguey, CAM, nopal, humidity restriction.

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