PHYSIOLOGICAL BEHAVIOUR OF MANGOS WITH DIFFERENT PLOIDY LEVELS

The effect of tetraploidy on net gas exchange and chlorophyll content was studied in diploid (2x) and tetraploid (4x) mango leaves. Comparisons between ploidy levels were made in two cultivars ‘Manga Blanca’ and ‘Manga Fina’ and these were compared with ‘Turpentine’, a diploid rootstock widely used in Spain. Measurements were carried out under high irradiance in two year old mango plants grown in a low light greenhouse. The results showed significant differences among the tested material. Lower light-saturated net CO₂ assimilation rates (Pn) and electron transport rate (ETR) were reached in ‘Turpentine’, ‘Manga Blanca’ was the cultivar with highest Pn values. In ‘Manga Fina’ significant differences were found between the diploids and tetraploids plants, with lower Pn, stomatal conductance (Gs) and ETR values in the tetraploid material. However no significant differences of Pn, Gs and ETR were found between the diploid and the tetraploid ‘Manga Blanca’ plants. The chlorophyll content was significantly higher in the tetraploid ‘Manga Blanca’ plants than in the diploid ones. Different seasonally behaviour in the mango cultivars studied is also discussed.