Changes in nutrient concentrations and leaf gas exchange parameters in banana plantlets under gradual soil moisture depletion

Changes in mineral nutrient concentration, growth, water Status and gas exchange parameters were investigated in young banana plants (Musa acuminata cv. 'Grand Nain') subjected to gradual soil moisture diminution. Experiments were performed in glasshouse under controlled temperature, and water stress was imposed by ceasing irrigation for 62 days. The data showed a parallel decrease of leaf gas exchange parameters and soil moisture initiated few days after the imposition of water stress. However, the leaf relative water content (RWC) showed a minor decrease in response to drought. The onset of growth reduction evaluated as plant height, pseudostem circumference, number of newly emerged leaves, leaf area, and leaf and root biomass took place approximately between 34 and 40 days after the beginning of the stress period. In addition, drought did not modify nitrogen and Phosphorus concentrations in foliar and root tissues; however, it increased potassium, Calcium, magnesium, sodium and chloride in leaves, and only Calcium, sodium and chloride in roots. Collectively, the data reveal chat banana plants show a drought avoidance mechanism in response to water stress. After a prolonged drought period, leaf RWC was hardly reduced, while gas exchange and growth parameters were reduced drastically. Increasing leaf mineral concentration could have help to maintain leaf RWC due to osmotic adjustment mechanism. (c) 2008 Elsevier B.V. All rights reserved.