Influence du niveau d'alimentation hydrique sur les variations du diametre des tiges, du potentiel hydrique, de la resistance stomatique, de la transpiration et de la photosynthese de l'aubergine (Solanum melangena L.)

Abstract The aim of this preliminary work was to test some biological criteria used for irrigation control. Microvariations of stem diameter, photosynthesis and plant growth were compared with previously recommended parameters such as leaf water potential and stomatal resistance, transpiration ...? Measurements were made on eggplants, grown in pots under a plastic greenhouse. Some of the pots were watered daily to compensate for transpiration losses. From Day J , watering was stopped for the “dry treatment” pots. As early as Day J + 2 stomatal resistances of both sides of the leaves were a little higher for the dry treatment than for the watered one. Net photosynthesis was only slightly reduced at the end of the afternoon. From Day J + 3, differences between the treatments increased for all the criteria: basic water potential, stomatal resistance, net photosynthesis. The stem diameter of the unwatered plants decreased and became smaller than for Day J + 2. All these results are coherent and indicate the interest of the stem diameter variation measurement as an irrigation control criterion. Compared with other criteria, it has the advantage of not needing any measurement on control plants, as water is the only acting factor. Moreover, for the watered plants, it has been pointed out that the stem diameter increase was linearly related to the cumulated net photosynthesis of the previous days. Such a relation would be an interesting criterion for greenhouse climate control.