Effect of drought stress and mycorrhizal inoculation on the growth, photosynthetic activity and water use efficiency of leek (Allium porrum L. 'Gigante Suizo')

Abstract

During the experiments it was examined two irrigation levels: 1. optimal water supply - the irrigation activation by available water capacity (AWC) < 65 %; 2. drought stress - irrigation activation by AWC < 45 %) and inoculation of plants by the vesicular-arbuscular mycorrhizal fungus Glomus in leek culture. The effect of treatments on the photosynthetic rate (A), transpiration rate (E), water use efficiency (WUE), biomass production (weight, dry matter content of different plant part), size of pseudostem, leaf area and specific leaf area (SLA) was observed. The drought stress had effect on all observed parameters: it decreased the photosynthetic and transpiration rate (A: from 5.04-5.37 to 3.33-3.43 μmol CO2.m-2. s -1, E: from 1.78-1.91 to 0.99-1.03 mmol H2O. m -2. s-1 in the average of 5 measuring date), the weight total fresh weight of plants: from 355-453 g to 152-255 g), and the leaf area, the length and diameter of pseudostem, too. The WUE, the dry matter content and the thickness of leaves increased under stress. In the most parameters, the water supply had stronger effect than the inoculation. The inoculation had positive effect mainly under drought stress: it improved the WUE at 3 measuring time (from 3.45 to 3.50 μmol CO2.mmol H2O-1, in the average of 5 measuring date), increased the weight (total fresh weight of plants: from 152 g to 255 g) and the leaf area (from 0.16 to 0.12 m 2).