Physiological responses associated to substrate water availability of Rosa ‘Eurored’ plants grown in soilless greenhouse conditions

Abstract

The aim of the present study was to provide a better insight into the adaptive processes to water deficit of Rosa hybrid plants grown in soilless cultivation. Rose plants were grown in a greenhouse under two water regimes, corresponding to 100% and 67% of the irrigation needs. Watering was stopped for 0, 72, and 96 h (dry-down period) and photosynthetic parameters, water relations, chlorophyll fluorescence, carbohydrate and ion content were determined. The imposed drought conditions, in both regimes, caused: (i) a negative effect on the photosynthetic rate and stomatal conductance but an increase in the intercellular CO 2, (ii) a decline in chlorophyll fluorescence (iii) a decrease in transpiration rate and leaf water potential (LWP) but had no effect on relative water content (RWC) and water use efficiency (WUE), (iv) an increase in carbohydrate and potassium content but no change in calcium. The data indicated that the adaptive responses of Rosa ‘Eurored’ to water stress combined with the dry-down program involved mechanisms at both stomatal and non-stomatal level. The plants maintained their metabolic and physiological processes not simply through stomatal closure but also through osmotic adaptation (higher carbohydrate and potassium concentration).